Adsorption Modeling of Polychlorinated Biphenyls on Fluorisil

Abstract

Among the chemicals known as persistent organic pollutants responsible to cause serious harmful effects both on environment and health, the class belonging to polychlorinated biphenyls (PCB) still arise problems related to instrumental techniques detection in order to enhance the analytical performances. In this context special preparative methods have been developed, such as solid—phase—micro—extraction, when a magnesium silicate matrix, fluorisil, can be successfully used to increase sensitivity and to decrease the detection limits. The aim of this paper is to provide experimental data on kinetics and equilibrium of adsorption of nine PCB congeners on fluorisil matrix. Correlation of adsorption parameters with structural characteristics results in differentiation of adsorption efficiency between two PCB groups, depending on whether one or both biphenyl rings are substituted with chlorine atoms. Adsorption correlations are discussed in terms of molecular volumes and areas, hydrophobicity, dipole moment and polarizability, which determine a perpendicular or parallel arrangement of PCB molecules of two PCB groups on magnesium silicate sorbent. Adsorption modeling of kinetic data indicates an intra-particle diffusion mechanism and a C type isotherm for equilibrium data is checked.

Keywords:

• Adsorption modeling
• fluorisil
• PCB congeners
• structural correlations