Journal of Environmental Biology

Role of active oxidative species onTiO₂ photocatalysis of tetracycline and optimization of photocatalytic degradation conditions

Zhaohui Luo^1*, Lu Li¹, Chuanlin Wei¹, Huixin Li¹ and Dan Chen²

¹College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing-210 095, China

²Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern China (Ministry of Education),

College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing-210 098, China

^*Corresponding Author?s Email : lzhui@njau.edu.cn

Publication Data

Paper received:

17 June 2014

Revised received:

30 September 2014

Re-revised received:

01 January 2015

Accepted:

07 February 2015

Abstract

The optimum operating conditions for TiO₂ photocatalytic degradation of tetracycline antibiotic (TC) in aqueous solution and the role of active oxidative species(AOS) from UV/TiO₂ in its degradation were investigated. Response surface methodology (RSM) and central composite design (CCD) were adopted to optimize three parameters: TiO₂ concentration, initial pH and UV irradiation time. Radical scavengers were added to reaction solution to assess the photocatalytic reaction mechanism of TC. The results showed that 93.1% degradation efficiency was obtained under optimum conditions established during experimentation (TiO₂ concentration=2.09 g l^-1, pH=5.56 and t=20.95 min). These results agree with the prediction made by the proposed model. Photocatalytic degradation of TC followed a pseudo first-order reaction rate. Photogenerated holes (h⁺_VB) with minor participation from superoxide anions (O₂^-), were responsible for TC oxidation on TiO₂, while hydroxyl radicals (?OH) played a negligible role in titania-TC oxidation.     

 Key words

Active oxidative species, Photocatalytic degradation, Response surface methodology, Tetracycline, UV/TiO₂ process 

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