Separation of arsenite and arsenate species from water by charged ultrafiltration membranes

Sezdi, Ayşegül
Arsenic is found in drinking waters in many countries and since maximum allowable concentration is as low as 10 µg/L, there are many research efforts to separate it from water. Membrane methods are used more and more widely in separation operations in recent years. Arsenic is mainly present in water as arsenite [As(III)] and arsenate [As(V)]. As pH of water changes, molecular formulas of As(III) and As(V) change. In this study, the performance of different ultrafiltration membranes for arsenic removal from water was investigated at different pH values, different feed concentrations and presence of other anions (SO42-, HPO42-, NO3-, Cl-). Donnan exclusion effect on separation was discussed since distribution of arsenite and arsenate anions change in water due to change in pH of the solution. Experiments were conducted via batch and continuous modes. For continuous ultrafiltration experiments, 30 kDa of polysulfone and 20 kDa of polyether sulfone membranes were used. Batch ultrafiltration experiments were performed with the usage of 3 kDa of regenerated cellulose membrane. Higher retention values for As(V) were obtained compared to retention values of As(III). When membranes’ performances were investigated, it was seen that highest As(V) removal was observed with the usage of polysulfone membrane. Increase in feed concentration and presence of other anions caused decrement in separation. Hydride Generation Atomic Absorption Spectrometry was used to perform analyses. Hydride generator part was designed, constructed and optimized to obtain reliable and accurate absorbance values.
Citation Formats
A. Sezdi, “Separation of arsenite and arsenate species from water by charged ultrafiltration membranes,” M.S. - Master of Science, Middle East Technical University, 2012.