Photo and Environmental Technology Co.

Gwangju, South Korea

Photo and Environmental Technology Co.

Gwangju, South Korea

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Shon H.K.,University of Technology, Sydney | Okour Y.,University of Technology, Sydney | Park S.M.,Chonnam National University | Kim J.B.,Photo and Environmental Technology Co. | And 2 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2014

In this study, titania photocatalyst was produced from the wastewater sludge of Ti-salt flocculation. The high photocatalytic activity of titania reported was evaluated based on a single organic substrate. However, the photocatalytic activity is a substrate-specific; one photocatalyst showed different photocatalytic degradation rates for different substrates. Thus, to investigate the substrate-specific photocatalytic activity of titania, various substrates of humic acid (HA), dichloroacetic acid (DCA), rhodamine B (RhB), metsulfuron methyl (M&M) and phenol were used under simulated solar light irradiation. Results showed titania had a high activity rate for RhB, moderate activity for HA and DCA and low activity for M&M and phenol indicating substrate-specific activities. When compared with Degussa-P25, titania showed higher activity for M&M, while the opposite was observed for HA and phenol. The specific-substrate behaviour of titania could depend on specific physicochemical and electronic interactions between titania, substrates, and their intermediates compounds formed. Copyright © 2014 American Scientific Publishers.


Nersisyan H.H.,Chungnam National University | Won H.I.,Chungnam National University | Won C.W.,Chungnam National University | Jo A.,Photo and Environmental Technology Co. | And 2 more authors.
Chemical Engineering Journal | Year: 2014

Magnesium was used as a reductant to synthesize directly titanium powder from titanium oxide (TiO2) through combustion. The feed material (TiO2), reductant (Mg), and calcium hydroxide (Ca(OH)2) were mixed and combusted under pressure in an argon atmosphere. The temperature-time profiles were intermittently measured during combustion in order to analyze the combustion temperatures and wave velocities. The combustion product was subsequently leached to produce Ti powder with ~1.5wt% oxygen. The Ti powder was further deoxidized with calcium to decrease the oxygen content in the powder to 0.2-0.3wt%. The morphology and size of the Ti particles was examined, and the mechanism by which Ca(OH)2 reduced the content of oxygen in the Ti powder was discussed. © 2013 Elsevier B.V.


Kim J.-H.,Photo and Environmental Technology Co. | Kim J.-H.,Chonnam National University | Cho D.L.,Photo and Environmental Technology Co. | Cho D.L.,Chonnam National University | And 5 more authors.
Catalysis Surveys from Asia | Year: 2011

Titania is the most widely used metal oxide for the applications of pigments, paper, solar cells and environmental purification. In order to meet the demand of a large amount of titania, our group has developed a novel process which could significantly lower the cost of waste disposal in water treatment, protect the environment and public health and yield economically valuable titania. Titanium tetrachloride (TiCl4) or titanium sulfate (Ti(SO4)2) as an alternative coagulant in water treatment has been explored for the removal of various pollutants from contaminated water or wastewater. Flocculation efficiencies of the Ti-salts were superior to those of Al- and Fe- salts with additional benefits in that a large amount of titania can be produced by calcinating the flocculated floc. The produced titania showed high photocatalytic activity for the removal of volatile organic compounds. The large amount of titania can be applied to pigments, environment and construction materials which require a lot of titania usages. This review paper presents an historical progress from fundamental to application in terms of the detailed production process, characterization, photoactivity of titania produced from Ti-salt flocculated sludge, and its various applications. © 2011 Springer Science+Business Media, LLC.


Na S.-H.,Chonnam National University | Shon H.K.,University of Technology, Sydney | Kim J.B.,Chonnam National University | Kim J.B.,Photo and Environmental Technology Co. | And 3 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2011

Sludge disposal after flocculation with paper mill wastewater is one of the most costly and environmentally problematic challenges. In this study, an effective sludge recycling process was proposed using Ti-salt coagulant instead of the currently used Fe-salt. Paper mill wastewater flocculation using TiCl4 and FeCl3 coagulants was investigated for organic removal and precipitation efficiency. A large amount of titania nanoparticle was produced after incineration of sludge of Ti-salt flocculation in paper mill wastewater. The titania nanoparticle was characterized in terms of physical and chemical properties. Results showed that the removal efficiency of organic matter at the optimum concentrations of Ti- and Fe-salt was 69% and 65%, respectively. The removal of turbidity was 99%. Titania recovered from 600°C incineration of the settled sludge consisted of the anatase titania structure. The titania from printing paper mill wastewater showed irregularly aggregated structures with round shape of dimension of 10-15nm as a primary crystal growth. Various dopant materials were found to be carbon (4.3%), magnesium (0.9%), aluminium (1.9%), silicon (1.7%), sulphur (0.7%) and calcium (3.8%). 60% of acetaldehyde concentration under UV irradiation was removed with the titania nanoparticles produced from the printing paper mill wastewater. © 2011 The Korean Society of Industrial and Engineering Chemistry.


