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1.
Research on Chemical Intermediates - An immobilized TiO2/polyaniline (TiO2/PANI) bilayer photocatalyst was fabricated to decolorize methyl orange (MO) dye in aqueous solution. The synergistic... 相似文献
2.
Photocatalytic decolorization of methyl orange solution with potassium peroxydisulfate 总被引:1,自引:0,他引:1
Zhong Junbo Ma Di Zhao Hong Lian An Li Min Jiao Huang Shengtian Li Jianzhang 《Central European Journal of Chemistry》2008,6(2):245-252
Increasing environmental pollution caused by toxic dyes due to their hazardous nature is a matter of great concern. It has
been generally agreed that methyl orange (MO) can be effectively degraded in aerated K2S2O8 homogeneous reaction system using near-UV irradiation. In this paper photocatalytic degradation of MO solutions with K2S2O8 was investigated, with particular attention on the possible underlying mechanisms. This report has shown decolorization efficiency
of MO increases with the increasing of the dosage of the catalyst. There is no optimal amount of catalyst in our case, where
special attention was paid on the nature of the photocatalyst itself. The current research revealed that the decolorization
reaction is a pseudo first-order reaction when the concentration of MO is below 20 mg L−1 and the decolorization reaction is zero-order reaction when the concentration of MO is above 100 mg L−1, but the Langmuir-Hinshewood kinetic model does not describe this. The influence of IO4−, BrO3− and H2O2 were investigated in detailed. Several observations indicate that the mechanism is not involved in hydroxyl radical attacks
in MO degradation with K2S2O8 by UV irradiation. The possible underlying mechanisms are direct oxidation of the MO by S2O82− and hydrogen attraction by SO4•−.
相似文献
3.
Yu L Xi J Li MD Chan HT Su T Phillips DL Chan WK 《Physical chemistry chemical physics : PCCP》2012,14(10):3589-3595
The properties of photo-generated reactive species, holes and electrons in bulk TiO(2) (anatase) film and nano-sized TiO(2) were studied and their effects towards decomposing pollutant dye methyl orange (MO) were compared by transient absorption spectroscopies. The recombination of holes and electrons in nano-sized TiO(2) was found to be on the microsecond time scale consistent with previous reports in the literature. However, in bulk TiO(2) film, the holes and electrons were found to be on the order of picoseconds due to ultra fast free electrons. The time-correlated single-photon counting (TCSPC) technique combined with confocal fluorescence microscopy revealed that the fluorescence intensity of MO is at first enhanced noticeably by TiO(2) under UV excitation and soon afterwards weakened dramatically, with the lifetime prolonged. Photo-generated holes in nano-sized TiO(2) can directly oxidize MO on the time scale of nanoseconds, while free electrons photo-generated in bulk TiO(2) film can directly inject into MO on the order of picoseconds. Through cyclic voltammetry measurements, it was found that MO can be reduced at -0.28 V and oxidized at 1.4 V (vs. SCE) and this provides thermodynamic evidence for MO to be degraded by electrons and holes in TiO(2). Through comparison of the hole-scavenging effect of MO and water, it was found that in polluted water when MO is above 1.6 × 10(-4) M, the degradation is mainly due to a direct hole oxidation process, while below 1.6 × 10(-4) M, hydroxyl oxidation competes strongly and might exceed the hole oxidation. 相似文献
4.
Novel ternary composite photocatalysts have been successfully prepared by TiO₂ nanofibers, reduced graphene oxide, and CdS nanoparticles (TiO₂/rGO/CdS) by using electrospinning technique with easy chemical methods. The structures and their properties are examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscope (FESEM). The structural characterization of the composite reveals that pure TiO₂ NFs and CdS NPs crystalline very well and the reduced graphene oxide is tightly composed with TiO₂ NFs and CdS Nps. The photodegradation of methyl orange (MO) under UV light illumination is significantly enhanced compared with that of bare materials. This ternary composite degrades methyl orange within 75 min. The enhanced photocatalytic degradation performance resulted from effective separation of e–h pairs with rGO sheets and also contributed for high rate degradation efficiency. This novel ternary composite has a potential application of wastewater purification and utilization for energy conversions. 相似文献
5.
Jianfei Lei Xiaoping Li Weishan Li Fengqiang Sun Dongsheng Lu Yuli Lin 《Journal of Solid State Electrochemistry》2012,16(2):625-632
Arrayed porous iron-doped TiO2 was prepared by sol–gel with polystyrene spheres as template and used as photocatalyst for the degradation of methyl orange.
