Recognition and effective degradation of 17beta-estradiol by anti-estradiol-antibody-immobilized TiO(2) nanoparticles

Polyelectrolyte polyacrylic acid (PAA), used in the chemical modification of titanium dioxide (TiO(2)) nanoparticles, allows TiO(2) nanoparticles to remain in suspension at neutral pH. The anti-17beta-estradiol (E2) antibody was immobilized on PAA-modified TiO(2) (PAA-TiO(2)) nanoparticles via covalent bonding between the carboxylic acid of PAA and the amino group of the antibody. The anti-E2-antibody-immobilized TiO(2) (E2Ab-PAA-TiO(2)) nanoparticles can form a suspension at neutral pH, with a particle size of less than 100 nm. The E2-PAA-TiO(2) nanoparticles caused the photocatalytic degradation of a typical TiO(2) substrate, methylene blue. The anti-E2 antibody immobilized on the TiO(2) surface recognized and bound E2 in the solution, thereby improving the efficiency of E2 degradation compared with that of PAA-TiO(2) nanoparticles. These results demonstrate that the E2Ab-PAA-TiO(2) nanoparticles developed in this study can be used in water treatment technology. Furthermore, this strategy of immobilizing proteins on nanoscale TiO(2) particles creates new applications not only in the treatment of environmental waste, but also in medical and public sanitation processes.     

Transformation of oxidation products and reduction of estrogenic activity of 17beta-estradiol by a heterogeneous photo-Fenton reaction

A novel photo-Fenton catalyst, alpha-FeOOH loaded resin (alpha-FeOO HR), was synthesized and evaluated through transformation of a steroidal endocrine disrupting compounds (EDC), 17beta-estradiol (E2), under weak UV irradiation in the presence of H2O2. E2 photodegradation intermediates elucidated in detail by GC/MS and LC/MS/MS analyses and detailed reaction pathways are proposed. A yeast-based estrogen screen for E2 and its photodegradation intermediates was performed to measure the reduction of estrogenic activity in different water matrices during the heterogeneous photo-Fenton process. The results showed that alpha-FeOOHR not only degraded E2 but also removed the estrogenic activity originating from E2, its degradation intermediates, and its products. However, the water matrix present in drinking water may impactestrogenic activity reduction. The results are important to evaluate the ability of photo-Fenton advanced oxidation processes in reducing EDCs and their associated estrogenicity from drinking water.     

Production mechanism of hydroxylated PCBs by oxidative degradation of selected PCBs using TiO2 in water and estrogenic activity of their intermediates

The oxidative photodegradation behaviors of selected polychlorinated biphenyls (PCBs) [2,3,3',4'-tetraCB (BZ number: CB56), 2,3',4',5-tetraCB (CB70), and 3,4,4',5-tetraCB (CB81: coplanar PCB)] using titanium dioxide (TiO2) in water were investigated. The main purposes were to clarify the structural relation between the original PCBs and the intermediates derived by TiO2 oxidation and to evaluate the estrogenic activity in the treated PCBs during the oxidative reactions. Approximately 90% of the three tetraCBs decomposed within 120 min. Intermediates by decomposition of three tetraCBs, such as some OH-tetraCBs and OH-triCBs, carboxylic intermediates, phenolic intermediates, and other intermediates produced by the cleavage of a benzene ring were identified and quantified. In the degradation pathways, the produced amounts of OH-tetraCB and OH-triCB increased within 60 min of irradiation time. Estrogenic activities of the intermediates from the three tetraCBs in water were assessed by using a yeast two-hybrid assay system for human estrogen receptor alpha (hERalpha). The maximal estrogenic activities were induced by the solutions of decomposed CB81 with irradiation time at 60 min. We found that the solutions at an irradiation time of 60-120 min contained several 4-OH-tetraCBs and 4-OH-triCBs substituted with OH and Cl at para- and para'-positions. It is presumed that the chemical structures of the 4-OH-PCBs are similar to that of 17beta-estradiol (beta-E2); these intermediates present strong estrogenic activities. Moreover, we learned that there is a high possibility of conversion from some low toxic PCBs congeners to strong estrogenic OH-PCBs.     

