Abstract The effects of TiO2 surface modification by Ru nanoparticles (NPs) deposition have been investigated in the photocatalytic decomposition of aqueous ammonia. Two main Ru NPs deposition routes were chosen, i.e. (i) the deposition of surfactant-stabilized preformed metal NPs and (ii) a modified version of the well-known deposition-precipitation technique, employing urea as precipitating agent. Other Ru/TiO2 photocatalysts were prepared (iii) by simply grafting Ru(III) metal ions on TiO2, which were tested either as prepared or (iv) after their thermal reduction under H2 atmosphere, in order to obtain Ru NPs in full metallic state. The role played also by the relative nominal metal amount on the so obtained photocatalyst powders was investigated in terms of both ammonia conversion and selectivity towards mildly oxidized N2 or highly oxidized nitrite and nitrate ions. The Ru NPs deposition technique was found to affect the reaction paths especially in terms of products selectivity, with fully reduced Ru NPs on TiO2 being able to promote the environmentally friendly, highly desirable photocatalytic conversion of ammonia into innocuous N2.
{"title":"Photocatalytic Abatement of Aqueous Ammonia on Ru/TiO2: Effects of the Route of Ru Nanoparticles Deposition on TiO2","authors":"M. Dozzi, E. Selli","doi":"10.1515/jaots-2016-0208","DOIUrl":"https://doi.org/10.1515/jaots-2016-0208","url":null,"abstract":"Abstract The effects of TiO2 surface modification by Ru nanoparticles (NPs) deposition have been investigated in the photocatalytic decomposition of aqueous ammonia. Two main Ru NPs deposition routes were chosen, i.e. (i) the deposition of surfactant-stabilized preformed metal NPs and (ii) a modified version of the well-known deposition-precipitation technique, employing urea as precipitating agent. Other Ru/TiO2 photocatalysts were prepared (iii) by simply grafting Ru(III) metal ions on TiO2, which were tested either as prepared or (iv) after their thermal reduction under H2 atmosphere, in order to obtain Ru NPs in full metallic state. The role played also by the relative nominal metal amount on the so obtained photocatalyst powders was investigated in terms of both ammonia conversion and selectivity towards mildly oxidized N2 or highly oxidized nitrite and nitrate ions. The Ru NPs deposition technique was found to affect the reaction paths especially in terms of products selectivity, with fully reduced Ru NPs on TiO2 being able to promote the environmentally friendly, highly desirable photocatalytic conversion of ammonia into innocuous N2.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"83 1","pages":"246 - 255"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85860174","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}
Abstract Sol-gel modified TiO2 powder composite films were prepared as photoeletrode for the hydrogen generation in a two-compartment photoelectrochemical cell. Commercial Degussa P25 TiO2 powders have been successfully incorporated into TiO2 sol prepared by sol-gel method using tetrabutyl orthotitanate as precursor material to form thick TiO2 films via coating on the indium-tin oxide (ITO) conductive glass. With assistance of polyethylene glycol (PEG), the macroporous structure TiO2 film was obtained after calcination. The film samples were characterized by XRD, SEM and UV-Vis spectrophotometer. The XRD result indicated that TiO2 films were composed of the anatase-rutile mischcrystal phase. Furthermore, the coating layer had a great effect on the photoelectrochemical properties and photocatalytic activity. The experimental results showed that TiO2-P25/ITO film with 5 coating layers demonstrated a maximum hydrogen production rate, which implied that TiO2-P25/ITO film prepared by this convenient and economic method is a promising photocatalyst for efficient hydrogen production.
