A novel desulphurization process of coal water slurry via sodium metaborate electroreduction in the alkaline system

► We investigated an desulfurization process for CWS using NaBO2 electroreduction under the ambient conditions. ► Desulfurization efficiency improved with the increases of NaBO2 concentration, electrolytic time, and electrolytic voltage. ► Desulfurization efficiency improved with the decreases of coal particle size and CWS concentration. ► NaBO2 was converted into NaBH4 by means of the electrochemical reduction (ER) on the cathode. ► The ED process described here is an environmental friendly method, since it only uses electricity to realize B recycling.