Changes of total organic carbon and kinetics of ultrasonic-assisted coal water slurry electrolysis in NaOH system

• Ultrasonic improved the total organic carbon concentration from electrolysis.
• The inherent mineral matters hindered coal electrolysis oxidation.
• The chemical reaction was the controlling-step of coal electrolysis.
• Ultrasonic improved mass transfer of coal particle for electrolysis.

Coal water slurry (CWS) electrolysis not only improved efficiency of water electrolysis for hydrogen, but also removed sulfur and mineral matters in coal. Fortunately, it may be a potential method which obtained directly organic compounds from coal. However, both the stability and mass transfer of coal particle were very poor during CWS electrolysis. As we known, ultrasonic wave can improve the stability for CWS and mass transfer strength of coal particle. In this paper, ultrasonic-assisted CWS electrolysis was carried out in NaOH solution. Results showed that the total organic carbon (TOC) concentration for CWS electrolysis increased. According to the results from kinetics study, it was not difficult to find that the chemical reaction is the controlling-step for CWS electrolysis. And the apparent activation energy (AAE) changed from 28.37 to 27.61 kJ mol− 1 with ultrasonic addition. The slight change in the AAE suggested that the ultrasonic improved the mass transfer of coal particle only in electrolyte, and did not change reaction path. Additionally, TOC concentration decreased with the increase in mineral matter content, indicating that the mineral matters inhibited the organic structure electrolysis.