Porous carbon/minerals interwoven particle electrodes co-constructed by residual carbon and ash from coal gasification fine slag and its synergistic electrocatalytic mechanism

Abstract

Complex distribution forms of carbon/ash in coal gasification fine slag (GFS) make it impossible to separate precisely. A combined alkali fusion-polymerization-hydrothermal process was designed to synthesize porous carbon/minerals interwoven particle electrodes (FSAPH) co-constructed by carbon/ash from GFS for electrooxidation treatment of m-cresol wastewater. Based on the hydrogen bonding and coordination capabilities of polyaniline (PAIN), the deconstructed aluminosilicate was regenerated in sheet-like form dispersedly on carbon matrix, effectively enhancing synergistic behavior of carbon and minerals. The electrochemical assessment exhibited superior properties, including a large voltammetry charge of 9.533 mC/cm3, high oxygen evolution potential of 2.15 V, low charge-transfer resistance of 0.36 Ω, and excellent cycle stability. The three-dimensional electrode filled with 0.15 g FSAPH performed pre-adsorption of m-cresol without electricity. Intraparticle diffusion is mainly controlled by SiOSi/AlOH groups on the mineral surface, and the adsorption rate constant KS1 reached 0.491·min−1. After being electrified, AlOH converted H2O2 via three pathways to generate reactive oxygen species (ROS). The rate-determining step in path 2 was the entry of oxygen atoms in OH into the AlOH lattice with the lowest energy barrier of 1.71 kcal/mol. 79.61 mg/L m-cresol can be rapidly degraded within 24 min, 2.6 times that of the two-dimensional electrode system. The electrostatic attraction of carbon ensured the continuous and rapid supply of H2O2 near mineral active sites due to the carbon/minerals interwoven structure. Extensive catalytic sites in thin sheet-like minerals accelerated the electrooxidation of m-cresol on carbon, boosting the catalytic reaction kinetics. Hence, the study realized the comprehensive utilization of carbon/ash in GFS and waste treatment with waste.