The structure and performances of the prepared photocatalyst were characterized with X-ray diffractometer, inductively coupled
plasma-atomic emission spectrometer, scanning electron microscope, UV-visible spectrometer, and methyl orange degradation
tests. It is found that the iron dopant does not change the crystal phase of TiO2 but affects its lattice constant, optical absorption, electronic conductivity, charge-transfer resistance, and activity toward
the degradation of methyl orange. The sample doped with 0.01 wt.% Fe (based on Ti) and with smaller pore size exhibits the
better photocatalytic activity. The degradation rate of methyl orange on the sample with a pore size of 190 nm is 2.3 times
that on the undoped sample with the same pore size. 相似文献
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7.
Se Hee Jang Yong Joo Kim Hark Jin Kim Wan In Lee 《Electrochemistry communications》2010,12(10):1283-1286
300-nm-sized nanoporous TiO2 spheres (SPs), blended with 25-nm-sized nanoparticles, were successfully applied to low-temperature fabrication of TiO2 electrodes for dye-sensitized solar cell (DSC). The introduction of SPs increased the adsorbed amount dye molecules, induced the efficient transport of photo-injected electrons through TiO2 layer, and offered an extended light-scattering efficiency in the long wavelength region. Furthermore, the adhesion of TiO2 layer to the FTO substrate was considerably improved. As a result, the photovoltaic conversion efficiency (η) of DSC processed at 140 °C was enhanced from 4.4% to 6.3%. 相似文献
8.
The photodegradation of an aqueous solution of methyl orange by the TiO2/SnS powders was studied in different ratios of SnS against TiO2. The effects of the initial pH value and light resource were investigated. The SnS extends the light absorption edge of the TiO2 to ~940 nm of the SnS (1.32 eV). The results indicated that the optimal SnS proportion for the maximum degradation efficiency increased in relation to a decrease in the initial pH in both sunlight and visible light, and decreased when changing from visible light to sunlight. The pure TiO2 powder had maximum efficiency in conditions of pH 9 and visible light irradiation or in conditions of pH 7 and sunlight irradiation. In visible light, the degradation efficiency on the powders containing the SnS was larger than that on the pure TiO2 powder in a range of pH 3–7. The maximum efficiency in visible light was found to be in conditions of pH 5 and TiO2:SnS = 3:2 and 2:3, beyond which the efficiency decreased. The efficiency was, overall, larger in sunlight than in visible light. The mechanism of the effects of pH and light resource was discussed in view of the surface charge of the catalysts. 相似文献
9.
We successfully prepared Ag quantum dots modified TiO2 microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO2 photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO2 microspheres for methyl orange degradation was proposed in detail. 相似文献
10.
The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu) adsorbed on TiO(2) (Degussa P25) surface has been investigated by carrying out the photodegradation of methyl orange (MO) under visible and ultraviolet light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV (DRS-UV-vis) and infrared spectra. Copper porphyrin-sensitized TiO(2) photocatalyst (CuP-TiO(2)) showed excellent activity for the photodegradation of MO whether under visible or ultraviolet light irradiation. Natural Bond Orbital (NBO) charges analysis showed that methyl orange ion is adsorbed easier by CuP-TiO(2) catalyst due to the increase of induced interactions. 相似文献
11.
《Journal of Saudi Chemical Society》2021,25(12):101383
Anatase TiO2/nanocellulose composite was prepared for the first time via a one-step method at a relatively low temperature by using cellulose nanofibers as carrier and tetrabutyl titanate as titanium precursor. The morphology, structure and element composition of the composite were characterized by SEM, EDS, TEM, XRD, XPS and UV–vis DRS. The specific surface area and thermal stability of the composite were investigated by N2 adsorption–desorption and thermogravimetric analysis, respectively, and the band gaps of the prepared photocatalysts were calculated based on the UV–vis DRS results. In addition, the prepared composite was used for the photocatalytic degradation of methyl orange (aqueous solution, 40 mg L−1). It was found that the composite had a good morphology and anatase crystal structure, and Ti-O-C bond was formed between TiO2 and nanocellulose. The specific surface area of composite was increased and the thermal stability was decreased compared with the cellulose nanofiber. Moreover, the degradation rate of methyl orange was achieved as 99.72% within 30 min, and no obvious activity loss was observed after five cycles. This work might give some insights into the design of efficient photocatalysts for the treatment of organic dye wastewater. 相似文献
12.
