CHAPTER 5:Mechanism of Adsorption on Nanomaterials

The disposal of large amounts of wastewater containing organic, inorganic and biological pollutants has become a serious issue today. Many technologies have been established for pollutant removal, including chemical oxidation/reduction, biological treatment, coagulation/flocculation, adsorption, membrane separation, and ion exchange. The most effective among them is the adsorption process because it is simple, highly efficient, and easy to operate. Adsorption is a surface phenomenon that takes place by physical forces but sometimes, weak chemical bonding also participates in the adsorption process. Different models, like Langmuir, Freundlich, Halsey, Henderson, intraparticle diffusion, and Lagergren, are used to explain the results of adsorption. A thermodynamic study is carried out to determine the feasibility of the process by interpreting the values of enthalpy, free energy, entropy, and energy of activation. Recently, a great deal of attention has been focused on the application of nanostructured materials as sorbents to remove toxic and harmful substances from aquatic media. Nanostructure sorbents, which include metal nanoparticles, carbon nanomaterials and dendrimers, as compared to traditional materials have exhibited much higher efficiency and faster rates in water treatment with enhanced redox and photocatalytic properties.