A novel layer-by-layer CNT/PbO2 anode for high-efficiency removal of PCP-Na through combining adsorption/electrosorption and electrocatalysis. (20th March 2019)

• Record Type: Journal Article
• Authors: Xu, Feng; Chang, Limin; Duan, Xiaoyue; Bai, Wenhui; Sui, Xinyu; Zhao, Xuesong
• Is Part Of: Electrochimica acta. Volume 300(2019)
• Page Start: 53
• Page End: 66
• Publication Date: 2019-03-20
• Subjects: Electrochemical oxidation -- Sodium pentachlorophenate -- CNT/PbO2 anode -- Adsorption -- Electrosorption; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.01.090
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Electrochemical oxidation is an effective mean to degrade non-biodegradable organics from the contaminated waters. However, its current efficiency is very low for the low-concentration organic pollutants treatment. In this work, combining with the outstanding adsorption property of CNT and the effective electrocatalytic oxidation performance of β-PbO2, we constructed novel layer-by-layer carbon nanotube/PbO2 anodes (CNT/PbO2 -3, CNT/PbO2 -4 and CNT/PbO2 -5) with high adsorbability to enhance the electrochemical degradation efficiency of low-concentration sodium pentachlorophenate (PCPNa). In electrochemical oxidation tests, the PCP-Na was rapidly enriched in the CNT/PbO2 film through adsorption/electrosorption and then efficiently degraded in site. The removal efficiency of low-concentration PCP-Na (5 mg/L) on CNT/PbO2 -4 reached 73.8% after only 5 min of electrolysis, whereas that on pure PbO2 was only 9.9%. To further clarify the mechanism of improvement of PCP-Na removal on CNT/PbO2 -4 anode, the generation capacity of·OH radicals, oxygen evolution overpotential, voltammetric charge quantity, interface resistance, and specific surface area of CNT/PbO2 -4 anode were also assessed and compared with those of other three anodes. Results showed that, in addition to the synergistic effect of adsorption/electrosorption and electrocatalysis, the more active sites, smaller electron transfer resistance and higher direct oxidation capacity of CNT/PbO2 -4 anode also contributed to improving degradation rate of PCP-Na on CNT/PbO2 -4 anode. Additionally the electrochemical degradation pathway of PCP-Na was also proposed based on the gas chromatography-mass spectrometry analysis. Finally, CNT/PbO2 -4 electrode exhibited longer accelerated lifetime of 116 h than pure PbO2 electrode (91 h). Thus, these findings provide a new anode to improve the removal of low-concentration organic pollutants through combining electrochemical oxidation and adsorption/electrosorption processes. Graphical abstract: Image 1 Highlights: A novel layer-by-layer CNT/PbO2 anode was fabricated. The degradation efficiency of PCP-Na on CNT/PbO2 anode was obviously improved. The low-concentration PCP-Na was enriched on the surface CNT/PbO2 anode. Adsorption/electrosorption and electrocatalysis were combined.