Biochar supported nanoscale zerovalent iron composite used as persulfate activator for removing trichloroethylene

• nZVI/BC was successfully prepared and characterized as an efficient activator of persulfate.
• The redox reaction and the electron-transfer process were accounted for SO4- generation.
• Trichloroethylene was efficiently degraded in nZVI/BC–persulfate system at various pH values.

Biochar (BC) supported nanoscale zerovalent iron (nZVI) composite was synthesized and used as an activator for persulfate to enhance the trichloroethylene (TCE) removal in aqueous solutions. The degradation efficiency of TCE (0.15 mmol L−1) was 99.4% in the presence of nZVI/BC (4.5 mmol L−1, nZVI to BC mass ratio was 1:5) and persulfate (4.5 mmol L−1) within 5 min, which was significantly higher than that (56.6%) in nZVI–persulfate system under the same conditions. Owing to large specific surface area and oxygen-containing functional groups of BC, nZVI/BC enhanced the SO4- generation and accelerated TCE degradation. On the basis of the characterization and analysis data, possible activation mechanisms of the Fe2+/Fe3+ (Fe(II)/Fe(III)) redox action and the electron-transfer mediator of the BC oxygen functional groups promoting the generation of SO4- in nZVI/BC–persulfate system were clarified.

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