Use of synthetic zeolites for arsenate removal from pollutant water.

Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. In the present work, the potential use of a variety of synthetic zeolites for removal of arsenic from water below the current and proposed EPA MCL has been examined at room temperature. Experiments have been conducted to examine the extent of arsenic removal as a function of pH. The effect of initial arsenic concentration and liquid to solid ratio in the batch reactions has also been studied. Zeolite NH4+/Y (NY6) showed significant arsenate removal capacity over a wide initial pH range of 2-12. Zeolite NY6 achieved this performance by buffering the initial pH to within a range of 3.5 < pH < 7 where uptake of arsenate onto aluminol surface groups is at a maximum. The high aluminum content of NY6 (i.e. low Si/Al ratio) was an important factor governing the improved performance of this zeolite relative to other tested zeolites with higher Si/Al ratio. The pH buffering capacity of NY6 could lead to savings in cost and process time for industrial effluent treatment due to avoidance of a pH pre-conditioning step prior to arsenate removal.