Adsorption of simple aromatic organic acids anions at the alumina water interface influence of functionality and background electrolytes

Abstract

The adsorption of a surface-active agent at the solid-liquid interface significantly changes the properties of the solid surface. As a result, adsorption of a surface-active agent onto a mineral oxide surface plays an important role in the field of mineral processing, soil remediation, wetting and dispersion stability and various practical fields of science (Brady et al., 1986; Davis and Hayes, 1986; Somasundaran and Moudgil, 1987; Stumm et al., 1986). The interactions of a well-defined and simple organic acid having different functional groups, like -COOH and phenolic - OH groups, with the mineral oxide surfaces are different in the presence of different background ions. The influence of functionality of a surface-active agent is reflected in the adsorption kinetics, adsorption isotherms and surface complexation onto a mineral oxide surface (Das and Mahiuddin, 2007; Guan et al., 2006a, 2006b). Nevertheless, the background electrolytes (anions and cations) also significantly govern the adsorption behaviour of a surface-active agent onto a mineral oxide surface (Ali and Dzombak, 1998a; Axe et al., 2006; Rahnemaie et al., 2007). A surface-active agent forms either outer- or inner- sphere surface complexes with the mineral oxide surfaces depending on the chemical environment of the system. The inner-sphere surface complexation causes mineral dissolution (Johnson et al., 2005; Nordin et al., 1997; Slowey et al., 2005; Stumm and Kummert, 1987; Yoon et al., 2005, 2004). The simple aromatic organic acids mimic the natural organic matter and behave like a surface-active agent but not like a typical surfactant (Macinnis et al., 2000). The thesis entitled quotAdsorption of simple aromatic organic acids/anions at the a-alumina/water interface: influence of functionality and background electrolytesquot consists of seven chapters. Chapter-I: Introduction A review on the adsorption of simple and well-defined organic acids onto metal oxides surfaces and the effect of functionality, pH and background electrolytes are described in this