Title

Origins of boron catalysis in peroxymonosulfate activation and advanced oxidation

Document Type

Journal Article

Publication Title

Journal of Materials Chemistry A

Publisher

Royal Society of Chemistry

School

School of Engineering

Funders

The authors appreciate the financial support from the Australian Research Council (DP190103548) and Open Research Projects from State Key Laboratory (SKL-ChE-16C05 and QAK201808). We also acknowledge the financial support from the National Science Foundation of China (NSFC, No. 21777033) and Science and Technology Program of Guangdong Province (2017B020216003).

Grant Number

ARC Number : DP190103548

Comments

Originally published as: Duan, X., Li, W., Ao, Z., Kang, J., Tian, W., Zhang, H., ... & Wang, S. (2019). Origins of boron catalysis in peroxymonosulfate activation and advanced oxidation. Journal of Materials Chemistry A, 7(41), 23904-23913.

Original article available here.

Abstract

Metal-free materials have exhibited great merits as substitutes for toxic and scarce metals/oxides in environmental catalysis. In this work, amorphous boron (A-Boron) is exploited as a nonmetal catalyst for peroxide activation. It is discovered that A-Boron is exclusively reactive for peroxymonosulfate (PMS) activation for the degradation of a diversity of organic contaminants in water, including benzenes, phenolics, dyes and antibiotics. Moreover, comparative tests show that A-Boron stands out among diverse heterogeneous catalysts, such as transition metal oxides, nanocarbons and non-carbonaceous materials (sulfur, phosphorus, boron nitride, and boron carbide). Competitive radical scavenging tests and in situ radical capture analysis by electron paramagnetic resonance (EPR) revealed that both sulfate (minor contribution) and hydroxyl radicals (dominant contribution) are generated and account for the organic oxidation. Advanced characterisation techniques suggest that the boron-based catalysis stems from the short-range ordered grain boundaries and amorphous domains in A-Boron. This is further evidenced by the fact that after thermal treatment, the surface-tailored boron samples (A-B-400 to 1000) exhibit inferior activities, with 10.4% to 28.3% phenol removal compared with A-Boron (74.3%); this is due to the formation of surface boric acid/hydroxide, which blocks the active boron phases. Theoretical calculations illustrate that the (1 0 0), (1 0 1) and (1 1 0) terminations and amorphous regions of elemental boron can directly cleave the peroxide O–O bond and decompose PMS to produce reactive hydroxyl radicals, which is in agreement with the experimental discoveries. This study provides a novel metal-free catalytic system for wastewater treatment and provides the first mechanistic insights into the origins of boron-based catalysis.

DOI

10.1039/c9ta04885e

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