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  • 1.
    Ahuja, Dipali
    et al.
    Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Castletroy, Co Limerick, Ireland..
    Svärd, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Transport Phenomena. Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Castletroy, Co Limerick, Ireland..
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Transport Phenomena. Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Castletroy, Co Limerick, Ireland..
    Investigation of solid-liquid phase diagrams of the sulfamethazine-salicylic acid co-crystal2019In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 21, no 18, p. 2863-2874Article in journal (Refereed)
    Abstract [en]

    The influence of temperature and solvent on the solid-liquid phase diagram of the 1 : 1 sulfamethazinesalicylic acid co-crystal has been investigated. Ternary phase diagrams of this co-crystal system have been constructed in three solvents: methanol, acetonitrile and a 7 : 3 (v/v) dimethylsulfoxide-methanol mixture, at three temperatures. The system exhibits congruent dissolution in acetonitrile and the co-crystal solubility has been determined by a gravimetric technique. The Gibbs energy of co-crystal formation from the respective solid components has been estimated from solubility data, together with the corresponding enthalpic and entropic component terms. The Gibbs energy of formation ranges from -5.7 to -7.7 kJ mol -1, with the stability increasing with temperature. In methanol and the DMSO-methanol mixture, the co-crystal dissolves incongruently. It is shown that the solubility ratio of the pure components cannot be used to predict with confidence whether the co-crystal will dissolve congruently or incongruently. The size of the region where the co-crystal is the only stable solid phase is inversely related to the pure component solubility ratio of salicylic acid and sulfamethazine.

  • 2. Alander, E. M.
    et al.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Mechanisms of crystal agglomeration of paracetamol in acetone-water mixtures2005In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 44, no 15, p. 5788-5794Article in journal (Refereed)
    Abstract [en]

    The mechanisms governing the influence of the solvent composition on the agglomeration in a crystallization process have been investigated. Narrowly sieved paracetamol crystals were suspended in supersaturated acetone-water solutions, and were allowed to grow at isothermal conditions, after which the agglomeration was recorded. In all experiments the same sieve size fraction was used as well as the same magma density. In each experiment the supersaturation was kept constant. Experiments were performed in different solvent compositions at different supersaturation, crystal growth rate, solution viscosity, and agitation rate. For a statistically sufficient number of particles from each experiment, the number of crystals in each product particle was determined by image analysis and multivariate data evaluation. From the resulting number distributions of crystals per product particle, parameters defining the degree of agglomeration were extracted. The experimental results clearly establish that there is an influence of the solvent composition on the degree of agglomeration, which cannot be explained by differences in crystal growth rate, or differences in solution viscosity. The degree of agglomeration is found to decrease with increasing solvent polarity. It is, suggested that the mechanism by which the solvent influence relates to the crystal-solvent interaction and the physicochemical. adhesion forces between crystals in the solution.

  • 3. Alander, E. M.
    et al.
    Uusi-Penttila, M. S.
    Rasmuson, Åke C.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Characterization of paracetamol agglomerates by image analysis and strength measurement2003In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 130, no 03-jan, p. 298-306Article in journal (Refereed)
    Abstract [en]

    Paracetamol is crystallized in different solvents and techniques are developed and used to characterize the product. The product particles from three different solvent compositions: ethylene glycol, acetone and an acetone-water mixture (30-70 wt.%) have been examined. Product properties visually observed are quantified by image analysis and evaluation of measured image descriptors with Principal Component Analysis (PCA). The agglomerate strength has been determined by crushing single agglomerates. Depending on the solvent, the content of single crystals and agglomerates differ. Agglomerates differ by the number and size of crystals grown together, as well as by the strength.

  • 4. Alander, Eva M.
    et al.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Agglomeration and adhesion free energy of paracetamol crystals in organic solvents2007In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 53, no 10, p. 2590-2605Article in journal (Refereed)
    Abstract [en]

    The agglomeration of paracetamol during crystallization in different pure solvents has been investigated. Narrowly sieved crystals were suspended as seeds and allowed to grow and agglomerate at constant supersaturation and temperature. Particles from each experiment were examined by image analysis and multivariate data evaluation, for the number of crystals per particle. From the resulting number distribution, parameters defining the degree of agglomeration were extracted. The degree of agglomeration among the product particles is fairly low in water, methanol, and ethanol, while it is substantial in acetone particularly, but also in acetonitrile and methyl ethyl ketone. Surfaces of large, well-grown paracetamol crystals have been characterized by contact angle measurements. The surface free energy components of different crystal faces have been estimated using Lifshitz-van der Waals acid-base theory. The data are used for estimation of the solid-liquid interfacial free energy of each face in the solvents of the agglomeration experiments and the corresponding crystal-crystal adhesion free energy of pairs of faces. The degree of agglomeration in different solvents does correlate to the free energies of adhesion. This supports the hypothesis that the influence of the solvent on the crystal agglomeration relates to physico-chemical adhesion forces between crystal faces in the solution.

  • 5.
    Albero Caro, Jesus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Woldehaimanot, Mussie
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke Christoffer
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Semibatch reaction crystallization of salicylic acid2014In: Chemical engineering research & design, ISSN 0263-8762, E-ISSN 1744-3563, Vol. 92, no 3, p. 522-533Article in journal (Refereed)
    Abstract [en]

    Reaction crystallization of salicylic acid has been investigated by experiments and modeling. In the experimental work, dilute hydrochloric acid has been added to an agitated aqueous solution of sodium salicylate in 1 L scale, and product crystals have been characterized by image analysis. The results show that the product crystal number mean size at first increases with increasing agitation rate but then gradually decreases again at further increase in stirring rate. At lower stirring rate, larger crystals are obtained when the feeding point is located close to the agitator instead of being located out in the bulk solution. The mean crystal size increases with decreasing feeding rate and with decreasing reactant concentrations. There is a decrease in mean size with increasing feed pipe diameter. These trends in the experimental results show great similarity with previous results on benzoic acid. The experimental results have been examined by a population balance model accounting for meso and micro mixing, and crystal nucleation and growth rate dispersion. It is found that the crystallization kinetic parameter estimation is quite complex, and the objective function hyper surface contains many different minima. Hence, parameter estimation has to rely on a combination of mathematical optimization strategies and a scientific understanding of the physical meaning of the parameters and their relation to current theories. As opposed to our previous work on benzoic acid, it has not been possible to find a set of kinetic parameters that provides for a good description of all experimental data.

