Sulfate radical induced degradation of Methyl Violet azo dye with CuFe layered doubled hydroxide as heterogeneous photoactivator of persulfate. (1st December 2018)

• Record Type: Journal Article
• Authors: Ma, Yinghao; Chen, Fei; Yang, Qi; Zhong, Yu; Shu, Xiaoyu; Yao, Fubing; Xie, Ting; Li, Xiaoming; Wang, Dongbo; Zeng, Guangming
• Is Part Of: Journal of environmental management. Volume 227(2018)
• Page Start: 406
• Page End: 414
• Publication Date: 2018-12-01
• Subjects: Cu-Fe layered doubled hydroxide -- Heterogeneous photo-activation -- Methyl Violet -- Persulfate -- Visible-light irradiation; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2018.08.030
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Persulfate (PS)-based advanced oxidation processes have aroused considerable attentions due to their higher efficiency and wider adaptability to the degradation of bio-recalcitrant organic contaminants. In this study, Cu-Fe layered doubled hydroxide (CuFe-LDH) was employed to degrade Methyl Violet (MV) through heterogeneous photo-activation of PS under visible-light irradiation. The reaction kinetics, degradation mechanism, catalyst stability were investigated in detail. Under the conditions of CuFe-LDH (3:1) dosage 0.2 g/L, PS concentration 0.2 g/L and without initial pH adjustment, 20 mg/L MV was almost completely degraded within 18 min. Electron Spin Resonance (ESR) test and radical quenching experiment indicated that sulfate radicals (SO4 - ) were the dominant reactive oxidants for the MV decolorization, while hydroxyl radicals (OH) were also involved. The CuFe-LDH/PS/Vis system was applicable at wide range of pH level (3–9). However, extreme pH level would lead to the reduction or transformation of SO4 - . The catalyst CuFe-LDH exhibited excellent stability and maintained relatively high catalytic activity to PS even after four recycles. Mechanism study revealed that the redox cycle of Fe 3+ /Fe 2+ and Cu 2+ /Cu 3+ assisted by visible-light irradiation accounted for the enhanced generation of radicals in CuFe-LDH/PS/Vis system, resulting in the improved degradation of organic contaminants. Overall, the CuFe-LDH/PS/Vis process could be a promising approach for the removal of refractory organic pollutants in wastewater. Graphical abstract: Highlights: A visible-light-responsive catalyst CuFe-LDH was prepared via co-precipitation method. The introduction of visible light and CuFe-LDH effectively accelerated PS activation. Superior photoactivation efficiency was maintained at wide range of pH level. The main active species were SO4 - and OH. Enhanced mechanism for CuFe-LDH/PS/Vis system was elucidated.