Water pollution is a major global issue which poses a serious threat to human health as well as the aquatic environment. In particular, dissolved heavy metal species and persistent organic pollutants (POPs) have been regarded as major problems due to their high toxicity and non-biodegradability. Adsorbents and membrane filtration are the most widely used technologies for the treatment of contaminated waste water, however the high cost and environmental implications of these technologies have encouraged a paradigm shift to the use of photocatalytic processes for wastewater treatment. In this work, an innovative photoelectrochemical process for simultaneous removal of heavy metal ions and POPs from wastewater was developed and demonstrated using a photoelectrochemical cell (PEC) with a W03 photoanode under sunlight irradiation. Synthetic wastewater samples containing 0.5 M of NaCI, 10 ppm of methylene blue (MB, organic pollutant), 500 ppm of CuCh or 500 ppm NiCh were tested as the first examples for demonstration of the principle, device and process. The results showed that upon irradiation of simulated sunlight on the photoanode, metal ions (Cu2+ and Ni2+) can be recovered as metals at the cathode. MB was simultaneously decomposed at the photoanode without using any additional chemicals. The cell voltage required for this dual purpose process was as much as 71 % or 57 % lower than that required for conventional electrodeposition of Cu or Ni respectively with an inert anode. Current efficiency for electrodeposition in the PEC could be adjusted close to 100 % depending on applied cell voltage, minimising charge loss for H2 evolution. Meanwhile, as a potential photocatalyst, CNTs/W03 hybrids were successfully synthesised by a surfactant aided sol-gel method and tested for their photocatalytic performance. It was found that the addition of CNTs to W03 by either hybridisation or mechanical mixing caused a significant drop of both photocurrent and photovoltage of W03, presumably due to the interfacial electronic structure between W03 and CNTs.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:659292 |
| Date | January 2014 |
| Creators | Kim, Gwangjun |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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