  • 6.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Korkmaz, Kivanc
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Dephosphorization and impurity removal from a rare earth phosphate concentrate2017Conference paper (Refereed)
  • 7.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Forsberg, Kerstin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Korkmaz, Kivanc
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Isolation of rare earth element phosphate precipitate in the nitrophosphate process for manufacturing of fertilizer2016In: IMPC 2016 - 28th International Mineral Processing Congress, Canadian Institute of Mining, Metallurgy and Petroleum , 2016Conference paper (Refereed)
    Abstract [en]

    In the present study, the recovery of rare earth elements (REE) in the nitrophosphate process of fertilizer production is investigated. The apatite has been recovered from iron ore tailings by flotation. After digestion of apatite in concentrated nitric acid, Ca(NO3)2.4H2O is first separated by cooling crystallization and then the REEs are recovered by precipitation. Optimum conditions in these steps have been determined in a previous study. The precipitate mainly consists of CaHPO4.2H2O and REE phosphates. In the present study, selective dissolution and re-precipitation have been studied in order to obtain a precipitate that is more concentrated in REEs. The precipitate was selectively dissolved in nitric and phosphoric acid at different acidities (pH 6 to 0) with the liquid /solid ratio of 100 mL/g. It is shown that most of the CaHPO4.2H2O and other calcium containing compounds will be dissolved at pH 2 while the REE phosphates are not dissolved above a pH of approximately 2. Thus, by partial dissolution of the REE precipitate at pH 2.5 most of the solid calcium phosphates will be dissolved and the remaining solid phase, which is more concentrated in REEs, can be filtered off as a fairly concentrated REE solid mass and the liquor can be recycled back to recover more P nutrients. Alternatively, the REE enriched precipitate was dissolved completely in nitric acid and re-precipitated again by addition of ammonium hydroxide to pH 1.2. A chemical equilibrium software, MEDUSA (Puigdomenech, 2013) has been used to evaluate the experimental results and to estimate the optimum conditions for selectively dissolving the precipitate. 

  • 8.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Korkmaz, Kivanc
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Isolation of Rare Earth Element Phosphate Precipitates in the Nitrophosphate Process for Manufacturing of Fertilizer2016Conference paper (Refereed)
    Abstract [en]

    In the present study, the recovery of rare earth elements (REE) in the nitrophosphate process of fertilizer production is investigated. The apatite has been recovered from iron ore tailings by flotation. After digestion of apatite in concentrated nitric acid, Ca(NO3)2.4H2O is first separated by cooling crystallization and then the REEs are recovered by precipitation. Optimum conditions in these steps have been determined in a previous study. The precipitate mainly consists of CaHPO4.2H2O and REE phosphates. In the present study, selective dissolution and re-precipitation have been studied in order to obtain a precipitate that is more concentrated in REEs. The precipitate was selectively dissolved in nitric and phosphoric acid at different acidities (pH 6 to 0) with the liquid /solid ratio of 100 mL/g. It is shown that most of the CaHPO4.2H2O and other calcium containing compounds will be dissolved at pH 2 while the REE phosphates are not dissolved above a pH of approximately 2. Thus, by partial dissolution of the REE precipitate at pH 2.5 most of the solid calcium phosphates will be dissolved and the remaining solid phase, which is more concentrated in REEs, can be filtered off as a fairly concentrated REE solid mass and the liquor can be recycled back to recover more P nutrients. Alternatively, the REE enriched precipitate was dissolved completely in nitric acid and re-precipitated again by addition of ammonium hydroxide to pH 1.2. A chemical equilibrium software, MEDUSA (Puigdomenech, 2013) has been used to evaluate the experimental results and to estimate the optimum conditions for selectively dissolving the precipitate.

  • 9.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Recovery of phosphorous and rare earth elements from an apatite concentrate2018Conference paper (Refereed)
  • 10.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Korkmaz, Kivanc
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Processing of a rare earth phosphate concentrate obtained in the nitrophosphate process of fertilizer production2019In: Hydrometallurgy, ISSN 0304-386X, E-ISSN 1879-1158Article in journal (Refereed)
  • 11.
    Alemrajabi, Mahmood
    et al.
    KTH.
    Rasmuson, Åke C.
    KTH.
    Korkmaz, Kivanc
    Forsberg, Kerstin
    KTH.
    Processing of a rare earth phosphate concentrate obtained inthe nitrophosphate process of fertilizer productionManuscript (preprint) (Other academic)
  • 12.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Korkmaz, Kivanc
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Forsberg, Kerstin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Recovery of rare earth elements from nitrophosphoric acid solutions2017In: Hydrometallurgy, ISSN 0304-386X, E-ISSN 1879-1158, Vol. 169, p. 253-262Article in journal (Refereed)
    Abstract [en]

    In the present study, the recovery of rare earth elements (REEs) from an apatite concentrate in the nitrophosphate process of fertilizer production has been studied. The apatite concentrate has been recovered from iron ore tailings in Sweden by flotation. In the first step, the apatite is digested in concentrated nitric acid, after which Ca(NO3)2.4H2O is separated by cooling crystallization. The solution is then neutralized using ammonia whereby the REEs precipitate mainly as phosphates (REEPO4.nH2O) and together with calcium as REEn Cam (PO4)(3n + 2m) / 3. In this work, the degree of rare earth coprecipitation during seeded cooling crystallization of Ca(NO3)2.4H2O has been studied. The solubility of calcium nitrate tetrahydrate (Ca(NO3)2.4H2O) in acidic nitrophosphoric acid solutions in the temperature range of − 2 °C to 20 °C has been determined. For the neutralization step, it is shown that the calcium concentration and the final pH play an important role in determining the concentration of REEs in the precipitate. It is found that reaching maximum recovery of REE with minimum simultaneous precipitation of calcium requires careful control of the final pH to about 1.8. It is further observed that the precipitation yield of REEs and iron is favored by a longer residence time and higher temperature. Finally, the effect of seeding with synthesized REE phosphate crystals as well as a mixture of REE and Ca phosphates on the precipitation rate and the composition of the precipitate was studied.

