Graphite felt incorporated with MoS2/rGO for electrochemical detoxification of high-arsenic fly ash

Research output: Conference Papers (RGC: 31A, 31B, 32, 33)32_Refereed conference paper (no ISBN/ISSN)peer-review

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Detail(s)

Original languageEnglish
Publication statusPublished - Jul 2019

Conference

Title2019 International Conference on Green Energy and Environmental Technology, GEET 19
LocationUniversité París 8
PlaceFrance
CityParis
Period24 - 26 July 2019

Abstract

1. Introduction – Accumulation of high-arsenic fly ash (HAFA) poses a serious environmental threat due to the toxicity. As(III) oxidation is a necessary step for HAFA detoxification and in situ H2O2 electrogeneration via the two-electron-pathway (2e-) oxygen reduction reaction (ORR) is considered a promising technique for As(III) oxidation [1, 2]. MoS2 has been reported to have attractive 2e- ORR catalytic activity [3]. However, there are still some problems to be solved: (i) its conductivity needs to be improved, (ii) gaseous O2 is difficult to be effectively utilized, and (iii) the assembled electrode is not flexible and durable enough to treat solid waste.
2. Experimental - the experimental flow is schematically illustrated in Image. 1. 
3. Results and Discussion - A novel graphite felt (GF) modified with the MoS2/reduced graphene oxide (rGO) heterojunction is developed and demonstrated as an efficient electrode for electrochemical detoxification of HAFA, as shown in Image 2(a). The modified GF has abundant microchannels (Image 2(b)), desirable surface properties, and fast electron transfer capability thereby enabling effective utilization of both dissolved O2 and gaseous O2 in 2e- ORR. The p-n junction consists of the p-type rGO substrate and uniformly distributed n-type MoS2 nanoflowers, seeing Images 2(c) and 2(d). Theoretical calculation indicates that gaseous O2 adsorb stably on sulfur vacancies and is reduced by electrons transferred from rGO. The modified GF exhibits superior ORR catalytic activity such as a high H2O2 yield of 47.53 mg·L-1·h1·cm-1 (Image 2(e)) and onset potential of -0.12 V vs. SCE. The ·OH generated by the autocatalytic mechanism promotes oxidative dissolution of As(III) during detoxification of HAFA and the As removal percentage is 96.10% after electrolysis for 135 min, displayed in Images 2(f) and 2(g). The modified GF with excellent stability and durability has large industrial potential in detoxification of HAFA and other As-bearing hazardous wastes. 
4. Conclusions - This study makes significant contributions. Firstly, the gaseous O2 reaction path in ORR is confirmed by the combination of experiment and calculation. Secondly, 2e ORR is innovatively applied to detoxification of high-arsenic solid waste.

Bibliographic Note

Author(s) information for this publication is provided by the author(s) concerned.

Citation Format(s)

Graphite felt incorporated with MoS2/rGO for electrochemical detoxification of high-arsenic fly ash. / Luo, Yang; Wu, Yinghong; Huang, Chao; Xiao, Dezhi; Zhang, Lizhai; Ma, Shuhua; Qu, Jingkui; Zheng, Shili; Chu, Paul K.

2019. Paper presented at 2019 International Conference on Green Energy and Environmental Technology, GEET 19, Paris, France.

Research output: Conference Papers (RGC: 31A, 31B, 32, 33)32_Refereed conference paper (no ISBN/ISSN)peer-review