Arsenic and lead removal from water using tailored zeolites

Arsenic and lead are toxic pollutants that can be present in water. These heavy metals may cause dangerous physiological effects to humans. Therefore, federal and state water standards for arsenic and lead are becoming increasingly stringent.; This research explored an economical alternative of removing a negatively charged contaminant (arsenite) in conjunction with a positively charged contaminant (lead) using tailored zeolite. Zeolites are porous aluminum-silicate minerals with cation exchange capacity. Lead is a positively charged contaminant and it has been proven that unmodified zeolites can remove lead from water, since zeolites have a negative charge in their natural form. Modified zeolites have the capacity to remove negatively charged contaminants. Ethylhexadecyldimethylammonium bromide (EHDDMA) was used to modify the surface of the zeolite to invert its charge from negative to positive.; Removal of arsenic and lead was evaluated with kinetic and equilibrium batch tests. Results showed that over 90% of lead could be removed with both natural and EHDDMA-tailored zeolite. However, optimum arsenic adsorption occurred with an 80 meq/100g EHDDMA-tailored zeolite. This degree of modification corresponds to the maximum adsorption of EHDDMA into the zeolite surface. Columns studies demonstrated that EHDDMA-tailored zeolite had better affinity for lead than for arsenic.