Intensification of Azo Dye Removal Rate in the Presence of Immobilized Nanoparticles and Inorganic Anions under UV-C Irradiation: Optimization by Response Surface Methodology

Mohammad A Behnajady,Mahsa Hajiahmadi

doi:10.1155/2013/289290

Mohammad A Behnajady, Mahsa Hajiahmadi

Open Access

https://doi.org/10.1155/2013/289290

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Abstract

Wastewaters contain inorganic anions that affect the removal rate of organic pollutants. The present study aims to optimize the effects of inorganic anions such as , Cl−, , and on the removal rate of an organic pollutant in the presence of immobilized TiO2nanoparticles using response surface methodology (RSM). C.I. Acid Red 17 (AR17) was used as a model organic pollutant. Thirty experiments were required to study the effects of anions in various concentrations. The results indicate that the addition of and ions intensifies the removal rate of AR17. The results of the analysis of variance (ANOVA) showed a high coefficient of determination value ( and ). The results indicate that RSM is a suitable method for modeling and optimizing the process. The results prove that in the presence of and and ions especially in the combination situation the removal rate of AR17 is enhanced considerably. An important synergy effect was observed in the combination of and ions, so that AR17 removal percent under the optimized RSM conditions was considerably more than the sum of removal percent when these ions are used individually.

Highlights

Producing many products such as clothes, leather accessories, and furniture, needs synthetic dyes
The results indicate the formation of a surface with root mean square (RMS) and average roughness of 37.1 and 28.9 nm, respectively
UV-C irradiation can be accelerated by inorganic anions such as NO3− and HCO3− ions

Summary

Introduction

Producing many products such as clothes, leather accessories, and furniture, needs synthetic dyes. Most of these dyes are toxic and potentially carcinogenic in nature. The discharge of their effluents into the environment is harmful for human and all living beings. Heterogeneous photocatalysis is one of the AOPs and has attracted extensive attention of many researchers. This method is based on producing photoexcited electrons (e−) in the conduction band and positive-charged holes (h+) in the valence band of an oxide semiconductor like TiO2under ultraviolet (UV) light. Reactions include oxidation of organic pollutants by photogenerated positive holes (h+) or by reactive oxygen species (HO∙, HOO∙, and O2∙−) formed on the TiO2 surface under UV light irradiation [8,9,10]

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