John L. Zhou
Professor, University of Technology Sydney, Australia
Professor Zhou is an environmental engineer interested in contamination remediation and energy recovery from waste. Following a PhD in environmental technology, he has worked in the UK and Australia. He is a panel member/assessor for funding agencies such as the EU, UK EPSRC, NERC, Defra, Royal Society, US NSF, Fondazione Cariplo of Italy, and ARC. He is a recipient of K.C. Wong science research prize, Royal Society of Chemistry J.W.T. Jones travelling fellowship, and Royal Society research grant. He has published 170 articles in environmental and energy journals, with 10 being ESI highly cited.
Photocatalysis of emerging pollutants under visible irradiation is a process that has attracted wide research interest. However, these studies are limited to bench scale, since the catalysts utilised are added in slurry form and also the light from the source cannot penetrate to the bottom of the reactor. Optical fibres allow the light to be transmitted to longer distances with minimum loss, potentially making bench studies practical in real environments. The objectives of this research are to utilise air-clad fibres to transfer light to the photocatalysts immobilised onto glass beads, to collapse the air-cladding to attain side-emission enabling successful light transmission to the catalysts, and to photodegrade emerging contaminants such as 17α-ethynylestradiol (EE2) an endocrine disrupting chemical. This study addressed two major drawbacks of suspended photocatalysis: the immobilisation of catalysts and the transmittance of light over greater distances. Efficient side emission from the fibres was obtained by collapsing the air-holes, P25 and 4 wt.% Au-TiO2 catalysts were immobilised onto glass beads. EE2 half-lives were 1.26 h-1 and 0.78 h-1, in the presence of P25 TiO2 and gold modified catalysts respectively. The rate of photodegradation by both catalysts was found to follow pseudo 1st order kinetics. The catalysts as well as the fibres were stable for multiple reaction cycles with 6% decrease in degradation efficiency after three cycles. Therefore, air-clad fibres are a promising mode of light transmittance for photocatalysis applications in contaminated groundwater.