  • 13.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Korkmaz, Kivanc
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Upgrading of a rare earth phosphate concentrate within the nitrophosphate process2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 198, p. 551-563Article in journal (Refereed)
    Abstract [en]

    In the nitrophosphate process of fertilizer production, rare earth elements (REE) can be recovered as a REE phosphate concentrate. In this process, after digestion of apatite in concentrated nitric acid, Ca(NO3)2.4H2O is first separated by cooling crystallization and then the REE are precipitated in phosphate form by a partial neutralization step using ammonia. The obtained REE phosphate concentrate is contaminated by mainly calcium and iron, and the main solid phases are CaHPO4.2H2O, FePO4.2H2O and REEPO4.nH2O.

    In this study, a process to obtain a concentrate more enriched with REE with low concentration of calcium and iron and free of phosphorous is developed. In the developed process, enrichment and dephosphorization of the rare earth phosphate concentrate has been achieved by selective dissolution and re-precipitation of the REE as a sodium REE double sulfate salt. It is shown that by selective dissolution of the REE concentrate in nitric acid at a pH of 2.4, most of the calcium and phosphorus are dissolved, and a solid phase more enriched in REE is obtained. Thereafter, the REE phosphate concentrate is first dissolved in a mixture of sulfuric-phosphoric acid and then the REE are reprecipitated as NaREE(SO4)2.H2O by addition of a sodium salt. More than 95% of the Ca, Fe and P are removed and a REE concentrate containing almost 30 mass% total REE is obtained.

  • 14.
    Alemrajabi, Mahmoud
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Recovery of REE from an apatite concentrate in the nitrophosphate process of fertilizer production.2015Conference paper (Refereed)
  • 15.
    Ashour, Radwa
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering. Nuclear Materials Authority, P.O. Box 530, 11381 El Maadi, Cairo, Egypt.
    Samouhos, Michail
    Swedish University of Agricultural Sciences, Department of Molecular Sciences, Uppsala BioCentre.
    Polido Legaria, Elizabeth
    Swedish University of Agricultural Sciences, Department of Molecular Sciences, Uppsala BioCentre.
    Svärd, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Transport Phenomena.
    Högblom, Joakim
    AkzoNobel, Pulp and Performance Chemicals AB.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Palmlöf, Magnus
    Kessler, Vadim G.
    Swedish University of Agricultural Sciences, Department of Molecular Sciences, Uppsala BioCentre.
    Seisenbaeva, Gulaim A.
    Swedish University of Agricultural Sciences, Department of Molecular Sciences, Uppsala BioCentre.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    DTPA-Functionalized Silica Nano- and Microparticles for Adsorption and Chromatographic Separation of Rare Earth Elements2018In: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 6, no 5, p. 6889-6900Article in journal (Refereed)
    Abstract [en]

    Silica nanoparticles and porous microparticles have been successfully functionalized with a monolayer of DTPA-derived ligands. The ligand grafting is chemically robust and does not appreciably influence the morphology or the structure of the material. The produced particles exhibit quick kinetics and high capacity for REE adsorption. The feasibility of using the DTPA-functionalized microparticles for chromatographic separation of rare earth elements has been investigated for different sample concentrations, elution modes, eluent concentrations, eluent flow rates, and column temperatures. Good separation of the La(III), Ce(III), Pr(III), Nd(III), and Dy(III) ions was achieved using HNO3 as eluent using a linear concentration gradient from 0 to 0.15 M over 55 min. The long-term performance of the functionalized column has been verified, with very little deterioration recorded over more than 50 experiments. The results of this study demonstrate the potential for using DTPA-functionalized silica particles in a chromatographic process for separating these valuable elements from waste sources, as an environmentally preferable alternative to standard solvent-intensive processes.

  • 16.
    Bäbler, Matthäus U.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Kebede, Mebatsion L.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rozada-Sanchez, Raquel
    Åslund, Per
    Gregertsen, Björn
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Isolation of Pharmaceutical Intermediates through Solid Supported Evaporation. Semicontinuous Operation Mode2012In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 51, no 45, p. 14814-14823Article in journal (Refereed)
    Abstract [en]

    Solid supported evaporation (SSE) is a simple, nonselective method for isolating nonvolatile compounds from a solution. The solution is put in contact with porous polymer beads onto which the compound deposits upon evaporation of the solvent. This brings some advantages over direct evaporation to dryness in terms of safety, thermal decomposition, and solid handling, as the loaded beads form a free flowing granular material that is easily recovered. In this paper, SSE in a semicontinuous operating mode is investigated where the solution is continuously fed to (respectively sprayed over) an agitated bed of dry beads put under vacuum. It is found that under conditions where the solvent evaporation fate is high with respect to the feed rate, high bead loadings can be achieved before extensive sticking of beads and compound to the vessel walls occurs. The type of compound and solvent had little influence on the process performance, and, in cases where this was explored, the bead loading was found to be homogeneous. Based on a balance equation for the solvent fed to the system, a model is developed that results in a simple scale up criterion. The latter was successfully applied for transferring SSE from lab to the kilo lab scale.

