Publication

Enhancing solar disinfection of water in PET bottles by optimized in-situ formation of iron oxide films. From heterogeneous to homogeneous action modes with H2O2 vs. O-2 - Part 2: Direct use of (natural) iron oxides

Abstract

Solar disinfection (SODIS) is a well-accepted intervention method, leading to an improvement in contaminated water sources. In this work, we attempted to further enhance the bacterial inactivation process during light exposure. By means of iron oxide addition, we generated a film on the inner surface of PET bottles used in SODIS, in order to induce further pathways of solar-mediated inactivation. More specifically, in this 2nd part, the deposition process has been systematically assessed, using iron oxides (Fe-Ox). The deposition parameters, namely, the precursor concentration (50 mg/L to 1 g/L), deposition time (1-4 h), oxide type (semiconductor, Fe species), size (mu m vs. nm), and specific surface area (similar to 5-150m(2)/g), were assessed. The use of H2O2 as the electron acceptor (and heterogeneous photo-Fenton induction) enhanced the efficacy without decreasing the reuse potential. More than 60% and 75% reduction in the treatment time was observed, compared with that for SODIS in a normal bottle, with O-2 and H2O2 (in situ photo-Fenton) as the electron acceptors, respectively. The semiconductor mode of action and controlled iron leaching in the system both demonstrated bactericidal capacity; particularly, it was found that the factors affecting the process partially correlated with the oxide characteristics (size, band gap, and isoelectric point), rather than the capacity to photo-dissolve iron. Consequently, the use of a natural Fe source yielded results (deposition parameters and efficacy) resembling those for iron salts, indicating the dominant inactivation pathways governing the process in the presence or absence of H2O2. Finally, the disinfection of natural lake water with natural Fe-deposed bottles showed similar results to those of Fe-salt-deposed bottles, indicating that in a suitable matrix, the process can work equally well.

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Related concepts (36)
Water purification
Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption (drinking water), but water purification may also be carried out for a variety of other purposes, including medical, pharmacological, chemical, and industrial applications. The history of water purification includes a wide variety of methods.
Iron
Iron is a chemical element with the symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, just ahead of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust, being mainly deposited by meteorites in its metallic state, with its ores also being found there.
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