El Saliby I.,University of Technology, Sydney | Erdei L.,University of Southern Queensland | McDonagh A.,University of Technology, Sydney | Kim J.-B.,Chonnam National University | And 4 more authors.
Materials Research Bulletin | Year: 2014

In this study, nitrogen doped and nitrogen/silver co-doped TiO2 photocatalsysts were fabricated using a sol-gel method at room temperature. The obtained gels were neutralized, washed with pure water, and calcined at 400 C for 4 h. The photocatalysts were characterized by scanning and transmission electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and BET specific surface area. The results showed that spherical particles with anatase structure were produced after annealing at 400 C. N 1s (400 eV) and Ag 3d (367.3 eV) states indicated that nitrogen doping and silver co-doping were in the form of NO bonds and AgO, respectively. The photocatalytic activity of photocatalysts was investigated using a batch reactor system exposed to artificial solar irradiation. Both nitrogen and silver/nitrogen co-doped materials were effective in the photocatalytic degradation of hexamethyl pararosaniline chloride. © 2013 Elsevier Ltd. All rights reserved.


Nersisyan H.H.,Chungnam National University | Won H.I.,Chungnam National University | Won C.W.,Chungnam National University | Kim J.B.,Chonnam National University | And 4 more authors.
Materials Chemistry and Physics | Year: 2013

The synthesis of titanium porous microspheres by a combustion technique was studied under an argon atmosphere by using a TiO2 - 2.5Mg reactive mixture. The precursor, a fine TiO2 powder, was thermally treated in the range 600-1300 C prior to the combustion experiments. TiO2 microspheres whose diameters were between 10 and 50 μm were obtained from precursor particles annealed in the range 900-1100 C. A biphase product consisting of Ti and MgO phases was obtained when the TiO2 microspheres were reduced with Mg. The spherical morphology of the final particles was retained despite the relatively high combustion temperatures (1630-1670 C) used in this study. Moreover, porous titanium microspheres were obtained when the MgO particles were dissolved using acid leaching. Scanning electron microscopy (SEM) images of the microspheres suggested that the spherical structure contained ∼0.5-2.0-μm-diameter porous windows. The Brunauer-Emmett-Teller (BET) surface area of the Ti microspheres was determined to be 2.8 m2 g-1© 2013 Elsevier B.V. All rights reserved.


Nersisyan H.H.,Chungnam National University | Won H.I.,Chungnam National University | Won C.W.,Chungnam National University | Jo A.,Photo and Environmental Technology Co. | And 2 more authors.
Powder Technology | Year: 2014

Magnesium was used as a reductant for the direct combustion synthesis of titanium alloy particles (Ti-6Al-4V) from titanium oxide (TiO2). The feed material (TiO2) and reductant (Mg) were mixed with Al (or AlCl3·6H2O), vanadium pentoxide (V2O5), and calcium hydroxide (Ca(OH)2), and the reaction mixture was combusted under pressurized argon. Temperature-time profiles were intermittently measured during combustion to analyze the combustion temperatures and wave velocities. The combustion product was subsequently acid-leached to eliminate secondary phases (MgO, MgCl2, CaO) and produce Ti-6Al-4V alloy particles whose oxygen content was ~1.3%. Further the content of oxygen was decreased to 0.2wt.% by deoxidizing the Ti-6Al-4V alloy particles with calcium in the range 850-900°C. The AlCl3·6H2O affected the particle morphology more than the Al metal did; i.e. the Al-doped alloy particles were porous and consisted of relatively small agglomerated particles whereas using AlCl3·6H2O produced dense, round particles. Pilot-scale production experiments revealed that Ti-6Al-4V alloy particles can be efficiently produced using our method. © 2014 Elsevier B.V.


