New Carbon Materials•2026•DOI: 10.1016/S1872-5805(26)61101-8
Phenolic compounds are typical refractory organic pollutants in coal chemical coking wastewater, posing significant risks to ecosystems and human health. Conventional treatment methods are inefficient, necessitating advanced oxidation processes (AOPs). Here, we report a low-cost Fe/N–C catalyst synthesized from coal-tar pitch, a common by-product of the coal chemical industry, via a self-assembly and pyrolysis strategy using graphitic carbon nitride (g-C3N4) as a template and nitrogen source, with dicyandiamide as an auxiliary nitrogen source and FeCl3·6H2O as the iron precursor. The resulting nitrogen-doped carbon nanosheets possess abundant defects (sp3-C/sp2-C = 0.66) and atomically dispersed iron species. The Fe/N–C catalyst exhibits outstanding catalytic activity for peroxydisulfate (PDS) activation, achieving over 98% phenol degradation within 30 minutes and a 60% total organic carbon (TOC) removal rate. Mechanistic studies, including radical quenching and electron paramagnetic resonance (EPR) experiments, reveal that both radical and non-radical pathways contribute to phenol degradation, with singlet oxygen (1O2) as the primary reactive oxygen species. Electrochemical analyses demonstrate that atomically dispersed Fe sites significantly enhance interfacial electron transfer. Post-reaction characterization indicates the consumption of pyrrolic-N, C=O, and carbon defects as active sites, while graphitic-N and Fe–N structures remain stable, confirming the catalyst's stability. This work provides an economical route to convert coal-tar pitch into high-performance catalytic materials for efficient water treatment, embodying the circular economy concept of waste-to-resource utilization.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202509009
Air-supplied jet aerators, combining hydraulic jet and gas induction principles, are critical equipment in aerobic biological wastewater treatment. However, low energy conversion efficiency and insufficient local gas-liquid mixing are core bottlenecks limiting their competitiveness. A three-dimensional flow field analysis method for jet aerators was developed based on the k-ε turbulence model and Euler-Euler multiphase flow model. The effects of different orifice plate distributions, shapes, sizes, hole numbers, and installation positions on average pressure, turbulent kinetic energy, and turbulent dissipation rate were systematically studied. Results show that the asterisk-shaped orifice plate yields the highest gas-liquid two-phase turbulent mixing intensity, followed by the annular shape, while the parallel arrangement yields the lowest. With increasing hole number and single-hole size, average pressure, velocity, turbulent kinetic energy, and turbulent dissipation rate for different plate shapes initially fluctuate downward and then stabilize. When the number of triangular holes is 9, mass transfer efficiency is significantly enhanced, and overall aerator performance is excellent. When the triangular hole diameter is 7 mm, the device achieves an optimal match between energy utilization and mixing efficiency across pressure distribution, velocity field, turbulent kinetic energy, and dissipation rate. The farther the porous thin plate is installed from the sewage nozzle, the further gas-liquid two-phase turbulence is enhanced. Experiments confirm that the boundary layer is fully developed, liquid and air are thoroughly mixed, and the orifice plate promotes bubble breakup and refinement through throttling and collision, significantly improving oxygen transfer efficiency. This research provides a theoretical basis and technical support for the transformation and upgrading of aeration technology towards high efficiency and low carbon, and for extending equipment service life.