Effect of fractionation on the sorption properties of NOM onto modified TiO2 surfaces

Abstract

Natural organic matters (NOM) can be broadly divided into two fractions: hydrophobic (humic substances), and hydrophilic or non-humic substances. Chemical composition of humic substance varies with molecular size and the differences in the chemical composition between size fractions may have significant consequences on the environmental chemistry and geochemistry of humic substances. They have a crucial role in transporting the contaminants in the environment because of their solubility. Contaminant distribution can be reduced by removing humic substances that have soluble subclass as humic and fulvic acids. Due to the heterogeneity of humic acids in terms of physical and chemical properties, they were fractionated into molecular fractions by using different suitable membranes. Due to the photocatalytic properties, TiO2 that is used for the degradation of undesirable chemical contaminants in water has been the focus of many investigations. By comparing the adsorption of the humic acid and its fractions onto bare and surface modified titanium dioxide, this work presented important information for understanding the photocatalytic efficiencies of TiO2. This study is conducted to investigate the complex interactions between the surface properties of titanium dioxide and the molecular size dependent fractions of the humic acid in order to provide information in relation to the photocatalytic degradation of humic acids with surface modified TiO2 powders.