Shon H.K.,University of Technology, Sydney | Phuntsho S.,University of Technology, Sydney | Vigneswaran S.,University of Technology, Sydney | Kandasamy J.,University of Technology, Sydney | And 6 more authors.
Environmental Science and Technology | Year: 2010

A comprehensive investigation of electrocoagulation using sacrificial titanium (Ti) electrodes in wastewater was carried out. The effects of specific process variables, such as initial pH, mixing, current density, initial organic loading, and ionic/electrolyte strength were first optimized to produce recyclable Ti-based sludge. The sludge was incinerated at 600 °C to produce functional TiO2 photocatalyst. X-ray diffraction analysis revealed that TiO2 produced at optimum electrocoagulation conditions was mostly anatase structure. The specific surface area of the synthesized TiO 2 photocatalyst was higher than that of the commercially available and widely used Degussa P-25 TiO2. Furthermore, energy dispersive X-ray and X-ray photoelectron spectroscopy analyses showed that in additional to titanium and oxygen, this photocatalyst is also composed of carbon and phosphorus. These elements were mainly doped as a substitute site for the oxygen atom. Transmission electron microscopy images exhibited sharply edged nanorods, round nanoparticles, and nanotubes with nonuniform shapes showing some structural defects. Photodecomposition of gaseous acetaldehyde by this photocatalyst was also conducted under UV and visible light irradiation to study the photocatalytic properties of the doped TiO2 photocatalyst. While no photocatalytic activity was observed under visible light irradiation, this doped TiO2 photocatalyst exhibited high photocatalytic activity under UV light. © 2010 American Chemical Society.


Na S.H.,Chonnam National University | Shon H.K.,University of Technology, Sydney | Kim J.B.,Chonnam National University | Park H.J.,Photo and Environmental Technology Co. | And 4 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2010

The highly strengthened treatment and disposal of excess sludge based on economic and environmental regulation factors is one of the important issues to be dealt with in the activated sludge process. In this study, the reduction and recycling technology of excess sludge were investigated for the aim of achieving a zero emission of excess sludge produced from the activated sludge process using titanium tetrachloride (TiCl4) as a flocculant aid with alkaline-thermal hydrolysis. Alkaline-thermal hydrolysis of excess sludge was obtained 73% and 40% reduction rate at pH 13 (60 8 °C) and pH 11 (60 8 °C), respectively. Flocculation was carried out using a Ti-salt flocculant and the collected sludge was dewatered and incinerated at 600 °C to produce TiO2 nanoparticles. The amount of total suspended solids and volatile suspended solids was significantly decreased with pH increase. The optimal dose of Ti-salt flocculation aid to improve dewatering ability of sludge breakage was 23.95 Ti-mg l-1. Also, in the batch culture, the supernatant after flocculation and the organic matter released from the lysed sludge were found to be useful as a source of energy for the growth of microorganisms during the aerobic operations period. TiO2 produced from Ti-salt flocculation of excess sludge (TES) was characterized by X-ray diffraction, scanning electron microscopy/energy dispersive X-ray and photocatalytic activity. © 2010 The Korean Society of Industrial and Engineering Chemistry.


Kim J.B.,Chonnam National University | Kim J.B.,Photo and Environmental Technology Co. | Park H.J.,Photo and Environmental Technology Co. | Shon H.K.,University of Technology, Sydney | And 5 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2010

Dye wastewater flocculation using TiCl 4 and FeSO 4 coagulants was studied for organic removal and precipitation efficiency. Moreover, TiCl 4 was assessed in a pilot-scale flocculation process to investigate organic removal and solution pH effect. A large amount of TiO 2 was produced from sludge of Ti-salt flocculation in dye wastewater. This flocculation process simultaneously reduces a large amount of sludge produced from wastewater. The TiO 2 nanoparticle was characterized in terms of physical and chemical properties. Results showed that 77.6% of organic matter was removed from dye wastewater when using FeSO 4 as coagulant, while TiCl 4 degraded 75.9% of organic matter. On the other hand, floc precipitation efficiency was better for TiCl 4 if compared with FeSO4. The optimum concentration of TiCl 4 for pilot-scale flocculation was found to be equal to 2.1 g/L DWT (Dye wastewater titania) size was 15-20 nm, mainly doped with carbon atoms and exhibited a dominant anatase structure. DWT was similar to P-25 in decomposing acetaldehyde under UV-irradiation and complete photocatalytic degradation was achieved after 140 min. Copyright © 2010 American Scientific Publishers All rights reserved.

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