title: New composites of nanoparticle Cu (I) oxide and titania in a novel inorganic polymer (geopolymer) matrix for destruction of dyes and hazardous organic pollutants.
abstract: New photoactive composites to efficiently remove organic dyes from water are reported. These consist of Cu2O/TiO2 nanoparticles in a novel inorganic geopolymer matrix modified by a large tertiary ammonium species (cetyltrimethylammonium bromide, CTAB) whose presence in the matrix is demonstrated by FTIR spectroscopy. The CTAB does not disrupt the tetrahedral geopolymer structural silica and alumina units as demonstrated by (29)Si and (27)Al MAS NMR spectroscopy. SEM/EDS, TEM and BET measurements suggest that the Cu2O/TiO2 nanoparticles are homogenously distributed on the surface and within the geopolymer pores. The mechanism of removal of methylene blue (MB) dye from solution consists of a combination of adsorption (under dark conditions) and photodegradation (under UV radiation). MB adsorption in the dark follows pseudo second-order kinetics and is described by Freundlich-Langmuir type isotherms. The performance of the CTAB-modified geopolymer based composites is superior to composites based on unmodified geopolymer hosts, the most effective composite containing 5wt% Cu2O/TiO2 in a CTAB-modified geopolymer host. These composites constitute a new class of materials with excellent potential in environmental protection applications.
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, New Zealand.
authors.forename: Mahroo
authors.initials: M
authors.lastname: Falah
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, New Zealand. Electronic address: Kenneth.mackenzie@vuw.ac.nz.
authors.forename: Kenneth J D
authors.initials: KJD
authors.lastname: MacKenzie
authors.affiliation: Robinson Research Institute, Victoria University of Wellington, New Zealand.
authors.forename: Ruth
authors.initials: R
authors.lastname: Knibbe
authors.affiliation: Department of Physics, Warwick University, Coventry CV4 7AL, United Kingdom.
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Page
authors.affiliation: Department of Physics, Warwick University, Coventry CV4 7AL, United Kingdom.
authors.forename: John V
authors.initials: JV
authors.lastname: Hanna
keywords: Modified geopolymers; Organic pollutants; Photocatalysis; TiO(2)/Cu(2)O nanoparticles