Kinetics and Mechanism of the Photo-oxidation of Thiophene by O_2 Adsorbed on Molecular Sieves

Photochemical oxidation of thiophene in n-octane/water extraction system using O2 as oxidant was studied. The reaction mechanism ofthiophene oxidation was proposed. Results obtained here can be used as the reference for the oxidative desulfurization of gasoline because thiophene is one of the main components containing sulfur in fluid catalytic cracking gasoline. Thiophene dissolved in n-octane was photodecomposed and removed into the water phase at ambient temperature and atmospheric pressure. A 500 W high-pressure mercury lamp （main wave length 365 nm, 0.22 kW/m） was used as light source for irradiation, and air was introduced by a gas pump to supply O2. Thiophene can be photo-oxidized to sulfone, oxalic acid, SO4^2-, and CO2. The desulfurization yield of thiophene in n-octane is 58.9% under photo-irradiation for 5 h under the conditions of air flow at 150 mL/min and V（water）：V（n-octane）=1：1. It can be improved to 92.3% by adding 0.15 g zeoliteartificial into 100 mL reaction system, which is the adsorbent for O2 and thiophene. And under such conditions, the photo-oxidation kinetics of thiophene with O2/zeoliteartificial is first-order with an apparent rate constant of 0.5047 h^-1 and a half-time of 1.37 h. The sulfur content can be depressed from 800 μL/L to less than 62 μL/L.

EFFECTS OF ORGANIC COLORANTS ON PHOTO-INITIATED CROSSLINKING AND PHOTO-OXIDATION DEGRADATION OF POLYETHYLENE AND RELATED MECHANISM

The effects of three organic colorants on photo-initiated crosslinking and photo-oxidation degradation of polyethylene (PE) samples irradiated by microwave excited (MWE) UV lamp in the melt and the related mechanism have been studied by gel content and thermal extension rate determinations,X-ray photoelectron spectroscopy (XPS),mechanical property tests,UV spectroscopy,and light microscope.The data from the gel content and thermal extension rate determinations of photo-crosslinked polyethylene (XLPE) sample...

PHOTOCHEMICAL OXIDATION OF BENZOTHIOPHENE IN SEAWATER

Kinetic investigation into the phogochemical oxidation of benzothiophene in seawater showed that photo-oxidation rates of benzothiophene were influenced by the medium,pH,heary metal ion,dissolved oxygen,and light intensity.The photo-oxidation of benzothiophene followed the first order reaction law, with the rate constants ranging from 1.21×10 -5 /s to 5.38×10 -5 /s.An interesting observation was that the presence of Hg 2+ could markedly enhance the photo-oxidation rate of benzothiophene in seawater;and that the photo-oxidation rate of benzothiophene increased with light intensity.The effect of oxygen on the rate constant for benzothiophene photolysis was also observed.Compared with purging with nitrogen,purging seawater with oxygen evidently increased the photolysis rate of benzothiophene. Based on this observation,a benzothiophene photo-oxidation mechanism including singlet oxygen (O 2 1 Δ g) was suggested.Two photolysis products of benzothiophene were identified.The photolysis of benzothiophene is considered to be important in the removal of this compound in seawater.

Heterogeneous Photooxidation of Phenol by Catalytic Membranes

In this work the heterogenization in polymeric membranes of decatungstate,a photocatalyst for oxidation reactions,was reported.Solid state characterization techniques confirmed that the catalyst structure was preserved within the polymeric membranes.The catalytic membranes were successfully applied in the aerobic photo-oxidation of phenol,one of the main organic pollutants in wastewater,providing stable and recyclable photocatalytic systems.The dependence of the phenol degradation rate by the catalyst loading and transmembrane pressure was shown.By comparison with homogeneous reaction,the catalyst heterogenized in membrane appears to be more efficient concerning the rate of phenol photodegradation and mineralization.

