Study of the supported liquid membrane for the estimation of the synergistic effects of influential parameters on its stability

Supported liquid membrane (hereafter referred as SLM) is considered as an impressive alternative and the improved version of the liquid–liquid extraction (hereafter referred as LLE) process owing to some its inherent advantages over the traditional LLE processes. The most crucial problem associated with the SLM technique is its stability i.e. the ability to operate for prolonged time without compromising the quality of the separation. The prevalent reasons for the instability are investigated experimentally to reach to the solutions. In this case study, the extent of stability has been quantified by measuring the performance of SLM in terms of percentage of extraction and recovery of phenol while it is transported across the membrane in a series of runs. The percentage of transportation of phenol at various time scales during the transportation is measured in order to quantify the stability. Initially, the components of the liquid membrane (hereafter referred as LM) e.g. solvent–carrier combination are selected based on their physical properties that yield best transportation and stability as well. Further, the components and concentrations of feed phase and LM are optimized for the more stable SLM system. The addition of electrolyte in the aqueous phases in order to enhance the interfacial tension between LM and either of the aqueous phases increases the stability up to 120 h. The addition of surfactant in LM reduces the loss of LM from pores of the membrane support and provides the SLM stability up to 144 h. Polymeric gel formation on the outer surface of SLM (LM into the micro-pores of membrane support) increases the stability of SLM up to 168 h with the reduction of recovery of phenol after 120 h only up to 10.3%.