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Photodesorption of organic matter from titanium dioxide particles in aqueous media
El Saliby, I.,Shahid, M.,McDonagh, A.,Shon, H.K.,Kim, J.H. Korean Society of Industrial and Engineering Chemi 2012 Journal of industrial and engineering chemistry Vol.18 No.5
Photo-induced desorption of organic compounds from TiO<SUB>2</SUB> particles in aqueous media during photocatalysis has promising applications in water treatment. Photodesorption is a relatively fast phenomenon that facilitates the regeneration of photocatalysts with low energy consumption while concentrating the waste products in an energy and water efficient process. We propose that this transport phenomenon involves a significantly reduced affinity between the photocatalyst and pollutants upon UV illumination, and leads to the rapid detachment/decomposition of adsorbed pollutants. In this study, we report the effect of experimental conditions (pH, photocatalyst loading, organic loading, UV light irradiation and flow rate) on this phenomenon in a recirculating photocatalysis continuous reactor. Initially, organic compounds were allowed to adsorb on the surface of the photocatalyst (Degussa P25) until adsorption equilibrium was achieved. The photodesorption phenomenon was observed shortly after UV-light illumination of TiO<SUB>2</SUB> but before the bulk photocatalytic oxidation takes place. The pH of the solution was found to affect both the adsorption and the desorption percentages revealing the role of particle charge on this phenomenon. Additionally, a 1g/L loading of photocatalyst showed an optimum photodesorption rate using a single strength synthetic wastewater at pH 7.
El Saliby, I.,Okour, Y.,Shon, H.K.,Kandasamy, J.,Lee, W.E.,Kim, J.H. Korean Society of Industrial and Engineering Chemi 2012 Journal of industrial and engineering chemistry Vol.18 No.3
In this study, dye and secondary effluent wastewaters were used to generate a non-hazardous sludge. Anatase TiO<SUB>2</SUB> nanoparticles have been successfully synthesised from the calcination of the TiCl<SUB>4</SUB> flocculated sludge. A conventional hydrothermal method was adopted to produce anatase nanofibres (calcined at 600<SUP>o</SUP>C) from TiO<SUB>2</SUB> nanoparticles. X-ray diffraction, scanning electron microscopy and transmission electron microscopy investigations showed the highly crystalline nanoparticles and nanofibres after calcination. The size of nanofibres was related to the size of their nanoparticles precursors. Nanoparticles had larger surface area than nanofibres, lower pore volume and bigger pore diameter. Energy dispersive X-ray analysis revealed that impurities can be successfully removed by a subsequent hydrothermal/acid wash of nanoparticles. Nanoparticles had better overall photocatalytic activity for the degradation of organics in synthetic wastewater compared to nanofibres. On the other hand, nanofibres had a better adsorption capacity.
El Saliby, Ibrahim J.,Okour, Yosef H.,Shon, Ho K.,Vigneswaran, Saravanamuthu,Kandasamy, Jaya,Kim, J.-H. De Gruyter 2009 Journal of advanced oxidation technologies Vol.12 No.2
<P><B>Abstract</B></P><P>In this study, the effect of washing TiO<SUB>2</SUB>produced from flocculated sludge was investigated. Produced TiO<SUB>2</SUB>was washed with HCl, NaOH and Milli-Q-water and the washed TiO<SUB>2</SUB>was then characterized in terms of X-ray diffraction imaging, scanning electron microscope/energy dispersive using X-ray analysis and surface area. Washed TiO<SUB>2</SUB>was tested for adsorption and photocatalytic oxidation of acetaldehyde, and the decomposition of organics from synthetic wastewater (SWW) in terms of total organic carbon (TOC) and absorbance at UV-254. Results revealed that the anatase structure was dominant and TiO<SUB>2</SUB>was mainly doped with C atoms. The surface area of TiO<SUB>2</SUB>generated form TiCl<SUB>4</SUB>flocculation was found to be twice larger than the TiO<SUB>2</SUB>generated from Ti(SO<SUB>4</SUB>)<SUB>2</SUB>flocculation. Acid and base washings of TiO<SUB>2</SUB>improved its photocatalytic ability in decomposing acetaldehyde under UV-irradiation. Similarly, acid, base and Milli-Q water washings of TiO<SUB>2</SUB>were better in reducing TOC and humic acids from SWW.</P>
Ibrahim El Saliby,Yousef Okour,Jaya Kandasamy,Woong Eui Lee,김종호,Ho Kyong Shon 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.3
In this study, dye and secondary effluent wastewaters were used to generate a non-hazardous sludge. Anatase TiO2 nanoparticles have been successfully synthesised from the calcination of the TiCl4flocculated sludge. A conventional hydrothermal method was adopted to produce anatase nanofibres (calcined at 600 8C) from TiO2 nanoparticles. X-ray diffraction, scanning electron microscopy and transmission electron microscopy investigations showed the highly crystalline nanoparticles and nanofibres after calcination. The size of nanofibres was related to the size of their nanoparticles precursors. Nanoparticles had larger surface area than nanofibres, lower pore volume and bigger pore diameter. Energy dispersive X-ray analysis revealed that impurities can be successfully removed by a subsequent hydrothermal/acid wash of nanoparticles. Nanoparticles had better overall photocatalytic activity for the degradation of organics in synthetic wastewater compared to nanofibres. On the other hand, nanofibres had a better adsorption capacity.