Fabrication of self-organized TiO_2 nanotubes by anodic oxidation and their photocatalysis

Self-organized TiO2 nanotubes were prepared on titanium foils at anodizing voltage of 20V in 0.5% HF solution for 2030min in order to provide a novel high-efficiency photocatalyst. And the resulting TiO2 nanotubes, in periodic ring structures around their exteriors, are open on the top, while closed on the bottom. After annealing for 3h in ambient atmosphere, the anatase phase was found, with the increasing content, in the originally amorphous TiO2 nanotubes treated at 350, 400 and 450℃; whereas the rutile phase emerged at 500℃, and the nanotube architecture could be preserved till 550℃. Furthermore, TiO2 nanotubes, fabricated at anodizing voltage of 20V for 20min and then annealed at 400℃, possesses the best photo-catalytic activity, i.e. the decolourisation of methyl orange irradiated for 40min is 99.6%.

TiO₂-Polysulfone Beads for Use in Photo Oxidation of Rhodamine B

The nano sized TiO2 has been synthesized by sol gel process. The titaniumisopropaxide diluted in propanol hydrolyzed under acidic condition to form a gel. The solvent from gel pores has been extracted at ambient pressure resulting in nano sized TiO2 crystallites. The crystalline phase of TiO2 could be assigned to anatase structure. An average crystallite size is about 12 nm. The surface area of TiO2 found to be 235 m2/g. The TiO2 nanocrystallites thus produced were blended with polysulphone to form its beads for ease of operation. These beads of TiO2 were used as photo catalyst in conjunction with H2O2 oxidizer in presence of UV light (254 nm) for treating the 50 ppm Rhodamine B aqueous solution. The solution decolorized within 10 minutes resulting in disappearance of absorption peak at around 600 nm in UV spectrometry. The organic entities degrade in about 60 minutes. The beads of nano sized TiO2 could be easily recovered from the treated effluent for further use.

Comparative Study of the Effects of Thermal and Photochemical Accelerated Oxidations on Quality of “Green Type” and “Black Type” French Olive Oils

Oxidative stability of two commercial olive oils of different specificity (green type and black type) has been studied during thermal and photochemical accelerated processes through the evolution of quality indices. It might help to assure a good utilisation of olive oil. In most of works described in literature, they are measured individually. In this study, a Principal Component Analysis (PCA) has been performed to emphasize their variation and describe in concise way the quality and the safety of extra-virgin olive oil after two oxidative stresses. No difference had been detected between both type oils when they are heated. Peroxides, aldehydes and conjugated dienes and trienes were formed but rapidly degraded into final oxidation compounds, mainly acid compounds. During the photochemical process, similar changes occurred slower and the green type oil had shown better stability because of its higher phenolic content. The fatty acids had been more impacted (higher disappearance of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA)) when the oils were heated than when irradiated. Saturated fatty acids (SFA), MUFA and PUFA were the most relevant indicators to characterize non-oxidized oils and PV characterized the early stage of oil oxidation.

Applied bias photon-to-current conversion efficiency of ZnO enhanced by hybridization with reduced graphene oxide

The role of reduced graphene oxide（rGO） in the enhancement of photo-conversion efficiency of ZnO films for photoelectrochemical（PEC） water-splitting applications was analyzed. ZnO and rGO-hybridized ZnO（rGO/ZnO） films were prepared via a two-step electrochemical deposition method followed by annealing at 300 °C under argon gas flow. The physical, optical and electrochemical properties of the films were characterized to identify the effect of rGO-hybridization on the applied bias photon-to-current efficiency（ABPE） of ZnO. Scanning electron microscopy and X-ray diffraction indicated the formation of verticallyaligned, wurtzite-phase ZnO nanorods. Diffuse-reflectance UV–visible spectroscopy indicated that rGO-hybridization was able to increase the light absorption range of the rGO/ZnO film. UPS analysis showed that hybridization with rGO increased the band gap of ZnO（3.56 eV） to 3.63 eV for rGO/ZnO sample,which may be attributed to the Burstein–Moss effect. Photoluminescence（PL） spectra disclosed that rGOhybridization suppressed electron-hole recombination due to crystal defects. Linear sweep voltammetry of the prepared thin films showed photocurrent density of 1.0 and 1.8 m A/cm;for ZnO and rGO/ZnO at+0.7 V, which corresponded to an ABPE of 0.55% and 0.95%, respectively. Thus, this report highlighted the multi-faceted role of rGO-hybridization in the enhancement of ZnO photo-conversion efficiency.

