Crystalline Boron Significantly Accelerated Fe(Iii)/Pms Reaction as Electron Donors: Iron Recycle, Reactive Species Generation, and Acute Toxicity Evaluation

Crystalline boron (C-boron) is regarded as electron donors due to internal electron-sharing B–B bonds. However, related research on boron chemistry is limited. In this study, we demonstrate that the addition of C-boron to the Fe(III)/peroxymonosulfate (PMS) system can effectively improve the degradation of flunixin meglumine, aspirin, nitrobenzene, and benzoic acid at pH 4.0–10.0 (without buffer). Compared to the Fe(III)/PMS system, the kobs of the C-boron/Fe(III)/PMS system for these four contaminants degradation at pH 7.0 was approximately 8.7–65.1 times higher. C-boron enhanced the aqueous Fe(II) concentration in the Fe(III)/PMS system from 5.4 to 16.2 mg/L in 20 min reaction, while the Fe(IV) was originated by the produced Fe(II) in system. Electron paramagnetic resonance and quenching experiments revealed the presence of •OH, 1O2, and •O2−, in which the corresponding contributions of •OH to FMME and ASA were 16.7% and 28.1% at pH 7.0. The toxicity of the C-boron/Fe(III)/PMS solution on the growth inhibition rate of Microcystis aeruginosa showed an obviously increase at 24 h, and then a decrease during 48-96 h, which was resulted from the inhibited photosynthetic system of chlorophyll a and chlorophyll b. Overall, this work provides new insights into radical and nonradical oxidation in the C-boron/Fe(III)/PMS system.