{"title":"Sol-gel Modified TiO2 Powder Composite Films for Photoelectrochemical Hydrogen Generation","authors":"Yan Sun, K. Yan","doi":"10.1515/jaots-2016-0223","DOIUrl":"https://doi.org/10.1515/jaots-2016-0223","url":null,"abstract":"Abstract Sol-gel modified TiO2 powder composite films were prepared as photoeletrode for the hydrogen generation in a two-compartment photoelectrochemical cell. Commercial Degussa P25 TiO2 powders have been successfully incorporated into TiO2 sol prepared by sol-gel method using tetrabutyl orthotitanate as precursor material to form thick TiO2 films via coating on the indium-tin oxide (ITO) conductive glass. With assistance of polyethylene glycol (PEG), the macroporous structure TiO2 film was obtained after calcination. The film samples were characterized by XRD, SEM and UV-Vis spectrophotometer. The XRD result indicated that TiO2 films were composed of the anatase-rutile mischcrystal phase. Furthermore, the coating layer had a great effect on the photoelectrochemical properties and photocatalytic activity. The experimental results showed that TiO2-P25/ITO film with 5 coating layers demonstrated a maximum hydrogen production rate, which implied that TiO2-P25/ITO film prepared by this convenient and economic method is a promising photocatalyst for efficient hydrogen production.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"6 1","pages":"376 - 380"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74161203","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}
XingYing Tang, Shuzhong Wang, Lili Qian, Mengmeng Ren, Panpan Sun, Yanhui Li, J. Yang
Abstract Corrosion of constructional materials in supercritical water oxidation (SCWO) is one of the main obstacles to commercializing the SCWO process. Statistical analysis of corrosion research results indicate nickel-based alloys are the most widely applied materials in SCWO system among the candidate metals. The present paper reviews the corrosion characteristics of iron-base alloy, nickel-based alloy, titanium-base alloy, ceramics, niobium, tantalum, thallium and gold under the condition of SCWO. The selection scheme of materials is presented in SCWO system flow diagram in detail. The effects of alloying elements on the corrosion behavior of materials in the water environment with high temperature and high pressure water are summarized in this paper. Moreover, some further researches for material corrosion in SCWO process are also proposed. All work was contributed to selecting the appropriate constructional materials and reducing the corrosion damage in SCWO system.
{"title":"Corrosion Properties of Candidate Materials in Supercritical Water Oxidation Process","authors":"XingYing Tang, Shuzhong Wang, Lili Qian, Mengmeng Ren, Panpan Sun, Yanhui Li, J. Yang","doi":"10.1515/jaots-2016-0119","DOIUrl":"https://doi.org/10.1515/jaots-2016-0119","url":null,"abstract":"Abstract Corrosion of constructional materials in supercritical water oxidation (SCWO) is one of the main obstacles to commercializing the SCWO process. Statistical analysis of corrosion research results indicate nickel-based alloys are the most widely applied materials in SCWO system among the candidate metals. The present paper reviews the corrosion characteristics of iron-base alloy, nickel-based alloy, titanium-base alloy, ceramics, niobium, tantalum, thallium and gold under the condition of SCWO. The selection scheme of materials is presented in SCWO system flow diagram in detail. The effects of alloying elements on the corrosion behavior of materials in the water environment with high temperature and high pressure water are summarized in this paper. Moreover, some further researches for material corrosion in SCWO process are also proposed. All work was contributed to selecting the appropriate constructional materials and reducing the corrosion damage in SCWO system.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"49 1","pages":"141 - 157"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82251303","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}
Abstract This work investigated the degradation of cationic red X-GRL by electrochemical oxidation on a novel PbO2 anode modified by Ce. The optimized molar ratio of Pb: Ce was 200 mol: 4 mol for the X-GRL and TOC removals. The results showed a high current efficiency for effective X-GRL treatment. Under the optimal condition of current density 50 mA/cm2, Na2SO4 0.2 mol/L, initial quality concentration of X-GRL 100 mg/L, after 2h degradation, the X-GRL and TOC removals reached 93.45% and 48.23%, respectively. Based on the degradation intermediates identification, a simplified degradation pathway of cationic red X-GRL was proposed. Based on the analysis of scanning environmental microscopy (SEM), the surface of electrode had a dense structure and the preferred crystalline orientation, which was helpful to improve the catalytic activity of electrode and finally enhance the mineralization of X-GRL.
