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- 저자 : Leticia M. Torres-Martínez (검색결과 3 건)
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Bi2InTaO7 compounds as promising photocatalysts for marine plankton removal
Leticia M. Torres-Martínez,Isaías Juárez-Ramírez,Juan S. Ramos-Garza,Francisco Vázquez-Acosta,Ricardo Gómez,ZhengYi Fu,Soo Wohn Lee 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.1
The removal of marine plankton, red (Amphidium carterae), and green (Tetraselmis suecica) tide algae, by heterogeneous photocatalysis was carried out using pyrochlore-type semiconductors. The semiconductor, Bi2InTaO7 , was prepared by the solgel method and a solid state reaction. The XRD patterns evidence formation of the pyrochlore phase in the sol-gel materials calcined at low temperatures (600-800 oC). Nanostructured sol-gel materials were observed by SEM. The sol-gel preparation allowed the formation of the pyrochlore-type compound with specific surface areas (7-13 m2g−1) higher than the solid obtained by solid state preparation (< 5 m2g−1). Band gap (Eg) values between 2.1-2.7 eV determined by UV-Vis spectroscopy were obtained. Bi2InTaO7 photocatalysts prepared by the sol-gel method were able to eliminate Tetraselmis suecica and Amphidium carterae algae totally after 50 minutes of UV-irradiation, whereas Bi2InTaO7 by solid state preparation needed more than 1 h.
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A. Martínez-de la Cruz,S. Obregón Alfaro,Leticia M. Torres-Martínez,I. Juárez Ramírez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5
Bismuth tungstate Bi2W2O9 has been synthesized using diethylenetriaminepentaacetic acid (H5DTPA), an organic chelating agent of metals in an aqueous solution. The formation of the oxide was followed through characterization techniques such as XRD, TGA/DTA, and SEM. The optimum temperature to decompose the organic matrix and to form Bi2W2O9 was determined to be around 720 oC. Below this temperature, Bi2W2O9 was formed with a high content of Bi2WO6. At 720 oC particles of the Bi2W2O9 with a surface area four times higher than that obtained by a solid-state reaction were obtained. The oxide was tested as a photocatalyst on the degradation of aqueous solutions of rhodamine B under VIS radiation. The photodegradation of the dye followed a kinetic first order with an apparent constant, k = 2.8 × 10−3 minute−1and t1/2= 247 minutes for an aqueous solution of 5 mg l−1 of rhodamine B. Bismuth tungstate Bi2W2O9 has been synthesized using diethylenetriaminepentaacetic acid (H5DTPA), an organic chelating agent of metals in an aqueous solution. The formation of the oxide was followed through characterization techniques such as XRD, TGA/DTA, and SEM. The optimum temperature to decompose the organic matrix and to form Bi2W2O9 was determined to be around 720 oC. Below this temperature, Bi2W2O9 was formed with a high content of Bi2WO6. At 720 oC particles of the Bi2W2O9 with a surface area four times higher than that obtained by a solid-state reaction were obtained. The oxide was tested as a photocatalyst on the degradation of aqueous solutions of rhodamine B under VIS radiation. The photodegradation of the dye followed a kinetic first order with an apparent constant, k = 2.8 × 10−3 minute−1and t1/2= 247 minutes for an aqueous solution of 5 mg l−1 of rhodamine B.
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Morales-Mendoza, Getsemani,Alvarez-Lemus, Mayra,Ló,pez, Rosendo,Tzompantzi, Francisco,Adhikari, Rajesh,Lee, Soo Wohn,Torres-Martí,nez, Leticia M.,Gó,mez, Ricardo Elsevier 2016 CATALYSIS TODAY - Vol.266 No.-
<P><B>Abstract</B></P> <P>Mn-doped Zn/Al layered double hydroxides (LDH) materials were synthesized by the co-precipitation method. X-ray diffraction (XRD) analysis confirmed the polytype structure of LDH materials obtained as well as the successful incorporation of Mn into the structure. Atomic absorption spectroscopy (AAS) and energy dispersive X-ray spectroscopy (EDS) studies showed a well dispersion of Mn and a good correlation between the nominal and experimental composition. Scanning electron microscopy (SEM) revealed the formation of grains close to 1μm length. Energy band gap (Eg) of the solids determined by UV–vis diffuse reflectance spectroscopy (DRS) showed high photoresponse in the ultraviolet (UV) region, which was increased with Mn incorporation into the LDH structure. The LDH materials were evaluated in the photocatalytic degradation of phenol in aqueous medium, under UV radiation with and without O<SUB>2</SUB> source in the reaction system. The results showed that the O<SUB>2</SUB> is not an effective electron scavenger as usually occurs in TiO<SUB>2</SUB> photocatalyst. The Mn effect in the photocatalytic activity was notably marked in anaerobic condition however in aerobic or anaerobic conditions the presence of Mn increases the photoactivity. The phenol mineralization reached in anaerobic conditions was 95% (1.5ppm) of the initial concentration (30ppm) and it is maintained constant after 6h of radiation while in aerobic conditions the TOC reaches only 55% (13.5ppm). The role of Mn as charges separator is discussed and a suitable mechanism is proposed. This study shows that the Mn doped-Zn/Al LDH materials could be a promising photocatalysts under anaerobic conditions for the removal of phenol from aqueous medium.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnAl LDH rebuilt in phenol solution have not capacity to open the interlayer space. </LI> <LI> A source of O<SUB>2</SUB> have not influence in the phenol photooxidation with ZnAl LDH. </LI> <LI> Mn doped-ZnAl LDH increases the optical properties of absorption. </LI> <LI> The role as electron and hole trap of Mn takes advantage to separate charge. </LI> <LI> The Mn incorporation in ZnAl LDH materials improves the photocatalytic activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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