Abstracts Book - IMRC 2018

• SWMC-O010 Invited Talk
ENGINEERED NANO-TIO2 IN SURFACE WATER AND EFFECTS ON
TRANSFORMATION OF ORGANIC POLLUTANTS
Lingyan Zhu 1,2 , Wei Wu 1 , Xiaomei Shi 1
1 Nankai University, Key Laboratory of Pollution Processes and Environmental Criteria, Ministry
of Education, College of Environmental Science and Engineering, China. 2 Northwest A&F
University, College of Natural Resources and Environment, China.
Nano-TiO 2 is ubiquitous in the environment due to its widely application. We
investigated the presence of nano-TiO 2 in natural water system in Shijiazhuang,
Hebei province in China. Surprisingly, the total concentration of Ti in the
receiving river streams of a Wastewater Treatment was relatively higher (52-86
μg/L), indicating the importance of other sources such as urban runoff. These
relatively high Ti concentrations are unlikely to originate natural sources since
they are significantly higher than those in the nearby Yuqiao Reservoir (2
releases through WWTP effluents and other sources (including runoff) are
contributing to the relatively high observed concentrations of suspended Ti in
the Xiaohe River, which results in accumulation in edible fish tissue.
Further, we investigated the effect of nano-TiO 2 at ambient concentration on the
degradation of bisphenol A (BPA, also at low concentration) in water under
simulated solar light irradiation. The results indicated that nano-TiO 2 at low
concentration (1 mg/L) could significantly facilitate BPA degradation under mild
solar light irradiation, with the pseudo ï¬Â•rst-order rate constant (k obs ) for BPA
degradation raised by 1-2 orders of magnitude. The reaction was affected by
water pH, and the degradation rate was higher at acidic or alkaline conditions
than that at neutral condition. Humic acid (HA) also affected the reaction rate,
depending on its concentration. At lower concentration (the mass ratio of
HA/nano-TiO 2 was 0.1:1), HA improved the dispersion and stability of nano-TiO 2
in aquatic environment. As a result, the yield of •OHs by nano-TiO 2 under
sunlight irradiation increased and BPA degradation was facilitated. When the HA
concentration increased, a coating of HA was formed on the surface of nano-
TiO 2 .and the light absorption by nano-TiO 2 was significantly reduced. As a
consequence, the yield of •OH decreased and BPA degradation was depressed.
The results imply that nano-TiO 2 at ambient concentration may effectively
mediate BPA degradation, and can contribute to the natural attenuation and
remediation of some organic pollutants in aquatic environment.