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  • 1.
    Ahuja, D.
    et al.
    Synthesis and Solid State Pharmaceutical Centre, Department of Chemical Sciences, Bernal Institute, University of Limerick, Castletroy, Co., Limerick, Ireland.
    Bannigan, P.
    Synthesis and Solid State Pharmaceutical Centre, Department of Chemical Sciences, Bernal Institute, University of Limerick, Castletroy, Co., Limerick, Ireland.
    Rasmuson, Åke Christoffer
    Synthesis and Solid State Pharmaceutical Centre, Department of Chemical Sciences, Bernal Institute, University of Limerick, Castletroy, Co., Limerick, Ireland.
    Study of three solvates of sulfamethazine2017Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 19, nr 43, s. 6481-6488Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three novel solvates of sulfamethazine (SMT), an anti-microbial and anti-infective sulfonamide drug with the solvents-dimethylacetamide, dimethylformamide and dimethyl sulfoxide have been identified and characterized by analytical techniques including differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and Raman spectroscopy. All three are 1:1 solvates. Crystal structure analysis revealed N-H-O type intermolecular hydrogen bonding interactions between SMT and the solvent imparting stability to the solvate structure. Thermal analysis measurements for the stoichiometry of the solvates were in good agreement with the single crystal data. The solubility of the solvates in their respective solvents at 25 °C has been determined. © 2017 The Royal Society of Chemistry.

  • 2.
    Ahuja, Dipali
    et al.
    Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Castletroy, Co Limerick, Ireland..
    Svärd, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Teknisk strömningslära. Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Castletroy, Co Limerick, Ireland..
    Rasmuson, Åke C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Teknisk strömningslära. 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-crystal2019Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 21, nr 18, s. 2863-2874Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 3.
    Aisling, Lynch
    et al.
    Univ Limerick, Synth & Solid State Pharmaceut Ctr, Mat & Surface Sci Inst, Dept Chem & Environm Sci, Limerick, Ireland..
    Rasmuson, Åke C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik. Synthesis and Solid State Pharmaceutical Centre, Department of Chemical and Environmental Science, University of Limerick, Limerick, Ireland.
    Crystal Growth of Single Salicylamide Crystals2019Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 19, nr 12, s. 7230-7239Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Growth of single salicylamide crystals was investigated in a nonstirred growth cuvette and on a rotating disk. In the growth cuvette the crystal growth rates were measured for both primary nucleated crystals and seed crystals manually inserted into the cuvette. In the rotating disk experiments multiple seed crystals were attached to a disk that was rotated in a supersaturated solution. The crystal growth rates in the length and width direction were precisely measured in situ for each individual crystal, and growth rates were also extracted for a specific crystal facet, that is, (200). In all cases, the growth rate was considerably faster in the rotating disk experiments, shown to be governed by surface integration. Solvent was found to impact the growth rates of the crystal facets in part by creating different surface features. The influence of the supersaturation on the crystal growth rate depended on the solvent; in general, an increasing trend was observed. At relatively low supersaturations, it was discovered that the growth process will focus on repairing morphological defects. Within the range of experimental conditions, the growth kinetics were strongly affected by the temperature as was further indicated by the relatively high activation energy values obtained. The crystal seed quality was found to have a substantial impact on the growth rate, with rougher crystals leading to quicker growth. A wide growth rate dispersion was obtained for both crystal growth methods, found to be reduced by using seed crystals with high quality, lower supersaturations, and also within certain solvents.

  • 4. Alander, E. M.
    et al.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Mechanisms of crystal agglomeration of paracetamol in acetone-water mixtures2005Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 44, nr 15, s. 5788-5794Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 5. Alander, E. M.
    et al.
    Uusi-Penttila, M. S.
    Rasmuson, Åke C.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Characterization of paracetamol agglomerates by image analysis and strength measurement2003Inngår i: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 130, nr 03-jan, s. 298-306Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 6. Alander, Eva M.
    et al.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Agglomeration and adhesion free energy of paracetamol crystals in organic solvents2007Inngår i: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 53, nr 10, s. 2590-2605Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 7.
    Albero Caro, Jesus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Woldehaimanot, Mussie
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Semibatch reaction crystallization of salicylic acid2014Inngår i: Chemical engineering research & design, ISSN 0263-8762, E-ISSN 1744-3563, Vol. 92, nr 3, s. 522-533Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 8.
    Alemrajabi, Mahmood
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Forsberg, Kerstin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Korkmaz, Kivanc
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Rasmuson, Åke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Dephosphorization and impurity removal from a rare earth phosphate concentrate2017Konferansepaper (Fagfellevurdert)
  • 9.
    Alemrajabi, Mahmood
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Forsberg, Kerstin
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Korkmaz, Kivanc
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Isolation of rare earth element phosphate precipitate in the nitrophosphate process for manufacturing of fertilizer2016Inngår i: IMPC 2016 - 28th International Mineral Processing Congress, Canadian Institute of Mining, Metallurgy and Petroleum , 2016Konferansepaper (Fagfellevurdert)
    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. 

