Evaluating an iron-coated sand for removing copper from water

Abstract

In drinking water treatment systems, the conventional process (coagulation, sedimentation and filtration units) cannot remove trace metals efficiently. Iron oxide is an excellent, regenerable adsorbent, and often controls free metals through adsorption. The utilization of heating process for coating iron oxide on sand surface allowed the media to be used in a packed column. The adsorbent media were investigated for removing copper ions from water using both batch and column experimental methods. A one-dimensional convective-dispersive transport model with a combination of second-order kinetic adsorption equation was adopted for predicting copper retention in a 80 cm depth filter bed. The concentration of copper ions in influent ranged from 0.64 to 3.2 mg/l. The experimental results indicated that the copper could be removed completely until the breakpoint. Once breakthrough occurred, the regeneration of the media could be achieved by soaking with acid solution (pH = 3.0). The simulation results of the transport-adsorption equation fit experimental data quite well. Consequently, the coated sand can be applied for the conventional rapid filtration process to remove copper ions from water.