The preparation of a gold nanoparticle monolayer on the surface of a polymer inclusion membrane using EDTA as the reducing agent

A polymer inclusion membrane (PIM) consisting of Aliquat 336 (20% m/m), 1-dodecanol (10% m/m) and PVC (70% m/m) has been used as a template to prepare gold nanoparticles (Au NPs). AuCl4− has been extracted into the membrane via ion-exchange and has been subsequently reduced by l-ascorbic acid, tri-sodium citrate, NaBH4 or EDTA to form Au NPs. EDTA at pH 6.0 has been shown to be an effective reducing agent capable of forming a uniform monolayer of Au NPs of average size 20 nm on the surface of the membrane. The other reagents have formed Au NPs of sizes depending on the reagent type and these have been embedded in the bulk of the membrane and not concentrated at the surface. The main factors influencing the formation of the surface Au NPs when EDTA is used as the reducing agent have been studied. A 24 h membrane exposure to the EDTA solution has ensured complete surface coverage with Au NPs. It has been observed that as the concentration of EDTA, the solution temperature and shaking rate increase, the size of Au NPs decreases. Therefore, these factors can be used to control the size of Au NPs on the membrane surface. The coated with Au NPs membranes are expected to be of interest in optical sensing and catalytic applications.