Distribution modes of residual carbon and ash in coal gasification fine slag and its feasibility analysis as particle electrodes

From the perspective of environmental protection and resource utilization, the feasibility of treating m-cresol wastewater with coal gasification fine slag (GFS) as particle electrodes in an electrocatalytic system was evaluated to achieve the purpose of treating waste with waste. Characterization by scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), Raman, and fourier transform infrared spectroscopy (FTIR) confirmed that the GFS featured a diverse inorganic framework, large specific surface area (as large as above 155 m2 g−1), hierarchical porous structure, and plenty of catalytic sites. The Venn diagram method was used to systematically propose the following distribution modes of residual carbon (RC) and ash in GFS: discrete distribution, embedded distribution, crosslinked distribution, and association and bonding. Only 8 g L−1 of GFS particle electrodes prevented the formation of a yellow sticky passivation film on the anode. Compared to the two-dimensional electrocatalytic system (47.89%), the wastewater treatment efficiency was increased by 108.81%. Zero-order kinetic results showed that the reaction rate constant was the highest (2.1106 mg L−1·min−1) when the secondary flotation RC was adopted as particle electrodes. It was indicated that GFS in discrete mode played either no role or at most a minor role. Last but not least, the synergy of RC and ash was revealed from a molecular perspective. The RC exhibited hierarchical microporous/mesoporous/macroporous structure, which facilitated the entry of H2O2 into the catalytic sites of ash. Abundant catalytic sites in ash accelerated adsorption and oxidation processes on RC surfaces. [Display omitted] •Coal gasification fine slag (GFS) could be used as particle electrodes.•Only 8 g L−1 GFS significantly mitigated or prevented anodic contamination.•Distribution modes of carbon and ash were proposed in the form of Venn diagrams.•The m-cresol degradation pathway and the synergy of carbon and ash were elucidated.