Modeling perchloroethylene degradation under ultrasonic irradiation and photochemical oxidation in aqueous solution

Mahdi Kargar,Ramin Nabizadeh,Simin Nasseri,Bagher Pahlevanzadeh,Mahmood Alimohammadi,Kazem Naddafi,Shahrokh Nazmara,Alireza Mesdaghinia,Amir Hossein Mahvi

doi:10.1186/1735-2746-9-32

Mahdi Kargar, Ramin Nabizadeh + Show 7 more

Open Access

https://doi.org/10.1186/1735-2746-9-32

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Abstract

Sonolysis and photochemical degradation of different compounds such as chlorinated aliphatic hydrocarbons are among the recent advanced oxidation processes. Perchloroethylene is one of these compounds that has been mainly used as a solvent and degreaser. In this work, elimination of perchloroethylene in aqueous solution by ultrasonic irradiation, andphotochemical oxidation by ultra violet ray and hydrogen peroxide were investigated. Three different initial concentrations of perchloroethylene at different pH values, detention periods, and concentrations of hydrogen peroxide were investigated. Head space gas chromatography with FID detector was used for analyses of perchloroethylene. This research was performed in 9 months from April through December 2011.Results showed that perchloroethylene could be effectively and rapidly degraded by ultrasonic irradiation, photochemical oxidation by ultra violet ray, hydrogen peroxide and a combination of these methods. Kinetics of perchloroethylene was strongly influenced by time, initial concentration and pH value. Degradation of Perchloroethylene increased with decrease in the initial concentration of perchloroethylene from 0.3 to 10 mg/L at all initial pH. The results showed an optimum degradation condition achieved at pH = 5 but did not affect significantly the perchloroethylene destruction in the various pH values. Kinetic modeling applied for the obtained results showed that the degradation of perchloroethylene by ultrasound and photo-oxidation followed first order and second order model. The percentage of removal in the hybrids reactor was higher than each of the reactors alone, the reason being the role of hydroxyl radical induced by ultrasound and photochemical reaction.

Highlights

AS the number of substances resistant to biodegradation have increased, and the conventional biological methods were unable to complete the treatment of these materials; new technologies are required to degrade these resistant molecules to smaller ones
Analytical methods Analyses were performed by head-space gas chromatography technique
The efficiency at different pH values and kinetic constants in these reactors are illustrated in Tables 5, 6 and 7

Summary

Introduction

AS the number of substances resistant to biodegradation have increased, and the conventional biological methods were unable to complete the treatment of these materials; new technologies are required to degrade these resistant molecules to smaller ones. The smaller molecules can be degraded by biological processes [1]. New technologies include advanced oxidation processes such as Fenton, peroxone, common use of ozone, UV irradiation, hydrogen peroxide and the use of ultrasonic and photo-catalytic oxidation processes [2]. One category of resistant material to biological degradation is chlorinated hydrocarbons. These materials cause water resources contamination and affect human health. Several studies have been carried out in removing various organic materials from water and aqueous solutions [3,4,5,6]

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