Fenton degradation of organic compounds promoted by dyes under visible irradiation

The influence of dyes on the Fenton reaction of organic compounds under visible irradiation (lambda > 450 nm) was examined. It was found that the presence of dyes could accelerate greatly the Fenton reaction of organic compounds such as salicylic acid, sodium benzenesulfonate, benzyltrimethylammonium chloride, and trichloroacetic acid under visible irradiation and that a complete mineralization of those compounds could also be achieved. The dyes such as Alizarin Violet 3B which has an anthraquinone structure unit showed much more significant effect on the reaction than the dyes such as malachite green without the quinone unit. A reaction mechanism of dye AV as a cocatalyst in the photo-Fenton reaction of organic compounds under visible irradiation is proposed based on the cycle of Fe(3+)/Fe(2+) catalyzed by quinone species and an electron transfer from the excited dye molecule to Fe3+.     

多元复合纳米光催化剂的制备及可见光下降解染料废水

以钛酸四丁酯为Ti源,通过溶胶-凝胶法制备TiO2、CdS/TiO2、BiPO4/TiO2、CdS/BiPO4/TiO2(BCT),对制备的材料进行UV-Vis、XRD、SEM、TG-DTG表征,并在可见光下对玫瑰红B模拟染料废水进行光催化,考察pH、煅烧温度、催化剂用量对降解效果的影响,对4种材料的光催化效果进行对比...     

有机酸对泡菜中亚硝酸盐的降解作用

通过高效液相色谱法对泡菜在自然发酵过程中产生的有机酸种类进行分析,对6种不同有机酸体外降解亚硝酸盐的作用进行研究。结果表明:泡菜中含有草酸、酒石酸、乳酸、乙酸、琥珀酸等有机酸。在72h反应周期内,6种有机酸均能降解亚硝酸盐,对亚硝酸盐降解能力顺序为草酸酒石酸柠檬酸苹果酸乳酸丁二酸乙酸;亚硝酸盐降解率随有机酸起始浓度的增加而增大,升高温度也能提高有机酸对亚硝酸盐的降解能力。     

A new route for degradation of volatile organic compounds under visible light: using the bifunctional photocatalyst Pt/TiO2-xNx in H2-O2 atmosphere

The bifunctional photocatalyst Pt/TiO2-xNx has been successfully prepared by wet impregnation. The properties of Pt/ TiO2-xNx have been investigated by diffuse reflectance spectra, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, a photoluminescence technique with terephthalic acid, and electric field induced surface photovoltage spectra. The photocatalytic activity of the sample was evaluated by the decomposition of volatile organic pollutants (VOCs) in a H2-O2 atmosphere under visible light irradiation. The results demonstrated that nitrogen-doped and platinum-modified TiO2 in a H2-O2 atmosphere could enormously increase the quantum efficiency of the photocatalytic system with excellent photocatalytic activity and high catalytic stability. The increased quantum efficiency can be explained by enhanced separation efficiency of photogenerated electron-hole pairs, higher interface electron transfer rate, and an increased number of surface hydroxyl radicals in the photocatalytic process. A mechanism was proposed to elucidate the degradation of VOCs over PtTiO(2-x)Nx in a H2-O2 atmosphere under visible light irradiation.     

Persistent organic pollutants in fish: biomonitoring and cocktail effect with implications for food safety

The impact of anthropogenic wastes of persistent organic pollutants (POPs) on the marine environment has increased in the last decades. POPs include polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCs). To assess the levels of these POPs in the wild fish population, pelagic and benthopelagic predator fish species were selected as biomonitors. For detection and quantification of POPs in muscular tissues, a simple extraction through Accelerated-Solvent-Extraction (ASE) with an ‘in-line’ clean up purification approach was applied, followed by a GC–MS/MS analysis. Concentrations of sum DDT, sum HCH and endrin correlated with all PCB concentrations. Significant differences among fish species were found for all OCs and all PCBs except PCB 31 and 101. Blackspot seabream had the highest PCB concentrations; OCs were highest in tuna. Due to major concerns regarding fish population losses and the possible human chronic exposure to contaminated fish, studies addressing combined effects of multiple POPs (‘cocktail effect’) should be implemented. Our data motivate further experimental and observational studies in fish to define adequate baseline levels for cumulative human exposure and potential role of these contaminants for food safety.     

