Coal gangue, one of the largest solid waste streams produced by coal mining, is commonly viewed as an environmental burden or an inexpensive filler material. A new review suggests that this mineral rich waste could play a much more active role in wastewater treatment.
Researchers have examined how coal gangue can be reconstructed and used to activate peroxymonosulfate, or PMS, a strong oxidant capable of breaking down difficult organic contaminants. Their analysis indicates that properly treated coal gangue is not merely a surface on which catalytic metals are placed. It can become part of the reactive interface that drives pollutant degradation.
"The most important change in perspective is to stop treating coal gangue as an inert carrier and begin asking how its own mineral structure can contribute to oxidation," said corresponding author Lixin Li. "By first unlocking the intrinsic reactivity of coal gangue and then matching it with suitable active components, we may be able to design more efficient and practical catalysts for wastewater treatment."
Coal gangue is generated during coal mining and processing and is often stored in large outdoor piles. These stockpiles occupy land and may contribute to soil erosion, air pollution and the release of acidic substances, salts and metals into surrounding water. At the same time, coal gangue contains silica, alumina, iron bearing minerals and trace metals that could provide useful catalytic properties.
The review explains how thermal, mechanical and chemical treatments can transform the material. Heating can disrupt stable mineral crystals and produce more reactive, disordered phases. Grinding can reduce particle size, expose fresh surfaces and create structural defects. Acid or alkaline treatments can alter pores, surface charges and chemical bonding. Carefully combining these approaches may create a surface that interacts more effectively with PMS.
Once activated, PMS can produce several highly reactive species, including sulfate radicals, hydroxyl radicals and singlet oxygen. It can also support direct electron transfer at the catalyst surface. The dominant degradation route depends on the structure of the catalyst, the chemical properties of the pollutant and the composition of the water.
The researchers highlight tetracycline antibiotics and phenolic compounds as especially useful test pollutants. Tetracycline contains several electron rich reaction sites, making it a demanding probe of whether the catalyst can coordinate adsorption, electron movement and oxidative attack. Phenolic compounds can help reveal whether degradation is controlled by radical reactions, non radical pathways or a mixture of both.
Among the review's central conclusions is that future catalyst development should prioritize maximizing coal gangue's intrinsic oxidative potential, particularly its ability to promote hydroxyl radical formation, before adding external metals or other active phases. Those additional components should then be selected to match the gangue's surface chemistry, defects and electronic structure.
However, the authors caution that high pollutant removal in laboratory water is not enough to demonstrate practical value. Future studies should compare reaction rates under standardized conditions and distinguish the contribution of raw coal gangue, reconstructed coal gangue and added catalytic components.
Testing should also include real industrial wastewater, repeated catalyst use, metal leaching, degradation product toxicity, energy consumption and treatment costs. Coal gangue can be considered a sustainable catalytic resource only when performance, durability, environmental safety and economic feasibility are demonstrated together.
The review provides a roadmap for moving coal gangue based PMS treatment from waste reutilization toward evidence based catalyst design, offering a possible strategy for addressing solid waste accumulation and persistent water pollution at the same time.
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Journal reference: Wu Y, Tan R, Huang L, Dong Z, Yang F, et al. 2026. Coal gangue-based catalyst activates peroxymonosulfate for efficient degradation of organic pollutants in wastewater. Environmental and Biogeochemical Processes 2: e014 doi: 10.48130/ebp-0026-0008
https://www.maxapress.com/article/doi/10.48130/ebp-0026-0008
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About the Journal:
Environmental and Biogeochemical Processes (e-ISSN 3070-1708) is a multidisciplinary platform for communicating advances in fundamental and applied research on the interactions and processes involving the cycling of elements and compounds between the biological, geological, and chemical components of the environment.
