The Cr(VI) adsorption with the presence of Cl−, SO42− and PO43− which have different elementary composition and chemical valence were tested with initial Cr(VI) concentration of 50 mg L−1 and 300 mg L−1 while the concentration of co-existing ions were set from 10−3 mol L−1 to 10−1 mol L−1. The Kd values of Cr(VI) in the presence of the three ions were shown in Fig. 4. Fig. 4a shows that when the initial concentration is 50 mg L−1 and the coexisting ions are 10−3 mol L−1, the Kd value reaches over 3.8 × 104 under a non-coexisting ions systems and it decreases largely to 1.6 × 104, 1.6 × 104, 1.2 × 104 in the presence of Cl−, SO42− and PO43−, respectively.