Photocatalytic Performance and Degradation Mechanism of Aspirin by TiO2 through Response Surface Methodology

Lezhuo Li,Bo Li,Qingfeng Cheng,Xiuwen Cheng,Sanxiang Song,Sanfan Wang,Ruonan Guo,Qiuling Ma

doi:10.3390/catal8030118

Abstract

In the present work, the photocatalytic performance of P25TiO2 was investigated by means of the degradation of aspirin, while the reaction system was systematically optimized by central composite design (CCD) based on the response surface methodology (RSM). In addition, three variables of initial pH value, initial aspirin concentration and P25 concentration were selected to assess the dependence of degradation efficiencies of aspirin. Meanwhile, a predicted model of degradation efficiency was estimated and checked using analysis of variance (ANOVA). The results indicated that the PC removal of aspirin by P25 was significantly influenced by all these variables in descending order as follows: P25 concentration > initial aspirin concentration > initial pH value. Moreover, the parameters were optimized by the CCD method. Under the conditions of an initial pH value of 5, initial aspirin concentration of 10 mg/L and P25 concentration of 50 mg/L, the degradation efficiency of aspirin was 98.9%with 60 min of Xenon lamp irradiation. Besides, based on the liquid chromatography-mass spectrometry measurements, two main PC degradation pathways of aspirin by TiO2 were deduced and the tentative degradation mechanism was also proposed.

Highlights

Among the large number of various organic pollutants that may enter into water resources, pharmaceuticals and personal care products (PPCPs) in surface and ground waters have been a major environmental concern [1,2]
We noted that P25 resulted in higher degradation efficiency of aspirin, with68.5% of aspirin removed within 60 min of Xenon lamp illumination
The PC performance and degradation mechanism of aspirin by TiO2 was evaluated and optimized by response surface methodology (RSM) based on central composite design (CCD) methods

Summary

Introduction

Among the large number of various organic pollutants that may enter into water resources, pharmaceuticals and personal care products (PPCPs) in surface and ground waters have been a major environmental concern [1,2]. Known as acetylsalicylic acid (ASA), is commonly used as a classic non-steroidal anti-inflammatory drug (NSAID) to relieve minor aches and treat inflammation and cardiovascular diseases [3,4] This type of pharmaceutical has been detected in the aquatic environment at trace concentrations (ng to μg/L), which can prolong exposure to environmentally relevant concentration and considerably increase the toxicity considerably, resulting in negative consequences for aquatic life and human beings [5,6,7]. Researchers have found that advanced oxidation processes (AOPs) can eliminate the refractory contaminants (including emerging contaminants and PPCPs) in aqueous environments, which deserves major attention [9,10,11,12,13,14] One of these technologies is solar photocatalysis (PC), which can degrade organic pollutants by means of the photocatalytic reaction promoted by the action of light on the surface of a semiconductor acting as a photocatalyst [15].

Methods

Results

Conclusion