  • 17. Cheuk, Dominic
    et al.
    Svärd, Michael
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. University of Limerick, Ireland.
    Seaton, Colin
    McArdle, Patrick
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. University of Limerick, Ireland.
    Investigation into solid and solution properties of quinizarin2015In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 17, no 21, p. 3985-3997Article in journal (Refereed)
    Abstract [en]

    Polymorphism, crystal shape and solubility of 1,4-dihydroxyanthraquinone (quinizarin) have been investigated in acetic acid, acetone, acetonitrile, n-butanol and toluene. The solubility of FI and FII from 20 degrees C to 45 degrees C has been determined by a gravimetric method. By slow evaporation, pure FI was obtained from n-butanol and toluene, pure FII was obtained from acetone, while either a mixture of the two forms or pure FI was obtained from acetic acid and acetonitrile. Slurry conversion experiments have established an enantiotropic relationship between the two polymorphs and that the commercially available FI is actually a metastable polymorph of quinizarin under ambient conditions. However, in the absence of FII, FI is kinetically stable for many days over the temperature range and in the solvents investigated. FI and FII have been characterized by infrared spectroscopy (IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission and ordinary powder X-ray diffraction (PXRD) at different temperatures. The crystal structure of FII has been determined by single-crystal XRD. DSC and high-temperature PXRD have shown that both FI and FII will transform into a not previously reported hightemperature form (FIII) around 185 degrees C before this form melts at 200-202 degrees C. By indexing FIII PXRD data, a triclinic P (1) over bar cell was assigned to FIII. The solubility of quinizarin FI and FII in the pure organic solvents used in the present work is below 2.5% by weight and decreases in the order: toluene, acetone, acetic acid, acetonitrile and n-butanol. The crystal shapes obtained in different solvents range from thin rods to flat plates or very flat leaves, with no clear principal difference observed between FI and FII.

  • 18.
    Chidambaram, R
    et al.
    Karobio.
    Garg, N
    Karobio.
    Rasmuson, Åke Christoffer
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Gracin, Sandra
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Improved crystalline material2006Patent (Other (popular science, discussion, etc.))
  • 19. Fichtner, F.
    et al.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Alderborn, G.
    Particle size distribution and evolution in tablet structure during and after compaction2005In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 292, no 02-jan, p. 211-225Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to investigate the effect of the distribution in size of free-flowing particles for the evolution in tablet structure and tablet strength. For sucrose and sodium chloride, three powders of different size distributions were prepared by mixing predetermined quantities of particle size fractions. For paracetamol, three batches with varying particle size distributions were prepared by crystallisation. The powders were formed into tablets. Tablet porosity and tensile strength were determined directly after compaction and after short-term storage at two different relative humidities. Tablets were also formed after admixture of a lubricant (magnesium stearate) and the tablet tensile strength was determined. For the test materials used in this study, the spread in particle size had no influence on the evolution in tablet porosity and tensile strength during compression. However, the spread in particle size had a significant and complex influence on the short-term post-compaction increase in tablet tensile strength. The effect of the spread was related to the instability mechanism and the presence of lubricant. It is concluded that the distribution in size of free-flowing particles is not critical for the tablet porosity but may give significant effects on tablet tensile strength due to a post-compaction reaction.

  • 20. Fichtner, Frauke
    et al.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Alander, Eva M.
    Alderborn, Goran
    Effect of preparation method on compactability of paracetamol granules and agglomerates2007In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 336, no 1, p. 148-158Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to investigate the effect of fracture strength of paracetamol particles on their compactability. For this purpose two series of paracetamol particles were prepared by crystal agglomeration and by granulation using different solvents. A free flowing particle size fraction of all types of particles was characterized with respect to their shape, degree of agglomeration and single fracture strength. The powders were compressed to tablets and the compression mechanism of the particles and the evolution in tablet micro-structure were assessed by compression parameters derived from the Heckel and Kawakita equations and by a tablet permeabililty coefficient. Tablet tensile strength and porosity were determined. The degree of deformation and fragmentation during compression varied between agglomerates and granules and was dependent on their failure strength. The granules varied in compactability with particle failure strength while the agglomerates showed limited variation. It is proposed that, the dominant mechanism of compression for the granules was permanent deformation while for the agglomerates it was fragmentation. It was thus found that the compression mechanism of the particles was dependent on both the degree of agglomeration and the particle failure strength.

  • 21.
    Forsberg, Kerstin M.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Mohammadi, M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Ghafarnejad Parto, S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Martínez de la Cruz, Joaquin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Fredriksson, A.
    LKAB.
    Recovery of REE from an apatite concentrate2014Conference paper (Refereed)
  • 22.
    Forsberg, Kerstin M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    The influence of hydrofluoric acid and nitric acid on the growth kinetics of iron(III) fluoride trihydrate2015In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 423, p. 16-21Article in journal (Refereed)
    Abstract [en]

    The influence of hydrofluoric acid and nitric acid concentration on the growth rate of beta-FeF3 center dot 3H(2)O crystals has been studied in different hydrofluoric acid (4.7-10.7 mol/(kg H2O)) and nitric acid (2.1-4.6 mol/(kg H2O)) mixtures at 50 degrees C. Seeded desupersaturation experiments were performed and the results were evaluated by considering the chemical speciation using two different speciation programs. The growth rate at 50 degrees C at a supersaturation ratio of 2, expressed in terms of free FeF3, was found to be in the range of (0.4-3.8) x 10(-11) m/s. The growth rate order was found to be two or higher in all experiments. The low growth rate and high growth rate order indicate that the growth rate is governed by the surface integration step. The growth rate was found to be independent of variations in acid concentrations: this is in accordance with the assumption of a surface integration controlled growth rate.