  • 10.
    Alemrajabi, Mahmood
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Forsberg, Kerstin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Rasmuson, Åke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Recovery of phosphorous and rare earth elements from an apatite concentrate2018Konferansepaper (Fagfellevurdert)
  • 11.
    Alemrajabi, Mahmood
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Rasmuson, Åke C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Korkmaz, Kivanc
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Forsberg, Kerstin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Processing of a rare earth phosphate concentrate obtained in the nitrophosphate process of fertilizer production2019Inngår i: Hydrometallurgy, ISSN 0304-386X, E-ISSN 1879-1158, Vol. 189, artikkel-id 105144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, different processes have been developed and applied to treat a rare earth phosphate concentrate obtained within the nitrophosphate process of fertilizer production. Methods to remove impurities such as Fe and Ca have been investigated as well as to separate the phosphorous and thereby facilitate dissolution of the rare earth elements (REE). These methods include thermal treatment with sodium hydroxide and sodium double sulphate precipitation with and without alkaline conversion, followed by selective dissolution in different acids. The proposed processes were compared and analyzed from the perspective of introducing an appropriate intermediate product for further individual REE separation. The results have shown that after thermal treatment with NaOH at 400 °C, the phosphorous can be removed from the rare earth phosphate concentrate by water leaching. Investigation of different REE phosphate concentrates demonstrated that mixed Ca and REE phases, e.g. REEmCan(PO4)3m+2n/3 and CaHPO4 are less likely to dephosphorize than REE(PO4).nH2O and FePO4.H2O under these conditions. The recovery of REE to a mild acidic solution is limited by the presence of remaining phosphate ions and by the formation of REE oxide phases during the thermal treatment. The results also show that a solution containing 40 g/L REE; free of phosphorous, calcium and iron can be obtained after reprecipitation of the rare earth phosphate concentrate as sodium rare earth double sulphates followed by alkaline conversion with sodium hydroxide and dissolution in nitric acid.

  • 12.
    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 productionManuskript (preprint) (Annet vitenskapelig)
  • 13.
    Alemrajabi, Mahmood
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Korkmaz, Kivanc
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Forsberg, Kerstin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Recovery of rare earth elements from nitrophosphoric acid solutions2017Inngår i: Hydrometallurgy, ISSN 0304-386X, E-ISSN 1879-1158, Vol. 169, s. 253-262Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 14.
    Alemrajabi, Mahmood
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Rasmuson, Åke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Korkmaz, Kivanc
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Forsberg, Kerstin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Upgrading of a rare earth phosphate concentrate within the nitrophosphate process2018Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 198, s. 551-563Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 15.
    Alemrajabi, Mahmoud
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Forsberg, Kerstin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Rasmuson, Åke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Recovery of REE from an apatite concentrate in the nitrophosphate process of fertilizer production.2015Konferansepaper (Fagfellevurdert)
  • 16.
    Ashour, Radwa
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik. 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, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Teknisk strömningslära.
    Högblom, Joakim
    AkzoNobel, Pulp and Performance Chemicals AB.
    Forsberg, Kerstin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    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, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    DTPA-Functionalized Silica Nano- and Microparticles for Adsorption and Chromatographic Separation of Rare Earth Elements2018Inngår i: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 6, nr 5, s. 6889-6900Artikkel i tidsskrift (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 17. Bodnar, K.
    et al.
    Hudson, S. P.
    Rasmuson, Åke C.
    Stepwise use of additives for improved control over formation & stability of mefenamic acid nanocrystals produced by antisolvent precipitation2017Inngår i: Crystal Growth and Design, Vol. 17, nr 2, s. 454-466Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method of introducing different additives at different times during the process, i.e., stepwise addition of additives, has been developed to produce stable nanoparticles of mefenamic acid (MEF) by antisolvent precipitation. In the absence of additives, at optimized conditions, MEF crystals were prepared in the size range of 0.25-3.05 μm; however, these crystals formed large agglomerates in suspension (∼12.1 μm). In the presence of all additives evaluated, with the exception of hydroxypropylmethylcellulose (HPMC), smaller particles were produced in suspension, the most effective additive being sodium docusate (DOSS), generating nanoparticles, ∼312 nm in size. However, the particle size was not stable but increased to ∼788 nm after 80 min in suspension associated with a polymorphic transformation. Combining the initial use of DOSS with the subsequent addition of HPMC or poly(vinyl alcohol) (PVA) allowed for the production of a stable suspension of MEF nanocrystals (∼317 and ∼311 nm, respectively). The interaction of HPMC and PVA with MEF particles delayed polymorphic transformation by inhibiting nucleation and/or growth of the stable MEF polymorph. The results show that using stepwise addition of additives, separately targeting nucleation and crystal growth/phase transformation, can improve the manufacturing and stabilization of nanocrystal suspensions. 

