AWWA ACE54252

The objective of this research was to determine the efficacy of using impregnated activated carbons for the removal of various heavy metals from aqueous solutions. Two impregnates (iron oxide and a ceramic cationic ion-exchanger) were impregnated onto two different commercial activated carbons and the resultant products were called FeAC and HD4000-ATC, respectively. In the first phase of research, acid-base behaviors of the non-impregnated and impregnated carbons were characterized at several ionic strengths by acidimetric-alkalimetric titrations and the pHzpc of the carbons was determined. The impregnated carbons required more acid/base to alter the pH, indicating that there were more surface sites available for metal removal in comparison with non-impregnated carbons. In the second phase, pH-adsorption edges (% metal removed versus pH) were developed for the impregnated and non-impregnated carbons using 1 mg/L solutions of either As(III), As(V), Hg(II), and Pb(I1). For all carbons studied, adsorption of all metals was a function of pH. The impregnated activated carbons removed significantly more metals (excluding Hg) than their non-impregnated counterparts at all pH values. Freundlich and Langmuir isotherm relationships were developed as a function of pH. Adsorption of heavy metals onto impregnated activated carbons was successful and warrants further investigation using continuous flow processes. Includes 18 references, figures.