  • 23.
    Forsberg, Kerstin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Mohammadi, M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Ghafarnejad Parto, S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Alemrajabi, Mahmoud
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Korkmaz, Kivanc
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Martínez De La Cruz, Joaquin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Novel hydrometallurgical methods for recovery and separation of REE2014Conference paper (Refereed)
  • 24.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystal growth of iron(III) flouride trihydrate in mixed acidManuscript (preprint) (Other academic)
  • 25.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystallization in hydrofluoric acid and nitric acid solutions containing iron(III), chronium(III) and nickel(II).Manuscript (preprint) (Other academic)
  • 26.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystallization of metal fluoride hydrates from mixed hydrofluoric and nitric acid solutions, Part I: Iron (III) and Chromium (III)2010In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 16-17, p. 2351-2357Article in journal (Refereed)
    Abstract [en]

    Crystallization from hydrofluoric acid/nitric acid solutions supersaturated with Fe(III) and Cr(III) has been investigated. Iron and chromium crystallizes into a solid solution in the form of Cr(Fe)F-3 center dot 3H(2)O, which is isostructural with CrF3 center dot 3H(2)O and alpha-FeF3 center dot 3H(2)O. By seeded isothermal desupersaturation experiments, the growth rate of beta-FeF3 center dot 3H(2)O crystals at 50 degrees C has been studied in hydrofluoric acid and nitric acid solutions containing Cr(III). It is found that the growth rate of beta-FeF3 center dot 3H(2)O is essentially uninfluenced by the presence of 5 g/kg Cr(III). At 50 degrees C and a supersaturation ratio of 2 (c(FeF3)(free)/c(s)(FeF3)(free)), the growth rate is (0.8-2.2) x 10(-11) m/s in 3 mol/(kg solution) HFfree and 3 mol/(kg solution) HNO3.

  • 27.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystallization of metal fluoride hydrates from mixed hydrofluoric and nitric acid solutions, part II: Iron (III) and nickel (II)2010In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 16-17, p. 2358-2362Article in journal (Refereed)
    Abstract [en]

    Crystallization of nickel fluoride hydrate from mixed pickle acid and the influence of Ni(II) on growth rate of beta-FeF3 center dot 3H(2)O have been studied. Iron and nickel crystallize into an unidentified Fe/Ni fluoride hydrate crystal having the overall mol ratio of Ni, Fe, and F equal to 1:2:8, which is in accordance with the number of fluoride ions needed to balance the positive charges of Ni and Fe. The most probable empirical formula of this material is (FeF3)(2)NiF2(H2O)(6-10). By seeded isothermal desupersaturation experiments, growth rate of beta-FeF3 center dot 3H(2)O crystals at 50 degrees C has been studied in a hydrofluoric acid and nitric acid solution containing Ni(II). It is found that the growth rate of beta-FeF3 center dot 3H(2)O is essentially uninfluenced by the presence of 4 g/kg Ni(II).

  • 28.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke C
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystal growth kinetics of iron fluoride trihydrate2006In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 296, no 2, p. 213-220Article in journal (Refereed)
    Abstract [en]

    Crystal growth of beta-FeF3 • 3H(2)O has been investigated in mixtures of 3 mol kg(-1) hydrofluoric acid and 3 mol kg(-1) nitric acid at 30, 40 and 50 degrees C. Seeded isothermal desupersaturation experiments have been performed in the range: 1.3 < S < 3.6. Solution samples were analysed for total iron concentration with inductively coupled plasma atomic emission spectroscopy. The true supersaturation driving force was estimated by a proper speciation using the software SSPEC using appropriate stability constants. Growth rate parameters of the BCF surface diffusion growth rate equation and the empirical power-law equation have been estimated by fitting the supersaturation balance equation using a nonlinear optimization procedure. The results show that the growth rate is surface integration controlled. The growth rate at a supersaturation ratio of 2 was found to be 3.5 x 10(-12) m s(-1) at 30 degrees C, 7.4 x 10(-12) m s(-1) at 40 degrees C and 16 x 10(-12) m s(-1) at 50 degrees C. The activation energy of the rate constant of crystal growth was found to be 61 kJ mol(-1). .

  • 29.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke C
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Recycling of waste pickle acid by precipitation of metal fluoride hydrates2007In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 20, no 9, p. 950-955Article in journal (Refereed)
    Abstract [en]

    Stainless steel is pickled in mixed acid solutions (1-3 M HNO3 and 0.5-4 M HF). The spent solution is usually neutralized with lime, and in Sweden about 18,000 tons/yr of metal hydroxide sludge is disposed as landfill waste. We are developing a cost-saving and environmentally friendly process, involving crystallization of beta-FeF3 . 3H(2)O, where the metal content is recovered and the acid is recycled. Iron has been successfully separated from spent pickle bath solutions by precipitation of beta-FeF3 . 3H(2)O in a continuous crystallizer (10 L scale) where the solution is concentrated by nanofiltration. The crystal growth rate of beta-FeF3 . 3H(2)O has been determined in industrial pickle bath solutions at 50 degrees C and the results have been compared to previous measurements in pure HF/HNO3 solutions prepared in the laboratory. The growth rate of beta-beta eF(3) . 3H(2)O crystals at 50 degrees C is in the order of 10(-11) m/s in both industrial and pure acid mixtures.

  • 30.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke Christoffer
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Precipitation from HF and HNO3 solutions containing iron (III), nickel (II) and chromium (III)2008In: Proc. 17’th International Symposium on Industrial Crystallization / [ed] JP Janssens; J Ulrich, 2008, p. 1175-1180Conference paper (Refereed)
  • 31.
    Forsberg, Kerstin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rodríguez Varela, Raquel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Martínez, Joaquin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Kloo, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Processing of a rare earth element concentrate by hollow fibre supported liquid membrane extraction2017Conference paper (Refereed)
  • 32.
    Gracin, Sandra
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Rasmuson, Åke C.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Prediction of Solubility of Solid Organic Compounds in Solvents by UNIFAC2002In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 41, no 20, p. 5114-5124Article in journal (Refereed)
    Abstract [en]

    Predictions of solubility of nine different solid organic fine chemical compounds in water and organic solvents of relevance to industrial processing are examined. UNIFAC interaction parameters are taken from standard reference literature, extracted from liquid-vapor equilibria. For most systems, predicted solubilities deviate more than 15% from experimental values. Deviations are due to uncertainties in the estimation of the activity of the pure solid as well as to deficiencies in the estimation of activity coefficients in the solution. By comparison with results from ab initio quantum chemical calculations of the elecrostatic potential on the molecular surface of the solutes, it can be shown that a key assumption of the UNIFAC approach is not necessarily fulfilled. The properties of a functional group may depend significantly on the properties of the rest of the molecule.

