Enhanced efficiency in HA removal by electrocoagulation through optimizing flocs properties: Role of current density and pH

Abstract

The performance of electrocoagulation (EC) significantly depends on flocs properties that could be improved through regulating electrochemical parameters. However, little information has been collected to date regarding the relationship between flocs characteristics and electrochemical parameters. In this study, the influences of pH and current density (j) were investigated to characterize the flocs generated from EC process with aluminum anode. The results indicated that higher j performed better on HA removal due to a larger Al dosage. A highest efficiency in HA removal by EC process occurred at weak acidic range, where the flocs presented a stronger adsorption ability. Higher j and higher water pH led to a larger flocs size. The EC time to form the largest flocs was consistent with that to reach zero point charge, where surface charge favors the aggregation of Al(OH)(3) precursors to form large flocs. Flocs strength was positively correlated with applied j and negatively correlated with water pH. The flocs generated with low applied j and at low initial pH had a higher value of BET surface area and a more porous surface structure. (C) 2016 Elsevier B.V. All rights reserved