Sorption/Desorption of Organic Pollutants from Complex Mixtures: Modeling, Kinetics, Experimental Techniques and Transport Parameters

Abstract

Sorption/desorption is one of the most important processes influencing movemement of organic pollutants in natural systems. Sorption with reference to a pollutant is its transfer from the aqueous phase to the solid phase; on the other hand, desorption is its transfer from the solid phase to the aqueous phase. Similar to all interphase mass-transfers, the sorption/desorption process can be defined by the final-phase equilibrium of the pollutant at the aqueous-solid phase interface and the time required to approach final equilibrium.

The main goal of this chapter is to review the most widely used modeling techniques to analyze sorption/desorption data generated for environmental systems. Since the definition of sorption/desorption (i.e., a mass-transfer mechanism) process requires the determination of the rate at which equilibrium is approached, some important aspects of chemical kinetics and modeling of sorption/desorption mechanisms for solid phase systems are discussed. In addition, the background theory and experimental techniques for the different sorption/desorption processes are considered. Estimations of transport parameters for organic pollutants from laboratory studies are also presented and evaluated.

An important and recently reported issue, namely slow sorption/desorption rates, their causes at the intra-particle level of various solid phases, and how these phenomena relate to contaminant transport, bioavailability, and remediation, is also discussed and evaluated. A case study showing the environmental impact of solid waste materials which are mainly complex organic mixtures and/or their reuse/recycling as highway construction and repair materials is presented and evaluated from the point of view of sorption/desorption behavior and data modeling.