Nanomaterials and Their Role in Removing Contaminants from Wastewater—A Critical Review

Removal of contaminants from wastewater has become an important research area because the amount of available drinking water in the world continues to decline due to rising demand and/or long periods of drought. Furthermore, the chemical and petrochemical industry generates a wide variety of highly toxic residues. Treatment of wastewater is a controversial field in terms of environment protection. In this chapter, several nanomaterials, which impart their unique properties, will be discussed. Among nanomaterials, carbon nanotubes (CNTs) are a form of carbon allotrope with a graphite-like structure, displaying various adsorption characteristics, as a result of the diameter, internal geometry, physical and chemical properties or the obtaining method. Contaminants removal using CNTs needs further research, only limited studies being available and more practical applications are needed to confirm the results. Several other adsorbent nanomaterials have been reported in literature. Among them, mesoporous materials have large surface areas and narrow pore size distribution, ranging from 20 to 100 A, being suitable for liquid phase reactions because they favor the diffusion of the reactants to the active site. The adsorbents can be very effective for adsorption of several types of contaminants, such as heavy metals and different types of dyes. Recently, advanced research targeted the wastewater treatment by using nano catalysts, nano photocatalysts or membranes. The purpose of this chapter was to accomplish a comprehensive overview on the use of nanomaterials in wastewater treatment. The renewed interest in the environment pollution has led to the development of effective models describing the performances of these technologies.