Nanocomposites for dye remediation from aqueous solutions

Water quality deterioration, due to industrialization and urbanization, has become a matter of worldwide concern. A lot of research is being done to purify the polluted water. Dyes and metal ions that are the major components of effluents from industries such as paper, leather, textile, plastic, and cosmetics are most harmful and toxic among all contaminants. Unlike heavy metals, dyes have complex molecular structures that make them difficult to biodegrade when discharged into waste streams. Therefore dyes become much more difficult to remove from water. Dyes can cause irreparable damage to human health and environment if left untreated. A number of methods such as adsorption, photochemical degradation, ion-exchange, chemical precipitation, membrane filtration, coagulation–flocculation, flotation, and electrochemical methods are being used for the removal of dyes from water. Out of all, the adsorption method is the most economical and cost-effective. This chapter presents, in brief, different methods for dyes removal from water with an emphasis on the use of nanocomposites (NCs) as adsorbents. NCs synthesized by green methods and their use for removal of dyes from water under different conditions have been discussed. Structure of (1) cationic, (2) anionic, and (3) neutral dyes are given. Different types of NCs, their preparation methods, properties, and effectiveness as adsorbents for water remediation have been described in detail. Mechanism of photocatalytic degradation of dyes by NCs has also been discussed in this chapter.