title: Removal of humic acid using TiO2 photocatalytic process--fractionation and molecular weight characterisation studies.
abstract: The photocatalytic removal of humic acid (HA) using TiO2 under UVA irradiation was examined by monitoring changes in the UV(254) absorbance, dissolved organic carbon (DOC) concentration, apparent molecular weight distribution, and trihalomethane formation potentials (THMFPs) over treatment time. A resin fractionation technique in which the samples were fractionated into four components: very hydrophobic acids (VHA), slightly hydrophobic acids, hydrophilic charged (CHA) and hydrophilic neutral (NEU) was also employed to elucidate the changes in the chemical nature of the HA components during treatment. The UVA/TiO2 process was found to be effective in removing more than 80% DOC and 90% UV(254) absorbance. The THMFPs of samples were decreased to below 20 microg l(-1) after treatments, which demonstrate the potential to meet increasingly stringent regulatory level of trihalomethanes in water. Resin fractionation analysis showed that the VHA fraction was decreased considerably as a result of photocatalytic treatments, forming CHA intermediates which were further degraded with increased irradiation time. The NEU fraction, which comprised of non-UV-absorbing low molecular weight compounds, was found to be the most persistent component.
authors.affiliation: ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Sciences and Engineering, The University of New South Wales, Sydney NSW 2052, Australia.
authors.forename: Sanly
authors.initials: S
authors.lastname: Liu
authors.forename: May
authors.initials: M
authors.lastname: Lim
authors.forename: Rolando
authors.initials: R
authors.lastname: Fabris
authors.forename: Christopher
authors.initials: C
authors.lastname: Chow
authors.forename: Ken
authors.initials: K
authors.lastname: Chiang
authors.forename: Mary
authors.initials: M
authors.lastname: Drikas
authors.forename: Rose
authors.initials: R
authors.lastname: Amal
mesh_terms: D002384:Catalysis / Q000528:radiation effects; D005591:Chemical Fractionation / Q000379:methods*; D002850:Chromatography, Gel; D006812:Humic Substances; D008970:Molecular Weight; D013056:Spectrophotometry, Ultraviolet; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D006812:Humic Substances; C009495:titanium dioxide; D014025:Titanium