Emulsion breakage behaviour on chromium (VI) removal using emulsion liquid membrane containing quaternary ammonium compounds

Abstract

Environmental pollution caused by heavy metals such as chromium, nickel, and lead has become a serious worldwide issue due to their threats to humans, animals and plants as well as to the stability of the overall ecosystem. Its removal from effluents such as electroplating rinse wastewater and tannery effluents is of primordial importance. In this study, the emulsion liquid membrane (ELM) technology was employed as a remediation technique that capable of removing Cr (VI) efficiently from wastewater where extraction and stripping processes are performed in a single operation. The ELM is consists of trioctylmethylammonium chloride (Alamine 336) as an extractant, palm oil as an organic diluent, sodium hydroxide (NaOH) as a stripping solution and sorbitan monooleate (Span-80) as a surfactant to stabilize the emulsion phase. The effect of operational parameters such as the agitation speed, phase contact time, extractant concentration and stripping agent concentration were studied to optimize the conditions for emulsion stability and maximum removal of chromium. The best removal efficiency was obtained at 350 rpm of agitation speed and 3 minutes of phase contact time with 0.04 M Alamine 336 as extractant and 0.1 M NaOH as stripping agent. In this condition, the maximum removal efficiency of 100% was obtained with a minimum breakage rate of 5%.