The mechanism of multi-electron reduction of methyl orange (MO) azo dye on TiO2 nanoparticles has been studied performing stopped flow technique. A multi-electron reduction of azo dye has been investigated. It was found that a multistep reduction of the dye takes place: the stored electrons reduce the conjugative system of the azo group resulting in the decolorization of the dye and leading to the formation of hydrazine derivative followed by further 2 electron transfer step leading to the cleavage of the N–N bond and the formation of aromatic amines. The FTIR analysis of the products confirms the proposed mechanism of the dye reduction. The kinetic parameters and of the multi-electrons reduction of the MO have been determined. The rate of MO reduction was found to be dependent on both the TiO2 electrons and the dye concentrations. 相似文献
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14.
All-solid-state inorganic-organic heterojunction solar cells (HSCs) were designed and fabricated using earth-abundant element, non-toxic, low-cost SnS-sensitized mesoporous spherical TiO(2) films under ambient conditions using a solution-processable, simple, and convenient fabrication technique. SnS-HSCs show a promising photovoltaic performance, with an efficiency of 2.8% and a significantly high V(OC) of 0.85 V. 相似文献
15.
Self‐doped TiO2 nanotube array (DTNA) electrodes were fabricated through anodic oxidation combined with cathodic reduction. The morphology and structural features of pristine TiO2 nanotube arrays and DTNA electrodes were studied through scanning electron microscopy, X‐ray diffractometry, and X‐ray photoelectron spectroscopy. An accelerated life test was used to test the electrode service lifetime and thus the electrode's stability. The service lifetime of the DTNA electrode prepared at constant 40 V for 6 hr was approximately 338.7 hr at constant 1 mA/cm2 in a 1 M NaClO4 solution. Methyl orange (MO) was employed as the degradation probe for measuring electrochemical oxidation performance. The color removal rate of 200 mg/L MO of the DTNA electrode (85.2% at 1 mA/cm2) was greater than that of the Ti/IrO2 electrode (31.1% at 1 mA/cm2). The larger the surface area of the DTNA electrode is, the more conductive the electrode is for the degradation of organic substances. Organic degradation on the DTNA electrode occurred primarily through an indirect pathway (producing [?OH]). 相似文献
16.
A sensitive method for carbon tetrachloride (CCl4) determination has been developed with the aid of ultrasonic oxidation decolorization of methyl orange (MO). It is found that the ultrasonic oxidation decolorization rate of MO can be significantly promoted by adding a little amount of CCl4. The increased ultrasonic decolorization rate of MO is strongly dependent on the concentration of CCl4 added, and a linear correlation is observed between the amount of CCl4 and the decolorization rate of MO in the ultrasonic oxidation process. Thus, the CCl4 determination is transformed to a simple and direct determination of the decoloration extent of MO solution at a given concentration. As an indirect spectrophotometric determination of CCl4, the new method is sensitive and easy of operation with a maximum wavelength of 508 nm, molar absorptivity of 3.83 × 104 L mol−1 cm−1, and a Sandell sensitivity of 7.96 × 10−3 μg cm−2. Under optimized conditions, Beer's law is obeyed in the range of 0.4-20 mg L−1 of CCl4 (DL = 0.19 mg L−1, r = 0.9996). The concentrations of CCl4 in several practical samples have been determined satisfactorily by using this method. 相似文献
17.
采用光沉积法制备了光稳定二氧化钛纳米管负载钯催化剂.通过X射线衍射、紫外-可见漫反射光谱、透射电子显微镜(TEM)、氮气吸附-脱附、X射线光电子能谱(XPS)、光致发光光谱和光电流等表征手段研究了催化剂的结构和性质.TEM表明二氧化钛纳米管经光照后仍然保持良好的管状结构;XPS结果表明大部分Pd以零价形式存在.以甲基橙溶液作为模拟废液研究了催化剂在紫外光及模拟日光条件下的光催化活性.当Pd的负载量为0.3 wt%时,催化剂的光催化活性最高并且优于P25的光催化活性.另外,通过在光降解过程中加入不同的捕获剂研究了不同氧化活性组分的作用.结果表明,光生空穴(hrb+)在光催化降解过程中起主要作用. 相似文献
18.
Ce Wang Chao Tan Weiqiang Lv Gaolong Zhu Zhaohuan Wei Kelvin H.L. Zhang Weidong He 《Materials Today Chemistry》2018
In this work, we report the synthesis of a Bi2O3-TiO2 hetero-junction (HJ) material through a facile colloidal method. The hetero-junction formation follows a growth with a 145°Bi2O3/TiO2 crystal angle, owing to the large lattice mismatch between Bi2O3 and TiO2 crystals. With the Bi2O3-TiO2 hetero-junction material as a photocatalyst, methyl orange is degraded completely within two hours under common UV-lamp irradiation. The photo-catalyst remains highly-active for complete photo-degradation of methyl orange even after multiple experiments. The remarkable photo-catalytic properties are attributed to the remarkable mono-dispersivity of the colloidal Bi2O3-TiO2 nano-structure as well as the refined band structure with a valence band of 0.85 eV below that of TiO2 crystal. 相似文献
19.
