A Kinetic and Equilibrium Study of Zinc Removal by Brazilian Bentonite Clay

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This paper aimed to study the removal of zinc using bentonite clay from the Northeastern Brazil, as an adsorbent. A study of the clay subjected to thermal and chemical treatment was performed in order to evaluate the optimization of the adsorption capacity of this material. For the evaluation of the kinetic equilibrium of the process, experimental tests were carried out in a finite bath system. The maximum amount of metal adsorbed was 0.151 mEq of metal per gram of calcined clay and 0.257 mEq of metal per gram of sodium saturated clay. The kinetic models of pseudo-first order, pseudo-second order and intraparticle diffusion were fitted to experimental data, and the pseudo-second order model provided the best result. The Langmuir and Freundlich models were used for the adsorption equilibrium analysis, and the Langmuir model provided the best fit for sorption isotherms. The physicochemical characterization of clay involved X-ray diffraction, scanning electron microscopy, chemical analysis by energy-dispersive X-ray spectroscopy, helium pyconometry and thermogravimetric analysis. The modified clay has potential use for removing Zn2+ ions replacing more expensive adsorbents, since good adsorption properties will be also associated with great availability and low cost.161128136Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Zinc adsorption in bentonite clay: influence of pH and initial concentration

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This paper evaluated the adsorption capacity of zinc by Bofe bentonite clay. Bofe clay was subjected to a thermal treatment for optimizing its adsorption capacity. The kinetic equilibrium of the process was studied in a finite bath system and experiments were performed by varying pH, the amount of adsorbent and initial concentration of the metal. The Langmuir and Freundlich models were used for the analysis of adsorption equilibrium. The physicochemical characterization of clay, before and after the adsorption process, included the techniques of scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and N-2 physisorption. The calcined Bofe clay is able to remove zinc from synthetic wastewater. Langmuir model provided the best fit for sorption isotherms with a maximum amount of metal adsorbed of 4.95 mg of metal g(-1) of calcined clay. The adsorption was strongly influenced by the initial conditions and modifies the physicochemical characteristics of the clay.352325332Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Mass Transfer Mechanism of Ion Exchange in Fixed Bed Columns

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)In this Work, the binary ion exchange of Zn(2+)-Na(+) ions has beer Studied by a column technique using a NaY zeolite as the cation exchanger. The experimental data (breakthrough curves) for the system were obtained at total concentrations of (1, 2, and 3) meq.L(-1) The mass action law was used to represent the ion exchange equilibrium. To represent the ion exchange in the column, two models were used. In the first model the rate-controlling step of mass transfer was considered only in the solid phase. The-experimental results were represented by a Linear Driving Force (LDF) model. In the second model, resistance to mass transfer in series in the solid phase and the external liquid film was considered. both models described ion exchange in the fixed-bed column properly, However; in the initial part of the breakthrough curve, the dual resistance model fit better.563375382Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES