Study on Adsorption of Arsenic from Water on Iron Hydroxide

Ferric hydroxide is used as adsorbent to study its adsorption of As(Ⅲ) in this paper.The effect and adsorption kinetics of pH,ionic strength and interfering ions are also investigated.The results show that iron hydroxide can effectively adsorb As(Ⅲ) in a wide range of pH from 4.1 to 8.5.Meanwhile,the adsorption isotherm can be well described by the Langmuir adsorption model and the maximum static adsorption capacity is 9.09 mg/g.Adsorption kinetics fits Lagergren second order kinetics equation.Phosphate,silicate,carbonate and other anions inhibit As(Ⅲ) from being adsorbed in various degrees and other coexisting anions have a very little effective on As(Ⅲ) being adsorbed.At the same time,the mechanism of the adsorption of As(Ⅲ) by ferric hydroxide is discussed and the adsorption of As by iron hydroxide may be the result of the interaction between the electrostatic non-specific adsorption and specific adsorption complexation.