{"title":"Study on Cationic Red X-GRL Removal with Ce Doped Electrode","authors":"Weidong Li, Qizhou Dai, Jiade Wang, Jiazhong Zhou","doi":"10.1515/jaots-2016-0118","DOIUrl":"https://doi.org/10.1515/jaots-2016-0118","url":null,"abstract":"Abstract This work investigated the degradation of cationic red X-GRL by electrochemical oxidation on a novel PbO2 anode modified by Ce. The optimized molar ratio of Pb: Ce was 200 mol: 4 mol for the X-GRL and TOC removals. The results showed a high current efficiency for effective X-GRL treatment. Under the optimal condition of current density 50 mA/cm2, Na2SO4 0.2 mol/L, initial quality concentration of X-GRL 100 mg/L, after 2h degradation, the X-GRL and TOC removals reached 93.45% and 48.23%, respectively. Based on the degradation intermediates identification, a simplified degradation pathway of cationic red X-GRL was proposed. Based on the analysis of scanning environmental microscopy (SEM), the surface of electrode had a dense structure and the preferred crystalline orientation, which was helpful to improve the catalytic activity of electrode and finally enhance the mineralization of X-GRL.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"56 1","pages":"134 - 140"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81487679","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}
J. R. Guimarães, Regiane Aparecida Guadagnini, Regina Maura Bueno Franco, Luciana Urbano dos Santos
Abstract This study evaluated the effectiveness of H2O2, UV radiation, and H2O2/UV processes to inactivate total coliforms, Escherichia coli, and Clostridium perfringens bacteria present in a treated sewage. The samples were collected at Samambaia Waste Water Treatment Plant in Campinas, Brazil. The photochemical assays were carried out using 125-3,640 mJ cm−2 doses of UV radiation. The initial H2O2 concentration was 30 mg L−1. The bacteria were quantified in samples of 100% raw effluent, which had an average of 1.1 × 106 most probable number (MPN)/100 mL of total coliforms, 2.3 × 105 MPN/100 mL of E. coli, and 1.4 × 104 MPN/100 mL of C. perfringens after treatment with activated sludge. Peroxidation did not efficiently inactivate the measured bacteria. The UV process incurred 5-log inactivation for total coliforms and E. coli bacteria, whereas advanced oxidation processes (AOPs) inactivated both bacteria. UV radiation and AOP incurred a 2-log inactivation of C. perfringens.
{"title":"Inactivation of Clostridium perfringens, Total Coliforms, and Escherichia coli by UV/H2O2 in Wastewater Treatment Plant Effluent","authors":"J. R. Guimarães, Regiane Aparecida Guadagnini, Regina Maura Bueno Franco, Luciana Urbano dos Santos","doi":"10.1515/jaots-2016-0112","DOIUrl":"https://doi.org/10.1515/jaots-2016-0112","url":null,"abstract":"Abstract This study evaluated the effectiveness of H2O2, UV radiation, and H2O2/UV processes to inactivate total coliforms, Escherichia coli, and Clostridium perfringens bacteria present in a treated sewage. The samples were collected at Samambaia Waste Water Treatment Plant in Campinas, Brazil. The photochemical assays were carried out using 125-3,640 mJ cm−2 doses of UV radiation. The initial H2O2 concentration was 30 mg L−1. The bacteria were quantified in samples of 100% raw effluent, which had an average of 1.1 × 106 most probable number (MPN)/100 mL of total coliforms, 2.3 × 105 MPN/100 mL of E. coli, and 1.4 × 104 MPN/100 mL of C. perfringens after treatment with activated sludge. Peroxidation did not efficiently inactivate the measured bacteria. The UV process incurred 5-log inactivation for total coliforms and E. coli bacteria, whereas advanced oxidation processes (AOPs) inactivated both bacteria. UV radiation and AOP incurred a 2-log inactivation of C. perfringens.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"69 1","pages":"93 - 97"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80355304","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}
Abstract Since the early 1980s, liquid phase kinetic studies of homogeneous and heterogeneous photochemistry (especially including photocatalysis), have routinely utilized well stirred laboratory scale photoreactors. Convenient as these reactors are, their operation may be limited by reactant concentration, or by a transport limitation for light flux or dissolved oxygen. Similarly, the mechanistic interpretation of most phootocatalyzed liquid phase data has assumed the validity of Langmuir-Hinshelwood kinetics, whereas recent papers have demonstrated decisively that a pseudo steady state prevails, rather than equilibrium adsorption circumstance. We briefly review these circumstances which have led to kinetic disguises, and offer simple recommendations for future homogeneous and heterogeneous photochemical liquid phase studies which will allow determination of true rate constants and avoid the transport phenomena and mechanistic disguises evident in prior work.
