Zn(II) removal from wastewater by an alkali-activated material prepared from steel industry slags: optimization and modelling of a fixed-bed process.

Removal of dissolved zinc (Zn) from water by a novel alkali-activated material (AAM) prepared from steel industry slags in a fixed-bed column was investigated. Design of experiments was used to find the optimum operation parameters [flow rate ( Q ) , adsorbent mass, ( m a d s ), and initial Zn concentration ( C 0 )] for the removal of Zn 2+ from a ZnCl 2 solution. Regression models for the breakthrough ( q b ), and saturation ( q s a t ) capacities of the bed and three other response parameters as functions of Q , m a d s and C 0 were fitted with coefficients of determination ( R 2 ) ranging from 0.48 to 0.99. Experimental values of q b and q s a t varied within 1.42-7.03 mg Zn/g and 10.57-17.25 mg Zn/g, respectively. The optimum operation parameters were determined to be Q = 1.64 ml/min and m a d s = 4.5 g, whereas C 0 had negligible effect on the response parameters in the range 73-107 mg Zn/l. Finally, three empirical breakthrough curve (BTC) models were employed to describe the individual BTCs of which the modified dose - response model was found to give the best fit (0.960 ≤ R 2 ≤ 0.998). The results of the present work demonstrate that the novel AAM has considerable potential to be utilized in water purification applications.