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  • 1.
    Benavente, Martha
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Adsorption of Metallic Ions onto Chitosan: Equilibrium and Kinetic Studies2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Equilibrium isotherms and the adsorption kinetics of heavy metals onto chitosan were studied experimentally. Chitosan, a biopolymer produced from crustacean shells, has applications in various areas, particularly in drinking water and wastewater treatment due to its ability to remove metallic ions from solutions. The adsorption capacity of chitosan depends on a number of parameters: deacetylation degree, molecular weight, particle size and crystallinity. The purpose of this work was to study the adsorption of copper, zinc, mercury, and arsenic on chitosan produced from shrimp shells at a laboratory level.

    The experimental work involved the determination of the adsorption isotherms for each metallic ion in a batch system. The resulting isotherms were fitted using the Langmuir model and the parameters of the equation were determined. Kinetic studies of adsorption for different metallic ions at different concentrations and with different particle sizes were performed in batch and column systems. Simplified models such as pseudo-first-order, pseudo-second-order, and intra-particle diffusion equations were used to determine the rate-controlling step. Some preliminary studies were carried out to address the application of chitosan as an adsorbent in the removal of heavy metals or other metallic ions from natural water and wastewater. The regeneration of chitosan was also studied.

    The results showed that the adsorption capacity depends strongly on pH and on the species of metallic ions in the solution. The optimum pH value for the metallic cation adsorption was between 4 and 6, whereas for arsenic adsorption it was about 3. When the pH is not controlled, the adsorption capacity is independent of the initial pH with the solution reaching a final pH of about 7. It was also found that the Langmuir equation described very well the experimental adsorption data for each metallic ion. The adsorption capacity for the metals on chitosan follows the sequence Hg>Cu>Zn>As.

    The study of the adsorption kinetics of these metallic ions shows that the particle size has a significant influence on the metal uptake rate for copper; but that it has only a slight influence on the adsorption rate of zinc and mercury in the range studied. Arsenic adsorption exhibited an interesting behaviour which depends strongly on the pH of the solution; the uptake increased at short adsorption times and then decreased at long times. The analysis of kinetic models showed that the pseudo-second-order adsorption mechanism is predominant, and the overall rate of the metallic ion adsorption process is therefore controlled by adsorption reactions and not by mass transfer for the range of particle sizes examined in this study.

    With regard to the regeneration of chitosan, it was found that sodium hydroxide is a good agent for zinc and arsenic desorption, whereas ammonium sulphate and sodium chloride were the most suitable for copper and mercury desorption, respectively. The ability of chitosan to remove arsenic from natural water, and copper and zinc from mining waste water was verified. The use of these results for designing purposes is a subject for future work.

  • 2.
    Benavente, Martha
    et al.
    Department of Chemical Engineering, National University of Engineering, Managua, Nicaragua.
    Arévalo, Marcos
    Department of Chemical Engineering, National University of Engineering, Managua, Nicaragua.
    Martinez, Joaquin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Speciation and Removal of Arsenic in column packed with chitosan2006In: Water Practice & Technology, ISSN 1751-231X, Vol. 1, no 4, p. 2006-89Article in journal (Refereed)
    Abstract [en]

    The arsenic speciation and arsenic removal in chitosan packed column were studied. Arsenic removal experiments were carried out with an arsenic standard solution (1.0 mg/l) and drilled well water samples from Limon Mine Community at different pH, water flowrate, and volume of adsorbent material. The simulation of arsenic speciation was carried out at a pH range from 0 to 12, a temperature of 25ºC, a pE equal to 4, and a total arsenic concentration of 1.34 x 10-5 mol kg-1. According to speciation calculations arsenic is found mainly in oxidized form in the conditions of Limon Mine’s drilled well waters, dihydrogen arsenate ion (H2AsO4-), and hydrogen arsenate ion (HAsO42-) being the major species. The experiments showed that arsenic adsorption depends mainly on the pH as well as the activity of functional groups that compose the chitosan structure. At pH 3 and volume of adsorbent material of 337.8 cm3 an adsorption of 94% was obtained from arsenic standard solution, and the arsenic present in the Limon Community’s water was almost totally removed at pH 3 and 7. The use of the results for designing purposes demands the breakthrough curves for chitosan to be determined.

