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Made available in DSpace on 2022-04-28T19:42:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-14 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Multilayered TiO2/TiO2−x/TiO2 films, deposited by twenty periodical interruptions of O2 flow during reactive sputtering deposition were submitted to photocatalytic tests and characterized. The O2 flow interruptions lasted 10 s, 38 s, 45 s, and 70 s, while the regular flow periods lasted 540 s. The photocatalytic tests were performed using UV irradiation from a mercury lamp and a solution of methylene blue dye. The best photocatalytic response was observed in samples corresponding to 10 s interruptions. The results show that the amount of degraded dye was increased by an average of 1.67 times in the interrupted flow sample as compared to the homogeneous TiO2 film deposited under similar conditions. The results show that this relatively simple deposition procedure can produce significant improvements to the photocatalytic activity of the TiO2-based catalysts. Graphic abstract: [Figure not available: see fulltext.] School of Sciences Graduate Program in Materials Science and Technology - POSMAT Universidade Estadual Paulista – UNESP Physics Department Fundamental Sciences Division – IEF Instituto Tecnológico de Aeronáutica – ITA School of Sciences Graduate Program in Materials Science and Technology - POSMAT Universidade Estadual Paulista – UNESP FAPESP: 2017/18916-2

The photo-induced fluorescence method is often applied to determine non-native fluorescent compounds. It typically uses UV irradiation from a high pressure mercury vapor discharge lamp to create photo-induced fluorescent compounds, which are then quantified by fluorescence spectroscopy. However, these mercury lamps require a high-voltage power supply and may accidentally induce electric shocks and the release of mercury vapors. As an alternative, we have evaluated in this technical note new UV-C germicidal lamps. These lamps exhibit a higher power at 254 nm and allowed us to obtain a far greater amount of photo-induced compounds in a shorter time. For the first time, this new irradiation system has been applied for the determination of pesticides in water and has shown a significant increase in the method sensitivity. These good results allowed us to conclude that the new UV-C lamps are a relevant alternative to high pressure mercury vapor discharge lamps for use with photo induced fluorescent methods.

Hybrid photochemical methods are considered for water disinfection in which treatment with ultraviolet (UV) and ultrasonic (US) radiations are combined (US/UV) and applied consecutively or simultaneously; the use of catalysts is also included. The literature survey shows that inactivation of pathogenic microorganisms in aquatic media by high-frequency US (>100 kHz) has not been studied adequately, whereas only low-frequency (

In this work, the effect of the methods of synthesis on the phase composition and photocatalytic properties of composites formed in the section of (SrO)0.2(Bi2O3)0.8–BiFeO3 is studied on the examples of the decomposition reactions of methylene orange (MO). The studied compositions have the MO degradation degree ranging from 30 to 62% (C0 = 20 mg/L, catalyst loading of 30 mmol/L) under irradiation for 3 h with a fluorescent mercury lamp. The band gap estimated by the Kubelka–Munk function is lower than 2.6 eV for the studied compositions. This indicates the possibility of their application as photocatalysts of the visible range.

A photochemical treatment with UV multi-wavelength irradiation was applied to investigate the degradation of the saponins mixture obtained from alfalfa leaves. The photo-degradation was studied in an aqueous solution at a pH range of 4–7 and temperature range of 20–80 °C. The samples were irradiated for 80 min using a mid-pressure mercury lamp with emission wavelengths between 250 and 740 nm. The dependence of the absorbed radiation on the concentration of alfalfa saponins was evaluated, and a linear dependence was found for the range of concentrations experimented throughout the photo-degradation. The alfalfa saponins mixture absorbed radiation between 470 and 610 nm with a maximum absorption peak at 543 nm. This means that any lamp emitting within this wavelength range could produce some degree of photo-degradation. A reaction mechanism was proposed, matching the experimental pseudo-first-order kinetic model that best fitted the evolution of the saponins mixture concentration. The photo-degradation rate was found to increase with increasing temperature and decreasing pH value, causing a reduction of 80% in the concentration of the alfalfa saponins mixture after 80 min at pH 4 and 80 °C.

A novel series of naphthodiazepines 4a-e, 6 were synthesized through the reaction of 1,8-diaminonaphthalene 1 with either hydrazonoyl chlorides 2a-e, or bis-hydrazonoyl chloride 5, respectively. Moreover, new derivatives of thiazinoperimidine 9, triazoloperimidine 13 , and thiazoloperimidines 14,17 were produced upon the interaction of 1H-perimidine-2-thiol 7 with the reagents; epichlorohydrin, hydrazonoyl chloride 10, bis-hydrazonoyl chloride 5, and α-chloroacetoacetanilide 15, respectively. Additionally, the irradiation of 1,8-diaminonaphthalene 1 was accomplished at λ > 313 nm using a high-pressure mercury lamp in the presence of oxygen. All the products were characterized using spectroscopic and analytical techniques

A new method has been proposed for photochemical reduction of silver cations into nanoparticles (NPs) of varying morphologies in aqueous solutions of sodium citrate. The silver NPs were prepared from silver nitrate by the citrate method in aqueous solutions at room temperature by irradiating with light of a high-pressure mercury lamp DRK 120 and BUV 15 lamp. The conversion of silver cations into the final silver NPs of varying morphologies is determined by the concentration of the initial components of the irradiated mixture, light wavelength, and exposure time.