Photochemical alkylation of inorganic selenium in the presence of low molecular weight organic acids

Using a flow-through photochemical reactor and a low pressure mercury lamp as a UV source, alkyl selenium species are formed from inorganic selenium(IV) in the presence of low molecular weight organic acids (LMW acids). The volatile alkyl Se species were cryogenically trapped and identified by GC-MS and GC-ICP-MS. In the presence of formic, acetic, propionic and malonic acids, inorganic selenium(IV) is converted by UV irradiation to volatile selenium hydride and carbonyl, dimethylselenide and diethylselenide, respectively. Se(IV) was successfully removed from contaminated agricultural drainage waters (California, U.S.A.) using a batch photoreactor system Se. Photochemical alkylation may thus offer a promising means of converting toxic selenium salts, present in contaminated water, to less toxic dimethylselenide. The LMW acids and photochemical alkylation process may also be key to understanding the source of atmospheric selenium and are likely involved in its mobility in the natural anaerobic environment.     

Peer reviewed: tracking the distribution of persistent organic pollutants

Control strategies for these contaminants will require a better understanding of how they move around the globe.     

酵母对无花果酒有机酸的影响

为研究不同商业酵母发酵对无花果酒有机酸的影响,通过5株商业酵母发酵无花果酒,测定无花果酒及汁中有机酸含量,通过主成分分析研究不同酵母与有机酸之间的相关性。结果表明:5株酵母发酵无花果汁后有机酸总量升高,乙酸、丁二酸、柠檬酸、马来酸含量升高,其中菌株D254发酵的酒中乙酸、丁二酸的含量最高分别为3 805.99,2 194.29mg/L,KD发酵的无花果酒中柠檬酸含量最高为1 635.31 mg/L,不同菌株发酵无花果汁后富马酸、草酸含量均下降,菌株KD对草酸含量的保留高于其它菌株,为104.99mg/L;通过主成分分析发现与菌株KD密切相关的有机酸种类最多,分别为苹果酸、柠檬酸、酒石酸、草酸。     

SPME-GC-MS analysis of volatile organic compounds in honey from Basilicata. Evidence for the presence of pollutants from anthropogenic activities

Solid‐phase microextraction gas chromatography‐mass spectrometry analysis of nineteen samples of honey from Basilicata (southern Italy) showed the presence of some flavour components never described before in honey. Furthermore, some phenyl‐substituted hydrocarbons were detected. These compounds may be derived from the wastewater treatment plant in the area. Furthermore, in honey collected near an oil extraction plant, hydrocarbons were found; these may be derived from such plants present in the area.     

果酒中有机酸的作用及检测方法研究

果酒中的有机酸种类和含量对其风味、功效、品质等有显著影响。该文介绍了常见果酒中主要有机酸的种类及其在不同果酒 中的含量,综述了有机酸对果酒口感、风味、稳定性等方面的影响以及果酒中有机酸的常用分析检测方法。为果酒酿造过程中酸度的 变化和控制提供依据,并为进一步提高果酒品质提供参考。     

Transformation of carbon tetrachloride by thiol reductants in the presence of quinone compounds

Quinones are present in trace amounts in natural organic matter. The addition of thiol compounds to quinones produces reactive electron-transfer species that may be important for the transformation of chlorinated hydrocarbons under sulfate-reducing conditions. This study systematically investigated the transformation of carbon tetrachloride (CCl4) in homogeneous aqueous solutions containing quinones as electron-transfer mediators and thiol compounds as bulk reductants. The thiol compounds, including sodium hydrosulfide (NaHS) and cysteine, were found to effectively transform CCl4. The transformation of CCl4 followed pseudo-first-order kinetics, and the pseudo-first-order rate constants (kobs) were (3.24 +/- 0.46) x 10(-7) and 1.04 x 10(-7) s(-1), respectively, when solutions contained NaHS and cysteine alone. Addition of quinone compounds, including anthraquinone-2,6-disulfonate (AQDS), benzoquinone (BQ), juglone (JQ), naphthoquinone (NQ), lawsone (LQ), and menadione (MQ), increased the transformation rate and efficiency of CCl4. The kobs values for CCl4 transformation in the presence of quinones were 2.6-71 times higher than those for the thiol compounds alone. The enhancement efficiency followed the order JQ > NQ > BQ > AQDS > LQ > MQ. Spectroscopic studies indicated that the quinone compounds generated various active electron-transfer mediators to transfer electrons from the bulk reductants to CCl4. BQ and NQ produced mercaptoquinones as active redox mediators that significantly enhanced the transformation rate of CCl4 in the presence of NaHS. The addition of thiol reductants produced large amounts of AQDS semiquinone radical as the electron shuttle. In addition, MQ and LQ were reduced by NaHS to give hydroquinone, which slightly enhanced the transformation efficiency of CCl4. These results clearly indicate that the enhanced efficiency of quinones for the transformation of chlorinated hydrocarbons is specifically related to the produced reactive species. Mercaptoquinone is a more active mediator than either semiquinone or hydroquinone for transferring electrons in a reducing environment containing thiol reductants.     