{"title":"The Well Stirred Liquid Phase Photochemical Reactor: Laboratory Tool or Master of Disguises?","authors":"D. Ollis","doi":"10.1515/jaots-2016-0202","DOIUrl":"https://doi.org/10.1515/jaots-2016-0202","url":null,"abstract":"Abstract Since the early 1980s, liquid phase kinetic studies of homogeneous and heterogeneous photochemistry (especially including photocatalysis), have routinely utilized well stirred laboratory scale photoreactors. Convenient as these reactors are, their operation may be limited by reactant concentration, or by a transport limitation for light flux or dissolved oxygen. Similarly, the mechanistic interpretation of most phootocatalyzed liquid phase data has assumed the validity of Langmuir-Hinshelwood kinetics, whereas recent papers have demonstrated decisively that a pseudo steady state prevails, rather than equilibrium adsorption circumstance. We briefly review these circumstances which have led to kinetic disguises, and offer simple recommendations for future homogeneous and heterogeneous photochemical liquid phase studies which will allow determination of true rate constants and avoid the transport phenomena and mechanistic disguises evident in prior work.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"1 1","pages":"192 - 198"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80539612","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}
Xiuhong Xu, R. Jiang, Hong-kai Shi, Kejuan Qiang, Peng Wang, Jing Wang
Abstract Microporous SAPO-5 with an AFI topology has been synthesized by hydrothermal method; using this material, TiO2/SAPO-5 composite zeolites were prepared using sol-gel technique. The structures of SAPO-5 molecular sieves and TiO2/SAPO-5 composite zeolites were characterized by several analytical techniques. XRD patterns show the high crystallinity and purity of SAPO-5 molecular sieves. The small particle size (500-600 nm) and the large specific surface area have been analyzed by SEM and BET. The photocatalytic activity of TiO2/SAPO-5 composite zeolite was evaluated by photocatalytic degradation of phenol as model reaction. TiO2/SAPO-5 exhibits a higher activity for the degradation of phenol in comparison with pure TiO2.
{"title":"Preparation of TiO2/SAPO-5 Composite Zeolite and its Photocatalytic Properties for the Degradation of Phenol","authors":"Xiuhong Xu, R. Jiang, Hong-kai Shi, Kejuan Qiang, Peng Wang, Jing Wang","doi":"10.1515/jaots-2016-0224","DOIUrl":"https://doi.org/10.1515/jaots-2016-0224","url":null,"abstract":"Abstract Microporous SAPO-5 with an AFI topology has been synthesized by hydrothermal method; using this material, TiO2/SAPO-5 composite zeolites were prepared using sol-gel technique. The structures of SAPO-5 molecular sieves and TiO2/SAPO-5 composite zeolites were characterized by several analytical techniques. XRD patterns show the high crystallinity and purity of SAPO-5 molecular sieves. The small particle size (500-600 nm) and the large specific surface area have been analyzed by SEM and BET. The photocatalytic activity of TiO2/SAPO-5 composite zeolite was evaluated by photocatalytic degradation of phenol as model reaction. TiO2/SAPO-5 exhibits a higher activity for the degradation of phenol in comparison with pure TiO2.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"23 1","pages":"381 - 386"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90098243","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}
Célia Lima, J. Madureira, M. M. Carolino, J. Noronha, F. Margaça, Sandra Cabo Verde
Abstract Wastewater from cork processing industry present high levels of organic compounds such as phenolics that must be degraded before discharge into the municipal sewer or into public water courses. The aim of this work was to find out if gamma radiation treatment could increase the biodegradability of recalcitrant compounds using a microbial consortium and a mixed solution of four phenolic acids as a model. Chemical and microbiological analyses were performed in non-irradiated (0 kGy) and irradiated (100 kGy) mixed phenolic acids cultures during incubation time. A preliminary HPLC and GC-MS analysis were performed to detect the major phenolic compounds in cork wastewater samples. Results indicated the presence of gallic, protocatechuic, vanillic and syringic acids in cork boiling water and gallic, protocatechuic and vanillic acids in sediment tank samples. The Total Phenolic content (TP) of mixed phenolic acids cultures during incubation time indicated a decrease of 38% for 100 kGy samples. The HPLC analysis suggested that the radiolytic products of syringic and vanillic acids are protocatechuic and gallic acids. The CFU counts pointed out to a decreasing tendency along the incubation time for phenolic acids cultures (0 kGy and 100 kGy) suggesting a non-degradation trend. The selected microbial consortium was not able to metabolize the phenolic compounds solutions at the used conditions. This could be due to the detected radiolytic degradation dynamics of the phenolic acids considering the antimicrobial activity of these compounds.
