Adsorption and desorption of binary mixtures of copper and mercury ions on natural and crosslinked chitosan membranes
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Adsorption and desorption of binary mixtures of copper and mercury ions on natural and crosslinked chitosan membranes R.S. Vieira · E. Guibal · E.A. Silva · M.M. Beppu
Received: 27 April 2007 / Revised: 3 July 2007 / Accepted: 11 September 2007 / Published online: 28 September 2007 © Springer Science+Business Media, LLC 2007
Abstract Copper and mercury ion adsorption on chitosan membranes was investigated in batch systems (with both single and binary solutions). The Langmuir model and its extensions (extended Langmuir, Jain-Snoeyink, and Langmuir-Freundlich models) were tested for the modeling of experimental data. Chitosan membranes presented more affinity for Hg ions than for Cu ions. The decrease of the amount of metal adsorbed on natural chitosan in binary systems (compared to single-metal solutions) showed the competition effects between the two metal ions. For glutaraldehydecrosslinked chitosan and epichlorohydrin-crosslinked chitosan, the mixture effect was present, producing unexpected result such as higher adsorption capacities, when compared to the monocomponent solution of each metal. The desorption of the metals was also investigated, and copper and mercury ions could be selectively recovered using a combined process by using NaCl and H2 SO4 as eluant. Keywords Copper · Mercury · Chitosan · Multicomponent adsorption Abbreviations bi heterogeneity parameter for each component, dimensionless R.S. Vieira () · M.M. Beppu Dep. de Termofluidodinamica, Faculdade de Engenharia Química, Universidade Estadual de Campinas, Campinas, SP, Brazil e-mail: [email protected] E. Guibal Laboratoire Génie de l’Environnement Industriel, Ecole des Mines d’Alès, Alès Cedex, France E.A. Silva Departamento de Engenharia Química, Universidade Estadual do Oeste do Paraná, Toledo, SP, Brazil
C Ci Ei K Ki Q
Qi
Qmax
Qmax,i Qimod n R2
concentration of the singe component at equilibrium, mmol·L−1 concentration of each component at equilibrium, mmol·L−1 root mean square error monocomponent Langmuir adsorption constant of the single component, L·mmol−1 individual Langmuir adsorption constant of each component, L·mmol−1 adsorbed amount of the single component per gram of dried chitosan membrane at equilibrium, mmol·g−1 dry chitosan adsorbed amount of each component per gram of dried chitosan membrane at equilibrium, mmol·g−1 dry chitosan maximum adsorbed amount of the single component per gram of dried chitosan membrane at equilibrium, mmol·g−1 dry chitosan maximum adsorbed amount of each component per gram of dried chitosan membrane at equilibrium, mmol·g−1 dry chitosan calculated maximum amount adsorbed of each component adsorbed number of experimental data adjustment coefficients from minimum square method for Langmuir model
1 Introduction The contamination of waste streams due to the uncontrolled discharge of industrial wastewaters has induced considerable changes in the regulations regarding effluent treatments. National regulatory agencies are considering with increased attention, the potential impact of heavy metals on
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