Abstract
The industrial waste red mud was used as the iron source, and economical and environmentally friendly anthracite was used as the reducing agent to prepare red mud-supported zero-valent iron (RA@ZVI) composite materials by the carbothermal reduction method. The system evaluated the effects of the preparation conditions and removal conditions of RA@ZVI material on the degradation effect of carmine. The experimental results show that under the conditions of anthracite with a ratio of 35%, calcination at 1000 °C for 60 min, the prepared RA@ZVI material with a RA@ZVI dosage of 0.5 g/L, an initial carmine concentration of 50 mg/L, a solution pH value of 3, and a reaction temperature of 25 °C, the carmine removal rate is close to 100%. The material characterization results reveal that the high efficiency of RA@ZVI stems from its unique physicochemical properties. XRD analysis confirmed that a higher calcination temperature (1000 °C) effectively promoted the reduction of iron oxides in red mud to ZVI. SEM-EDS analysis indicated that micrometer-sized and well-dispersed zero-valent iron particles were formed in the prepared RA@ZVI material. Mechanism research has confirmed through free radical capture experiments that in the degradation process of carmine, hydroxyl radicals (·OH) and superoxide radicals (·O2−) play a key role. RA@ZVI undergoes a direct REDOX reaction with carmine through the strong reducing property of ZVI, and induces the generation of the above-mentioned highly active free radicals, which work in synergy to attack carmine molecules. Specifically, the azo bond (–N=N–) and anthraquinone ring structure of carmine are effectively disrupted, thereby achieving efficient mineralization and removal of the dye. This study not only provides an economically efficient and environmentally friendly high-value utilization approach for red mud waste, but also offers a new type of RA@ZVI material for the advanced treatment of complex azo dye wastewater. This material shows certain potential in the treatment of printing and dyeing wastewater.
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The data in this manuscript are all derived from experiments and tests, and they are all new experimental results. The data in the manuscript can be provided by the corresponding author upon request.
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Acknowledgements
This work was supported by the National Natural Science Foundation of China (Grant No. 51464007), Research Project of Panzhihua Iron and Steel Research Institute of Pansteel Group Co., Ltd. (2024520103000481), and Technology Support Plan of Guizhou Province (Grant No. [2021]482).
Funding
This work was supported by the National Natural Science Foundation of China (Grant No. 51464007), Research Project of Panzhihua Iron and Steel Research Institute of Pansteel Group Co., Ltd. (2024520103000481), and Technology Support Plan of Guizhou Province (Grant No. [2021]482).
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Z.W.: Writing-commenting and editing; B.T.: Supervision, data curation; S.L.: Verification; P.Z.: Validation and visualization.
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Wang, Z., Tuo, B., Li, S. et al. Removal of carmineusing red mud-supported ZVI materials. Sci Rep (2026). https://doi.org/10.1038/s41598-026-37767-6
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DOI: https://doi.org/10.1038/s41598-026-37767-6
