Photocatalysis of Volatile Organic Compounds in water: Towards a deeper understanding of the role of cyclodextrins in the photodegradation of toluene over titanium dioxide

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• 作者：Anthony Lannoy^a ; ^b ; Nicolas Kania^a ; ^b ; Rudina Bleta^a ; ^b ; Sophie Fourmentin^c ; Cé ; cile Machut-Binkowski^a ; ^b ; ^{cecile.machut@univ-artois.fr" class="auth_mail" title="E-mail the corresponding author} ; Eric Monflier^a ; ^b ; Anne Ponchel^a ; ^b
• 关键词：Photocatalysis ; Cyclodextrins ; Toluene ; Adsorption ; Inclusion complex
• 刊名：Journal of Colloid and Interface Science
• 出版年：2016
• 出版时间：1 January 2016
• 年：2016
• 卷：461
• 期：Complete
• 页码：317-325
• 全文大小：764 K

文摘

Cyclodextrin-assisted photodegradation of toluene was investigated in water in the presence of a photo-irradiated commercial titanium dioxide photocatalyst. It was expected that cyclodextrins could form water-soluble supramolecular host/guest complexes with the toluene and thus promote the approach of the pollutant on the TiO₂ surface and enhance the phototocatalytic oxidation efficiency.

Experiments

Photodegradation kinetics of toluene were investigated under UV-C and near-visible light radiation in aqueous suspensions of TiO₂. Impact of cyclodextrin (CD) on the photocatalytic efficiency of TiO₂ was evaluated with different cyclodextrins: 伪-CD, 尾-CD, 纬-CD and RAME-尾-CD. Host–guest association constants were determined by static headspace gas chromatography and affinity of cyclodextrins for the TiO₂ surface by isothermal adsorption studies. Issue of the cyclodextrin stability during the degradation process was examined using Total Organic Carbon, NMR and MALDI-TOF analyses.

Findings

Toluene could be fully mineralized by TiO₂ in water within hours, even if the presence of cyclodextrin caused a delay in the photodegradation process. The chemical nature of cyclodextrins was found to exert a significant influence on the extent of inhibitory effect, which was discussed in terms of balance between solubilization efficiency, substrate protection and coverage of active sites of TiO₂ by competitive adsorption. The cyclodextrin degradation was also studied and discussed.