{"title":"A Biodegradation Bench Study of Cork Wastewater using Gamma Radiation","authors":"Célia Lima, J. Madureira, M. M. Carolino, J. Noronha, F. Margaça, Sandra Cabo Verde","doi":"10.1515/jaots-2016-0109","DOIUrl":"https://doi.org/10.1515/jaots-2016-0109","url":null,"abstract":"Abstract Wastewater from cork processing industry present high levels of organic compounds such as phenolics that must be degraded before discharge into the municipal sewer or into public water courses. The aim of this work was to find out if gamma radiation treatment could increase the biodegradability of recalcitrant compounds using a microbial consortium and a mixed solution of four phenolic acids as a model. Chemical and microbiological analyses were performed in non-irradiated (0 kGy) and irradiated (100 kGy) mixed phenolic acids cultures during incubation time. A preliminary HPLC and GC-MS analysis were performed to detect the major phenolic compounds in cork wastewater samples. Results indicated the presence of gallic, protocatechuic, vanillic and syringic acids in cork boiling water and gallic, protocatechuic and vanillic acids in sediment tank samples. The Total Phenolic content (TP) of mixed phenolic acids cultures during incubation time indicated a decrease of 38% for 100 kGy samples. The HPLC analysis suggested that the radiolytic products of syringic and vanillic acids are protocatechuic and gallic acids. The CFU counts pointed out to a decreasing tendency along the incubation time for phenolic acids cultures (0 kGy and 100 kGy) suggesting a non-degradation trend. The selected microbial consortium was not able to metabolize the phenolic compounds solutions at the used conditions. This could be due to the detected radiolytic degradation dynamics of the phenolic acids considering the antimicrobial activity of these compounds.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"159 1","pages":"73 - 78"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88898122","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}
E. Kusiak-Nejman, A. Wanag, Ł. Kowalczyk, J. Kapica-Kozar, A. Morawski
Abstract This work investigated the photocatalytic performance of TiO2 photocatalysts modified with graphitic carbon under visible light with a very small component of UV. The graphitic carbon modification was conducted at 200-500 °C using thermal anthracene decomposition. The increase of calcination temperature leads to typical increase of crystallites size, decrease of the specific surface area and carbon content in modified samples. The characteristic peak for a skeletal in-plane vibrations of the anthracene ring located at 1522 cm-1 as well as the band at 1410 cm-1 assigned to C=C aromatic stretching vibrations mode were possible to observe. The analysis of the morphology using SEM confirmed the presence on new multi-layer carbonaceous flakes decorated with TiO2 nanoparticles. TEM analysis and Raman studies proved the presence of graphitic structures covering the surface of the prepared TiO2/C photocatalysts. The highest photocatalytic activity, calculated on the basis of phenol photodegradation under visible light, was found for the photocatalyst modified with graphitic carbon at 400 °C (TiO2/C-400).
