Synthesis of nZVI-Ni@BC composite as a stable catalyst to activate persulfate: Trichloroethylene degradation and insight mechanism

In Fenton-like oxidation processes, the use of biochar (BC) as support material for the nanoscale zero valent ironnickel (nZVI-Ni) bimetallic particles attained much attention to activate persulfate (PS) for TCE degradation in aqueous medium. In present work, nZVI-Ni@BC particles with nZVI-Ni to BC mass ratio of 1:5 exhibited excellent results (> 99 % +/- 0.24) for TCE degradation. The physico-chemical characteristics, surface morphologies, and elemental mapping of the synthesized nZVI-Ni@BC particles investigated through SEM, EDX, TEM, XPS, XRD, BET and FTIR spectroscopy. For the nZVI-Ni@BC-persulfate system, the effects of PS concentration, initial pH, inorganic ions and natural organic matter (NOM) on TCE degradation were evaluated. Batch experiments revealed that complete removal of TCE (> 99 % +/- 0.25) was attained at 250 mg L-1 of nZVI-Ni@BC and 4.0 mM PS dosages at pH 3.49 +/- 0.55. Scavenging and electron paramagnetic resonance (EPR) verified the dominant role of both SO4 center dot- and OH (center dot)radicals in acidic environment for degradation of TCE. Moreover, high level of carbonate, bicarbonates and NOM inhibited the overall TCE oxidation reaction. In summary, these results suggested that nZVI-NI@BC composite was an alternative, economic and promising catalyst for the activation of PS to degrade chlorinated contaminants in aqueous medium.

Automated summary

The study shows that the nZVI-Ni@BC composite material performs well in activating PS to degrade chlorinated contaminants in water, achieving over 99% TCE degradation. The experimental results also indicate that in acidic environments, both SO4·- and OH· radicals play a dominant role in TCE degradation, while high levels of carbonates, bicarbonates, and NOM inhibit the oxidation reaction of TCE.