  • 18. Bodnár, K.
    et al.
    Hudson, S. P.
    Rasmuson, Åke C.
    Promotion of Mefenamic Acid Nucleation by a Surfactant Additive, Docusate Sodium2019Inngår i: Crystal Growth and Design, Vol. 19, nr 2, s. 591-603Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of docusate sodium (DOSS) on the nucleation of mefenamic acid (MEF) has been studied in different dimethylacetamide (DMA)-water mixtures. A series of induction time experiments were conducted under moderate supersaturations, varying the solvent composition and the concentration of DOSS. In 40% DMA-60% water, the presence of 0.1 and 0.2 mg/mL DOSS increased the nucleation rate. Evaluating the results by the classical nucleation theory reveals that the pre-exponential factor (A) increases by approximately 50% while the interfacial energy is essentially uninfluenced. It is also found that the crystal growth rate becomes higher in the presence of DOSS. It is thus hypothesized that transport and desolvation of MEF molecules are facilitated in the presence of DOSS. With increasing amount of DMA in the binary solvent mixture, the influence of DOSS appears to decrease. 

  • 19. Bohlin, M.
    et al.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Application of controlled cooling and seeding in batch crystallization1992Inngår i: The Canadian Journal of Chemical Engineering, Vol. 70, nr 1, s. 120-126Artikkel i tidsskrift (Fagfellevurdert)
  • 20. Bohlin, M.
    et al.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Importance of Macromixing in Batch Cooling Crystallization1996Inngår i: AIChE Journal, Vol. 42, nr 3, s. 691-699Artikkel i tidsskrift (Fagfellevurdert)
  • 21. Bohlin, M.
    et al.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Modeling of growth rate dispersion in batch cooling crystallization1992Inngår i: AIChE Journal, Vol. 38, nr 12, s. 1853-1863Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Bäbler, Matthäus U.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Kebede, Mebatsion L.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Rozada-Sanchez, Raquel
    Åslund, Per
    Gregertsen, Björn
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Isolation of Pharmaceutical Intermediates through Solid Supported Evaporation. Semicontinuous Operation Mode2012Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 51, nr 45, s. 14814-14823Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 23. Cheuk, D.
    et al.
    Khamar, D.
    McArdle, P.
    Rasmuson, Åke Christoffer
    Univ Limerick, Dept Chem & Environm Sci, Mat & Surface Sci Inst, Synth & Solid State Pharmaceut Ctr,.
    Solid Forms, Crystal Habits, and Solubility of Danthron2015Inngår i: Journal of Chemical and Engineering Data, Vol. 60, nr 7, s. 2110-2118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The polymorphism, crystal habits, and solubility of 1,8-dihydroxyanthraquinone (danthron) were investigated in acetic acid, acetone, acetonitrile, n-butanol, and toluene. The solubility was determined for the commercially available form (FI) from 293.15 K to 318.15 K. by the gravimetric method. The influence of solvents on crystal habit and polymorphic form has been investigated. Three different crystal habits of danthron were obtained from slow evaporation and cooling experiments. By evaporation, thin squares of FI were obtained from n-butanol and toluene solutions while both FT and fine needles of FIT were obtained from acetone and acetonitrile solutions. In addition, needle-shaped solvate crystals were obtained from acetic acid solutions and the structure of the solvate was solved by single crystal X-ray diffraction. From cooling crystallization experiments, mixtures of FI and FIT were often obtained from various solvents, but FT and FIT possess distinct habits which can be easily distinguished by visual comparison. Slurry conversion experiments have established that FT is the thermodynamically stable polymorph of danthron at ambient conditions. Differntial scanning calorimetry (DSC) and high-temperature powder X-ray diffraction (PXRD) have shown that both FI and FII will transform into a high-temperature form (FIV) around 435 K to 439 K before this form melts at 468.5 K. FI, FIT, and FIV have been characterized by transmission and high-temperature PXRD, scanning electron microscopy, infrared spectrometry, Raman spectrometry, thermogravimetric analysis, and DSC. The solubility of danthron FI in the pure organic solvents of the present work and in the temperature range investigated is below 4.3 % by weight and decreases in the order toluene, acetone, acetonitrile, and n-butanol.

