A Vegetable Oil-based Green Process for the Membrane Extraction of Ionic Solutes

Abstract

Extraction or removal of the polluting components can be accomplished by a variety of physical, chemical and biological methods. Solvent extraction has demonstrated as one of the promising methods to accomplish the extraction or removal of ions more or less selectively from the source streams. The processes, especially when operated in membrane modules, have been successful and effective in reducing the pollutant concentration. In the development of these processes in to industrial operations the solvents (or the extracting phase) used or recommended in the literature are from non-sustainable source, they have undesirable properties (toxic, corrosive and health and safety issues). In recent years there have been research work to examine the feasibility of other solvents from sustainable sources and with good characteristics to overcome or minimize some of the above adverse effects. In this paper, the effectiveness of sunflower oil (as a model for vegetable oil), is described in extraction (or removal) of a polluting component in a small-scale membrane contactor. The components are: chromate ion and ammonium ion and the process is developed using a carrier molecule (di-2-ethylhexyl phosphate for ammonium and Aliquat 336 for chromate) in sunflower oil. The removal percentages are very good (in the range of 43-99%) and obtained at their natural conditions (with no chemical added for the adjustment of pH) of the aqueous feed. The main attraction of the process is the good performance of sunflower oil, which can be considered a “green†solvent system as it has the benefit of being environmentally friendly, less costly, non-toxic and sustainable.