Novel synthesis of cerium oxide nano photocatalyst by a hydrothermal method

Crystalline cubic cerium oxide nano particles have been synthesized from cerium(Ⅲ)nitrate(Ce(NO_(3))_(3).6H2_(O))and sodium hydroxide by a hydrothermal method.The effect of three different molar ratios of the NaOH precipitating agent on structural,optical,and photo catalytic activity was investigated.The synthesized cerium oxide nano particles were characterized by X-ray diffraction(XRD),a UV-vis spectrometer,scanning electron microscope(SEM),energy-dispersive X-ray spectroscopy(EDAX),Raman spectroscopy and X-ray photo electron spectroscopy(XPS).According to the findings,hydrothermally synthesized cerium oxide NPs have a high efficiency for photocatalytic degradation of methylene blue when exposed to UV light.Environmental water pollution is the major issue of the atmosphere.To get fresh water,humans could search the resources to purify the water in simple way and degradation is the one of the methods to purify salt water.

Studies on Photocatalytic Degradation of Acridine Orange and Chloroform Sensing Using As-Grown Antimony oxide Microstructures

Flower shaped antimony oxide (Sb2O3) microstructures were synthesized in a large quantity via simple solution method using aqueous mixtures of antimony chloride and hexamethylene diamine (HMDA). The morphological characterizations were done by field emission scanning electron microscopy (FESEM), which revealed that the synthesized products possess flower-shaped microstructures. The detailed structural characterizations performed by X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FT-IR) and Raman spectrophotometer confirmed that the synthesized microstructures are well-crystalline antimony oxide. The Energy dispersive spectroscopy (EDS) shows that the grown products are composed of Sb and O. Optical properties of the synthesized products were characterized by UV-Visible spectrophotometer which exhibits a well defined peak at ~ 291.0 nm. The photo-catalytic activity of the Sb2O3 microstructures was evaluated by degradation of acridine orange (AO), which mineralized almost 63.0% in 150 min. The chemical sensing properties of Sb2O3 microstructures was also studied by I-V technique using chloroform as a detecting solvent. The fabricated chloroform sensor demonstrates good sensitivity of 0.1154 μA cm–2 mM–1, lower-detection limit (~0.1 mM), large-linear dynamic range (LDR, 0.122 mM to 1.22 M) with linearity (R = 0.7898) in short response time (10.0 sec).

Performance of a Demonstrative (Scale-Pilot) Double Advanced Oxidation Wastewater Treatment Plant to Treat Discharges from a Small Community in Morelia, Michoacán, México

This paper,reports the performance of a wastewater treatment scale-pilot plant to treat 2 GPM(Gallons per Minute)discharges with 5,205 mg/L of pollutants expressed in COD(Chemical Oxygen Demand),from“Lomas de la Maestransa”a small community in Morelia City,Michoacan,Mexico.The scale-pilot plant is a train with(1)pretreatment with a triturated pump for floating solid,(2)primary treatment with“in line”coagulation,and rapid filtration to retain suspended colloids and dissolved solids higher of 5μm diameter,(3)double advanced oxidation as secondary treatment with ozone and heterogeneous photo catalysis to oxidize volatile solids,and(4)tertiary treatment with activated carbon to retain refractory compounds.Plant performance was analyzed by a certified laboratory that belongs to Potable Water,Sewage and Sanitation Department from Morelia City Government.Results show that treated water effluent complied with the Mexican Official Standard NOM-001-SEMARNAT-1996 for discharges into national waters,with exception of fecal coliforms,since the raw water contains an average of 64,228,351 MNP/100 mL of fecal coliforms,and in spite that we obtained a 99.998%efficiency,the maximum level allowable 2,000 MPN/100 mL standard,was exceeded by 400 MPN/100 mL.After this experience,the wastewater treatment plant is equipped with a residual chlorine tank to keep a 1.5 ppm chlorine residual concentration to keep the treated water clean.This project was possible because we had the support of the Morelia Sanitation Department.

