Oxidative functionalization of carbon nanotubes for enhanced adsorptive removal of phthalate esters in environmental systems

Abstract

Phthalic acid esters (PAEs) are high-volume manufacturing organic materials used in plasticisers to increase the elasticity of the core polymer. They are reported to spread into the surroundings from plastic products and are now a global environmental contaminant. Several environmental sources, particularly water, have been examined for phthalate contaminant levels. These substances are discharged directly into the environment and cannot be chemically bound. The presence of PAEs in different ecological environments is a major concern since they are endocrine disruptors and can interact with hormones, which can lead to problems with development and reproduction. Earlier studies have explored the occurrence, fate, and concentration of phthalates. This review discusses how different oxidative techniques employed for modifying carbon nanotubes (CNTs) can improve their ability to remove PAEs by changing their surface chemistry. Several oxidation approaches introduce oxygenated functional groups on the CNT surface, which increase their specific surface area, making them suitable for adsorbing contaminants like phthalate esters. The adsorption capacity was found to be controlled by the nanotubes' specific surface areas, which varied with their outer diameters. Because of the π–π interaction between the graphitic surface of the nanotubes and the benzene ring of the phthalates, as well as hydrogen bonds, charge-assisted hydrogen bonding, van der Waals forces, and electrostatic interactions between PAEs and CNTs, the adsorption capacity was much higher than that of other materials. PAEs' toxicological and environmental effects have drawn global attention. The present article reviews the use of oxidised CNTs in advanced carbon materials for removing PAEs from polluted and hazardous environments.