  • 33.
    Gracin, Sandra
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Rasmuson, Åke C.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Polymorphism and Crystallization of p-Aminobenzoic Acid2004In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 4, no 5, p. 1013-1023Article in journal (Refereed)
    Abstract [en]

    p-Aminobenzoic acid (PABA) crystallizes in two different polymorphic forms: the alpha-polymorph, which is the commercially available form and appears as long, fibrous needles, and the beta-polymorph, which appears in the form of prisms. The thermodynamic stability and crystallization from different solvents have been studied experimentally. The system is found to be enantiotropic with a transition temperature of 25degreesC, below which the beta-form is the stable polymorph. The compound has been crystallized from 13 different solvents, either by slow cooling after which the product is allowed to mature in suspension, or by rapid cooling followed by immediate isolation. Needles were obtained from all solvents by both methods. In water and in ethyl acetate, at slow cooling below 20degreesC, the prismatic beta-form is obtained, however, often together with the needles. The beta-form crystals usually needed hours or days to grow at the very slow cooling used, while needles usually appeared in seconds. By careful control of supersaturation and temperature, cooling crystallization can be performed to produce the pure beta-form in water and in ethyl acetate. The influence of the solvent is explained by analysis of the crystal structures versus the possible interaction of the solvent molecules with the solute in solution. The alpha-form structure is governed by carboxylic acid dimers and is kinetically favored since it is believed that the corresponding dimers easily form in the solution, especially in less polar solvents.

  • 34.
    Gracin, Sandra
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Rasmuson, Åke C.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Solubility of Phenylacetic Acid, p-Hydroxyphenylacetic Acid, p-Aminophenylacetic Acid, p-Hydroxybenzoic Acid, and Ibuprofen in Pure Solvents2002In: Journal of Chemical and Engineering Data, ISSN 0021-9568, E-ISSN 1520-5134, Vol. 47, no 6, p. 1379-1383Article in journal (Refereed)
    Abstract [en]

    The solubility of phenyl acetic acid, p-hydroxyphenylacetic acid, p-aminophenylacetic acid, p-hydroxybenzoic acid, and ibuprofen in water and in a range of organic solvents of relevance to industrial processing is reported. The solvents used are water, methanol, ethanol, 2-propanol, acetone, 4-methyl-2-pentanone, ethyl acetate, chloroform, and toluene. Solubility data are discussed from the standpoint of molecular aspects of solute-solvent interactions and by estimated solid-phase activity.

  • 35.
    Gracin, Sandra
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Uusi-Penttilä, Marketta
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Influence of ultrasound on the nucleation of polymorphs of p-aminobenzoic acid2005In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 5, no 5, p. 1787-1794Article in journal (Refereed)
    Abstract [en]

    p-Aminobenzoic acid crystallizes in two different polymorphic forms: the alpha-form and the beta-form. The alpha-form crystals are needle-shaped, while the beta-form crystals have a more favorable prismatic shape. The system is enantiotropic with the transition temperature at approximately 25 degrees C. Below the transition temperature, the beta-form is the thermodynamically stable polymorph but can only be produced at very slow supersaturation generation either in water or in ethyl acetate. In the present work, the influence of ultrasound on the nucleation of p-aminobenzoic acid polymorphs has been investigated by use of several different sonication intensities and schemes. It is shown that sonication significantly reduces the induction time for nucleation. By using controlled sonication, we were able to more reproducibly crystallize the beta-form at more reasonable cooling rates. In addition, sonication is found to quite selectively favor the appearance of the beta-polymorph. It is even possible to produce the pure beta-form above the transition temperature where it is the metastable form and impossible to produce without sonication. The alpha-form structure is based on centro symmetric dimers formed by the association of carboxylic acid groups, while the beta-form contains four-membered hydrogen-bonded rings of alternating amino and carboxylic acid groups. It is suggested that ultrasound disturbs the building up of the dimers in the solution and thus favors the crystallization of the beta-polymorph.

  • 36.
    Gracin, Sandra
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Uusi-Penttilä, Marketta
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke Christoffer
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Controlling polymorphism of p-aminobenzoic acid by sonication2005In: the 16th International Symposium on Industrial Crystallization, VDI verlag Dusseldorf , 2005, p. 677-682Conference paper (Refereed)
    Abstract [en]

    The influence of ultrasound on the nucleation of p-aminobenzoic acid in supersaturated aqueous solutions has been investigated. The induction time and the solid phase structure has been determined in experiments with and without ultrasound. Different sonication schemes and intensities have been evaluated. It is found that sonication leads to a much shorter and reproducible induction time. In addition, it has been found that sonication preferentially favor the formation of one of the polymorphs.

  • 37. Granberg, R. A.
    et al.
    Ducreux, C.
    Gracin, S.
    Rasmuson, Åke C.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Primary nucleation of paracetamol in acetone-water mixtures2001In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 56, no 7, p. 2305-2313Article in journal (Refereed)
    Abstract [en]

    The influence of solvent composition on primary nucleation of 4-hydroxyacetanilide (paracetamol) in acetone-water mixtures is investigated. The induction time for primary nucleation is determined, at various degrees of supersaturation and at different temperatures, in different solvent mixture compositions. Supersaturation is generated by the addition of water. and the homogeneous, agitated, isothermal solution is allowed to nucleate. The supersaturation driving force is calculated as the difference in the chemical potential. At equal thermodynamic driving force, the induction time depends on the composition of the solvent mixture. The interfacial energy is in the range 1-3 mJ/m(2) and tends to increase with decreasing solubility, i.e. increasing water content. The interfacial energy is slightly lower than a value calculated from a contact angle measurement (5 mJ/m(2)) in pure water and is significantly lower than values predicted by equations derived From simplified theories.

