The removal of toxic lead ions from aqueous solution by a combined nano-membrane separation
technique was investigated. Biodegradable poly-gamma-glutamic acid (γ-PGA), a linear
biopolymer, and its cross-linked nanoparticles were used to capture the metal ions
by forming nanosized particles. The polymer-metal ion particles, with sizes in the
range of 80–350 nm, were then removed by membrane separation. Two ultrafiltration
techniques were studied with the aim of developing a nanoparticle-enhanced separation
process for the efficient removal of lead ions from aqueous solution. The influence
of parameters such as the feed lead ion and γ-PGA concentrations and their proportions,
the γ-PGA cross-linking ratio and the pH of the solution on the lead-removal efficiency
and permeate flux was studied. It was found that γ-PGA could bind and remove more
than 99.8% of the lead ions from water through a convenient, low-pressure ultrafiltration
technique, resulting in a permeate that satisfied the standard for drinking water
recommended by the WHO.