Rapid quantitative determination of hydrogen peroxide by oxidation decolorization of methyl orange using a Fenton reaction system 总被引:3,自引:0,他引:3
In this study, a sensitive and rapid method for hydrogen peroxide (H(2)O(2)) determination has been developed with the aid of oxidation decolorization of methyl orange (MO) by using Fenton reactions, because the decolorization extent of MO solution (at the maximum absorption wavelength of 507 nm) is proportion to the concentration of H(2)O(2). Under optimum conditions, this spectrophotometric method for the H(2)O(2) analysis yields a dynamic range of H(2)O(2) concentration from 5.0 x 10(-7) to 1.0 x 10(-4) mol L(-1) (r=0.997) and a detection limit (3 sigma/k) of 2.0 x 10(-7) mol L(-1). This method for the determination of H(2)O(2) (0.04 mmol L(-1)) is able to tolerate the interference from NaCl (0-5.0 mmol L(-1)), Na(2)SO(4) (0-5.0 mmol L(-1)), MgCl(2) (0-5.0 mmol L(-1)), sodium humate (0-0.1 mmol L(-1)), benzene (0-0.2 mmol L(-1)), toluene (0-0.2 mmol L(-1)), chlorobenzene (0-0.2 mmol L(-1)) and chloroform (0-0.2 mmol L(-1)). The analysis results for practical rainwater samples are in good agreement with the classical N,N-diethyl-p-phenylenediamine (DPD) method for H(2)O(2) determination. 相似文献
20.
利用太阳能驱动半导体光催化剂进行光催化降解污染物和产氢被认为是解决环境问题和能源危机最有效的方法之一.在众多的半导体光催化剂中,TiO2因其优异的化学稳定性、环境友好和成本低等优点,在光催化领域具有不可或缺的作用.介孔TiO2由于具有独特的介孔结构,更有利于光催化过程中反应物的吸附和传输.然而,单一TiO2具有较高的光生载流子重组效率和低的光利用率等缺点,导致其光催化活性低.通过负载助催化剂可以增强光吸收、促进光生载流子的分离以及提供更多活性位点,是提高光催化活性的一种有效策略.目前,常用的高效助催化剂主要为贵金属,如Pt,Pd和Au等,但昂贵的价格及稀缺性限制了其在未来的广泛应用.因此,寻找新型的非贵金属助催化剂来提高光催化剂的活性具有重要意义.MXene作为一种新型的二维过渡金属碳化物和/或氮化物,具有丰富的表面亲水性官能团、良好的金属导电性和较高的载流子迁移率等特性,适合用于光催化中作为助催化剂来提高光催化性能.受此启发,本文利用静电自组装策略将介孔TiO2纳米颗粒均匀地固定在Ti3C2MXene助催化剂上,构建了紧密的介孔TiO2/Ti3C2复合材料,并研究其光催化降解甲基橙(MO)和产氢性能.Zeta电位测试结果表明,带有相反表面电荷的介孔TiO2和Ti3C2可以通过静电作用构筑稳定的复合材料.X-射线粉末衍射、拉曼光谱、X-射线光电子能谱(XPS)、透射电子显微镜和高分辨透射电子显微镜等表征也进一步表明,成功制备了介孔TiO2/Ti3C2复合材料.XPS也证明在复合材料中光生电子从TiO2转移到Ti3C2助催化剂上,表明两者之间具有强相互作用.BET测试结果表明,相比单一的介孔TiO2,复合材料具有更大的比表面积和孔体积,可提供更多的活性位点,有利于提高光催化活性.紫外-可见漫反射光谱表明,Ti3C2助催化剂的引入提高了材料的光吸收能力.荧光光谱、时间分辨荧光光谱、光电流密度和电化学阻抗等测试结果表明,复合材料具有优异的光生载流子分离和转移能力.在光催化性能测试中,最佳Ti3C2含量(3wt%)的介孔TiO2/Ti3C2复合材料在40 min内对MO的光催化降解效率可达99.6%,并利用自由基捕获实验和电子自旋共振表征证实了活性物种·O2-和·OH在光催化降解过程中起主要作用.此外,该复合材料也表现出了较好的产氢性能(218.85μmolg-1h-1),约为单一介孔TiO2的5.6倍,且三次循环后仍保持稳定的产氢效率.综上,MXene族材料可以作为一种高效的非贵金属助催化剂应用于光催化领域. 相似文献