  • 38. Granberg, R. A.
    et al.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystal growth rates of paracetamol in mixtures of water plus acetone plus toluene2005In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 51, no 9, p. 2441-2456Article in journal (Refereed)
    Abstract [en]

    Crystal growth rates of paracetamol (4-hydroxyacetanilide) have been determined by seeded isothermal desupersaturation experiments at 16 degrees C in 23 different solvent mixtures of water + acetone + toluene. Parameters of different growth rate equations have been estimated by direct nonlinear optimization. At equal thermodynamic driving force, the growth rate depends on the composition of the solvent mixture. In the surface diffusion spiral growth model, this dependency can be described in terms of the interfacial energy between the solid and the solution. A reasonable prediction of the influence of the solvent composition on this interfacial energy is obtained if a proper estimation of the enthalpy of dissolution is done. For the case of paracetamol crystals growing in water + acetone + toluene mixtures this estimation needs to include an estimation of the entropy of fusion at the temperature of growth as well as of the nonideal entropy of mixing.

  • 39. Granberg, R. A.
    et al.
    Rasmuson, Åke C.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Solubility of paracetamol in binary and ternary mixtures of water plus acetone plus toluene2000In: Journal of Chemical and Engineering Data, ISSN 0021-9568, E-ISSN 1520-5134, Vol. 45, no 3, p. 478-483Article in journal (Refereed)
    Abstract [en]

    The solubility of paracetamol (4-hydroxyacetanilide) in binary mixtures of acetone + water and acetone + toluene and in ternary mixtures of water + acetone + toluene is reported. The temperature range is -5 to +30 degrees C. In acetone + water the solubility increases to a maximum at approximately 25 mass % water before decreasing to a much lower value in pure water as compared to pure acetone. In acetone + toluene the solubility decreases monotonically with increasing toluene concentration. The water content has a strong influence also in ternary mixtures. Activity coefficients in the saturated solutions are estimated.

  • 40.
    Hammer-Olsson, Roy
    et al.
    Perstorp AB.
    Jansson, Inger
    Perstorp AB.
    Hultén, Felix
    Perstorp AB.
    Forsberg, Kerstin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke Christoffer
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Method of purifying potassium hydroxide2007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method of purifying potassium hydroxide comprising (a) providing a solution of saturated potassium hydroxide solution having a temperature in the range from about -25 to about 60 0C (b) controling the temperature of the solution in such a way that the variation in temperature is in a range from about 0 to about 5 °C/h to form crystals of potassium hydroxide (c) separating the crystals from the solution.

  • 41.
    Hjorth, Timothy
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Svärd, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering. Univ Limerick, Dept Chem & Environm Sci, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Castletroy, Ireland..
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering. Univ Limerick, Dept Chem & Environm Sci, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Castletroy, Ireland..
    Rationalising crystal nucleation of organic molecules in solution using artificial neural networks2019In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 21, no 3, p. 449-461Article in journal (Refereed)
    Abstract [en]

    In this study, the method of artificial neural networks (ANNs) is applied to analyse the effect of various solute, solvent, and solution properties on the difficulty of primary nucleation, without bias towards any particular nucleation theory. Sets of ANN models are developed and fitted to data for 36 binary systems of 9 organic solutes in 11 solvents, using Bayesian regularisation without early stopping and 6-fold cross validation. An initial model set with 21 input parameters is developed and analysed. A refined model set with 10 input parameters is then evaluated, with an overall improvement in accuracy. The results indicate partial qualitative consistency between the ANN models and the classical nucleation theory (CNT), with the nucleation difficulty increasing with an increase in mass transport resistance and a reduction in solubility. Notably, some parameters not included in CNT, including solute molecule bond rotational flexibility, the entropy of melting of the solute, and intermolecular interactions, also exhibit explanatory importance and significant qualitative effect relationships. A high entropy of melting and solute bond rotational flexibility increase the nucleation difficulty. Stronger solute-solute or solvent-solvent interactions are correlated with a facilitated nucleation, which is reasonable in the context of desolvation. A dissimilarity between solute and solvent hydrophobicities is connected with an easier nucleation.

  • 42.
    Jia, Lijun
    et al.
    University of Limerick, Ireland.
    Svärd, Michael
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. University of Limerick, Ireland.
    Crystal Growth of Salicylic Acid in Organic Solvents2017In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 17, no 6, p. 2964-2974Article in journal (Refereed)
    Abstract [en]

    The crystal growth rate of salicylic acid has been determined by seeded isothermal desupersaturation experiments in different organic solvents (methanol, acetone, ethyl acetate, and acetonitrile) and at different temperatures (10, 15, 20, and 25 °C). In situ ATR-FTIR spectroscopy and principal component analysis (PCA) were employed for the determination of solution concentration. Activity coefficient ratios are approximately accounted for in the driving force determination. The results show that the dependence of the growth rate on the solvent at equal driving force varies with temperature; e.g., at 25 °C, the growth rate is highest in ethyl acetate and lowest in acetonitrile, while at 15 °C the growth rate is highest in acetonitrile. The growth rate data are further examined within the Burton Cabrera Franck (BCF) and the Birth and Spread (B+S) theories, and the results point to the importance of the surface diffusion step. Interfacial energies determined by fitting the B+S model to the growth rate data are well-correlated to interfacial energies previously determined from primary nucleation data.

