Continuous fixed-bed column study and adsorption modeling:removal of arsenate and arsenite in aqueous solution by organic modified spent grains

The adsorption of arsenate (As(V)) and arsenite (As(III)) was conducted in a continuous fixed-bed column by using organic modified spent grains (OSGs). The column performances were evaluated by varying the influent flow rate (0.91, 1.36, and 2.72 ml/min) and arsenic ions initial concentration (1.0, 2.0, and 6.0 mg/l for As(V); 0.5, 1.0, and 3.0 mg/l for As(III)) in order to obtain experimental breakthrough curves. The maximum adsorption capacity was at 6.0 mg/l for As(V) and 3.0 mg/l for As(III) influent concentration and 1.36 ml/min flow rate. The Thomas model, Adams-Bohart model, and Yoon-Nelson kinetic models were used to analyze column performance. The value of rate constant for Thomas and Adams-Bohart models decreased with increase of influent concentration, but increased with increasing flow rate. The rate constant for the Yoon-Nelson model decreased with increases in both initial influent arsenic ions concentration and flow rate.