Addition of :P[triple bond, length as m-dash]C-tBu to the NHC-coordinated trisilacyclopropylidene Si3Mes4NHCiPr2Me2 afforded a heavier analogue of a bicyclo[2.1.0]pentane, a so-called "housane", that rearranges under irradiation with a high-pressure mercury lamp or at 60 °C to an NHC-stabilized cyclopentenyl anion isomer with a three-center four-electron (3c-4e) π-bond.

Diols and primary alcohols were subjected to the action of a system FeCl3–NaNO2/O2 (air) under mercury lamp irradiation to synthesize unsubstituted and 2-methyl-1,3-dioxacyclanes: 1,3-dioxolane, 1,3-dioxepane, 1,3-dioxocane, 2-methyl-1,3-dioxolane, 2-methyl-1,3-dioxepane, 2-methyl-1,3-dioxocane. The probable mechanism of the photocatalytic synthesis of 1,3-dioxacyclanes was described by an example of 2-methyl-1,3-dioxolane.

UV and IR photochemistries of malonaldehyde, the simplest molecule exhibiting an intramolecular proton exchange, have been studied in four cryogenic matrices at 4.3 K, N2, Ne, Ar, and Xe. Samples have been irradiated using a UV and IR OPO type tunable laser, and with a broad band UV mercury lamp. UV and IR spectra have been recorded and compared with theoretical calculations carried out at the SAC–CI/6-31++G(d,p) (UV transitions) and B3LYP/6-311++G(2d,2p) (IR spectra) levels of theory. After deposition, the intramolecularly H-bonded form is found exclusively, while several open forms are formed upon UV irradiation. These open forms show ability to interconvert upon UV irradiation too. Some of them are also able to isomerize upon selective IR irradiations. The whole set of results allowed us to identify seven isomers among the eight postulated. The photodynamics of the electronic relaxation of malonaldehyde have also been investigated. By following the decay or rise of suited specific vibrational bands in ...

Light source is a crucial factor in the application of a photochemical process, which determines the energy efficiency. The performances of acetylacetone (AA) in conversion of aqueous contaminants under irradiation with a low-pressure mercury lamp, a medium-pressure mercury lamp, a xenon lamp, and natural sunlight were investigated and compared with those of H2O2 as reference. In all cases, AA was superior to H2O2 in the degradation of Acid Orange 7. Using combinations of the different light sources with various cut-off and band-pass filters, the spectra responses of the absorbed photons in the UV/AA and UV/H2O2 processes were determined for two colored and two colorless compounds. The photonic efficiency (φ) of the two photochemical processes was found to be target-dependent. A calculation approach for the inner filter effect was developed by taking the obtained φ into account, which provides a more accurate indication of the reaction mechanisms.

CF2ClBr mixed with oxygen was photolyzed using a low pressure mercury lamp, and the kinetics of photolysis was studied. The absorption spectra of the starting material and products of photolysis were recorded in the wavelength range from 200 to 900 nm on an Agilent 8453 spectrophotometer. The concentrations of the main photolysis products at different irradiation times were calculated by the mathematical processing of the absorption spectra. The scheme of CF2ClBr photolysis was suggested, the model calculations according to this scheme were performed, and the results of simulation were compared with experimental data.

An efficient, oxidant and photocatalyst-free approach for the synthesis of polycyclic-fused isoindolinone derivatives is reported via annulation of 3,4-diphenyl-3-pyrrolin-2-ones along with release of the hydrogen gas under an argon atmosphere in EtOH by irradiation with a 500 W mercury lamp at room temperature. The described approach is atom-economic and environmentally friendly and tolerates various electron-donating and electron-withdrawing groups. In addition, selected annulation products, dibenzo[e,g]isoindole-1-ones, were successfully oxidized into dibenzo[e,g]isoindole-1,3(2H)- diones in DMSO in the presence of CH3ONa at room temperature.

2-Propoxy-1-naphthamide possessing a chiral 2-methylpyrrolidine group exists as a mixture of four diastereomers owing to the rotation of the Ar (C O) and C( O) N bonds. The diastereomers existed in the ratio of 32:32:14:22 in CD3OD. When the MeOH solution of the mixture of diastereomers was irradiated with Pyrex filtered UV light (>290 nm) from a high-pressure mercury lamp, the ratio changed to 27:4:43:26. The diastereomeric ratio was reversibly controlled by irradiation and heat. The change was accurately reflected in the intensity of the CD spectra. Furthermore, the reversible axial chirality was transferred to the optical activity of asymmetric reaction products via the photochemical cycloaddition reaction with 9-cyanoanthracene.

