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Significant enhancement on ammonia removal by thermal/peroxymonosulfate system with bromide ion: Performance, influencing factors and mechanism

[Display omitted] •Br- improved the removal of NH4+-N in thermal/PMS system significantly.•HBrO was identified as the dominant oxidant responsible for NH4+-N removal.•HBrO was mostly produced by the reaction between PMS and Br- under high temperature.•HO⋅, SO4⋅- and Br⋅ were generated and made minor...

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Published in:Separation and purification technology 2025-02, Vol.354, p.128740, Article 128740
Main Authors: Zhang, Shuyin, Zou, Jing, Chen, Lingxuan, Shen, Chunhua, Lu, Jian, Zhang, Jianlin, Cui, Hangyu, Huang, Geng, Ma, Jun
Format: Article
Language:English
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Summary:[Display omitted] •Br- improved the removal of NH4+-N in thermal/PMS system significantly.•HBrO was identified as the dominant oxidant responsible for NH4+-N removal.•HBrO was mostly produced by the reaction between PMS and Br- under high temperature.•HO⋅, SO4⋅- and Br⋅ were generated and made minor contribution to NH4+-N removal.•Br--enhanced system was superior to thermal/PMS and Cl--enhanced systems for TN removal. Although thermal-activated peroxymonosulfate (PMS) system possesses good performance on the removal of organic pollutants, thermal/PMS system exhibited poor capacity to remove ammonia nitrogen (NH4+-N). This study demonstrated the huge enhancement on the removal of NH4+-N by thermal/PMS system with the commonly coexistent bromide ion (Br-). The elimination of NH4+-N by thermal/PMS/Br- system fitted the pseudo-zero-order kinetics model well, while the corresponding kobs in the presence of 200 μM Br- was 5.76 times greater than that by thermal/PMS system. Bromine (HBrO) was confirmed as the dominant oxidant responsible for removing NH4+-N and TN, while the radicals of HO⋅, SO4⋅- and Br⋅ were also generated but made minor contribution to removing NH4+-N. HBrO was mostly produced by PMS reacting directly with Br-, while these radicals were produced from the cleavage of the O-O bond in PMS and the reaction between PMS and HBrO under high temperature. Thermal/PMS/Br- system exhibited superior performance on TN removal (up to 90 %) than that by thermal/PMS system (less than 5 %) and Cl--enhanced system (about 80 %). The main removal product of NH4+-N was identified as the environmentally friendly gas of N2, although nitrate was also detected. Neutral pH condition was the optical pH for NH4+-N removal. Increasing reaction temperature, PMS dosage and Br- concentration were beneficial to accelerating the removal of NH4+-N. Cations of Cu2+ and Fe3+, anions of SO42-, CO32- and NO3-, humic acid and the actual water matrix of landfill leachate negligibly influenced the removal of NH4+-N, while Cl- exhibited strong enhancement on NH4+-N removal. In summary, this study provided an effective method to improve the oxidizing capacity of thermal/PMS system, especially for NH4+-N removal in wastewater containing Br-.
ISSN:1383-5866
DOI:10.1016/j.seppur.2024.128740