Study on the adsorption of Ni²⁺ by fly ash, clay,silty clay and bentonite

Adsorption of Ni(Ⅱ) from aqueous solutions by fly ash, clay, silty clay and bentonite was investigated. The results of kineti experiments showed that the adsorption process of Ni(Ⅱ) was rapid. The adsorption data showed that adsorption capacity of Ni(Ⅱ) by fl ash and bentonite was much larger than those by clay and silty clay, and adsorption capacity of Ni(Ⅱ) by fly ash was larger than that b bentonite. Equilibrium modeling of the adsorption showed that at high concentration, the adsorption of Ni(Ⅱ) by fly ash, clay, silty cla and bentonite was fitted to a Langmuir isotherm, while the adsorption of Ni(Ⅱ) by clay and silty clay was also fitted to linear an Freundlich isotherm. The results also showed that when Ni(Ⅱ) loading in absorbents increased,the percentage of Ni(Ⅱ) adsorption b absorbents such as fly ash decreased.