Chromium Sorption Research Articles

Competing ion effect on chromium adsorption with fresh and starved subsurface bacterial consortium

The sorption of chromium (Cr+6) was investigated for 50 day starved and fresh cells in the presence of sulfate ion as a competing ion at three pH values (pH 6.0, 7.5 and 9.0). The chromium distribution in the subcellular components was also determined by conducting cell fractionation. Although a previous study showed that cells which had been starved for 50 days prior to being exposed to a chromium containing solution sorbed 10–15% more chromium than did fresh cells (Kong et al., 1992a), this study demonstrated that such cells did not sorb more chromium in the presence of sulfate ion.

Sorption of heavy metals by untreated red fir sawdust

Equilibrium and rate relationships have been determined for the sorption of divalent copper (Cu2+) and hexavalent chromium (Cr6+) onto untreated Red Fir sawdust. For both ions, the equilibrium sorption levels were determined to be a function of the solution pH and temperature. The equilibrium adsorption capacity of the sawdust for Cu2+ was found to increase with increasing pH. However, for Cr6+ the sorption capacity increased with decreasing pH. For both ions, the rate of adsorption and the equilibrium adsorption capacity increased with temperature. The sorption capacity of α-cellulose was at least an order of magnitude less than the untreated sawdust.

Sorption of chromium(VI) and chromium(III) on aluminium hydroxide

Factors that influence the sorption of Cr(VI) and Cr(III) on aluminium hydroxide were investigated. The sorption of chromates decreases as the pH of the suspension increases. The mechanism of CrO 4 2− sorption was interpreted in terms of reactions between chromates and −OH and/or H2O groups at the hydroxide/liquid interface. It has been shown that chromates are more tightly sorbed on aluminium hydroxide compared to other anions, e.g. chlorides. On the other hand, specifically absorbed anions, such as molybdates, compete strongly with chromates for the sorption sites. The sorption of chromium(III) increases with the pH of the suspension. Also, the sorption of chromium(III) is suppressed in the presence of citrate ions. The best conditions for the fixation of Cr(VI) and Cr(III) by aluminium hydroxide are presented.

Sorption of chromium(III) and chromium(VI) on lead sulfide

The sorption of chromium(III) and chromium(VI) on lead sulfide has been investigated in dependence on pH, time of sorption and the concentrations of sorbate and sorbent. The mechanisms of the sorption of Cr3+ and CrO42− traces on lead sulfide are discussed; a difference between CrO42− sorption on PbS and α-Fe2O3 has been found. Sulfates and molybdates affect the removal of chromates from aqueous solutions. Lead sulfide carrier prepared in this work was also used for the preconcentration of chromium(III) and chromium(VI) from tap water.