Jonathan Chávez-Villanueva, D. Hernandez‐Uresti, A. Vázquez, S. Obregón
{"title":"Photocatalytic Degradation of Pharmaceuticals through Bulk and Mesoporous g-C3N4/TiO2 Systems","authors":"Jonathan Chávez-Villanueva, D. Hernandez‐Uresti, A. Vázquez, S. Obregón","doi":"10.2174/2665976x02666210122160124","DOIUrl":"https://doi.org/10.2174/2665976x02666210122160124","url":null,"abstract":"\u0000\u0000In recent years, pharmaceutical pollutants have emerged as a growing threat\u0000to the environment. To mitigate this situation, heterogeneous photocatalysis has been considered a\u0000promising advanced oxidation technology, where TiO2-based systems have exhibited outstanding efficiency\u0000in the degradation of organic compounds.\u0000\u0000\u0000\u0000 In this work, we have studied the photocatalytic performance of the coupled g-C3N4/TiO2\u0000system in the degradation of the pharmaceuticals tetracycline, ciprofloxacin, and ibuprofen. Moreover,\u0000the effect of the graphitic carbon nitride (g-C3N4) was examined through the study of two different\u0000samples, a bulk g-C3N4 prepared from the direct calcination of melamine and a mesoporous g-C3N4\u0000synthesized through a nanocasting process using SBA-15 silica as hard template.\u0000\u0000\u0000\u0000The hybrid photocatalysts were prepared by forced hydrolysis of titanium isopropoxide using\u0000two g-C3N4 samples, a bulk material and a mesoporous one. The samples were characterized by\u0000X-ray powder diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS), Fourier-Transform Infrared\u0000Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and N2 adsorption-desorption measurements.\u0000The photocatalytic activity was examined through the degradation of tetracycline, ciprofloxacin,\u0000and ibuprofen under simulated solar irradiation.\u0000\u0000\u0000\u0000The textural properties of g-C3N4 play a preponderant role in the photoactivity of the g-\u0000C3N4/TiO2 system. In this sense, high dispersion of the TiO2 nanoparticles could be obtained using a\u0000mesoporous g-C3N4 sample. All hybrid photocatalysts exhibit higher degradation rates than the pristine\u0000materials, including bare TiO2. In this regard, the samples with 1 wt.% g-C3N4 attained the highest\u0000photocatalytic performance in the degradation of tetracycline, ciprofloxacin, and ibuprofen.\u0000\u0000\u0000\u0000 The coupling of TiO2 with graphitic carbon nitride leads to the formation of hybrid photocatalysts\u0000with outstanding photoactive properties in the degradation of pharmaceutical pollutants. In\u0000this way, the g-C3N4/TiO2 samples can be considered as excellent photocatalysts for the degradation\u0000of organic pollutants.\u0000","PeriodicalId":246025,"journal":{"name":"Journal of Photocatalysis","volume":"130 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134291980","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. M. de la Fournière, J. Meichtry, G. Custo, E. Gautier, M. Litter
{"title":"New insights on the UV/TiO2 photocatalytic treatment of thiomersal and its 2-sulfobenzoic acid product","authors":"E. M. de la Fournière, J. Meichtry, G. Custo, E. Gautier, M. Litter","doi":"10.2174/2665976x02666210629104521","DOIUrl":"https://doi.org/10.2174/2665976x02666210629104521","url":null,"abstract":"\u0000\u0000Thiomersal (TM), a complex between 2-mercaptobenzoic acid (2-MBA) and ethylmercury (C2H5Hg+), is an antimicrobial preservative used in immunological, ophthalmic, cosmetic products, and vaccines. \u0000\u0000\u0000\u0000TM has been treated by UV/TiO2 photocatalysis in the presence or absence of oxygen at acidic pH. C2H5Hg+, 2-MBA, and 2-sulfobenzoic acid (2-SBA) were found as products. A 2-SBA photocatalytic treatment was undertaken to study sulfur evolution. \u0000\u0000\u0000\u0000Photocatalytic runs were performed using a UVA lamp (λmax = 352 nm), open to the air or under N2. A suspension of the corresponding TM or 2-SBA salt and TiO2 was prepared, and pH was adjusted. Suspensions were stirred in the dark for 30 min and then irradiated. TM, 2-MBA, 2-SBA, and C2H5Hg+ were quantified by HPLC, sulfur by TXRF, and the deposits on the photocatalyst were analyzed by chemical reactions. The mineralization degree was followed by TOC. Sulfate was determined using BaCl2 at 580 