MICELLAR-ENHANCED ULTRAFILTRATION OF HEAVY-METALS USING LECITHIN

Conventional treatment methods for removal of heavy metals from metal finishing operations are usually energy-intensive and costly. Micellar -enhanced ultrafiltration (MEUF) with synthetic surfactants is a recen tly developed technique which can remove heavy metals and other small molecular weight ions from wastestreams at relatively lower costs and without a phase change. Lecithin, a natural, inexpensive, nontoxic, an d biodegradable surfactant exhibits emulsifying characteristictics whi ch can be used in a MEUF. The binding of various lecithins to cadmium, copper, lead, nickel, and zinc--in a mixture and individually--was st udied using a continuous diafiltration method. This technique uses sma ll volumes of toxic waters and produces an entire isotherm with just o ne experiment. In the presence of all five heavy metals, the lecithin in this study showed the following affinity: Cu > Cd approximately Zn > Ni. In experiments when only one metal was present, lecithin exhibit ed the following affinity: Ni > Cu approximately Zn > Cd. Lead was not bound significantly in either scenario.