CHAPTER 11: Factors Affecting Surfactant Modification of Solid Media for Removal of Oxo Ions

In search of new, inexpensive, and green materials that exhibit ion-exchange properties suitable for removal of oxo anions from water, researchers have examined approaches that involve surface modification of existing commercially available sorbent media with positively charged surfactants. When compared to ion-exchange media, these approaches have demonstrated satisfactory promise in the removal of oxo anions for a fraction of the cost of commercially available ion-exchange media. The concept involves reversing the negative surface charge to a positive one using surfactants with positively charged groups similar to those found in ion-exchange resins. The efficiency of the ion-exchange process is closely related to a number of factors that could affect the surfactant modification of solid sorbent media for removal of oxo ions. The most important factors are: (1) the specific surface area of the sorbent media; (2) the surface charge/ion exchange capacity of the sorbent media; (3) the porosity and pore size distribution of the sorbent media; and (4) the surfactant properties. During research, the importance of some of these factors is often neglected, which may lead to unrealistic performance results for the media. Therefore, it is important to identify critical factors that could potentially lead to unrealistic experimental results and other misconceptions related to the performance of oxo anion removal from water by surfactant-modified media.