Recent advances on water disinfection using bismuth based modified photocatalysts: Strategies and Challenges

Among the various problems associated with environment, water pollution is a critical concern. Harmful microorganisms present in polluted water cause various dangerous diseases and ultimately lead to millions of deaths, worldwide. Various techniques like chlorination, ozonation, UV radiations etc. are used for water disinfection but most of them are either less efficient or give rise to secondary toxic products. Nowadays, photocatalysis is considered as one of the most efficient cleaner production technique for water disinfection. In the present review, we have discussed water disinfection via bismuth based photocatalysts. Most of bismuth based photocatalysts are stable, visible light active, reusable, cost-effective and non-toxic. By reviewing the current literature, we have explored the basic mechanism of bacterial inactivation via photocatalysis. Further, various bismuth based photocatalysts (bismuth oxides, bismuth sulfides, Bi2MoO6, Bi2WO6, BiVO4 and bismuth oxyhalides) for bacterial inactivation are discussed. Furthermore, due to some drawbacks of pristine photocatalysts such as charge carrier recombination, slow migration of charge carriers, low visible light absorption, etc., we have discussed the modified bismuth based photocatalysts for water disinfection. Modifications viz. heterojunction, Z-scheme, doping etc. are investigated for some important bismuth based photocatalysts. Finally, challenges against bismuth based photocatalysts and future aspects for further research are also explored.