Directed synthesis of hierarchical nanostructured TiO2 catalysts and their morphology-dependent photocatalysis for phenol degradation

Nanostructured TiO2 with different hierarchical morphologies were synthesized via a warmly hydrothermal route. The properties of the products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 adsorption, UV-vis spectroscopy, etc. Two of the products, TiO2 1D nanorods (one-dimensional rutile TiO2 nanorods) and TiO2 3D0D microspheres (three-dimensional anatase TiO2 nanoparticle-assembled microspheres) exhibited superior photocatalytic effects on phenol degradation under UV illumination, compared with TiO2 3D1D microspheres (three-dimensional rutile TiO2 nanorods-assembled microspheres). Moreover, TiO2 3D0D was superior to TiO2 1D, as indicated by a 30% higher mineralization of dissolved phenol. Dihydroxybenze, 4,4'-dihydroxybiphenyl, benzoquinone, maleic anhydride, etc. were identified as the degradation intermediates. The excellent catalytic effect was attributed to the structural features of TiO2 1D nanorods and TiO2 3D0D microspheres, that is, a larger amount of surface active sites and a higher band gap energy resulted in more efficient decomposition of organic contaminants.     

Influence of preparation method on morphology and photocatalysis activity of nanostructured TiO2

Supported TiO2 photocatalysts on aerosol silica were prepared by adsorption phase reaction technique (APRT) and impregnation method (IMP) under different water concentrations. Energy dispersive X-ray microanalysis indicated that Ti concentration in samples prepared by both methods increased with the content of water rising. There was a sharp increase in Ti content curve of APRT samples, while Ti concentration of IMP samples changed slowly. The grain size of TiO2 by APRT was below 6 nm and TiO2 particles dispersed uniformly on surface of silica. But the size of TiO2 by IMP was larger than 20 nm and the number of large particles increased rapidly when water concentration increased. The photocatalysis activity of as-prepared catalysts was characterized by methyl-orange photodegradation. The results showed that APRT photocatalysts had higher photocatalysis activity than IMP photocatalysts. Ti concentration and TiO2 crystalline form were two factors which affected photocatalysis activity the most. The grain size of TiO2 had little influence on photocatalysis activity, which might be counteracted by the decrease of anastase TiO2.     

纳米TiO2光催化氧化处理直接耐晒翠蓝染色废液

采用纳米级TiO2悬浮法光催化氧化处理直接耐晒翠蓝染液，讨论pH值、催化剂用量、染料浓度和脱色时间等因素对脱色与降解的影响。试验发现，纳米TiO2对染料的脱色效率高，降解彻底，是一种很有前途的印染废水处理方法。     

Visible-light-Mediated TiO2 photocatalysis of fluoroquinolone antibacterial agents

This study reports on the photocatalytic transformation of fluoroquinolone antibacterial agents (ciprofloxacin, enrofloxacin, norfloxacin, and flumequine) in aqueous titanium dioxide (TiO2) suspensions irradiated with ultraviolet (UV; lambda > 324 nm) or visible light (lambda > 400, > 420, or > 450 nm). Visible-light-mediated fluoroquinolone degradation is unexpected from direct photolysis or established TiO2 band gap photoexcitation mechanisms, which both require UV light. Visible-light-mediated photocatalysis requires an appropriate conduction band electron acceptor (e.g., O2, BrO3-), but is not dependent upon hydroxyl radical, superoxide, or other reactive oxygen species generated upon TiO2 band gap excitation. The process slows considerably when fluoroquinolone adsorption is inhibited. Whereas fluoroquinolone decomposition in UV-irradiated TiO2 suspensions is accompanied by mineralization, no changes in dissolved organic carbon occur during visible-light-photocatalyzed degradation. Results are consistent with a proposed charge-transfer mechanism initiated by photoexcitation of surface-complexed fluoroquinolone molecules. Complexation to the TiO2 surface causes a red shift in the fluoroquinolone absorption spectrum (via ligand-to-metal charge transfer), enabling photoexcitation by visible light. Fluoroquinolone oxidation then occurs by electron transfer into the TiO2 conduction band, which delivers the electron to an adsorbed electron acceptor. The lack of organic carbon mineralization indicates formation of stable organic byproducts that are resistant to further degradation by visible light. In UV-irradiated TiO2 suspensions, the charge-transfer mechanism acts in parallel with the semiconductor band gap photoexcitation mechanism.     

