Removal of high concentration of chloride ions by electrocoagulation using aluminium electrode

Wastewater containing a high concentration of chloride ions (Cl- ions) generated in industrial production will corrode equipment and pipelines and cause environmental problems. At present, systematic research on Cl- removal by electrocoagulation is scarce. To study the Cl- removal mechanism, process parameters (current density and plate spacing), and the influence of coexisting ions on the removal of Cl- in electrocoagulation, we use aluminum (Al) as the sacrificial anode, combined with physical characterization and density functional theory (DFT) to study Cl- removal by electrocoagulation. The result showed that the use of electrocoagulation technology to remove Cl- can reduce the concentration of Cl- in an aqueous solution below 250 ppm, meeting the Cl- emission standard. The mechanism of Cl- removal is mainly co-precipitation and electrostatic adsorption by forming chlorine-containing metal hydroxyl complexes. The current density and plate spacing affect the Cl- removal effect and operation cost. As a coexisting cation, magnesium ion (Mg2+) promotes the removal of Cl-, while calcium ion (Ca2+) inhibits it. Fluoride ion (F-), sulfate (SO42-), and nitrate (NO3-) as coexisting anions affect the removal of Cl- ions through competitive reaction. This work provides a theoretical basis for the industrialization of Cl- removal by electrocoagulation.

Automated summary

In this study, aluminum (Al) was used as the sacrificial anode to investigate the Cl- removal mechanism by electrocoagulation. The research showed that electrocoagulation technology can reduce the Cl- concentration in the aqueous solution below 250 ppm, meeting the emission standard. The removal mechanism of Cl- involves co-precipitation and electrostatic adsorption by forming chlorine-containing metal hydroxyl complexes. The current density and plate spacing have an impact on the efficiency of Cl- removal and the operation cost. The coexistence of magnesium ion (Mg2+) promotes Cl- removal, while calcium ion (Ca2+) inhibits it. Coexisting anions such as fluoride ion (F-), sulfate (SO42-), and nitrate (NO3-) affect the removal of Cl- ions through competitive reactions. This work provides a theoretical basis for the industrialization of Cl- removal by electrocoagulation.