X-Ray Absorption Fine Structure Spectroscopy: A Structural Probe for Addressing Remediation Mechanisms Using Nanoadsorbents

Abstract

Nanoparticles (NPs) lead the way in the field of environmental remediation and have shown promise to effectively remove toxic metals from water. The most reliable, simple, applicable and cost effective technique for water purification is the adsorption of the metal pollutants onto the surface of NPs. A powerful structural probe for unraveling the adsorption mechanism is X-ray absorption fine structure (XAFS) spectroscopy. Its element specific nature renders XAFS excellent for revealing the interactions between the adsorbate and adsorbent at the atomic level and analyzing the chemical and physical environments of both the metal atom and the particle surface. It can identify reduction and oxidation reactions with increased sensitivity, resolve directly the elemental oxidation states with high resolution, determine active surface sites and account for different types of sorption geometries. This chapter begins with a brief description of the concepts of XAFS, followed by an overview on its applications to element speciation in water treatment technology. Special focus is placed on the use of XAFS as a structural probe in NPs that are especially synthesized and used for the adsorption and immobilization of metal pollutants in water sources.