Photodesorption of organic matter from titanium dioxide particles in aqueous media
Ibrahim El Saliby,Mohammad Shahid,Andrew McDonagh,김종호,Ho Kyong Shon 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.5
Photo-induced desorption of organic compounds from TiO2 particles in aqueous media during photocatalysis has promising applications in water treatment. Photodesorption is a relatively fast phenomenon that facilitates the regeneration of photocatalysts with low energy consumption while concentrating the waste products in an energy and water efficient process. We propose that this transport phenomenon involves a significantly reduced affinity between the photocatalyst and pollutants upon UV illumination, and leads to the rapid detachment/decomposition of adsorbed pollutants. In this study, we report the effect of experimental conditions (pH, photocatalyst loading, organic loading, UV light irradiation and flow rate) on this phenomenon in a recirculating photocatalysis continuous reactor. Initially, organic compounds were allowed to adsorb on the surface of the photocatalyst (Degussa P25) until adsorption equilibrium was achieved. The photodesorption phenomenon was observed shortly after UVlight illumination of TiO2 but before the bulk photocatalytic oxidation takes place. The pH of the solution was found to affect both the adsorption and the desorption percentages revealing the role of particle charge on this phenomenon. Additionally, a 1 g/L loading of photocatalyst showed an optimum photodesorption rate using a single strength synthetic wastewater at pH 7.
Development of visible light sensitive titania photocatalysts by combined nitrogen and silver doping
Ibrahim El Saliby,손호경,Laszlo Erdei,김종호 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.2
In this study we present the effects of non-metal (nitrogen) and metal/non-metal (silver/nitrogen)dopants on titanium dioxide (TiO2) in synthesising visible-light reactive photocatalysts. Nanopowders of TiO2-N and TiO2-N–Ag were synthesised using a simple procedure at room temperature. For nitrogen doping, a dispersion of Degussa P-25 was treated with ammonium hydroxide. The obtained modified catalyst was further treated with silver nitrate powder to facilitate silver-nitrogen co-doping. The produced catalysts were characterised using X-ray diffraction, X-ray photoelectron spectroscopy, and specific surface area measurements. Scanning electron microscopy/energy dispersive X-ray and transmission electron microscopy were adapted to detect changes in the morphology and in the chemical composition of synthesised catalysts. The results show that both the morphology and appearance of catalysts were modified to yield nanopowders of yellowish color and relatively high specific surface area. Methylene blue (MB) dye was used as a model aquatic contaminant in 23 mg/L concentration to study the performance of these novel photocatalysts in an aerobic mixed batch reactor system under white light irradiation. Both nitrogen and nitrogen-silver co-doping lead to visible light sensitivity and the new catalysts showed remarkable activities in the decolorisation of MB.
Adsorption Behavior of Pb(II) Onto Potassium Polytitanate Nanofibres
Shahid, Mohammad,Tijing, Leonard D.,El Saliby, Ibrahim,McDonagh, Andrew,Kim, Jong-Beom,Kim, Jong-Ho,Shon, Ho Kyong American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.2
<P>Potassium polytitanate nanofibres prepared by a hydrothermal method were investigated for their possible application in removing toxic metals from aqueous solution. Particular attention was paid to employing the titanate as a novel effective adsorbent for the removal of Pb(II). Batch adsorption experiments demonstrated that the adsorption was influenced by various conditions such as solution pH, adsorbent dosage and initial Pb(II) concentration. The results showed that the adsorption rate was faster in the first 5 min and equilibrium was achieved after 180 min. The maximum amount of adsorption was detected at pH 5. Potassium titanate showed much higher adsorption capacity compared to P25. The kinetic studies indicated that the adsorption of Pb(II) onto titanate best fit the pseudo-second-order kinetic model. FTIR spectra revealed that the hydroxyl groups in titanate were responsible for Pb(II) adsorption. The principal mechanism of the adsorption of Pb(II) in the present study is attributed to both ion exchange and oxygen bonding. The adsorption desorption results demonstrated that the titanate could be readily regenerated after adsorption. Therefore, the present titanate exhibits great potential for the removal of Pb(II) from wastewater.</P>