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Grisdanurak, Nurak,Chiarakorn, Siriluk,Wittayakun, Jatuporn 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.5
The adsorption of trichloroethylene (TCE), tetrachloroethylene (PCE), and carbon tetrachloride was studied over our synthesized mesoporous material, MCM-41, from rice husk silica source, abbreviated as RH-MCM-41. More than 99% silica for RH-MCM-41 synthesis was extracted from rice husk under refluxing in HBr solution and then calcined at 873K for 4 hours. RH-MCM-41 possessed surface area around 750-1,100 ㎡/g with a uniform pore size with an average diameter of 2.95 ㎚, narrow range of pore distribution and somewhat hexagonal structure, similar to properties of parent MCM-41. The adsorption of CCl₄ to RH-MCM-41 was stronger than that of TCE and PCE. The adsorption capacity of RH-MCM-41 for CVOCs (chlorinated volatile organic compounds) was higher than commercial mordenite and activated carbons.
Laksana Laokiat,Nurak Grisdanurak,Pongtanawat Khemthong,Paiboon Sreearunothai,Wanwisa Pattanasiriwisawa,Wantana Klysubun 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.3
Transition metal (Fe, V and W)-doped TiO2 was synthesized via the solvothermal technique and immobilized onto fiberglass cloth (FGC) for uses in photocatalytic decomposition of gaseous volatile organic compounds--benzene, toluene, ethylbenzene and xylene (BTEX)--under visible light. Results were compared to that of the standard commercial pure TiO2 (P25) coated FGC. All doped samples exhibit higher visible light catalytic activity than the pure TiO2. The V-doped sample shows the highest photocatalytic activity followed by the W- and Fe-doped samples. The UV-Vis diffuse reflectance spectra reveal that the V-doped sample has the highest visible light absorption followed by the W- and Fe-doped samples. The X-ray diffraction (XRD) patterns indicate that all doped samples contain both anatase and rutile phases with the majority (>80%) being anatase. No new peaks associated with dopant oxides can be observed, suggesting that the transition metal (TM) dopants are well mixed into the TiO2 lattice, or are below the detection limit of the XRD. The X-ray absorption near-edge structure spectra of the Ti K-edge transition indicate that most Ti ions are in a tetravalent state with octahedral coordination, but with increased lattice distortion from Fe- to V- and W-doped samples. Our results show that the TM-doped TiO2 were successfully synthesized and immobilized onto flexible fiberglass cloth suitable for treatment of gaseous organic pollutants under visible light.
Visible light-irradiated degradation of alachlor on Fe-TiO_2 with assistance of H_2O_2
Kitirote Wantala,Nurak Grisdanurak,Pongtanawat Khemthong,Jatuporn Wittayakun 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.11
0.1 Fe/Ti mole ratio of Fe-TiO_2 catalysts were synthesized via solvothermal method and calcined at various temperatures: 300, 400, and 500 ℃.The calcined catalysts were characterized by XRD, N_2-adsorption-desorption, UVDRS,XRF, and Zeta potential and tested for photocatalytic degradation of alachlor under visible light. The calcined catalysts consisted only of anatase phase. The BET specific surface area decreased with the calcination temperatures. The doping Fe ion induced a red shift of absorption capacity from UV to the visible region. The Fe-TiO_2 calcined at 400 ℃ showed the highest photocatalytic activity on degradation of alachlor with assistance of 30 mM H_2O_2 at pH 3under visible light irradiation. The degradation fitted well with Langmuir-Hinshelwood model that gave adsorption coefficient and the reaction rate constant of 0.683 L mg^−1 and 0.136 mg/L·min, respectively.
