Efficient Removal Of Phosphate From Aqueous Solution By Burnt Brick Clay: Static Conditions

Phosphate species, the main nutrient pollutant, contributes to eutrophication, causing harmful effects to aquatic life. Adsorption of phosphate from synthetic solutions prepared using KH2PO4 shows 87% removal from 10.0 mg L-1 phosphate solution at 1:10 adsorbent/solution ratio, under the optimized conditions, by brick clay particles burnt at 200 degrees C (BBC). Based on error analysis and regression coefficients, removal of phosphate by BBC could be explained by the Freundlich isotherm model in general and the Dubinin-Radushkevich (D-R) isotherm at high concentrations. More importantly, the saturation capacity (q(max)) determined by the D-R model is 4,531 mg kg(-1), which is significantly higher when compared to other adsorbents reported. Further, kinetics data show the validity of the pseudo-second-order model, with the rate constant (k') and initial adsorption rate (h(0)) of 2.25 x 10(-2) kg mg(-1) min-1 and 156 mg kg(-1) min(-1), respectively. The use of BBC accelerates the mass transfer process providing more vacant sites for adsorption of phosphate, while unbound Ca and Fe particles may also result in strong bonds with phosphate species.