Nanoporous composites for chromium(VI) removal from water

In this study, nanofiltration and adsorption methods were used for the removal of Cr(VI) ions from aqueous solution. Polyaniline/poly(acrylonitrile-butyl acrylate) and polyaniline/poly(acrylonitrile-tbutyl acrylate) nanoporous composite membranes were used in nanofiltration experiments. On the other hand, polyaniline/NafionTM and polyaniline/poly(acrylonitrile-2ethylhexyl acrylate) composite adsorbents were prepared for adsorbent study. FTIR analyses was used to clarify the chemical structure. Surface morphology was characterized by Scanning Electron Microscopy (SEM). Swelling ratio of composites measurements were reported. In nanofiltration experiments, Cr(VI) rejection were tested by dead-end filtration method. Almost complete Cr(VI) removal (99%) was observed. In batch adsorption experiments, influence of initial Cr(VI) ion concentration, contact time and temperature on adsorption efficiency of adsorbents was investigated. The adsorption isoterm were analyzed by Langmuir, Freundlich and Dubinin-Radushkevich models. The results showed that Langmuir model appear to fit the Cr(VI) adsorption better than other adsorption models. Two kinetic models, pseudo-first-order and pseudo-second-order were used to predict the adsorption rate constants. It was found that kinetic of the adsorption of Cr(VI) ions on composite materials was best described by the pseudo-second-order model. Thermodynamic parameters such as standard Gibbs free energy (?G0), enthalpy (?H0) ve entropy (?S0) change were calculated. The results indicated that Cr(VI) adsorption was spontaneous in nature. Nanoporous composite membranes and composite adsorbents exhibited high performance Cr(VI) removal. Rather than the porosity effect, it can be concluded that swelling ratio of composites were more effective on adsorption process.