An effective method for improving electrocoagulation process: Optimization of Al13 polymer formation

Al-13 polymer has been believed to be the most active species responsible for coagulation. The character of Al species distribution and the formation of Al-13 polymer in electrocoagulation (EC) process were investigated in order to provide insight into optimizing EC operation and design. The results indicated that predominant Al species shifted from monomer toward medium polymer then to larger polymer or Al( OH)(s) with increasing EC time. The in-situ Al-13 polymer could be generated in EC process, and became the dominant species during 5-15 min. In EC process, Al-13 species fraction positively correlated with the removal of turbidity and organic. The increase of pH and current density could accelerate the hydrolysis-polymerization process of Al3+. pH 5-7 and lowering current density favored the formation of Al-13 polymer during EC process, EC process with bipolar electrodes had a higher yield of monomeric and Al-13 species, while EC process with monopolar electrodes facilitated the formation of larger polymer or Al(OH)(s). The content of Al-13 polymer can reach more than 60% under optimal conditions. (C) 2015 Elsevier B.V. All rights reserved.