Fenton oxidation products derived from hydroxycinnamic acids increases phenolic‐based compounds and organic acid formation in sugar processing

The hydroxycinnamic acids (HCAs), caffeic acid (CaA), p‐coumaric acid (pCoA) and ferulic acid (FeA) are the main phenolic acid colour precursors present in sugar cane juice. The Fenton oxidative degradation products of these HCAs and mixture using Fe²⁺/H₂O₂ at pH 4.72 at 25 °C were identified using chromatography and mass spectrometry techniques. Oxalic (≤14 wt%), isobutyric (≤13.5 wt%) and formic acids (≤1.3 wt%) were the main organic acids formed. CaA produced the highest proportion of oxalic and isobutyric acids, while FeA produced the highest proportion of formic acid. The presence of increased proportion of oxalic acid in juice will increase the proportion of calcium oxalate scale in sugar mill heat exchangers. The phenolic‐based products identified include protocatechuic aldehyde and 4‐hydroxybenzoic acid and the basic phenols, p‐allyphenol, p‐vinylguaiacol, trans‐isoeugenol, which when present in juice may react with juice constituents to increase juice colour in subsequent processing.     

织物基CNT/BiVO4光催化材料的制备及其在可见光下对染料的降解

利用钒酸铋(BiVO₄)具有无毒、降解效率高等优点,研究采用酸化碳纳米管(α-CNT)对BiVO₄进行改性,制备α-CNT/BiVO₄复合催化剂,采用泡沫法将α-CNT/BiVO₄复合催化剂处理在棉织物上,对亚甲基蓝(MB)溶液进行降解。结果显示:可见光照射90 min的降解效率高达95.8%,更容易降解有机污染物,同时还能解决催化剂颗粒在废水处理中难以回收利用的问题,对处理印染废水具有广阔的应用前景。     

Enhanced photocatalytic degradation of dye pollutants under visible irradiation on Al(III)-modified TiO2: structure, interaction, and interfacial electron transfer

Aluminum(III)-modified TiO2 was prepared by sol-gel process via a sudden gelating method. The structure of the modified material and the local environment of aluminum were investigated using X-ray diffraction, HRTEM, XPS, 27Al MAS NMR, and xi-potential measurements. The effect of the aluminum modification on interaction between the dye and photocatalyst, the interfacial electron transfer process, and thereby the degradation of dye pollutants under visible irradiation were also examined by FTIR spectra and UV-vis diffuse reflectance spectra. It was found that, rather than incorporating into the crystal lattice of TiO2, the aluminum forms an overlayer of Al2O3 on the surface of TiO2, interfaced with Ti-O-Al bonds. It is interesting that the carboxylate-containing dyes such as Rhodamine B (RhB) adsorb preferentially on the Al2O3, rather than the Ti(IV) sites on the surface of TiO2. The photodegradation rate observed for RhB is nearly 5-fold faster than that obtained in the pristine TiO2 system. The photodegradation of dyes on the aluminum(III)-modified photocatalyst is of great dependence on the structure and anchoring group of the dyes. Structure with carboxylate as anchoring group and amino group as electron donor is favorable for degradation. The mechanistic details are discussed on the basis of experimental results.     

Indigo carmine degradation in the presence of maltose and ethanol

The majority of important reactions in beer are associated with the action of oxygen during malting and brewing. With respect to oxygen, beer is considered to possess a relatively strong reducing environment. The gradual reduction of oxygen gives rise to reactive oxygen species (ROS) capable of attacking beer components that are important to consumers. Indigo carmine (IC) bleaching was used to prove ROS formation formed by oxidation of beer energy sources such as maltose and ethanol. This paper examines oxygen radical oxidation of organic matter in the presence of the radical initiator potassium peroxodisulphate. A mixture of organic sources of energy such as maltose and ethanol, oxygen, radical initiator and cupric ions generates ROS formation in a broad range of concentrations even at room temperature. ROS irreversibly split blue dye IC into the colourless form and takes part in the radical transformation of organic matter, which is similar to its burning at low temperature or to radical oxidation of reducing agents. Other organic matter can suppress ROS formation and be incorporated into the radical chain of the pathway of its ‘cold burning’. Ethanol inhibited phenylalanine oxidation during its oxidative Maillard reaction. IC bleaching can serve as simple indicator of ROS generation in aerated food. Copyright © 2015 The Institute of Brewing & Distilling     

