Recent developments in photocatalytic remediation of textile effluent using semiconductor based nanostructured catalyst: A review

The textile industry makes a significant contribution to the Indian economy. This textile industry creates a demand for producing 1.3 million tons of dyes and pigments and most of them are produced in a synthetic way. These Dyes are capable of absorbing and reflecting sunlight in water. This affects the photosynthetic cycle of algae and other biotic components which seriously influences the food web. Textile effluent is mostly composed of 70% of Azo dyes. However, most among those dyes and their breakdown products which are carcinogenic, mutagenic, and toxic to life in nature. The recent technology that deals with treating textile effluent is heterogeneous photocatalysis which uses various types of semiconductor-based nanoparticles that have the ability to act as catalysts when accompanied with visible-light. This review focuses on the recent developments of different types of semiconductor based nano-structures which include doping, polymer supported nanocomplex, magnetic nanocomposites, heterojunction photocatalyst and newly introduced compound photo-catalysts. Polymerised Ni0.5Zn0.5Fe2O4@polyaniline decorated BiOCl is the most efficient photocatalyst in degrading methyl orange in 60 min under visible light. Non-metal doped photocatalyst worked best for dye concentration in the range 5 mg/L to 20 mg/L. Most of the heterojunction photocatalyst was reused for 5 times and the catalytic activity resulted in the range 90-100%. Furthermore, the impact of the parameters such as dopant concentration, pH, catalyst concentration, solution concentration on the photocatalytic activity were studied.