Pub Date : 2018-02-13DOI: 10.5772/INTECHOPEN.74193
K. A. Saharudin, S. Sreekantan, R. Mydin, N. Basiron, Warapong Krengvirat
TiO 2 nanotube arrays (TNA) have attracted scientific interest due to the combination of functional material properties with controllable nanostructure. Superior properties of TNA, including vectorial pathway of e (cid:1) transport, minimized e (cid:1) recombination, and high specific surface area render them as the most promising candidate for environment remediation, energy conversion and biocompatibilityapplications. The superior properties and efficacyof the TNA in various applications influenced by structural characteristics such as pore size, length and wall thickness. Therefore in this chapter the effect of various electrochemical parameters such as applied voltage, anodization time, electrolyte composition on the forma- tion of controlled dimension of TNA in aqueous and organic electrolytes are reviewed.
{"title":"Factor Affecting Geometry of TiO2 Nanotube Arrays (TNAs) in Aqueous and Organic Electrolyte","authors":"K. A. Saharudin, S. Sreekantan, R. Mydin, N. Basiron, Warapong Krengvirat","doi":"10.5772/INTECHOPEN.74193","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.74193","url":null,"abstract":"TiO 2 nanotube arrays (TNA) have attracted scientific interest due to the combination of functional material properties with controllable nanostructure. Superior properties of TNA, including vectorial pathway of e (cid:1) transport, minimized e (cid:1) recombination, and high specific surface area render them as the most promising candidate for environment remediation, energy conversion and biocompatibilityapplications. The superior properties and efficacyof the TNA in various applications influenced by structural characteristics such as pore size, length and wall thickness. Therefore in this chapter the effect of various electrochemical parameters such as applied voltage, anodization time, electrolyte composition on the forma- tion of controlled dimension of TNA in aqueous and organic electrolytes are reviewed.","PeriodicalId":23104,"journal":{"name":"Titanium Dioxide - Material for a Sustainable Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75220607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-20DOI: 10.5772/INTECHOPEN.72193
A. Petsas, M. Vagi
The photocatalytic degradation of five selected organophosphorus pesticides (OPPs), azinphos methyl, azinphos ethyl, disulfoton, dimethoate, and fenthion, has been investigated using TiO 2 (photocatalyst) and UV irradiation. The addition of H 2 O 2 (oxidant agent) into the illuminated aquatic suspensions was also surveyed. The degradation kinetics was studied under different experimental conditions such as pesticides’ and catalyst’s concentration. Experiments were performed in a Pyrex UV laboratory-constructed photoreactor equipped with 4 × 18 W low-pressure Hg lamps emitting at 365 nm (maximum intensity 14.5 mW cm −2 at distance 15 cm). The concentration of pesticides was determined by GC-NPD means. The extent of pesticide mineralization was assessed through TOC measurements. The results demonstrated that photolysis of target organophosphates in the absence of catalyst or oxidant is a slow process resulting in incomplete mineralization. Contradictory, studied pollutants were effectively degraded in the presence of TiO 2 ; evolution of inorganic hetero- atoms (SO 4 2− , PO 4 3− , NO 2 − , NO 3 − , and NH 4 + ) as final products provided evidence that pesticide deterioration occurred. The photolysis efficiencies decreased in the order: disulfoton > azinphos ethyl > azinphos methyl > fenthion > dimethoate. Furthermore, a synergistic effect was observed with the addition of H 2 O 2 in the pesticide-TiO 2 suspensions. In all cases examined, reduction process appeared to follow pseudo first-order kinetics (Langmuir-Hinshelwood model). In conclusion, both catalytic systems investigated (UV-TiO 2 and UV-TiO 2 -H 2 O 2 ) have good potential for small-scale applications. into
{"title":"Photocatalytic Degradation of Selected Organophosphorus Pesticides Using Titanium Dioxide and UV Light","authors":"A. Petsas, M. Vagi","doi":"10.5772/INTECHOPEN.72193","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.72193","url":null,"abstract":"The photocatalytic degradation of five selected organophosphorus pesticides (OPPs), azinphos methyl, azinphos ethyl, disulfoton, dimethoate, and fenthion, has been investigated using TiO 2 (photocatalyst) and UV irradiation. The addition of H 2 O 2 (oxidant agent) into the illuminated aquatic suspensions was also surveyed. The degradation kinetics was studied under different experimental conditions such as pesticides’ and catalyst’s concentration. Experiments were performed in a Pyrex UV laboratory-constructed photoreactor equipped with 4 × 18 W low-pressure Hg lamps emitting at 365 nm (maximum intensity 14.5 mW cm −2 at distance 15 cm). The concentration of pesticides was determined by GC-NPD means. The extent of pesticide mineralization was assessed through TOC measurements. The results demonstrated that photolysis of target organophosphates in the absence of catalyst or oxidant is a slow process resulting in incomplete mineralization. Contradictory, studied pollutants were effectively degraded in the presence of TiO 2 ; evolution of inorganic hetero- atoms (SO 4 2− , PO 4 3− , NO 2 − , NO 3 − , and NH 4 + ) as final products provided evidence that pesticide deterioration occurred. The photolysis efficiencies decreased in the order: disulfoton > azinphos ethyl > azinphos methyl > fenthion > dimethoate. Furthermore, a synergistic effect was observed with the addition of H 2 O 2 in the pesticide-TiO 2 suspensions. In all cases examined, reduction process appeared to follow pseudo first-order kinetics (Langmuir-Hinshelwood model). In conclusion, both catalytic systems investigated (UV-TiO 2 and UV-TiO 2 -H 2 O 2 ) have good potential for small-scale applications. into","PeriodicalId":23104,"journal":{"name":"Titanium Dioxide - Material for a Sustainable Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90944438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-20DOI: 10.5772/INTECHOPEN.72279
