Investigation of Organic Matter Release in Emulsion Liquid Membrane Treatments

Abstract

The emulsion liquid membrane (ELM) technique is a process used for separation. It uses organic diluents, extractants, and surfactants. Due to the organic nature of these constituents, an unwanted organic matter release to the external phase occurs during the separation process. The present study demonstrates this organic matter release to the external phase in the ELM process used for the removal of lead ions from industrial storage battery wastewater. Toluene, kerosene, mineral oil, and xylene, as organic diluents, sorbitan monooleate (Span 80) and polyoxyethylene (20) sorbitan trioleate (Tween 85), as surfactants, and di-2-ethylhexyl phosphoric acid (D2EHPA), as extractant, were used. In the process of lead ion removal from storage battery wastewater, while lead ion concentration decreased to < 0.4 mg/l from its initial value of 2.8 mg/l, the organic matter load (COD) of the treated wastewater increased to about 160 mg/l. Additionally, Span 80 exhibited better results than Tween 85 in terms of CODs and lead removal. Kerosene had a more stable membrane than the other organic diluents used. The optimum membrane components and their rates were 70% kerosene, 18% mineral oil, 3% Span 80, and 9% D2EHPA. When wastewater pH was adjusted to improve lead ion removal, COD of the treated wastewater increased to > 200 mg/l. © Tübitak.