{"title":"Modification of Titanium Dioxide with Graphitic Carbon from Anthracene Thermal Decomposition as a Promising Method for Visible- Active Photocatalysts Preparation","authors":"E. Kusiak-Nejman, A. Wanag, Ł. Kowalczyk, J. Kapica-Kozar, A. Morawski","doi":"10.1515/jaots-2016-0206","DOIUrl":"https://doi.org/10.1515/jaots-2016-0206","url":null,"abstract":"Abstract This work investigated the photocatalytic performance of TiO2 photocatalysts modified with graphitic carbon under visible light with a very small component of UV. The graphitic carbon modification was conducted at 200-500 °C using thermal anthracene decomposition. The increase of calcination temperature leads to typical increase of crystallites size, decrease of the specific surface area and carbon content in modified samples. The characteristic peak for a skeletal in-plane vibrations of the anthracene ring located at 1522 cm-1 as well as the band at 1410 cm-1 assigned to C=C aromatic stretching vibrations mode were possible to observe. The analysis of the morphology using SEM confirmed the presence on new multi-layer carbonaceous flakes decorated with TiO2 nanoparticles. TEM analysis and Raman studies proved the presence of graphitic structures covering the surface of the prepared TiO2/C photocatalysts. The highest photocatalytic activity, calculated on the basis of phenol photodegradation under visible light, was found for the photocatalyst modified with graphitic carbon at 400 °C (TiO2/C-400).","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"1 1","pages":"227 - 235"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78996613","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}
Stefano Bertinetti, M. Minella, Francesco Barsotti, V. Maurino, C. Minero, Emrah Özensoy, D. Vione
Abstract A method to assess the ability of a photocatalyst to induce reactions with free or trapped hydroxyl radicals versus direct charge-transfer processes is here proposed, based on the use of phenol and 2-hydroxybenzoic acid (salicylic acid) as test substrates. The rationale is that phenol degradation would be preferentially (although not exclusively) induced by hydroxyl radicals, while salicylic acid would mainly undergo direct charge-transfer oxidation. The use of t-butanol as selective ·OH scavenger is helpful to understand how much each substrate is a selective indicator of the intended reaction pathway in the presence of a given semiconductor oxide. Phenol and salicylic acid should be used at low concentration (e.g. 25 μmol L-1) to limit the occurrence of the back-reactions, the importance of which can be highlighted by using higher initial concentration values (e.g. 1 mmol L-1). The method was optimized with the well-studied photocatalysts Evonik P25 and Wackherr's “Oxyde de titane standard”, and it was then applied to study the behavior of two TiO2/Al2O3 binary oxide systems (where TiO2 occurs as a mixture of anatase and rutile). The latter photocatalysts were poorly efficient toward the degradation of phenol, but they performed better with salicylic acid. These findings, which are coherent with the results of t-butanol addition, suggest that the two binary oxide systems would induce charge-transfer rather than ·OH reactions.
{"title":"A Methodology to Discriminate Between Hydroxyl Radical-induced Processes and Direct Charge-transfer Reactions in Heterogeneous Photocatalysis","authors":"Stefano Bertinetti, M. Minella, Francesco Barsotti, V. Maurino, C. Minero, Emrah Özensoy, D. Vione","doi":"10.1515/jaots-2016-0207","DOIUrl":"https://doi.org/10.1515/jaots-2016-0207","url":null,"abstract":"Abstract A method to assess the ability of a photocatalyst to induce reactions with free or trapped hydroxyl radicals versus direct charge-transfer processes is here proposed, based on the use of phenol and 2-hydroxybenzoic acid (salicylic acid) as test substrates. The rationale is that phenol degradation would be preferentially (although not exclusively) induced by hydroxyl radicals, while salicylic acid would mainly undergo direct charge-transfer oxidation. The use of t-butanol as selective ·OH scavenger is helpful to understand how much each substrate is a selective indicator of the intended reaction pathway in the presence of a given semiconductor oxide. Phenol and salicylic acid should be used at low concentration (e.g. 25 μmol L-1) to limit the occurrence of the back-reactions, the importance of which can be highlighted by using higher initial concentration values (e.g. 1 mmol L-1). The method was optimized with the well-studied photocatalysts Evonik P25 and Wackherr's “Oxyde de titane standard”, and it was then applied to study the behavior of two TiO2/Al2O3 binary oxide systems (where TiO2 occurs as a mixture of anatase and rutile). The latter photocatalysts were poorly efficient toward the degradation of phenol, but they performed better with salicylic acid. These findings, which are coherent with the results of t-butanol addition, suggest that the two binary oxide systems would induce charge-transfer rather than ·OH reactions.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"11 1","pages":"236 - 245"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89977154","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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