Enhanced degradation of azo dye in wastewater by pulsed discharge plasma coupled with MWCNTs-TiO2/γ-Al2O3 composite photocatalyst

Xin Li; Tiecheng Wang; Guangzhou Qu; Dongli Liang; Shibin Hu

doi:10.1016/j.jenvman.2016.02.040

Enhanced degradation of azo dye in wastewater by pulsed discharge plasma coupled with MWCNTs-TiO2/γ-Al2O3 composite photocatalyst

J Environ Manage. 2016 May 1:172:186-92. doi: 10.1016/j.jenvman.2016.02.040. Epub 2016 Mar 4.

Authors

Xin Li¹, Tiecheng Wang², Guangzhou Qu³, Dongli Liang², Shibin Hu²

Affiliations

¹ College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province 712100, PR China.
² College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province 712100, PR China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, PR China.
³ College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province 712100, PR China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, PR China. Electronic address: qugz@nwsuaf.edu.cn.

PMID: 26946167
DOI: 10.1016/j.jenvman.2016.02.040

Abstract

In order to improve the photocatalytic performance of TiO2 in pulsed discharge plasma systems, easily recycled multi-walled carbon nanotubes (MWCNTs)-TiO2 supported on γ-Al2O3 (MWCNTs-TiO2/γ-Al2O3) composite photocatalyst were prepared. The morphology and physicochemical properties of the prepared catalysts were investigated using XRD, SEM, FTIR and UV-vis spectroscopy. The photocatalytic activity was evaluated by degradation of azo dye acid orange II (AO7) in wastewater under pulsed discharge plasma. The results indicate that the MWCNTs-TiO2/γ-Al2O3 composite catalyst possesses enhanced photocatalytic activity facilitating the decomposition of AO7 compared with TiO2/γ-Al2O3 composite in pulsed discharge plasma systems. Under pulsed discharge plasma, almost 100% AO7 is degraded by the MWCNTs-TiO2/γ-Al2O3 composite after 60 min at optimal conditions. The degradation efficiency of AO7 is also affected by the dosage of the composite catalyst and pulsed discharge peak voltage. As the amount of MWCNTs-TiO2/γ-Al2O3 composite and pulsed discharge peak voltage increases, the degradation efficiency of AO7 increases. The photocatalyst was implemented for 6 cycles and the degradation efficiency of AO7 remains higher than 85% under pulsed discharge plasma. Results indicate that the catalyst displays easy separation and minimal deactivation after several uses. Possible decomposition mechanisms were also investigated. MWCNTs are capable of improving the photocatalytic activity of TiO2/γ-Al2O3 composite in pulsed discharge plasma systems primarily due to the photo-induced-electron absorption effect and the electron trap effect of MWCNTs. The results of this study establish the feasibility and potential implementation of MWCNTs-TiO2/γ-Al2O3 composites in pulsed discharge plasma systems for the degradation of dye wastewater.

Keywords: Azo dye; Carbon nanotubes; Degradation; Pulsed discharge plasma; TiO(2).

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aluminum Oxide / chemistry
Azo Compounds / chemistry*
Catalysis
Coloring Agents / chemistry
Nanotubes, Carbon / chemistry*
Naphthalenes / chemistry*
Photochemistry / methods*
Recycling
Titanium / chemistry*
Waste Disposal, Fluid / instrumentation
Waste Disposal, Fluid / methods
Wastewater / chemistry*

Substances

Acid Orange II
Azo Compounds
Coloring Agents
Nanotubes, Carbon
Naphthalenes
Waste Water
titanium dioxide
Titanium
Aluminum Oxide