Construction of a novel magnetic levitation iron–carbon micro-electrolysis treatment system for dye wastewater and its anti-passivation strategy

Abstract

Micro-electrolysis is an efficient and green method for the treatment of dye wastewater, but the passivation of the material limits its development; therefore, a novel magnetic levitation iron–carbon micro-electrolysis (ICME) treatment system was constructed for the passivation problem. The optimal conditions for the preparation of the material and wastewater treatment were studied in this study. The performance and anti-passivation ability of the magnetic levitation device (MLD), physical levitation device and stationary bed were compared and analyzed, and the results showed that the MLD was superior to the other two devices. The magnetic levitation micro-electrolysis had also achieved ideal results in the treatment and anti-passivation of the actual wastewater. This study also explored the principle of anti-passivation of the MLD and the factors affecting the passivation of materials. The reason of passivation is the metal oxide coating the surface of the material, which prevents the formation of tiny galvanic cells. It is affected by the ion type, the ion concentration and the magnetic field strength, and increasing the concentration of inorganic anions leads to an increase in the passivation rate of the material, while metal cations slow down the passivation of the material. The passivation rate of the material was 19.3% at the optimum magnetic force strength of 7.5 N. On this basis, increasing or decreasing the magnetic force strength would increase the passivation degree of the material. The micro-electrolysis MLD had a better anti-passivation effect in experiments. This study can provide a new idea for the anti-passivation of micro-electrolysis, and provide a basis for the optimization of wastewater treatment.