REMOVAL OF HEAVY METAL FROM AQUEOUS WASTEWATER BY EMULSION LIQUID MEMBRANE.

Extraction and recovery of heavy metal from waste water using Liquid Membrane technology is more efficient than methods such as precipitation that form sludge that needs to be disposed in landfills. A green emulsion liquid membrane (ELM) has been formulated in this work using an environmental-friendly refined palm oil as the main diluent of ELM to recover zinc ions from aqueous waste solution using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as a highly selective carrier with double Water-Oil-Water emulsion. This system promotes many advantages including simple operation, high selectivity, low energy requirement, and single stage extraction and stripping process. In this study ELM process was used to transport zinc metal ion from aqueous feed phase to stripping phase which was prepared by using H2SO4, HCl, and HNO3. This extraction was done in a Batch-type stirred tank at room temperature with different types of vegetable oils green solvent. For green ELM process the various vegetable oils have been studied as diluents, such as palm oil, sesame oil, coconut oil, soyabean oil and for further studies we found that palm oil is more effective vegetable oil which gives more recovery of zinc ion from wastewater. The effect of various parameters such as, pH of the feed solution, concentration of the stripping phase, surfactant concentration, carrier concentration, F/M phase ratio, O/I phase ratio, contact time of the double emulsion etc. were studied. After determining the optimum conditions it was possible to extract zinc metal ion up to 62% from aqueous feed phase in a single stage extraction.