Arsenic and Lead Removal from Water by Nano-photocatalytic Systems (A Review)

Water is an essential component in the world. The presence of heavy metals in water has dramatic effects on health and ecological process in the environment. Heavy metal pollution in water bodies is an existing and developing problem in the world. There are several methods for removing these pollutions in water. A photocatalytic degradation is a useful approach to removal a variety of heavy metals from contaminated water. In this study, we summarized different types of methods for the removal of heavy metals especially arsenic and lead from water. Studies include different nano-photocatalyst and methods such as the use of TiO2 substrates, TiO2 nanotubes, and nanocrystals, organic and inorganic nanoparticles based on silica, a variety of nanomaterial-based polymers, magnetic nanoparticles such as zero-valent iron and zinc oxide, or using two or more of these nanomaterials at the same time as an adsorbent or oxidizer of pollutants, all under visible or ultraviolet light. Each method has some limitations and advantages and based on different research that scientists presented, the efficiency of each technique is depended on some conditions such as pH, adsorption time, solvent type, and UV light, so we still can’t introduce the best method. Nowadays researchers are trying to find a method with high efficiency, low cost, least risk for the environment, and without secondary contamination. Hopefully, researchers find many promising methods that can be used with high efficiency in the future by continuing the research.