title: Adsorption of natural organic matter and disinfection byproduct precursors from surface water onto TiO2nanoparticles: pH effects, isotherm modelling and implications for using TiO2for drinking water treatment.
abstract: Titanium dioxide is a photocatalyst that can remove organic contaminants of interest to the drinking water treatment industry, including natural organic matter (NOM) and disinfection byproduct (DBP) precursors. The photocatalytic reaction occurs in two steps: adsorption of the contaminant followed by degradation of the adsorbed contaminant upon irradiation with UV light. The second part of this process can lead to the formation of reactive intermediates and negative impacts on treated water quality, such as increased DBP formation potential (DBPfp). Adsorption alone does not result in the formation of reactive intermediates and thus may prove to be a safe way to incorporate TiO2into drinking water treatment processes. The goal of this study was to expand on the current understanding of NOM adsorption on TiO2and examine it in a drinking water context by observing NOM adsorption from real water sources and evaluating the effects of the resulting reductions on the DBPfp of the treated water. Bottle point isotherm tests were conducted with raw water from two Canadian water treatment plants adjusted to pH 4, pH 6 and pH 8 and dosed with TiO2nanoparticles. The DOC results were a good fit to a modified Freundlich isotherm. DBP precursors and liquid chromatography with organic carbon detection NOM fractions associated with DBP formation were removed to some extent at all pHs, but most effectively at pH 4.
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada. Electronic address: stephanie.gora@mail.utoronto.ca.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Gora
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada. Electronic address: sandrews@civ.utoronto.ca.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Andrews
mesh_terms: D000327:Adsorption; D004203:Disinfection; D060766:Drinking Water / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008962:Models, Theoretical; D053758:Nanoparticles / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry* / Q000302:isolation & purification; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014866:Waste Products; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*; D060753:Water Quality
chemical_list: D060766:Drinking Water; D009930:Organic Chemicals; D014866:Waste Products; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium
keywords: Adsorption; Advanced oxidation; Disinfection byproducts; Drinking water; Natural organic matter; Titanium dioxide