Characteristics and anode reaction of organic wastewater-assisted coal electrolysis for hydrogen production

Electrolytic hydrogen production has the advantages of distributed on-demand hydrogen production, high purity and facile coupling with renewable energy sources, but this process is very energy intensive. In this study, the organic wastewater-assisted coal electrolysis process for hydrogen production was studied in an H-type electrolytic cells. Part of the energy can come from the carbon sources in coal and wastewater to reduce power consumption. Linear sweep voltammetry and potentiostatic techniques were used to study the electrolysis characteristics and anode reaction of the wastewater coal slurry. The results showed that the difference in the composition of the wastewater made the electrolysis characteristics quite different. The gas washing water, sulfur water and slag water produced by coal conversion could significantly increase the current density of coal slurry electrolysis. As for the gas washing water, it has no obvious effect on the catalytic effect of Fe³⁺, and the increase in current density was mainly due to the effects of organic matter and chloride. With increasing voltage, the main anode reaction of the wastewater coal slurry was divided into three stages, namely oxidation of coal particles (0.7–1.0 V), oxidation of organic matter in wastewater (1.0–1.5 V) and oxidation of chloride ions (1.5–2.0 V). Below the chlorine oxidation potential, chloride ions could also promote the oxidation of coal particles. The oxidation mechanism of coal slurry in the presence of wastewater was proposed.