Adsorption Characteristics of As(III) and As(V) with Titanium Dioxide Loaded Amberlite XAD-7 Resin

Abstract

The adsorption characteristics of As(V) and As(III) on titanium dioxide loaded Amberlite XAD-7 resin have been studied. The resin was prepared by impregnation of Ti(OC₂H₅)₄ followed by hydrolysis with ammonium hydroxide. Batch adsorption experiments were carried out as a function of the pH, shaking time and the concentration of As(V) and As(III) ions. The resin showed a strong adsorption for As(V) from pH 1 to 5 and for As(III) from pH 5 to 10. The adsorption isotherm data for As(V) at pH 4 fitted well to a Langmuir equation with a binding constant of 59 dm³ mol^-1 and a capacity constant of 0.063 mmol g^-1. The data for As(III) at pH 7 also fitted well to a Langmuir equation with a binding constant of 5.4 dm³ mol^-1 and a capacity constant of 0.13 mmol g^-1. The effect of diverse ions on the adsorption of arsenic was also studied. Column adsorption experiments showed that the adsorption of As(III) is more favorable compared to As(V), due to both the faster adsorption and larger capacity for As(III) than As(V).