COD removal from gasfield produced water using photoelectrocatalysis process on coil type microreactor

A special type of reactor with a high active surface-to-volume ratio was used for investigation of organic pollutants degradation from a gasfield produced water by photoelectrocatalysis process. The GC–MS analysis showed that there were more than 50 organic substances in this wastewater; therefore, COD was considered as the target parameter for studying. A simple evaporation process used for decreasing high TDS of the wastewater reduced its electrical conductivity from 6300 μS/cm to 1100 μS/cm and also initial COD decreased simultaneously from 9500 mg/L to 750 mg/L. Distilled wastewater from the evaporation process was treated again by the photoelectrocatalysis process using a coil type microreactor, and its COD dropped off to 143 mg/L. Instead of usual semiconductors in photoelectrocatalysis like TiO₂, boron carbon nitride (BCN) nanosheets are used as a photocatalyst in this study. Investigating the impact of different parameters on COD removal efficiency showed that the greatest COD removal efficiency (81%) was obtained at residence time 15 min, pH = 3, applied cell voltage 20 V, electrical conductivity = 2500 μS/cm and H₂O₂ concentration of 8 mM.