Photoinduced Cu^(+)/Cu^(2+)interconversion for enhancing energy conversion and storage performances of CuO based Li-ion battery

Pursuing appropriate photo-active Li-ion storage materials and understanding their basic energy storage/conversion principle are pretty crucial for the rapidly developing photoassisted Li-ion batteries(PA-LIBs).Copper oxide(CuO)is one of the most popular candidates in both LIBs and photocatalysis.While CuO based PA-LIBs have never been reported yet.Herein,one-dimensional(1D)CuO nanowire arrays in situ grown on a three-dimensional(3D)copper foam support were employed as dualfunctional photoanode for both‘solar-to-electricity’and‘electricity-to-chemical’energy conversion in the PA-LIBs.It is found that light energy can be indeed stored and converted into electrical energy through the assembled CuO based PA-LIBs.Without external power source,the photo conversion efficiency of CuO based photocell reaches about 0.34%.Impressively,at a high current density of 4000 m A g^(-1),photoassisted discharge and charge specific capacity of CuO based PA-LIBs respectively receive 64.01%and 60.35%enhancement compared with the net electric charging and discharging process.Mechanism investigation reveals that photogenerated charges from CuO promote the interconversion between Cu^(2+)and Cu^(+)during the discharging/charging process,thus forcing the lithium storage reaction more completely and increasing the specific capacity of the PA-LIBs.This work can provide a general principle for the development of other high-efficient semiconductor-based PA-LIBs.

Amino-Functionalized Reduced Graphene-Oxide-Copper (I) Oxide Composite: A Prospective Catalyst for Photo-Reduction of CO2

In the present article, an easy synthetic strategy of a novel composite photo-catalyst comprising of amino-functionalized reduced graphene oxide and Cu2O has been proposed. Role of this composite catalyst in photo reduction of CO2 has been analyzed and it is shown that both amino groups and reduced grapheme oxide, participate in enhancing quantum yield of the photo reduction process.

Photo-Fenton反应研究进展

Photo Fenton氧化法是一种近几年来引起极大关注的新的有效的高级氧化技术 ,并逐渐应用于环境污染物的处理领域 .本文简要介绍了这方面的研究进展情况 ,包括其机理研究和应用研究以及一些新的改进的Photo Fenton氧化方法 .

敌百虫农药废水Photo-Fenton处理方法研究

以含敌百虫有机磷农药的溶液为研究对象,采用Photo-Fenton试剂进行氧化降解处理,使其成功转化成为无机磷(PO43-)。实验表明,在pH值=3.0,c(Fe2+)=0.72 mmol/L,c(H2O2)=3 mmol/L的酸性条件下,Photo-Fenton处理方法对敌百虫废水有机磷转化成无机磷的转化率可达70%,这可能是因为Fe3+络合物对光的吸收产生的配合基的作用以及产生羟基自由基(OH.)的速率加快。还对photo-Fenton处理有机磷农药的影响因素进行探讨。

光辅助直接甲醇燃料电池阳极催化剂的研究进展

直接甲醇燃料电池(DMFCs)因其能够在较低工作温度下提供清洁、可持续能源方面的潜力而备受关注,但阳极缓慢的甲醇氧化反应(MOR)限制了其商业化应用。光辅助直接甲醇燃料电池(PMFCs)能利用光电耦合机制加速MOR过程,实现甲醇的化学能高效转化为电能,为开发高效、可持续的能源转换系统带来了巨大希望。本文首先简要回顾了PMFCs的背景、意义和在能源研究中的价值。从PMFCs的基本结构组成和酸碱介质下甲醇光电催化氧化的基本路径出发,总结了PMFCs阳极光电催化剂的研究进展。重点针对不同类型的PMFCs阳极光电催化剂,讨论光辅助下的MOR增强机制,如催化剂的尺寸效应、晶面效应、吸光性能、导电性以及表面等离激元共振(SPR)效应等方面的影响。PMFCs未来需要重点关注的研究方向是深入理解PMFCs的光电耦合机制和PMFCs阳极催化剂的构效关系,以及解决实际二电极系统下PMFCs光阳极的设计问题。

