Recent Research on Development and Modification of Nontoxic Semiconductor for Environmental Application

ABSTRACT Today various wastewater treatment methodologies such as chemical oxidation, biological treatment, chemical precipitation, fenton technology, and advanced oxidation processes are used to resolve water scarcity concerns. The advanced oxidation processes are considered to be suitable for solving some water issues due to their enhanced features in photo-oxidation of organic compounds. Recent nanoparticle-mediated photo-oxidative processes, involving zinc oxide and titanium dioxide semiconductors, constitute a proficient, resourceful, and sustainable method which is developed primarily to remove phenols and aromatic dyes from groundwaters and wastewaters. This review focuses on the evolution of nanoparticle-mediated titanium dioxide and zinc oxide catalysts with a band edge effective in the UV region. This catalytic medium has subsequently been modified to be effective in the visible region. In this regard, a brief discussion on the substitution of metals and nonmetals on Zn2+, Ti4+, or O2- sites for efficient photocatalytic performance under visible light is also emphasized. The emphasized points are: (i) degradation kinetics and (2) operating parameters affecting the catalytic photo-oxidation and (3) concluding remarks drawn from collected surveys. The recent progresses made in the production of doped photocatalysts for the mineralization of phenols and dyes are also highlighted.