The feasibility and efficiency of simultaneous removal of multiple cations as well as anionic heavy metals from wastewater into a mixed extractant kept stagnant on the shell side of a 2-fiber-set hollow fiber membrane extractor operated as a fixed bed adsorber was explored. The novel extracting solvent was a mixture of an acidic or chelating extracting agent for one or more cations and a basic extracting agent, e.g., trioctylamine (TOA) for extracting anions; both were dissolved in the same diluent kerosene for simultaneous and synergistic extraction of cations and anions. In the stripping part of the fixed bed operation, alkaline stripping solution was passed through one set of fibers to strip anions while acidic stripping solution was passed through the second fiber set to recover and concentrate cations. For removal and individual recovery of Cu(II), Cr(VI) and Zn(II), one module of this research will replace five modules needed for individual removal and recovery of these heavy metals.
Batch experiments conducted for Cu(II) and Cr(VI) system using a mixed extractant containing LIX 84 and TOA in kerosene showed that Cu(II) and Cr(VI) can be efficiently removed simultaneously. Fixed bed studies showed that Cu(II) and Cr(VI) concentrations can be reduced to less than I ppm from a feed containing about 200 ppm Cu(II) and 100 ppm Cr(V1). Batch and fixed bed experiments conducted for Cu(lI), Zn(lI) and Cr(VI) system using a mixed extractant containing LIX 84, di-2-ethylhexyl phosphoric acid (D2EHPA) and TOA in kerosene showed that, Cu(II), Zn(II) and Cr(VI) can be efficiently removed simultaneously