Effect of Fe^(3+) doping on the performance of TiO_2 mechanocoated alumina bead photocatalysts
Cyril Jose Escopete Bajamundi,Nurak Grisdanurak,Maria Lourdes Pascual Dalida,Kitirote Wantala,Pongtanawat Khemthong 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.8
Ferric ion was introduced to the commercial photocatalyst P25 (Degussa) by ultrasonic wet impregnation technique. The concentration of the dopant was varied from 0.0 to 3.0% Fe/Ti ratio. The doped TiO_2 was then loaded to alumina balls using mechanical coating technique and followed by calcination in air at 400, 450, 500 and 550 ℃. The fabricated photocatalyst was characterized by X-ray diffraction, N_2 adsorption-desorption isotherms, scanning electron microscopy, UV-Vis diffuse reflectance spectroscopy, X-ray adsorption near edge structure and photoluminescence spectroscopy. The photocatalytic activity was tested by following the degradation of methylene blue (MB). It was found that the Fe^(3+) doped TiO_2/Al_2O_3 has a combination of anatase and rutile phase and free of iron oxide phases. The optimum calcination temperature is 400℃ with 0.1% Fe^(3+) concentration. The catalyst addresses the entrainment in photocatalytic reactors, eliminating the need for a post filtration process.
Suppression of CO on methanol decomposition over SnO2 catalysts
Arthit Neramittagapong,Sutasinee Neramittagapong,Nurak Grisdanurak 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.4
Methanol conversion was studied in the temperature range 350–400 8C at atmospheric pressure over a SnO2 catalyst. The results show SnO2 catalyzed methanol conversion to form methane, carbon dioxide and hydrogen selectively. This suggests that formaldehyde was an intermediate in producing methyl formate, which readily decomposed into methane and carbon dioxide. Both activity and selectivity were found to be independent on the specific surface area. The deactivation of the catalyst at high temperature was attributed to the decrease of surface area by formation of metallic tin.
Rattabal Khunphonoi,Kitirote Wantala,Nurak Grisdanurak 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.1
Copper sulfide was prepared by a hydrothermal method at 130°C. The copper to sulfur molar ratio (6-10) and ageing time (24-72 h) were their synthesis parameters. The obtained materials were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscope (TEM), UV-DR spectroscopy and X-ray photoelectron spectroscopy (XPS). In order to obtain monocopper sulfide, CuS, named as covellite, the molar recipe ratio of sulfur to copper should be less than 8 in any hydrothermal ageing time. The morphology showed spherical-like structure with energy band gap of 1.88-2.04 eV. CuS was tested for its photocatalytic degradation of paraquat under visible light irradiation. It exhibited excellent activities in the presence of H₂O₂. The kinetic of paraquat degradation was also investigated using Langmuir-Hinshelwood-Hougen-Watson (LHHW) model. The reaction rate constant was three times higher than TiO₂ under the same studied conditions.
Characteristics and photocatalytic degradation of methyl orange on Ti-RH-MCM-41 and TiO2/RH-MCM-41
Surachai Artkla,Kitirote Wantala,Bang-orn Srinameb,Nurak Grisdanurak,Wantana Klysubun,Jatuporn Wittayakun 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6
Our purpose was to synthesize, characterize and test photodegradation of methyl orange on two catalysts containing 10 wt% titanium supported on mesoporous MCM-41 synthesized with rice husk silica. The first catalyst was Ti-RH-MCM-41 prepared by adding tetrabutyl orthotitanate (TBOT) in a synthetic gel of RH-MCM-41, and the second catalyst was TiO2/RH-MCM-41 prepared by grafting TBOT on the preformed RH-MCM-41. The mesoporous structures were observed on both catalysts and they had surface area of 1,073 and 1,006 ㎡/g. The Ti in Ti-RHMCM- 41 was in the form of Ti(IV) with tetrahedral geometry residing in the mesoporous structure. This form was less active for photodegradation of methyl orange than the other one. The Ti in TiO2/RH-MCM-41 was anatase titania with octahedral geometry located outside the mesoporous framework. This form was more an active phase for the photodegradation and the reaction parameters on this catalyst were further investigated. The optimum catalyst weight to methyl orange volume ratio was 5 g/L and the optimum initial concentration of the dye was 2.0 ppm. The degradation rate obeyed pseudo-first order and the adsorption of methyl orange on TiO2/RH-MCM-41 obeyed Langmuir isotherm.