Adsorption of Ni2+ from aqueous solutions using chitosan-attapulgite composite as biosorbent

A novel chitosan/attapulgite (CTS/APT) composite adsorbent was prepared. Adsorption experiments were carried out as a function of types of adsorbent, ratio, contact time, pH, temperature. It was found that the adsorption capacity of Ni
²⁺
on composite adsorbent was the highest. The composite adsorbent had the highest adsorption efficiency when the ratio was 30 wt%. The adsorption of Ni
²⁺
reached equilibrium within 60 min. The composite adsorbent was particularly effective for the Ni
²⁺
removal at pH 5.0. Evaluation of adsorption process from 288 K to 318 K identified its endothermic nature. Equilibrium data of Ni
²⁺
onto this composite adsorbent was well described by Langmuir isotherm model which indicated a physical adsorption process.