4.7 Article

One-step preparation of ZVI-sludge derived biochar without external source of iron and its application on persulfate activation

Journal

SCIENCE OF THE TOTAL ENVIRONMENT
Volume 714, Issue -, Pages -

Publisher

ELSEVIER
DOI: 10.1016/j.scitotenv.2020.136728

Keywords

Biochar; Environmental remediation; 1n-situ chemical oxidation; Persulfate; Sewage sludge; Zero valent iron

Funding

  1. National Key Research and Development Program of China [2018YFC1802302]
  2. National Natural Science Foundation of China [21671072]
  3. Fundamental Research Funds for the Central Universities [2019kfyRCPY058]
  4. Chutian Scholar Foundation from Hubei province

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Zero Valent Iron (ZVI) is an important and widely employed environmental remediation material in brownfield. However, the instability of fine size ZVI and the strong aggregation of nanoscale-ZVI limited its further application. To overcome these drawbacks, ZVI-Sludge Derived Biochar (SDBC) was prepared without external iron source through the one-step process of pyrolysis. The characterization results including SEM-EDX, XRD and XPS confirmed the successful loading of Fe-0 on the surface of SDBC. The activation efficiency of persulfate (PS) in in-situ chemical oxidation system was studied. The environmental remediation properties of ZVI-SDBC/PS system were evaluated employing acid orange (AO7) and landfill leachate as target pollutants. ZVI-SDBC/PS system was highly efficient as that 99.0% of AO7 (0.06 mM) was removed by 0.925 mM of PS and 0.5 g L-1 of ZVI-SDBC. In addition, total organic carbon (TOC) and ammonia in leachate were removed by 62.8% and 99.8%, respectively. The removal efficiency of AO7 was nearly independent on initial pH as that 89.1% and 99.1% of AO7 were removed at pH of 9.08 and 2.13 respectively. Hydroxyl radicals dominated in the reaction under neutral and alkaline conditions with contribution rates of 71.9% and 86.1% respectively. Noticeably, not only free radicals but also non-radical species such as singlet oxygen contributed to the degradation, which favored the pH-independent performance. The reuse performance of ZVI-SDBC was higher than these of previously reported ZVI-based catalysts as that the first-order rate constant of AO7 removal decreased not much from 0.0718 to 0.0502 min(-1) after the three-cycle reuse assays. In summary, ZVI-SDBC showed advantages such as the facile and chemical-saving preparation method, reliable disposal of municipal sewage sludge, remarkable efficiency and stability. These advantages proved ZVI-SDBC/PS system as an effective strategy of controlling waste by waste, and implicated its potential application in full-scale for environmental remediation in brownfield. (C) 2020 Published by Elsevier B.V.

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