Remediation of simulated aquatic sites contaminated with recalcitrant substrates by TiO2/ozonation under natural sunlight

The fates of four aquatic contaminants, namely the 2,4-dichlorophenoxyacetic acid herbicide (2,4-D), the bisphenol A endocrine disruptor (BPA), and the sodium butylnaphthalenesulfonate (BNS) and benzyldodecyldimethylammonium bromide (BDDAB) surfactants by the TiO2-photoassisted ozonation (TiO2/O3/UV method) were investigated indoors under laboratory conditions (super-high-pressure Hg lamp) and outdoors under natural Sunlight. In laboratory experiments the TiO2/O3/UV methodology led to significant increases in degradation efficiency relative to ozonation (dark: O3; or under UV light: O3/UV) and to the TiO2-photoassisted method of oxygenated dispersions (TiO2/O2/UV). Mineralizations of the substrates were monitored by total organic carbon (TOC) assays. The BDDAB surfactant, being most recalcitrant to biodegradation and to the TiO2-photoassisted degradation, was mineralized efficiently by the TiO2/O3/UV method under natural Sunlight at relatively high concentrations of contaminants (1.0 mM) using a tubular-type photoreactor consisting of Pyrex glass tubes and a solar cell system that supplied the needed electrical power.