title: Chemical functionalization of diatom silica microparticles for adsorption of gold (III) ions.
abstract: Diatom silica microparticles from natural diatomaceous earth (DE) silica have been functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) and their application for adsorption of gold (III) ions from aqueous solutions is demonstrated. Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron spectroscopy (XPS) analyses of the MPTMS modified diatom microparticles revealed that the silane layer with functional group (-SH) was successfully introduced to the diatom surface. The adsorption study of Au(III) ions using MPTMS-DE indicated that the process depends on initial gold (III) concentration and pH showing maximum adsorption capacity at pH = 3. The Au(III) adsorption kinetics results showed that the adsorption was very fast and followed a pseudo-second-order reaction model. The Langmuir model was used to provide a sound mechanistic basis for the theoretical of the adsorption equilibrium data. Gold recovery from MPTMS-DE structures was also investigated by using acidified thiourea solution and found to be high (> 95%). These results show that chemically modified DE microparticles can be used as a new, cost effective and environmentally benign adsorbent suitable for adsorption of gold metal ions from aqueous solutions.
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, 5095 SA, Australia.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.forename: Jonas
authors.initials: J
authors.lastname: Addai-Mensah
authors.forename: Dusan
authors.initials: D
authors.lastname: Losic