nm. \u0000\u0000\u0000\u0000Photocatalytic destruction of TM and total C2H5Hg+ was complete under N2 and air, but TM degradation was much faster in air. The evolution of TM and the products followed a pseudo-first-order kinetics. \u0000\u0000\u0000\u0000TiO2-photocatalytic degradation is a suitable technique for the treatment of TM and its degradation products. In contrast to other organomercurial compounds, TM degradation is faster in the presence of O2, indicating that the oxidative mechanism is the preferred pathway. A significant TM mineralization (> 60%, NPOC and total S) was obtained. TM was more easily degraded than 2-SBA. Sulfate was the final product.\u0000","PeriodicalId":246025,"journal":{"name":"Journal of Photocatalysis","volume":"222 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131655198","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}
{"title":"Photocatalytic Hydrogen Evolution Over Pt/Co-TiO2 Photocatalysts","authors":"Soukaina Akel, R. Dillert, D. Bahnemann","doi":"10.2174/2665976x01999200718010443","DOIUrl":"https://doi.org/10.2174/2665976x01999200718010443","url":null,"abstract":"\u0000\u0000 In this study, the photocatalytic hydrogen evolution reaction from aqueous methanol\u0000was investigated upon simulated solar light using platinum loaded on cobalt doped TiO2 (Pt/Co-TiO2)\u0000composites.\u0000\u0000\u0000\u0000Controversial results of cobalt-based composites create doubts about their photocatalytic\u0000activity. Thus, cobalt doped TiO2 composites were synthesized differently, and the photocatalytic\u0000activity was examined for the photocatalytic hydrogen generation.\u0000\u0000\u0000\u0000The current study aims to investigate the influence of cobalt doping and platinum loading\u0000on the photocatalytic activities of TiO2 nanoparticles for the photocatalytic H2 generation.\u0000\u0000\u0000\u0000The 0.5 wt.% Co-TiO2 and bare TiO2 photocatalysts were synthesized using two different\u0000methods, namely, reflux and hydrothermal synthesis. Additionally, the Pt deposition on the prepared\u0000Co-TiO2 and TiO2 catalysts (1 wt.% Pt) was performed using a photo-platinization method.\u0000\u0000\u0000\u0000The as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy/\u0000energy dispersive X-ray analysis (SEM/EDX), transmission electron microscopy (TEM), ultraviolet-\u0000visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), electron paramagnetic\u0000resonance (EPR), and electrochemical impedance spectroscopy (EIS).\u0000\u0000\u0000\u0000 The XRD and EPR studies clearly indicated that the Co was incorporated into the titanium\u0000dioxide lattice. The EIS results suggested that the reduction of protons over Co-TiO2 and bare TiO2\u0000materials was possible from a thermodynamic point of view. However, the photocatalytic results revealed\u0000that the formed amount of H2 was extremely low and close to the detection limit. The evolution\u0000of H2 from aqueous methanol (10 vol%) showed higher rates when employing 1 wt.% Pt loaded on\u00000.5 wt.% Co-TiO2 photocatalysts under simulated solar light irradiation. A maximum of 317 ± 44\u0000μmol.h-1 was observed over the Pt/Co-TiO2-HT photocatalyst.\u0000\u0000\u0000\u0000 EPR results confirmed that the cobalt ions were introduced into the TiO2 lattice by trapping\u0000the photogenerated conduction band electrons and decreasing the defects in the crystal cell. The\u0000Mott−Schottky analysis of electrochemical impedance measurements showed that all catalysts were ntype\u0000semiconductors and that cobalt doping induces impurity level within the band gap of TiO2. The\u0000experimental results of photocatalytic H2 generation from methanol-reforming demonstrated that no\u0000significant impact of Co-doping on the photocatalytic H2 formation was observed neither for bare\u0000TiO2 samples nor for the platinized materials. Based on these experimental findings, a possible mechanism\u0000for the continuous photocatalytic activity of Pt/Co-TiO2 photocatalysts under simulated solar\u0000light was proposed.\u0000","PeriodicalId":246025,"journal":{"name":"Journal of Photocatalysis","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114475450","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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