The influence of pH and phosphorus on the adsorption of chromium (VI) on boehmite

Chromium, particularly Cr(VI), is a potential threat to groundwater supplies because of industrial contamination, Recent research efforts have been focused on describing and simulating Cr(VI) adsorption on a variety of naturally occurring and synthetic substrates, including whole soil, phyllosilicate minerals, and Fe and Al oxides, This investigation describes the influence of Cr(VI) concentration, pH, and o-phosphate concentration on Cr (VI) adsorption on synthetic boehmite, Chromate adsorption isotherms were produced using a batch protocol involving sequences of increasingly concentrated Cr(VI) solutions equilibrated with 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 the isotherm's shape, Chromate adsorption was favored in acidic media, whereas o-phosphate suppressed Cr(VI) adsorption, Additionally, the proton coefficients for a proposed outer-sphere complex [AlOHn+1+ - Cro(4)(2-)] suggests that each Cr(VI) species requires multiple protonated Al surface sites.