Abstract:
A novel approach of visible light-emitting diode (Vis-LED) radiation was employed to activate permanganate (Mn(VII)) for efficient organic micropollutant (OMP) removal. The degradation rates of OMPs by Vis-LED/Mn(VII) were 2-5.29 times higher than those by Mn(VII) except for benzoic acid and atrazine. Increasing wavelengths (445-525 nm) suppressed the degradation of diclofenac (DCF) and 4-chlorophenol (4-CP) owing to the decreased quantum yields of Mn(VII). Comparatively, light intensity and Mn(VII) dosage had a positive effect on the degradation of DCF and 4-CP. Experimental data revealed that Mn(V) dominated the DCF degradation whereas Mn(III) was the active oxidant in the 4-CP degradation. Mn(V) and Mn(III) formed from the photo-decomposition of Mn(VII), meanwhile, Mn(III) also formed from the Mn(V) photo-decomposition. The increase in solution pH inhibited DCF degradation but had a positive impact on 4-CP degradation, mainly due to the changing speciation of DCF and 4-CP. Inorganic anions (Cl- and HCO3-) had little impact on DCF and 4-CP degradation, while humic acid (HA) showed a positive impact because of the π-π interaction between HA and DCF/4-CP. The transformation products of DCF and 4-CP were identified and transformation pathways were proposed. Finally, the Vis-LED/Mn(VII) exhibited great degradation performance in various authentic waters. Overall, this study boosts the development of Mn(VII)-based oxidation processes.
摘要:
采用可见光发光二极管(Vis-LED)辐射的新方法激活高锰酸盐(Mn(VII)),以有效去除有机微污染物(OMP)。除苯甲酸和阿特拉津外,Vis-LED/Mn(VII)对OMPs的降解率是Mn(VII)的2-5.29倍。由于Mn(VII)的量子产率降低,增加波长(445-525nm)抑制了双氯芬酸(DCF)和4-氯苯酚(4-CP)的降解。相对而言,光照强度和Mn(VII)用量对DCF和4-CP的降解有积极影响。实验数据表明,Mn(V)主导DCF降解,而Mn(III)是4-CP降解中的活性氧化剂。由Mn(VII)的光分解形成的Mn(V)和Mn(III),同时,Mn(III)也由Mn(V)光分解形成。溶液pH值的增加抑制了DCF降解,但对4-CP降解有积极影响,主要是由于DCF和4-CP的形态变化。无机阴离子(Cl-和HCO3-)对DCF和4-CP降解影响不大,而腐殖酸(HA)由于HA和DCF/4-CP之间的π-π相互作用而显示出积极的影响。鉴定了DCF和4-CP的转化产物,并提出了转化途径。最后,Vis-LED/Mn(VII)在各种真实水域中表现出良好的降解性能。总的来说,这项研究促进了Mn(VII)基氧化过程的发展。