Design and performance analysis of solar-tio2 immobilized bed in the treatment of AZO dye

Abstract

Textile industry plays a vital role in the economic development of Bangladesh and around 6000 textile industries have been developed. Although it provides significant economic benefits, it also faces the social and environmental impacts associated with the generation of toxic wastewaters from its wet processing operations. Recently, advanced oxidation processes (AOPs) are considered as a highly attractive and competitive technology for the degradation of toxic compounds from industrial wastewater than conventional technology and make the technology more effective and efficient. In AOP, a strong oxidizing radical known as hydroxyl radical (˙OH) is generated that can react with toxic compounds in wastewater until mineralization. Among AOPs, the Solar-TiO2 immobilized photocatalytic reactor is one of the most promising alternative technologies for the removal of toxic compounds from textile wastewater because the whole world is moving towards the application of renewable energy due to shortage of fossil fuel. Thus, the major objectives of this study were a synthesis of TiO2 nanoparticles, design and construction of TiO2-immobilized reactors (with borosilicate glass, cement coated borosilicate glass, steel wire mesh) and investigation of the performance of these reactors in the degradation of methyl orange (MO) under solar irradiation. TiO2 nanoparticles were synthesized by sol-gel and thermal treatment methods. The physico-chemical properties of TiO2 nanoparticle were characterized by various analytical and spectroscopic techniques such as UV-Vis, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) with EDX and Brunauer–Emmett–Teller (BET). The photocatalytic performance of MO dye with the help of immobilized-TiO2 nanoparticles on borosilicate glass, cement coated borosilicate glass, and wire mesh in the presence of solar irradiation were investigated. The photocatalytic degradation of MO dyes was 97.8%, 88.6%, and 21.5%, respectively by using immobilized-TiO2 on borosilicate glass, cement coated borosilicate glass and steel wire mesh with 5 h of contact time. The initial concentration and pH of MO dye were 10 ppm and 6.2, respectively. The photocatalyst doses were varied from 0.060 g to 0.150 g in all experiments. The result suggests that the solar-TiO2 immobilized borosilicate glass reactor has high potential in the treatment of toxic compounds in textile wastewater. Based on that, the impacts of changing of different operational parameters such as dye concentration and oxidant H2O2 concentration on the performance of the borosilicate glass photoreactor was evaluated. The experimental results showed that removal rates were decreased with the increase of initial concentration of MO but increased with the increase of H2O2 oxidant concentration.