Photocatalytic Removal of Ethylene Dichloride Using PAni-TiO2 Nanocomposites Supported on Glass Beads: Process Optimization by RSM-CCD Approach

• Main Authors: Mahdi Mohsenzadeh, Seyed Ahmad Mirbagheri
• Format: Article
• Language: English
• Published: Water and Wastewater Consulting Engineers Research Development 2020-03-01
• Series: آب و فاضلاب
• Subjects: ethylene dichloride; pani-tio2 nanocomposite; photocatalytic oxidation; response surface methodology
• Online Access: http://www.wwjournal.ir/article_92084_e8510a97dbf681ce84deb293621f00e3.pdf

Ethylene dichloride is one of the most important chlorinated hydrocarbons in the petrochemical industry, which is mainly used to produce vinyl chloride monomer, the main precurser of PVC production. Iran is one of the largest PVC producers in the world. During the production of 1000 kg of ethylene dichloride, about 0.4 m³ wastewater is produced containing 50-200 mg / L of ethylene dichloride. In this study, heterogeneous photocatalysis was used for degradation of this chlorinated hydrocarbon. PAni-TiO₂ nanocomposite was immobilized on glass beads by a modified dip coating and heat attachment method. The morphology characteristics were confirmed by scanning electron microscope, energy dispersive X-ray spectroscopy and ultraviolet–visible spectroscopy. A pilot scale packed bed recirculating batch photocatalytic reactor was used for conducting photocatalytic experiments. response surface methodology based on central composite design was used to evaluate and optimize the effect of ethylene dichloride concentration, residence time, pH and coating mass as independent variables on the photocatalytic degradation of ethylene dichloride as the response function. Based on the results, actual and RSM predicted results were well fitted with R² of 0.9870, adjusted R² of 0.9718 and predicted R² of 0.9422. Optimum conditions were the ethylene dichloride concentration of 250 mg/L, reaction time of 240 min, pH of 5 and immobilized mass of 0.5 mg/cm², which resulted in 88.84% photocatalytic degradation. Kinetic of the photocatalytic degradation at optimal condition followed the Langmuir-Hinshelwood first order reaction with k=0.0095 min^-1 with R²=0.9455. Complete photocatalytic degradation of ethylene dichloride was achieved after 360 min. Based on the results, it may be argued that the designed and constructed photocatalytic reactor has the potential for industrialization.