The removal of lead, copper and cadmium ions from aqueous streams using lecithin
enhanced micro filtration with 0.2μm pore size tubular ceramic membranes has been
Measurements of the surface tension at varying lecithin concentrations were carried
out to determine the critical micelle concentration (CMC) of lecithin and the effects of
lead ions, mixtures of lead and copper ions, and mixtures of lead, copper and
cadmium ions in solutions on the CMC of lecithin. The zeta potential and the effects of
the single and multiple metal ions on the zeta potential of lecithin were also
investigated. The influence of lecithin concentrations, cross flow velocity and
transmembrane pressure on the rejections and steady state permeate flux behaviours
The CMC of lecithin was found to be 9 grl. An increase in metal ion concentration
caused a decrease in the CMC and an increase in the zeta potential of lecithin
solutions, suggesting the binding of the metal ions onto the lecithin. An increase in
lecithin concentration was found to improve metal ions removal. Lecithin showed
preference for the metal ions in the order Pb2+ > Cd 2+ > Cu 2+. Metal ion removal
was influenced more by lecithin concentration and less by transmembrane pressure
and cross flow velocity. The steady state permeate flux and rejection behaviours have
been explained by microscopic phenomena and a mathematical model has been
developed to predict the steady state permeate flux. The lecithin concentration that
remains in the permeate was less than 9% of the feed solution.
The study has shown that lecithin enhanced micro filtration is a technically suitable
technique for removal of lead, copper and cadmium ions in aqueous solution.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.