2,4,5-Trichlorophenol degradation using a novel TiO2-coated biofilm carrier: roles of adsorption, photocatalysis, and biodegradation

Intimate coupling of photocatalysis and biodegradation (ICPB) offers potential for degrading biorecalcitrant and toxic organic compounds. This study reports on a novel sponge-type, TiO(2)-coated biofilm carrier that showed significant adherence of TiO(2) and ability to accumulate biomass in its interior. This carrier was tested for ICPB in a continuous-flow photocatalytic circulating-bed biofilm reactor (PCBBR) to mineralize 2,4,5-trichlorophenol (TCP), which is biorecalcitrant. Four mechanisms possibly acting in ICPB were tested separately: TCP adsorption to the carrier, UV photolysis, UV photocatalysis, and biodegradation by biofilm inside the carrier. The carrier exhibited strong TCP adsorption that followed a Freundlich isotherm with an exponent near 2. Whereas UV photolysis was negligible, photocatalysis produced TCP-degradation products that could be mineralized, and the strong adsorption of TCP to the carrier enhanced biodegradation by relieving toxicity. Validating the ICPB concept, biofilm was protected inside the carriers, although biomass originally on the outer surface of the carriers was eliminated. ICPB significantly lowered the diversity of the bacterial community, but five genera known to biodegrade chlorinated phenols (Ralstonia, Bradyrhizobium, Methylobacterium, Cupriavidus, and Pandoraea) were markedly enriched.     

Antifungal activity of TiO2 photocatalysis against Penicillium expansum in vitro and in fruit tests

The antifungal activity of TiO2 photocatalytic reaction in the form of TiO2 powder and TiO2 coated on a plastic film against Penicillium expansum was investigated in vitro and in fruit tests. The mixture of P. expansum conidial suspension and TiO2 powder was added to potato dextrose agar (PDA) plates for vitro test. The TiO2 photocatalytic reaction reduced conidial germination of the fungal pathogen. It was found that the ability of the TiO2 photocatalytic reaction to suppress P. expansum growth correlated to the amount of TiO2 added. Lower numbers of viable colonies of P. expansum were observed with increasing amount of TiO2. Regardless of the kind of selected fruit inoculated with P. expansum, both TiO2 powder and TiO2-coated film exhibited antifungal activity to control fruit rot. Development of Penicillium rot in apple was significantly (P = 0.05) retarded by the TiO2 photocatalytic reaction. Similarly the TiO2 photocatalytic reaction was the only treatment where no tomato fruit rot was noticeable after 1 week of storage. TiO2-coated film also decreased brown lesions and Penicillium rot infection in lemons. The mean severity fruit rot scores (browning and softening flesh) were 3.2 and 1.9 for uncoated and TiO2-coated film, respectively. Our findings suggest that "TiO2 photocatalytic reaction" shows antifungal activity against P. expansum which may have potential for postharvest disease control.     

TiO2溶胶光催化降解亚甲基蓝

以钛酸四正丁酯[Ti(OC4H9)4]为前驱体,乙醇为溶剂,盐酸为催化剂,在20℃制备了有光催化活性的TiO2溶胶.在40 W紫外灯光照条件下,通过对亚甲基蓝的降解试验,研究了溶胶制备条件、溶胶用量、光照时间和亚甲基蓝溶液初始质量浓度与光催化效果的关系.试验结果表明:当Ti(OC4H9)4与H2O量比为1:100,20℃下陈化7 d,制得的TiO2溶胶对0.20g/L亚甲基蓝溶液的降解率达到97.5%,具有较好的光催化性能.     

Ensiling as a means of reducing ochratoxin a concentrations in contaminated barley

The feasibility of ensiling barley contaminated with ochratoxin A (OA) as a practical method of inactivating OA was examined in in-vitro and in-vivo studies. In the in-vitro study, OA concentrations in barley decreased by approximately 68% after being ensiled for 56 days. To verify the destruction of the OA, a chick feeding trial was conducted. Samples of a toxin-and mould-free barley, mould-contaminated barley, a barley sample naturally contaminated with OA or a barley with added OA were each divided into two equal portions, one of which was ensiled for a period of 28 days. The mould-contaminated barley was naturally contaminated with Penicillium cyclopium and Aspergillus flavus. Diets containing either the ensiled or non-ensiled barley samples were then fed to 7-day-old Leghorn chicks for two 7-day periods. Changes in feed consumption (RFC) and body weight gain (RWG) relative to control birds, feed to gain ratio and mortality were monitored. The OA concentration in the two OA-containing barley samples decreased by 58% after 28 days of ensiling, but there was no improvement (P >0.05) in chick performance or mortality compared with the non-ensiled diets. The average RFC values for chicks fed the mould- and OA-containing diets were less than 50% of the controls and RWG generally less than 30%. In absolute terms, chicks fed the ensiled barley diets also performed about 6% poorer (P <0.003) than those given the non-ensiled barley. Ensiling did not appear to be a practical method of reducing teh toxic effect(s) of OA, despite the apparent decrease in OA concentration. Grain sampkles should be tested for the presence of a toxin prior to ensiling to avoid possible toxin analysis problems later.     