WO_(3)-TiO_(2)负载的Pt单原子催化剂光热协同催化丙烷和丙烯氧化

单原子催化剂(single-atom catalyst,SAC)可以最大化金属原子利用率,并具有独特的电子特性,已经在各种催化反应中进行了广泛的探索。然而,与纳米催化剂相比,贵金属SAC在烃类氧化反应中通常被认为是不活泼的。在本文中,证明了WO_(3)-TiO_(2)负载的Pt SAC(Pt1/WO_(3)-TiO_(2))在光热协同催化氧化C3H8和C3H6这两种典型的挥发性有机化合物(VOCs)中表现出比相应的纳米催化剂(PtNP/WO_(3)-TiO_(2))高得多的活性。研究发现,Pt1/WO_(3)-TiO_(2)和PtNP/WO_(3)-TiO_(2)都可以通过克服氧中毒来提高光热协同催化C3H8氧化的活性。值得注意的是,Pt1/WO_(3)-TiO_(2)的反应速率达到了3792μmol∙gPt−1∙s^(−1),这对C3H8氧化是一个新的突破。更有趣的是,由于C3H6在PtNP/WO_(3)-TiO_(2)上的强吸附导致催化剂C3H6中毒,因此PtNP/WO_(3)-TiO_(2)上的光热协同催化C3H6氧化无法进行。但是,得益于C3H6和Pt单原子之间适中的相互作用,Pt1/WO_(3)-TiO_(2)上的C3H6中毒在光照下可以被克服。因此,Pt1/WO_(3)-TiO_(2)在光热协同催化C3H6氧化中显示出更高的活性。这项工作表明,SAC的优势不仅在于节约贵金属,还在于可以根据其独特的电子特性发现新的催化反应。

Photo-Fenton氧化法处理废水的原理及影响因素

Photo-Fenton高级氧化技术是处理难降解有毒有机废水的一种有效的方法。本文阐述了该氧化法的原理及其影响因素,photo-Fenton氧化法在反应中会产生大量羟自由基(·OH),它是一种非常活泼及非选择性物种,其氧化电位为2.8V,氧化能力很强,能够引发水溶液中大部分有机物的氧化还原反应。其优点是操作简便及无二次污染等,反应产物Fe3+可与OH反应形成Fe(OH)3沉淀而对环境无害。缺点是反应必须在pH≤3条件下进行,且H2O2消耗量大而导致价格昂贵,处理成本较高等。

Boosting multi-hole water oxidation catalysis on hematite photoanodes under low bias

The accumulation of multiple surface holes is considered to be the key to efficient photoelectrochemical(PEC)water oxidation.Previous PEC water oxidation studies commonly apply high potentials(>1.2 VRHE)to achieve this key.But how to complete multi-hole transfer under low bias(<1.2 VRHE)remains unknown.Herein,we find that,on a typical visible-light photoanode,hematite(α-Fe_(2)O_(3)),UV excitation plays a indispensable role in driving multi-hole water oxidation under low bias.Compared with the visible-light excitation,the UV excitation promotes the formation of adjacent surface-trapped holes onα-Fe_(2)O_(3) at 0.9VRHE,thereby increasing the reaction order of surface holes from~1 to~2 and improving the PEC water oxidation activity by one order of magnitude.The UV irradiation reduces the formation probability of self-trapped excitons and results in~3 to 5-fold increase of surface holes.These advantages enable the UV excitation to contribute about 40%to the total photocurrent under 1 solar illumination,even though its energy only occupies 6%of the incident light.This mechanism is also applicable to boost selective two-hole oxidation of thioether at 0.1 VFc/Fc+and nitrite at 0.9 VRHE.

Photo Fenton氧化/絮凝组合处理含弱凝胶油田污水技术研究

以青海油田某井含弱凝胶产出污水为研究对象,选用Photo Fenton氧化/絮凝方法去除污水COD值。利用Photo Fenton试剂对污水进行氧化破乳、破胶、降解、降粘,再利用反应后污水中Fe3+或Fe2+和絮凝剂(无机药剂)、助凝剂(有机药剂)联合对污水进行絮凝处理。研制出了Photo Fenton氧化/絮凝的最佳配方,H2O2的浓度为800mg/L,H2O2与Fe2+的摩尔浓度比为15∶1,适宜的pH值为3,絮凝剂浓度为300mg/L,助凝剂浓度为10mg/L。经该方法处理后的污水COD值为97 mg/L,COD去除率高达92.1%,达到了污水综合排放一级标准(COD<150 mg/L)。