Preparation, characterization and application of tio2 nano-composite for the treatment of textile wastewater under solar radiation

Abstract

Advanced oxidation process (AOP) is considered a very effective treatment process for the degradation of biopersistent and toxic organics in industrial wastewater. In this process hydroxyl radical (∙OH) is generated which can react unselectively with organics until mineralization. Several types of AOPs such as ozonation, peroxone, Fenton, photochemical, photocatalytic processes have been utilized in the past for the treatment of textile wastewater. Among these, titanium dioxide (TiO2) based photocatalytic AOP has been utilized widely in recent years because of its powerful photocatalytic activity to degrade organics from wastewater. Although, TiO2 is a widely used photocatalyst in the treatment of textile wastewater, it has major drawback from its large band gap energy for activation to produce ∙OH. Considering this, the main objective of the current study was to synthesize TiO2 nano-composites with lower band gap energy by doping TiO2 with other metals. The other objectives were to characterize TiO2 nano-composites and the application of TiO2 nano-composites in presence of solar radiation in the treatment of model azo-dye used in textile processing. The nano-composite photocatalysts of TiO2, MoO3-TiO2 and Ag-MoO3-TiO2 were prepared by sol–gel and thermal treatment method. The characterization of the nano-composites showed that a predominately anatase phased TiO2 based nano-composites were synthesized. The doping of Ag and MoO3 increased the structural roughness, specific surface area, pore volume and reduced the band gap energy of the nano-composites. The photocatalytic degradation experiments demonstrated that the degradation of Methyl orange under solar radiation from TiO2, MoO3-TiO2 and Ag-MoO3-TiO2 nano-composites were 81%, 91% and 97%, respectively. The enhanced photocatalytic degradation under solar radiation indicates that the pairing between Ag, MoO3 and TiO2 was effective in the preparation of the nano-composites. Thus, the outcomes from the current study suggest that the TiO2 based nano-composites have potential for the treatment of organics present in textile wastewater under solar radiation.