  • 3.
    Benavente, Martha
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. National University of Engineering (UNI), Nicaragua.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Martinez, Joaquin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Sorption of heavy metals from gold mining wastewater using chitosan2011In: Journal of the Taiwan Institute of Chemical Engineers / Elsevier, ISSN 1876-1070, E-ISSN 1876-1089, Vol. 42, no 6, p. 976-988Article in journal (Refereed)
    Abstract [en]

    This study is concerned with the use of chitosan produced from shrimp shell waste for the removal of Cu(II), Hg(II), Pb(II) and Zn(II) from gold ore tailing solutions containing cyanide. This work involved the study of equilibrium and kinetic adsorption, the physicochemical characterization of mining effluents and desorption using different regenerating solutions. The experimental results showed that the adsorption capacity of chitosan is a function of the solution pH and that the optimum pH for these metallic ions is 6, except for Hg (pH 4). The equilibrium data were described using the Langmuir, Freundlich, Redlich-Peterson and SIPS isotherm models. The Langmuir equation was used to find the maximum adsorption capacity for Cu (79.94 mg/g), Hg (109.55 mg/g), Pb (58.71 mg)g) and Zn (47.15 mg/g). To determine the rate-controlling mechanism for metallic ion adsorption, pseudo-first-order, pseudo-second-order and the Elovich equation kinetic models were tested with experimental adsorption kinetic data. Tests conducted with gold ore tailing solutions indicated that chitosan is effective to remove these metallic ions above 70%. Desorption studies revealed that the regeneration of chitosan saturated with these metallic ions depends on the type and concentration of the regenerating solution ((NH(4))(2)SO(4), H(2)SO(4), HCl, NaOH and NaCl).

  • 4.
    Benavente, Martha
    et al.
    Faculty of Chemical Engineering, National University of Engineering (UNI), Managua, Nicaragua.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Adsorption Kinetic of Copper and Zinc from Binary Solutions using Chitosan2010In: Hydro Process 2010: Proceedings of the 3rd International Workshop on Process Hydrometallurgy / [ed] Marcelo Jo, Juan Patricio Ibáñez, Jesús Casas, Santiago, Chile: GECAMIN, 2010, p. 22-23Conference paper (Refereed)
  • 5.
    Benavente, Martha
    et al.
    Faculty of Chemical Engineering, National University of Engineering (UNI), Managua, Nicaragua.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Biosorption of Lead using Chitosan2009In: Advances in Chitin Science, Volumen XI: EUCHIS 2009 / [ed] Franco Rustichelli, Carla Caramella, Sevda Senel, Kjell M. Vaarum, Venice, Italy, 2009, p. 487-492Conference paper (Refereed)
  • 6.
    Benavente, Martha
    et al.
    Faculty of Chemical Engineering, National University of Engineering (UNI), Managua, Nicaragua.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Production of Glucosamine Hydrochloride from Crustacean Shell2011In: Advances in Chitin Science, Volume XIII: EUCHIS 2011 / [ed] Valery Varlamov, Svetlana Bratskaya, Irina Yakovleva, Sevda Senel, SAINT-PETERSBURG, RUSSIA, 2011, p. 29-35Conference paper (Refereed)
  • 7.
    Benavente, Martha
    et al.
    National University of Engineering, Nicaragua.
    Sjörén, Anna
    KTH, School of Chemical Science and Engineering (CHE).
    Westergren, Robin
    KTH, School of Chemical Science and Engineering (CHE).
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Martinez, Joaquin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Biosorption of Heavy Metals on Chitosan2007In: Hydro Copper 2007 / [ed] Jorge M. Menacho and Jesús M. Casas de Prada, Santiago, Chile: GECAMIN Ltda. , 2007, p. 283-290Conference paper (Refereed)
  • 8.
    Benavente, Martha
    et al.
    National University of Engineering, Nicaragua.
    Álvarez, Erick
    National University of Engineering, Nicaragua.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Martinez, Joaquin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Removal of Copper and Zinc from Gold Ore Tailings Solutions using Chitosan2008In: Hydro Process 2008 / [ed] Jorge M. Menacho and Jesús M. Casas de Prada, Santiago, Chile: GECAMIN Ltda. , 2008, p. 139-152Conference paper (Refereed)
  • 9.
    Garcia, Indiana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Benavente, Martha
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Sorption kinetics of fulvic and humic acid onto chitosan of different molecular weightsArticle in journal (Other academic)
  • 10.
    Garcia, Indiana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Benavente, Martha
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Use of chitosan as coagulant in the removal of natural organic matter from four different raw waters2011In: Proceedings of the 10th International Conference of the European Chitin Society (EUCHIS 2011), 2011, p. 106-110Conference paper (Other academic)
1 - 10 of 10
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