Nanosized Oxides of Different Compositions as Adsorbents for Hazardous Substances Removal from Aqueous Solutions and Wastewaters

摘要

8.1 Introduction Due to industrialization and urbanization processes, large quantities of effluents containing hazardous substances are discharged into the environment. Not only inorganic contaminants such as heavy metals, e.g. Cd, Cr, Cu, Ni, As, Pb and Zn, but also organic compounds like phenol (and its salts), polyalcohols, polyacids (and other macromolecular compounds), azo dyes, dioxins, furanes as well as many others are generated by metallurgical, engineering, mining, electroplating, nuclear, chemical, textile, petroleum, plastic, cellulose, etc. industries. Many of them are known to be toxic or carcinogenic. Thus removal of such hazardous substances is of crucial importance to protect the human and the environment. Several techniques have been used to remove organic and inorganic impurities from industrial wastewaters. Recently increasing attention has been focused on adsorption techniques using metal and semimetal oxide sorbents such as aluminium oxide, iron oxide, titanium oxide, manganese oxide, zirconium oxide and silica oxide. The nanosized metal, semimetal and mixed oxides are classified as the promising sorbents because of their large surface areas and pore sizes as well as mechanical and thermal stability.