Sandra Svilović

Modeling batch kinetics of copper ions sorption using synthetic zeolite NaX.

The sorptive removal of copper ions from aqueous solutions using zeolite NaX has been studied by a batch technique. The influences of solute concentration, temperature and particle size on the sorption process were examined. Several kinetic models were used to test the experimental rate data and to examine the controlling mechanism of the sorption process. Lagergren pseudo-first order, the pseudo-second-order (Ho) and Ritchie second-order models were analyzed using nonlinear regression technique while Weber-Morris model was analyzed using linear least squares method. The obtained results indicated that synthetic zeolite NaX could be used as an efficient material for the sorption of copper ions. A kinetic study has shown that the best fit is achieved when the Ritchie model was applied and that sorption did not involve film or intraparticle diffusion, i.e., they were not the rate controlling steps. The activation energy was found to be 12kJ/mol in the present study.

Fly ash-based geopolymeric adsorbent for copper ion removal from wastewater

AbstractThe batch experiments were carried out to study the removal of copper ions from aqueous solutions by sorption process on geopolymer synthesized from fly ash (FA). The influence of solute concentration and temperature on the sorption process were examined at constant particle size and the sorption capacity of copper ions increases with the initial concentration and temperature. Several kinetic models were used to test the experimental kinetic data: Lagergren pseudo-first-order, the pseudo-second-order (Ho), and Elovich models were analyzed using nonlinear regression technique. A kinetic study has shown that the best fit is achieved when the Ho model was applied. The results obtained indicate that geopolymer synthesized from FA has excellent adsorption ability and could be used as an efficient material for the sorption of copper ions.

Removal of copper and cobalt ions by fly ash-based geopolymer from solutions-equilibrium study

AbstractFly ash-based geopolymer was used for removal of copper and cobalt ions from aqueous solutions by a batch technique. The experimental data were obtained at constant geopolymer particles size (0.071–0.090xa0mm) for the different initial concentrations (in the range from 3.881 to 39.390xa0mmolxa0L−1) of copper and cobalt solutions, respectively, and at various temperatures (Txa0=xa0298, 308 and 318xa0K). For characterization of synthesized geopolymer, before and after sorption of heavy metals, FTIR, XRD, and SEM/EDS analyses were used to confirm the dissolution of geopolymer structure. SEM/EDS analysis also confirmed that sorption process occurred, as well as the fact that Na ions are outgoing ions. Various types of isotherm models, two-parameter isotherms: Langmuir, Freundlich, Jovanovic, and Dubinin–Radushkevich and three-parameter isotherms: Hill, Redlich–Peterson, and Sips were fitted to the experimental data obtained. In order to calculate parameters of the isotherms a nonlinear regression method was used....

Kinetic studies of cobalt ion removal from aqueous solutions using fly ash-based geopolymer and zeolite NaX as sorbents

ABSTRACT This study explored the cobalt ions removal efficiency from aqueous solutions by the sorption process on geopolymer and zeolite NaX. The influence of concentration and temperature on the sorption process was examined. FTIR and SEM analyses were conducted to elucidate the structure of sorbents. An additional goal was to test the experimental kinetic data using several kinetic models. A kinetic study has shown that the best fit is achieved when the Blanchard model was applied, suggesting that the sorption of cobalt ions on geopolymer and zeolite NaX is a second-order reaction.

Modelling the supercritical CO2 extraction kinetics of soybean oil.

Different empirical models were used to describe the supercritical CO2 extraction of soybean oil obtained at series of operational parameters namely pressure, temperature, solvent flow rate and characteristic particle size. Process yields obtained by supercritical CO2 were up to 19.33%. Several kinetic models: Brunner, Kandiah and Spiro, Tan and Liou, Martinez et al. and Esquivel et al. were used to test the experimental yield data. All models were analysed using nonlinear regression method. Also a new model, modified Esquivel et al., was proposed and analysed using nonlinear regression method as well. According to the obtained results for extraction yield of soybean oil, the modified Esquivel et al. model show the best agreement between experimental and model calculated data.