Arsenite and arsenate sorption by hydrous ferric oxide/polymeric material

The occurrence of arsenic in natural ground waters is due to geological composition of soil. There are several methods for removal of arsenic from drinking water, such as coagulation followed by filtration, membrane processes, ion exchange and adsorption. Adsorption methods proved to be effective, economic, easy to perform and construct. The objective of this study was to investigate the removal of arsenic from drinking water using adsorbents prepared by coating the surface of the following polymeric materials: natural alum silicate exchanger zeolite clinoptilolite and ionic exchanger Dowex Marathon C with hydrous ferric oxide. Modified adsorbents were saturated with Fe3+ ions from the FeCl3 solution in acetate buffer solution (pH 3.6) and then converted to hydrous ferric oxide by thermo chemical procedure (NaOH, NaCl, 50°C). Adsorption kinetics of arsenic was investigated as a function of initial arsenite and arsenate concentrations (ranging from 100 to 500 μg/L), contact time (from 15 to 360 min) and pH (6.4, 6.9, 7.4, 7.9). The results and sorption characteristics of the prepared hydrous ferric oxide/polymeric material adsorbents were determined using Freundlich and Langmuir adsorption isotherms.