THE INFLUENCE OF PH AND PHOSPHORUS ON THE ADSORPTION OF CHROMIUM(VI) ON BOEHMITE

Chromium, particularly Cr(VI), is a potential threat to groundwater su pplies because of industrial contamination, Recent research efforts ha ve been focused on describing and simulating Cr(VI) adsorption on a va riety of naturally occurring and synthetic substrates, including whole soil, phyllosilicate minerals, and Fe and Al oxides, This investigati on describes the influence of Cr(VI) concentration, pH, and o-phosphat e concentration on Cr (VI) adsorption on synthetic boehmite, Chromate adsorption isotherms were produced using a batch protocol involving se quences of increasingly concentrated Cr(VI) solutions equilibrated wit h boehmite, The o-phosphate concentrations [0, 0.13, and 0.25 mmole P L-1] and eight pH levels were discretely varied in the preparation of these Cr(VI) isotherms to assess the influence of these variables on t he isotherm's shape, Chromate adsorption was favored in acidic media, whereas o-phosphate suppressed Cr(VI) adsorption, Additionally, the pr oton coefficients for a proposed outer-sphere complex [AlOHn+1+ - Cro( 4)(2-)] suggests that each Cr(VI) species requires multiple protonated Al surface sites.