The key role of crystal boron in enhanced degradation of refractory contaminants using heterogeneous Fe3+/SPC system

An origin Fenton-like system was discussed for the abatement of refractory contaminants. Sodium percarbonate (SPC) was utilized as the source of H2O2 and crystal boron (C-boron) was applied to enhance the activation of H2O2. Under the conditions of 0.50 mM Fe3+, 0.34 mM SPC, and heterogeneous catalysis using 100 mg L-1 C -boron, four target pollutants, at the initial concentrations of 20 mu M, could be efficiently degraded by the Fenton -like system, with a degradation rate within 20 min up to 81.1% (aspirin, ASA), 92.8% (nitrobenzene, NB), 94.7% (flunixin meglumine, FMME), and 94.3% (benzoic acid, BA) respectively and total organic carbon removal up to 25.0%. The increase of Fe2+ concentration indicated that the conversion of Fe2+/Fe3+ was remarkably promoted by C-boron. Degradation reactions at acidic pH were comparatively fast, with pH-dependent kobs of 9.9 x 10-2 min-1 (ASA), 1.5 x 10-1 min-1 (NB), 1.7 x 10-1 min- 1 (FMME), and 1.9 x 10-1 min- 1 (BA), whereas those at neutral and alkaline pH were slower. Furthermore, reactive oxygen species including center dot OH, 1O2, and O2 center dot-were identified by in-situ electron paramagnetic resonance tests. The contribution ratios of center dot OH turned out to be about 71.3-86.7% for the decomposition of four contaminants. The elimination of natural organic matter and the performance of material recycling highlighted the potential for its application in water treatment. The inhibition rate of Chlorella pyrenoidosa reached 211.9% in the C-boron/Fe3+/SPC system. The relatively high algae toxicity limited its application scope, which requires additional research to resolve.

Automated summary

An origin Fenton-like system using sodium percarbonate (SPC) as the source of H2O2 and crystal boron (C-boron) as an enhancer was discussed for the removal of refractory contaminants. The system efficiently degraded four target pollutants, with degradation rates up to 81.1% (aspirin), 92.8% (nitrobenzene), 94.7% (flunixin meglumine), and 94.3% (benzoic acid) respectively, and total organic carbon removal up to 25.0%. The conversion of Fe2+/Fe3+ was promoted by C-boron, and degradation reactions at acidic pH were faster than at neutral and alkaline pH. Reactive oxygen species including ·OH, 1O2, and O2·- were identified, with ·OH contributing most to the decomposition of contaminants. The system also exhibited potential for water treatment through the elimination of natural organic matter and material recycling, although additional research is needed to address the high algae toxicity.