食品中持久性有机污染物现状及对策研究

当前,生态环境持续恶化问题已经引起国际社会的高度重视,从全球范围内看,环境污染问题的加剧,给人类的身体健康带来了极大的威胁,在此背景下,各国政府针对环境污染对人类身体健康所带来的危害与影响问题加大了研究力度,并以专门机构与部门的设置为进一步解决环境问题探寻出路。而持久性有机污染物(POPs)在农药中的运用,使得农产品农药污染问题加剧,并引起了社会的高度重视。本文就食品中持久性有机污染物的现状进行调查与评价,阐述了持久性有机污染的特征,分析了食品中持久性有机污染物的来源与危害,并针对食品中POPs污染现状进行了分析,最后为如何实现对POPs污染物的有效防治提出了对策。     

Fenton反应技术在纺织染料氧化降解中的应用进展

Fenton反应是一种价廉而有效的高级氧化技术,由于其在溶液中产生自由基而能够氧化染料等有机化合物并使之降解为二氧化碳和水,因此被用于印染废水处理研究.文中对近-来Fenton氧化技术在纺织染料特别是活性、酸性和直接染料脱色降解反应中的应用现状进行了较为详尽的评述.     

双壳贝类中的持久性有机污染物生物标志物的研究及其应用

双壳贝类不仅是中国重要的经济水产品种,因其营底栖和滤食的生活习性,常被作为海洋生态系统的指示物种。持久性有机污染物（P0Ps）具有持久性、易蓄积、难降解等特点,对生物造成消极的影响。生物标志物因对污染物响应灵敏,在生物受到严重损害之前即可显示出明显变化,在环境监测领域应用广泛。本文关注了近年来该领域的研究进展,系统介绍了贝类中的POPs生物标志物、主要类型及其相关技术,并对其存在的问题及下一步发展的趋势进行了分析和展望。     

泡豇豆发酵过程中有机酸变化及对亚硝酸盐降解的影响

为了探究泡菜发酵过程中有机酸变化规律,以豇豆为原料自然发酵制作泡菜。采用高效液相色谱法(HPLC)对泡豇豆在发酵过程中蔬菜组织和发酵液中的有机酸种类及含量进行分析测定,并对各有机酸降解亚硝酸盐的能力进行比较。结果表明,蔬菜组织和发酵液中含有8种有机酸,分别为草酸、酒石酸、苹果酸、乳酸、乙酸、柠檬酸、富马酸和琥珀酸;各有机酸变化趋势有所不同,发酵7 d后,蔬菜组织中柠檬酸含量最高,为641. 59 mg/(100 g),发酵液中苹果酸含量最高,为195. 39 mg/(100 g);各有机酸降解亚硝酸盐能力大小顺序依次为草酸、酒石酸、苹果酸、柠檬酸、琥珀酸、乙酸、乳酸、富马酸。此研究为阐明泡菜中亚硝酸盐降解机理提供了理论基础。     

Altitudinal and seasonal variations of persistent organic pollutants in the Bolivian Andes Mountains

Polyurethane foam disk passive air samplers were deployed over four periods of approximately 3 months along an altitudinal gradient (1820, 2600, 4650, and 5200 masl) on the east side of the Andean mountain range in Bolivia. The purpose of the study was to assess the gas-phase concentration and the altitudinal and seasonal trends of organochlorine pesticides and polychlorinated biphenyls (PCBs). Target compounds that were regularly detected included alpha- and gamma-hexachlorocyclohexane (HCH), endosulfans, and select PCB congeners. Endosulfans and HCH concentrations increased with altitude. Enrichment factors (concentration at the highest altitude divided by concentration at the lowest altitude) ranged from 10 to 20 for HCHs and 3 to 10 for endosulfans. Air parcel back trajectory analysis indicated that, in general, the high-altitude sites were exposed to a larger airshed and hence susceptible to long-range atmospheric transport from more distant regions. Seasonal differences were also observed with SigmaHCH concentrations peaking during periods 2 and 3 (March-September 2005). Airsheds (derived from the analysis of back trajectories) for periods 2 and 3 were less oriented along the Andes range (mountain air) with greater input from coastal regions. Endosulfans peaked during periods 1 and 2 (February-June 2005) and also exhibited the highest air concentrations of the target compounds, reaching approximately 1500 pg/m3 at the two highest elevation sites. PCB air concentrations at all sites were generally typical of global background values (<12 pg/m3) and showed no increase with altitude. This is the first study to measure air concentrations of persistent organic pollutants (POPs) in Bolivia and one of only a few studies to investigate altitudinal gradients of POPs.