Beef hide antimicrobial interventions as a means of reducing bacterial contamination

This project was designed to evaluate interventions capable of reducing bacterial counts on the hide prior to opening. In Trial I, fresh beef hides (n=12) were cut into sections and assigned to serve as either clipped (hair trimmed) or non-clipped sections. Sections were inoculated with a bovine fecal slurry and sampled following a water wash. Treatments (distilled water, isopropyl alcohol, 3% hydrogen peroxide, 2% l-lactic acid, 10% povidone-iodine, and 1% cetylpyridinium chloride (CPC)) were then applied to each section and the sections were sampled for enumeration of aerobic plate counts (APCs), coliforms, and Escherichia coli. Within clipped samples, 1% CPC and 3% hydrogen peroxide caused the greatest reductions in APCs (4.6 and 4.4 log(10)CFU/100-cm(2), respectively), and 1% CPC, 2% l-lactic acid, and 3% hydrogen peroxide caused the greatest reductions in coliform counts (4.5, 4.1, and 3.9 log(10)CFU/100-cm(2), respectively). In Trial II, beef carcasses with hides on were sampled initially and clipped, and then 2% l-lactic acid, 3% hydrogen peroxide, or 1% CPC were applied before sampling. For APCs, 1% CPC produced the greatest reduction on the hide surface (3.8 log(10)CFU/100-cm(2)). Selective application of these antimicrobials to clipped hide opening sites reduced bacterial counts on hide surfaces, and therefore could reduce final carcass counts in these areas by decreasing the bacterial load before opening.     

阳离子染料溶液的光催化氧化降解研究

研究了纳米TiO2降解阳离子染料时的影响因素及处理效果。试验发现，光催化氧化法对染料的降解过程是逐步进行的。光催化剂产生的高活性羟基自由基首先破坏染料分子中活性较高的生色团，然后逐步将其降解为低分子有机化合物。试验条件下，pH值对脱色效果影响最大，酸性和碱性较中性效果好。TiO2用量为1000mg／L时，效果较好。此外，随着染料浓度的增加，脱色率会迅速下降。     

Assessing the antioxidant and pro-oxidant activity of phenolic compounds by means of their copper reducing activity

The antioxidant or pro-oxidant activity of some dietary phenolic compounds has been determined by their reducing activity over Fe³⁺ and Cu²⁺. The FRAP method has shown that phenolic acids exert a high reducing activity that give rise to a decrease in linoleic acid oxidation mediated by Fe³⁺, measured as TBARS. However, the reducing activity of phenolic compounds over Cu²⁺ leads to linoleic acid oxidation. Reducing capability against copper has been measured by a new approach called CRAI (Copper Reducing Activity Index), and results agreed with the degree of hydroxylation of the studied compounds. Sensibility and reproducibility of the method have been checked by measuring the inter-day and intra-day variation (1.08 and 1.89%, respectively). Possible pro-oxidant activity of phenolic compounds should be considered when the overall antioxidant activity in Cu naturally rich or Cu-enriched foodstuffs for dietetic purposes has to be evaluated.     

Visible light Cr(VI) reduction and organic chemical oxidation by TiO2 photocatalysis

Here we report the simultaneous Cr(VI) reduction and 4-chlorophenol (4-CP) oxidation in water under visible light (wavelength > 400 nm) using commercial Degussa P25 TiO2. This remarkable observation was attributed to a synergistic effect among TiO2, Cr(VI), and 4-CP. It is well known that TiO2 alone cannot remove either 4-CP or Cr(VI) efficiently under visible light. Moreover, the interaction between Cr(VI) and 4-CP is minimal if not negligible. However, we found that the combination of TiO2, Cr(VI), and 4-CP together can enable efficient Cr(VI) reduction and 4-CP oxidation under visible light. The specific roles of the three ingredients in the synergistic system were studied parametrically. It was found that optimal concentrations of Cr(VI) and TiO2 exist for the Cr(VI) reduction and 4-CP oxidation. Cr(VI) was compared experimentally with other metals such as Cu(ll), Fe(lll), Mn(IV), Ce(IV), and V(V). Among all these metal ions, only Cr(VI) promotes the photocatalytic oxidation of 4-CP. The amount of 4-CP removed was directly related to the initial concentration of Cr(VI). The system was also tested with four other chemicals (aniline, salicylic acid, formic acid, and diethyl phosphoramidate). We found that the same phenomenon occurred for organics containing acid and/or phenolic groups. Cr(VI) was reduced at the same time as the organic chemicals being oxidized during photoreaction under visible light. The synergistic effect was also found with pure anatase TiO2 and rutile TiO2. This study demonstrates a possible economical way for environmental cleanup under visible light.     

