Biochar supported Ni/Fe bimetallic nanoparticles to remove 1,1,1-trichloroethane under various reaction conditions

•Biochar supported Ni/Fe nanoparticles was successfully synthesized.•BC-Ni/Fe system degraded 200 mg/L 1,1,1- trichloroethane efficiently.•The generation of H species represented the primary redox-active entity.•Humic acid inhibited the BC-Ni/Fe nanoparticles to degrade TCA.

In this study, Ni/Fe nanoparticles supported by biochar to stimulate the reduction of 1,1,1-trichloroethane (1,1,1-TCA) in groundwater remediation was investigated. In order to enhance the reactivity of ZVI (zero valent iron) nanoparticles, surface modification of ZVI was performed using nickel and biochar. The removal efficiency of 1,1,1-TCA increased from 42.3% to 99.3% as the biochar-to-Ni/Fe mass ratio increased from 0 to 1.0. However a higher biochar-to-Ni/Fe ratio showed little difference in the 1,1,1-TCA degradation efficiency. In the presence of Ni, atomic hydrogen generated by ZVI corrosion could be absorbed in the metal additive's lattice and then produce a hydride-like species (H) that represented the primary redox-active entity. The effects of various factors were evaluated, including pH, humic acid (HA) and inorganic matters (Cl−, CO32-, HCO3−, NO3− and SO42-). The degradation of 1,1,1-TCA was greatly affected by pH. The presence of Cl−, CO32-, HCO3− and SO42− had negligible effects, but NO3− and HA showed a significant inhibitory effects on 1,1,1-TCA degradation. In conclusion, biochar supported Ni/Fe nanoparticles could be highly effective for 1,1,1-TCA degradation.

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