BiOBr nanoparticle-modified Ti3C2Tx MXenes for photocatalytic degradation of organic arsenic in wastewater
Abstract
Arsenic (As) contamination in water remains a serious concern due to its high toxicity and harmful effects on human health and the environment. Herein, we successfully synthesized a novel photocatalyst (BiOBr/Ti3C2) by in situ inserting BiOBr nanoparticles into Ti3C2Tx MXenes for the photocatalytic degradation of organic arsenic roxarsone (3-nitro-4-hydroxyphenylarsonic acid) in wastewater. BiOBr/Ti3C2 exhibited a unique morphology characterized by uniform BiOBr nanoparticles within more dispersed Ti3C2Tx layers. Heterojunctions were formed between Ti3C2Tx and BiOBr, which were conducive to photogenerated charge separation and electron transfer in Ti3C2Tx layers. An optimal BiOBr/Ti3C2 photocatalyst achieved a removal efficiency of 1.27 mg gcat.−1 h−1 for 2 mg L−1 of roxarsone wastewater within 0.5 h and a higher removal rate (about 1.5 times at 3 h) than pure Ti3C2Tx. In addition, BiOBr/Ti3C2 exhibited an apparent quantum yield (AQY) of 29.5% and good reusability for 4 cycles. The enhanced photocatalytic performance was mainly attributed to the intercalation of BiOBr nanoparticles within Ti3C2Tx layers, which increased reaction space and improved the separation and transport of photocarriers. Holes (h+) and ˙OH in the valence band (VB) of BiOBr/Ti3C2 were involved in the main route of roxarsone oxidative mineralization. The present BiOBr/Ti3C2 system provides fundamentals for the sustainable photocatalytic treatment of wastewater containing organic arsenic.