title: Functionalized diatom silica microparticles for removal of mercury ions.
abstract: Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (-SH or -NH2) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g-1for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions.
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
authors.forename: Jonas
authors.initials: J
authors.lastname: Addai-Mensah
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia; School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia.
authors.forename: Dusan
authors.initials: D
authors.lastname: Losic
keywords: 3-mercaptopropyl-trimethoxysilane (MPTMS); Diatom silica; Diatoms; Mercury adsorption; Organosilane modifications