  • 24. Cheuk, Dominic
    et al.
    Svärd, Michael
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära. University of Limerick, Ireland.
    Seaton, Colin
    McArdle, Patrick
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära. University of Limerick, Ireland.
    Investigation into solid and solution properties of quinizarin2015Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 17, nr 21, s. 3985-3997Artikkel i tidsskrift (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 25.
    Chidambaram, R
    et al.
    Karobio.
    Garg, N
    Karobio.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Gracin, Sandra
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Improved crystalline material2006Patent (Annet (populærvitenskap, debatt, mm))
  • 26. Croker, D. M.
    et al.
    Davey, R. J.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik. Univ Limerick, Mat & Surface Sci Inst, Dept Chem & Environm Sci.
    Seaton, C. C.
    Nucleation in the p-toluenesulfonamide/triphenylphosphine oxide co-crystal system2013Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 13, nr 8, s. 3754-3762Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nucleation has been studied in pure co-crystal and mixed co-crystal phase regions of the ternary phase diagram (TPD) in acetonitrile at 20 C using cooling crystallization experiments. Direct nucleation of each of the co-crystal phases in this system was independently observed in regions of the TPD where each is stable. In mixed regions, regions where either a co-crystal and a coformer, or both co-crystals, are stable, the phase that initially nucleated was a function of the mass composition in that region. The relative amount of each phase nucleating could be controlled by adjusting the relative mass fraction of each component. The kinetic return to equilibrium was also observed as the systems were held over time, with the selected mass fractions always returning to the equilibrium dictated by the TPD after 24 h

  • 27. Croker, D. M.
    et al.
    Davey, R. J.
    Rasmuson, Åke Christoffer
    Univ Limerick, Mat & Surface Sci Inst, Dept Chem & Environm Sci.
    Seaton, C. C.
    Solution mediated phase transformations between co-crystals2013Inngår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 15, nr 11, s. 2044-2047Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A solution mediated transformation between two co-crystal phases has been observed for the p-toluensulfonamide-triphenylphosphine oxide co-crystal system. This system has two known co-crystals with 1 : 1 and 3 : 2 stoichiometry respectively, and the ternary phase diagram (TPD) for the system has been determined in acetonitrile previously. By manipulating the solution composition in this solvent to a region of the TPD where the 1 : 1 co-crystal is stable, the 3 : 2 co-crystal could be observed to convert to the 1 : 1 co-crystal. The corresponding transformation was true for the 1 : 1 co-crystal in a region of the TPD where the 3 : 2 co-crystal is stable; the 1 : 1 co-crystal converted to the 3 : 2 co-crystal.

  • 28. Croker, D. M.
    et al.
    Kelly, D. M.
    Horgan, D. E.
    Hodnett, B. K.
    Lawrence, S. E.
    Moynihan, H. A.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik. University of Limerick.
    Demonstrating the Influence of Solvent Choice and Crystallization Conditions on Phenacetin Crystal Habit and Particle Size Distribution2015Inngår i: Organic Process Research & Development, ISSN 1083-6160, E-ISSN 1520-586X, Vol. 19, nr 12, s. 1826-1836Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phenacetin was used as a model pharmaceutical compound to investigate the impact of solvent choice and crystallization conditions on the crystal habit and size distribution of the final crystallized product. The crystal habit of phenacetin was explored using crash-cooling crystallization (kinetically controlled) and slow evaporative crystallization (thermodynamically controlled) in a wide range of organic solvents. In general, a variety of needle-type shapes (needles, rods, or blades) were recovered from fast-cooling crystallizations, in contrast to hexagonal blocks obtained from slow evaporative crystallizations. The solubility of phenacetin was measured in five solvents from 10-70 degrees C to allow for the design of larger-scale crystallization experiments. Supersaturation and the nucleation temperature were independently controlled in isothermal desupersaturation experiments to investigate the impact of each on crystal habit and size. The crystal size (needle cross-sectional area) decreased with increasing supersaturation because of higher nucleation rates at higher supersaturation, and elongated needles were recovered: Increasing the nucleation temperature resulted in the production of larger crystals with decreased needle aspect ratios. Antisolvent phenacetin crystallizations were developed for three solvent/antisolvent systems using four different antisolvent addition rates to simultaneously probe the crystal habit and size of the final product. In general, increasing the antisolvent addition rate, associated with increased rate of generation of supersaturation, resulted in the production of shorter needle crystals.

