A review on nanomaterial-based heterogeneous photocatalysts for removal of contaminants from water
Vishal Kumar Parida, Suneel Kumar Srivastava, Ashok Kumar Gupta, Akash Rawat
Abstract
The rising concentration of pollutants in the environment due to partially treated or untreated wastewater entering the surface waters has seriously challenged the integrity of the ecosystem and the quality of water for human health. Therefore, it is crucial to establish a productive and economical process to degrade recalcitrant pollutants from various water matrices owing to the ineffectual removal of these contaminants by conventional treatment methods. In this regard, advanced oxidation processes (AOPs), especially photocatalysis, have gained much attention due to their unique properties, such as low-cost, easy synthesis, and ability to produce reactive radicals under light irradiation with complete mineralization of recalcitrant pollutants. In this review, heterogenous photocatalysts, their fundamental properties, and their working mechanism have been described, along with their applications in the degradation of contaminants in water. Recent progress on pristine and modified nanomaterial-based photocatalysts for the degradation of various pollutants in water has been discussed. In particular, the removal of toxic heavy metals, pesticides, dyes, pathogens, pharmaceuticals, and other miscellaneous contaminants from water using a wide variety of nanomaterial-based heterogeneous photocatalysts has been summarized. The effect of temperature, solution pH, and loading of photocatalysts was found to be the most critical factors influencing the photocatalytic degradation of pollutants. Subsequently, the photocatalyst immobilization process using various support materials including carbon-based materials, glass, zeolites, and polymers in designing the efficient photocatalysts and future perspectives have been outlined.