Modeling of the electrocoagulation process: A study on the mass transfer of electrolysis and hydrolysis products

•A 2D model considering mass transfer of ionic species was established to simulate EC process.•There are three areas in electrocoagulation channel: acid front, base front and buffering area.•The insoluble hydroxides or flocs are trapped and collected in the buffering area.

Electrocoagulation (EC) which is characterized by in-situ generation of coagulant and hydroxide flocs with high absorption ability is an environmental-friendly process for treating wastewater with heavy metal ions and toxic organics. In order to get a systematic understanding of EC process, a steady state model considering electrochemical, hydrolysis reaction, mass and momentum transfer was established. The coagulant (Al3+), H+ and OH− are generated at the direction of streamline. However, the concentration of these species increases and reaches its maximum near inlet and after that they decrease gradually to a much lower level. We found that there are three areas in EC channel: acid front, base front and buffering area, which has also been found in electro-kinetic remediation. At the direction of streamline, the electro-generated Al3+ is gradually hydrolyzed to hydroxides. The anionic and cationic hydroxides accumulate in acid front and base front respectively. The insoluble hydroxides will accumulate in buffering area, which could be considered as a trap for hydroxide flocs and pollutants.

Graphical abstractDownload high-res image (102KB)Download full-size image