  • 29. Croker, D. M.
    et al.
    Rasmuson, Åke Christoffer
    University of Limerick.
    Isothermal suspension conversion as a route to cocrystal production: One-pot scalable synthesis2014Inngår i: Organic Process Research & Development, ISSN 1083-6160, E-ISSN 1520-586X, Vol. 18, nr 8, s. 941-946Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Isothermal suspension conversion is presented as a suitable method for the manufacture of pure cocrystal products once the ternary phase diagram (TPD) for the cocrystal system in the desired solvent is available. One:one and 3:2 cocrystals of p-toluenesulphonamide/triphenylphosphine oxide were produced in acetonitrile and dichloromethane using this method. Eight individual batches of product were prepared with complete conversion to pure product achieved in seven batches. Product recovery (77-99%), reaction conversion (17-89%), and volumetric productivity (0.03-0.63 g/cm(3)) were calculated for each product batch. These parameters are essentially determined by the batch operating mass fraction composition selected from the TPD, allowing for tailoring of processing conditions to suit process requirements and capabilities by careful selection of the optimum operating mass fraction composition.

  • 30.
    Croker, Denise
    et al.
    Chemical and Environmental Science, University of Limerick, Ireland.
    Foreman, Michael
    University of Cork, Ireland.
    Hogan, Bridget
    University of Cork, Ireland.
    Maguire, Nuala
    University of Cork, Ireland.
    Curtis, Elcoate
    University of Cork, Ireland.
    Hodnett, Kieran
    Chemical and Environmental Science, University of Limerick, Ireland.
    Maguire, Anita
    University of Cork, Ireland.
    Rasmuson, Åke C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Teknisk strömningslära. Univ Limerick, Ireland.
    Lawrence, Simon
    University of Cork, Ireland.
    Understanding the p-toluenesulfonamide / triphenylphosphine oxide crystal chemistry: a new 1:1 cocrystal and ternary phase diagram2012Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 12, nr 2, s. 869-875Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel 1:1 cocrystal between p-toluenesulfonamide and triphenylphosphine oxide has been prepared and structurally characterized. This 1:1 cocrystal was observed to form during solid state grinding experiments, with subsequent formation of a known 3:2 cocrystal in the presence of excess sulfonamide. Both cocrystals are stable in the solid state. The ternary phase diagram for the two coformers was constructed in two different solvents: acetonitrile and dichloromethane. Examination of these diagrams clarified solution crystallization of both the newly discovered 1:1 cocrystal and the previously reported 3:2 cocrystal, and identified regions of stability for each cocrystal in each solvent. The choice of solvent was found to have a significant effect on the position of the solid state regions within a cocrystal system.

  • 31. Fichtner, F.
    et al.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Alderborn, G.
    Particle size distribution and evolution in tablet structure during and after compaction2005Inngår i: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 292, nr 02-jan, s. 211-225Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 32. Fichtner, Frauke
    et al.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Alander, Eva M.
    Alderborn, Goran
    Effect of preparation method on compactability of paracetamol granules and agglomerates2007Inngår i: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 336, nr 1, s. 148-158Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 33.
    Forsberg, Kerstin M.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Mohammadi, M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Ghafarnejad Parto, S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Martínez de la Cruz, Joaquin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Rasmuson, Åke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Fredriksson, A.
    LKAB.
    Recovery of REE from an apatite concentrate2014Konferansepaper (Fagfellevurdert)
  • 34.
    Forsberg, Kerstin M.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    The influence of hydrofluoric acid and nitric acid on the growth kinetics of iron(III) fluoride trihydrate2015Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 423, s. 16-21Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 35.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Mohammadi, M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Ghafarnejad Parto, S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Alemrajabi, Mahmoud
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Korkmaz, Kivanc
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Martínez De La Cruz, Joaquin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Rasmuson, Åke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Novel hydrometallurgical methods for recovery and separation of REE2014Konferansepaper (Fagfellevurdert)
  • 36.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Crystal growth of iron(III) flouride trihydrate in mixed acidManuskript (preprint) (Annet vitenskapelig)
  • 37.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Crystallization in hydrofluoric acid and nitric acid solutions containing iron(III), chronium(III) and nickel(II).Manuskript (preprint) (Annet vitenskapelig)
  • 38.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Rasmuson, Åke
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Crystallization of metal fluoride hydrates from mixed hydrofluoric and nitric acid solutions, Part I: Iron (III) and Chromium (III)2010Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, nr 16-17, s. 2351-2357Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 39.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Rasmuson, Åke
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Crystallization of metal fluoride hydrates from mixed hydrofluoric and nitric acid solutions, part II: Iron (III) and nickel (II)2010Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, nr 16-17, s. 2358-2362Artikkel i tidsskrift (Fagfellevurdert)
    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).

