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RISS 인기검색어
- 검색키워드
- 저자 : ElShorafa, Rand (검색결과 2 건)
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Han, D.,Elshorafa, R.,Yoon, S.,Kim, S.,Park, H.,Abdel-Wahab, A. Royal Society of Chemistry 2018 Photochemical & photobiological sciences Vol.17 No.4
<P>A metal oxide-heterojunction photocatalyst is developed to harvest sunlight, store the energy in electrons, and apply the stored energy in water treatment. Light-absorbing nanoparticular and nanotubular TiO2 are hybridized with electron-storing WO3 at different weight ratios of TiO2 to WO3 (e.g., TW25 represents a composite of 25 wt% TiO2 and 75 wt% WO3). The ability of the TW composite to utilize the stored electrons is examined for the reduction of hexavalent chromium (Cr(VI)). In the photoelectrochemical (PEC) tests, irradiation using simulated sunlight (AM 1.5, 100 mW cm(-2)) leads to a rapid shift in the open-circuit potential (OCP) of the TW electrodes to the negative potential region (photocharging process). The termination of irradiation causes a gradual shift of the OCP to the positive potential region over 20 h (discharging process). Spiked Cr(VI) added to the solution with pre-photocharged TW electrodes is efficiently removed; the kinetics of this process depends on the TW composition (25, 50, or 75 wt%), TiO2 morphology (particular or tubular), initial Cr(VI) concentration (0.125 or 0.25 ppm), and whether the conditions are aerated or non-aerated. Based on this knowledge, TW composite-embedded inorganic membranes are synthesized and charged using sunlight. For Cr(VI) removal, single-pass and continuous circulation filtration systems are employed. The fraction of Cr(VI) removed from the circulation system is similar to 30% in 4 h, which is 1.5 times that removed using the single-pass filtration system (similar to 20%). An X-ray photoelectron spectroscopy analysis of the TW membranes used for Cr(VI) removal reveals that Cr is not sorbed in the membrane. The W(VI) inWO(3) is partially reduced to W(6-x)+ upon photocharging and is oxidized during the reduction of Cr(VI), leading to the co-existence of W6+ and W(6-x)+.</P>
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Yoon, Sun Hee,ElShorafa, Rand,Katbeh, Mary,Han, Dong Suk,Jeong, Hye Won,Park, Hyunwoong,Abdel-Wahab, Ahmed Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.423 No.-
<P><B>Abstract</B></P> <P>This study investigated the effect of TiO<SUB>2</SUB> morphology-driven intrinsic oxygen defects on photocatalytic activities for removal of Cr(VI). To do so, two different-shaped TiO<SUB>2</SUB> particles, nano-granular TiO<SUB>2</SUB> particles (TiNP) and TiO<SUB>2</SUB> nanotube particles (TiNT), were prepared and applied. The surface analyses indicated that TiNP was found to have a greater photocatalytic activity than TiNT because of its more crystallinity and lower bandgap energy, more oxygen vacancies closer to the conduction band (CB), and its resulting more amounts of photogenerated electrons. Accordingly, these photocatalytic properties of TiO<SUB>2</SUB> particles were more evident in experimental result for photocatalytic reduction of Cr(VI) that was tested as a model target compound. The batch system showed that TiNP completely reduced Cr(VI) to Cr(III) at acidic and neutral pH, whereas TiNT were less effective even at low pH.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Different-shaped TiO<SUB>2</SUB> particles (granular (TiNP) and tubular (TiNT)) were applied. </LI> <LI> Relatively more intrinsic oxygen defect sites in TiNP, whereas more interstitial oxygen in TiNT. </LI> <LI> Relatively rapid reduction of Cr(VI) by TiNP due to facile electron transfer through oxygen defect sites. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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