  • 43.
    Katta, Jyothi
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Spherical Crystallization of benzoic acid2008In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 348, no 1-2, p. 61-69Article in journal (Refereed)
    Abstract [en]

    This paper deals with the development of a method for spherical crystallization of benzoic acid. Benzoic acid is dissolved in ethanol, water is used as anti-solvent and chloroform is used as bridging liquid. After an introductory screening of different methods, the influence of the amount of the bridging liquid, the solute concentration and the stirring rate is investigated. The product particle characterization includes the particle size distribution, morphology and strength. The mechanical strength of single agglomerates has been determined by compression in a materials testing machine, using a 10 N load cell. It is found that favourable properties are obtained if the bridging liquid is added during the crystallization. Larger and stronger well-shaped agglomerates are formed. The stress-strain curves are J-shaped with no clear fracturing of the particles, and are well correlated by an exponential-polynomial equation.

  • 44.
    Kebede, Mebatsion L.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Bäbler, Matthäus U.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rozada-Sanchez, Raquel
    Gregertsen, Björn
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Isolation of Pharmaceutical Intermediates through Solid Supported Evaporation. Batch Operation Mode2012In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 51, no 41, p. 13445-13453Article in journal (Refereed)
    Abstract [en]

    Solid supported evaporation (SSE) is a simple method to isolate dissolved compounds as a solid material. The solution is put in contact with granular porous polymer beads onto which the compounds deposit upon evaporation of the solvent. This brings some advantages over direct evaporation to dryness in terms of safety and handling of the solids. In this paper, SSE in batch mode is explored where the solution is added to the polymer beads at once, i.e. opposite to the semicontinuous mode where the solution is sprayed over a bed of beads. A number of compounds varying widely in their physical and chemical properties is studied. It is found that all compounds could be loaded onto the beads; however, the loading capacity depends on the properties of the compound and in general was lower than in the semicontinuous operating mode studied in an accompanying paper. For highly soluble compounds, higher loadings could be achieved when solvent evaporation was slow. In cases where tested, bead loading was found to be homogeneous within a batch. Recovery of compound from loaded beads was achieved by dispersing the beads in a solvent and washing of the filter cake after filtration. A relatively large amount of solvent is required to achieve full recovery.

  • 45. Khamar, Dikshitkumar
    et al.
    Zeglinski, Jacek
    Mealey, Donal
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. University of Limerick, Limerick, Ireland .
    Investigating the Role of Solvent-Solute Interaction in Crystal Nucleation of Salicylic Acid from Organic Solvents2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 33, p. 11664-11673Article in journal (Refereed)
    Abstract [en]

    In previous work, it has been shown that the crystal nucleation of salicylic acid (SA) in different solvents becomes increasingly more difficult in the order: chloroform, ethyl acetate acetonitrile, acetone, methanol, and acetic acid. In the present work, vibration spectroscopy, calorimetric measurements, and density functional theory (DFT) calculations are used to reveal the underlying molecular mechanisms. Raman and infrared spectra suggest that SA exists predominately as dimers in chloroform, but in the other five solvents there is no dear evidence of dimerization. In all solvents, the shift in the SA carbonyl peak reflecting the strength in the solvent-solute interaction is quite well correlated to the nucleation ranking. This shift is corroborated by DFT calculated energies of binding one solvent molecule to the carboxyl group of SA. An even better correlation of the influence of the solvent on the nucleation is provided by DFT calculated energy of binding the complete first solvation shell to the SA molecule. These solvation shell binding energies are corroborated by the enthalpy of solvent-solute interaction as estimated from experimentally determined enthalpy of solution and calculated enthalpy of cavity formation using the scaled particle theory. The different methods reveal a consistent picture and suggest that the stronger the solvent binds to the SA molecule in solution, the slower the nucleation becomes.

  • 46.
    Korkmaz, Kivanc
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Alemrajabi, Mahmood
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Recovery of rare earth elements from spent NiMH HEV batteries via selective roasting and water leaching2017Conference paper (Refereed)
  • 47.
    Korkmaz, Kivanc
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Alemrajabi, Mahmood
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Recoveries of Valuable Metals from Spent Nickel Metal Hydride Vehicle Batteries via Sulfation, Selective Roasting, and Water Leaching2018In: Journal of Sustainable Metallurgy, ISSN 2199-3823, Vol. 4, no 3, p. 313-325Article in journal (Refereed)
    Abstract [en]

    The recoveries of rare earth elements (REEs), nickel, and cobalt from hybrid electric vehicle batteries by sulfation, selective roasting, and water leaching have been studied. The cathode and anode materials of a Panasonic Prismatic Module nickel metal hydride (NiMH) battery were used in the study. The optimal conditions for each step of the process were determined by performing lab-scale experiments. It was found that 8 mol/L of sulfuric acid was sufficient for the sulfation with a solid-to-liquid ratio of 1/5. The optimal roasting conditions was determined to be 850 °C for 2 h. Under optimal conditions, 96% of the REEs could be obtained in the aqueous phase with negligible contamination of Ni and Co. The Ni and Co remained in solid phase as oxides together with traces of aluminum, zinc, and iron oxides. This method provides a way for the separation of the REEs from nickel, cobalt, and other elements present in the NiMH battery, into a leachate suitable for further processing.

  • 48.
    Korkmaz, Kivanc
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Alemrajabi, Mahmood
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Separation of Valuable Elements from NiMH Battery Leach Liquor via Antisolvent Precipitation2019In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794Article in journal (Refereed)
  • 49.
    Korkmaz, Kivanc
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Alemrajabi, Mahmood
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Sustainable Hydrometallurgical Recovery of Valuable Elements from Spent Nickel-Metal Hydride HEV Batteries2018In: Metals, ISSN 2075-4701, Vol. 8, no 12Article in journal (Refereed)
  • 50.
    Korkmaz, Kivanc
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Alemrajabi, Mahmood
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Sustainable hydrometallurgical recovery of valuable elements from spent nickel-metal hydride HEV batteries2016Conference paper (Refereed)
1234 1 - 50 of 159
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