  • 40.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke C
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Crystal growth kinetics of iron fluoride trihydrate2006Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 296, nr 2, s. 213-220Artikkel i tidsskrift (Fagfellevurdert)
    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). .

  • 41.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke C
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Recycling of waste pickle acid by precipitation of metal fluoride hydrates2007Inngår i: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 20, nr 9, s. 950-955Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 42.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Precipitation from HF and HNO3 solutions containing iron (III), nickel (II) and chromium (III)2008Inngår i: Proc. 17’th International Symposium on Industrial Crystallization / [ed] JP Janssens; J Ulrich, 2008, s. 1175-1180Konferansepaper (Fagfellevurdert)
  • 43.
    Forsberg, Kerstin
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Resursåtervinning.
    Rodríguez Varela, Raquel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Martínez, Joaquin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Kloo, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Rasmuson, Åke C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Processing of a rare earth element concentrate by hollow fibre supported liquid membrane extraction2017Konferansepaper (Fagfellevurdert)
  • 44. Gamidi, R. K.
    et al.
    Rasmuson, Åke Christoffer
    University of Limerick.
    Estimation of melting temperature of molecular cocrystals using artificial neural network model2017Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 17, nr 1, s. 175-182Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    quantitative structure-activity relationship model has been constructed by artificial neural networks for estimation of melting temperature (T-m) of molecular cocrystals (CCs). On the basis of a literature, analysis using SciFinder and Cambridge Structural Database softwares, a database has been created of CCs for four active pharmaceutical ingredients, namely, caffeine, theophylline (THP), nicotinamide (NA), and isonicotinamide (INA). In total, of 61 CCs were included: 14-CAF, 9-THP, 29-INA, and 9-NA. A good correlation was obtained with ANNs to quantify the T-m of the CCs with respect to various coformers. The training process was completed with an average relative error of 2.38%, whereas the relative error for the validation set was 2.89%.

  • 45.
    Gracin, Sandra
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Rasmuson, Åke C.
    KTH, Tidigare Institutioner, Kemiteknik.
    Prediction of Solubility of Solid Organic Compounds in Solvents by UNIFAC2002Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 41, nr 20, s. 5114-5124Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 46.
    Gracin, Sandra
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Rasmuson, Åke C.
    KTH, Tidigare Institutioner, Kemiteknik.
    Polymorphism and Crystallization of p-Aminobenzoic Acid2004Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 4, nr 5, s. 1013-1023Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 47.
    Gracin, Sandra
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Rasmuson, Åke C.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Solubility of Phenylacetic Acid, p-Hydroxyphenylacetic Acid, p-Aminophenylacetic Acid, p-Hydroxybenzoic Acid, and Ibuprofen in Pure Solvents2002Inngår i: Journal of Chemical and Engineering Data, ISSN 0021-9568, E-ISSN 1520-5134, Vol. 47, nr 6, s. 1379-1383Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 48.
    Gracin, Sandra
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Uusi-Penttilä, Marketta
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Influence of ultrasound on the nucleation of polymorphs of p-aminobenzoic acid2005Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 5, nr 5, s. 1787-1794Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 49.
    Gracin, Sandra
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Uusi-Penttilä, Marketta
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Controlling polymorphism of p-aminobenzoic acid by sonication2005Inngår i: the 16th International Symposium on Industrial Crystallization, VDI verlag Dusseldorf , 2005, s. 677-682Konferansepaper (Fagfellevurdert)
    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.

  • 50. Granberg, R. A.
    et al.
    Bloch, D. G.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Crystallization of paracetamol in acetone-water mixtures1999Inngår i: Journal of Crystal Growth, Vol. 198-199, nr pt 2, s. 1287-1293Artikkel i tidsskrift (Fagfellevurdert)
12345 1 - 50 of 225
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