TiO2/蒙脱土复合光催化材料的制备与结构性能

以钛酸丁酯为原料,采用溶胶-凝胶法制备TiO2光催化材料,研究了水、硝酸用量和反应温度对TiO2性能的影响.以蒙脱土为复合基质制备TiO2/MMT复合材料,采用XRD和FT-IR表征了产物的结构,并考察了该材料对亚甲基蓝的降解行为.结果表明:锐钛矿型TiO2已插层柱化到蒙脱土层间,形成分子级别的TiO2支柱,钛的掺入导致原土层间域内离子性质发生变化,从而使TiO2/MMT复合材料的光降解效率远远高于纯TiO2粉体,并形成吸附-光降解协同作用,在降解40 min后对亚甲基蓝溶液的降解率可达到95%.     

Enhanced sonocatalytic degradation of azo dyes by Au/TiO2

Au-loaded TiO2 (Au/TiO2) has been reported for the first time as a sonocatalyst. It was found that the catalyst Au/TiO2, with a low Au loading 0.5 wt % and under common and commercial frequency (40 kHz) ultrasonic irradiation, greatly accelerated both the discoloration and total organic carbon (TOC) removal of azo dyes such as orange II (Org II), ethyl orange (EO), and acid red G (ARG), as compared to bare TiO2 and nano-Au catalyst. About 80% TOC removal was achieved after complete discoloration of 2.5 x 10(-4) M Org II. H2O2 and H2 formation as well as their accumulation was greatly enhanced due to Au loading on TiO2. Both oxidative and reductive degradation intermediates have been detected, and thus the mechanism involves both enhanced oxidation and enhanced reduction via the accelerated formation of active *OH and *H radicals due to Au loading on TiO2, which is supported by electron spin resonance (EPR) and other evidence. The study provides an admirable way to raise the efficiency of sonication and to treat azo dye-containing wastewaters with sonocatalytic processes.     

Photoelectrocatalytic activity of highly ordered TiO2 nanotube arrays electrode for azo dye degradation

A highly ordered titanium dioxide nanotube arrays (HOTDNA) electrode was prepared in hydrofluoric acid solution by electrochemical anodization technique on a pure titanium sheet. The HOTDNA electrode was characterized by FE-SEM microscopy, X-ray diffraction, and UV-vis spectra. The linear-sweep photovoltammetry response on the HOTDNA electrode is presented in this work. The photogenerated current of 0.3 mA/cm2 was observed significantly upon illumination with applied potential of 0.5 V in the UV regions at the central wavelength of 253.7 nm. Photoelectrocatalytic (PEC) and photocatalytic (PC) activities of the HOTDNA electrode were evaluated in the degradation of methyl orange (MeO) in aqueous solution. A set of optimized conditions such as anodic potential, calcinations temperature, and MeO concentration on the PEC activity was investigated. The PEC and PC activities of HOTDNA electrode were compared. We concluded that the HOTDNA electrode was an effective photoelectrode for achieving an enhanced MeO degradation.     

锐钛矿型TiO2的制备与光催化性能研究

以溶胶-凝胶法制备锐钛矿型纳米TiO2光催化荆,采用X射线衍射、透射电镜、热重分析、红外光谱等技术对样品进行表征.以甲基橙的光催化降解为反应模型.分析了焙烧温度、反应体系中催化剂投加量、溶液pH值对光催化性能的影响,并研究了甲基橙的光催化反应动力学.结果表明.采用适宜的制备方法和光催化降解工艺,纯锐钛矿型纳米Ti02能够获得较高的光催化活性.在焙烧温度450～500℃,催化剂加入量为1.0～1.5g/L和反应液pH值为2～4的条件下,紫外光照30 min时甲基橙的降解率达98%,甲基橙的光催化反应动力学符合Langmiur-Hinshelwood模型,反应速率常数k=0.429 mg(L·min).表观吸附平衡常数K=0.0379 L/mg.