Pretreatment of liquid industrial streams by adsorption: challenges and perspectives

Abstract

Liquid phase adsorption is a common process in waste water purification, desiccation applications or in (analytical) laboratory applications; e.g. chromatography. However, this economic separation process has even more potential. The removal of undesired poisonous, environmentally harmful or corrosive contaminants from organic liquids by adsorption is such an application. Here, contaminant concentrations can be brought down to the detection limit or even below. These contaminants can be e.g. sulfur or nitrogen compounds or heavy metals like mercury. In the liquid phase adsorption process the chemical and physical properties of the mobile components (adsorptive and bulk phase) as well as the nature of the adsorbent play an important role. Each industrial stream to be treated requires a precise analysis of the components involving the interactions between the components as well as possible resulting side reactions which may occur during the adsorption or desorption process. The paper focuses on the possibilities of desulfurization of liquid propane gas streams depending on the nature of the side components of the stream and the availability and the composition of the regeneration gas. The limitations of the adsorption capacity and selectivity of the adsorbent towards sulfuric compounds in the liquid phase are discussed. On the other hand the potential of the adsorption technology in purification of liquid streams as an inexpensive and readily available method is demonstrated.