Abstract: To examine the adsorption of Ni2+ in aqueous solution using bentonite as adsorbent，a series of experiments were conducted with different concentration of Ni²⁺ prepared as simulated wastewater and natural calcium bentonite from Xinda Mining Company in Laiyang County，Shandong Province as adsorbent.Results show that the adsorption decreases with increasing of initial Ni²⁺ concentration but increases with ratio increasing of solid to liquid.Moreover，increasing of ratio of solid to liquid will reduce the unit utilization of adsorbent and increases the difficulty of subsequent processing.Oscillation speed has less impact on the adsorption and it can be ignored.The Ni²⁺ adsorption rate increases with pH increasing.The adsorption rate of Ni²⁺ is nearly above 95% with conditions of the initial concentration of 100 mg/L and the ratio of solid to liquid of 12.5 g/L.The saturated adsorption amount of bentonite for Ni²⁺ is examined under different pH and the influencing mechanism of pH is also analyzed in order to study the effect of pH on the adsorption with bentonite.The adsorption of Ni2+ decreases when pH<7 due to the competitive adsorption of H+ and Ni²⁺ with bentonite.The increase of pH is benefit for the adsorption，but the hydrolysis becomes the dominant removal mechanisms when pH>7.5.Furthermore，the existing form of Ni²⁺ under different pH also influences the adsorption mechanism.The results have great significance for bentonite used as adsorbent material in industrial application.

Key words: Bentonite, Ni2+, Adsorption, pH