J. C. Contreras-Ruiz, S. Martínez-Gallegos, J. L. García-Rivas, J. C. González-Juárez, E. Ordoñez
Three different TiO2 catalysts are prepared using different methods. MgAl-CO3 layered double hydroxides (LDH) were obtained by the sol-gel method. In the preparation of the composites, the three photocatalysts were combined with LDH following different methodologies. The composites were characterized using X-ray diffraction (XRD), specific surface area (SA), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The influence of the synthesis method on the preparation of the composites was evaluated by analyzing their photocatalytic activity against phenol as a model organic pollutant under UV irradiation. The photocatalytic activity of the composites improves when the chemical interaction, determined by XPS, between the TiO2 and the LDH decreases. The same happens when the ratio of the anatase-rutile phases, determined by XRD, approaches optimum (80:20%). The effect of the composite concentration in the solution (0.5–2.0 g/L) was investigated, and the light-shielding phenomenon due to high composite concentration decreases the phenol photodegradation. The reduction of photocatalytic activity in reuse cycles is due to loss and partial deactivation of the material. The elimination of phenol is attributed primarily to the photocatalytic process due to the generation of ●OH radicals and to a lesser extent the adsorption process also present in the samples.
{"title":"Influence of the Synthesis Method on the Preparation Composites Derived from TiO2-LDH for Phenol Photodegradation","authors":"J. C. Contreras-Ruiz, S. Martínez-Gallegos, J. L. García-Rivas, J. C. González-Juárez, E. Ordoñez","doi":"10.5772/INTECHOPEN.72279","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.72279","url":null,"abstract":"Three different TiO2 catalysts are prepared using different methods. MgAl-CO3 layered double hydroxides (LDH) were obtained by the sol-gel method. In the preparation of the composites, the three photocatalysts were combined with LDH following different methodologies. The composites were characterized using X-ray diffraction (XRD), specific surface area (SA), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The influence of the synthesis method on the preparation of the composites was evaluated by analyzing their photocatalytic activity against phenol as a model organic pollutant under UV irradiation. The photocatalytic activity of the composites improves when the chemical interaction, determined by XPS, between the TiO2 and the LDH decreases. The same happens when the ratio of the anatase-rutile phases, determined by XRD, approaches optimum (80:20%). The effect of the composite concentration in the solution (0.5–2.0 g/L) was investigated, and the light-shielding phenomenon due to high composite concentration decreases the phenol photodegradation. The reduction of photocatalytic activity in reuse cycles is due to loss and partial deactivation of the material. The elimination of phenol is attributed primarily to the photocatalytic process due to the generation of ●OH radicals and to a lesser extent the adsorption process also present in the samples.","PeriodicalId":23104,"journal":{"name":"Titanium Dioxide - Material for a Sustainable Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73005399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-20DOI: 10.5772/INTECHOPEN.72856
Lijia Liu, T. Sham
Understanding the optical property of nanostructured TiO2 is crucial for their use in a variety of applications such as solar cells, photocatalysis, and light emitting devices. Herein, we introduce the use of synchrotron radiation-based spectroscopic techniques: X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) in analyzing the luminescence properties of anodized TiO2 nanotubes (TiO2 NT) and related materials. A description on the spectroscopic technique is first given, including conventional XANES-XEOL combined analysis and a more recently developed 2D XANES-XEOL probing technique. We then discuss several examples of analyzing the luminescence mechanism of TiO2 NT using XANES and XEOL technique, which are the phase transformation accompanied luminescence, luminescence from TiO2 NT hierarchical structure, and metal particle–coated TiO2 NT.
{"title":"Luminescence from TiO2 Nanotubes and Related Nanostructures Investigated Using Synchrotron X-Ray Absorption Near-Edge Structure and X-Ray Excited Optical Luminescence","authors":"Lijia Liu, T. Sham","doi":"10.5772/INTECHOPEN.72856","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.72856","url":null,"abstract":"Understanding the optical property of nanostructured TiO2 is crucial for their use in a variety of applications such as solar cells, photocatalysis, and light emitting devices. Herein, we introduce the use of synchrotron radiation-based spectroscopic techniques: X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) in analyzing the luminescence properties of anodized TiO2 nanotubes (TiO2 NT) and related materials. A description on the spectroscopic technique is first given, including conventional XANES-XEOL combined analysis and a more recently developed 2D XANES-XEOL probing technique. We then discuss several examples of analyzing the luminescence mechanism of TiO2 NT using XANES and XEOL technique, which are the phase transformation accompanied luminescence, luminescence from TiO2 NT hierarchical structure, and metal particle–coated TiO2 NT.","PeriodicalId":23104,"journal":{"name":"Titanium Dioxide - Material for a Sustainable Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82918319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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