DEVELOPMENT OF SULFATED TITANIUM DIOXIDE PHOTOCATALYSTS FOR THE REMOVAL OF ORGANIC POLLUTANTS FROM REVERSE OSMOSIS CONCENTRATE

Abstract

Reverse osmosis desalination has been one of the key steps in a typical wastewater treatment processes. Reverse osmosis concentrate (ROC) is usually disposed to water bodies which posts risks to ecosystems. The research objective of this thesis is to develop efficient photocatalysts for the treatment of ROC. Sulfated TiO2 photocatalysts were synthesized, characterized and evaluated. Trace surface sulfate species on the surface of TiO2 semiconductor act as electron traps, which enhance the photogenerated electron-hole separation and photocatalytic efficiency. The structures and spatial distribution of sulfate species were elucidated and their activities were also compared. Band positions based on XPS data and Mott-Schottky plots agreed with each other and partially explained the activity difference. Internal (in-situ) sulfation was more efficient than external sulfation due to more Ti-OH groups available. Beyond photocatalysts, adsorption and coagulation methods were evaluated for the r