Model solutions of polychlorinebiphenyls, containing 12 congeners in ethanol were irradiated by gamma rays at 14–140 kGy absorption doses, as well as by UV-rays for 2–30 minutes using middle pressure mercury lamp (PRK‑4, λ = 253 ÷ 546 nm.), and the kinetics of the radiolytic PCBs degradation processes was investigated. The PCBs identification was conducted using a Gas Chromatography (Agilent Technologies 7820A).

The buildup of–SH groups in methemoglobin by irradiation with emission of spark discharge plasma in air and UV light from a low-pressure mercury lamp (λ = 253.7 nm) has been studied. The concentration of–SH groups increases the during spark discharge treatment, with the methionine amino acid residue in the methemoglobin molecule being reduced by nitrous and peroxynitrous acids; the bonds in the methemoglobin molecule are destroyed within 20 minutes of the spark treatment. By the action of UV radiation, methionine is reduced through chromophores (tryptophan, tyrosine) and methemoglobin is reduced by O2.- radical ions to oxy- and deoxyhemoglobin.

The surface of the hair is the region most exposed to solar radiation and to the environment in general. Many of the well-known damaging effects of sun exposure on hair must start or even be restricted to the most external cuticle layers. As such, this work investigates morphological, ultrastructural and chemical changes in the outermost cuticle layer of dark brown hair, using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The results showed that after 230 h of irradiation with a mercury lamp, small bumps with globular shape (heights lying in the 1-5 nm range) appeared on the cuticle surface and their size increased with increasing irradiation times. In addition, the enlargement of pre-existing holes was also observed (holes increase around 350% in depth) and the height of the steps formed between the edges of two cuticle scales increased around 65%, as a result of 500 h of irradiation. The damages in hair strands were accurately identified by analyzing exactly the same surface region before and after irradiation by AFM images. Finally, the results were discussed in terms of the chemical differences between the non-irradiated and the irradiated hair, for instance, the increased level of cystine oxidation as a consequence of photodegradation.

Herein we modified TiO2 anatase with carbon material using an electrical arc discharge technique in liquid medium to produce a nanoparticle of TiO2/Carbon photocatalyst. The electrical arc discharge was performed using two graphite electrodes submerged in TiO2 suspended in ethanol by passing electrical 20-40 V (10-50 A). X-ray Diffraction (XRD) peak profile analysis shows the successful modification confirmed from the presenting peaks which represent to crystalline TiO2 and carbon element. The fabrication was then followed by the assessment of photocatalytic activity of fabricated nanoparticles in methylebe blue degradation under mercury lamp irradiation. After 60 minutes irradiation, the photocatalytic activity of TiO2/Carbon increased more than three times higher compared to the photocatalytic activity of pristine TiO2.

It is experimentally shown that irradiation of silver-containing glasses by nanosecond laser pulses with a wavelength of 248 nm leads to the formation of unstable point defects (having absorption bands in the UV and visible spectral ranges) in the irradiated region and causes the transition of ions and charged molecular silver clusters to the neutral state, which is accompanied by an increase in the luminescence intensity in the visible spectral range. The influence of pulsed laser irradiation is compared with the effect of exposure to cw UV light of a mercury lamp. Some models are proposed to explain the influence of the laser effect on the optical properties of glasses.

The photochemical behavior of methyl-substituted aromatic γ,δ-epoxy ketones was investigated by irradiation with a 500 W high-pressure mercury lamp in benzene which led to the formation of 4-methyleneisochromanols through δ-hydrogen abstraction–epoxy rearrangement–1,5-biradical cyclization reactions.

Two conifers and two deciduous wood species were irradiated by strong UV emitter mercury lamp at elevated temperatures up to 160 °C. Other series of samples were treated in the same chamber at the same temperatures but without light. Results showed that UV light irradiation produced much greater discolouration at elevated temperatures above 80 °C than at ambient temperature. The combined light irradiation and thermal treatment at 160 °C generated much larger discolouration than the sum of the discolouration data caused by UV light irradiation at 30 °C and by pure thermal treatment at 160 °C. The thermal effect during photodegradation was not only the simple addition of two effects, but the elevated temperature multiplied the effect of photodegradation. The greatest difference was shown by the redness change. The Arrhenius plots of all tree colour coordinates had a breaking point close to 100 °C, showing that above this temperature the chemical changes are more complex than below this value.

In this research, photocatalytic decolorization and its kinetics study of auramine dye at various aqueous buffer and non-buffer media using nano-titanium dioxide in two different sizes of 15 and 70 nm in a photocatalyic reactor under 400 W high pressure mercury lamp irradiation under aerobic condition is described. The effects of some physico-chemical parameters such as photocatalyst dosage, medium pH and irradiation time were investigated in the presence of two different nano-photocatalysts and then the results were compared with each other. Kinetics study of photocatalytic treatment of auramine dye resulted that the dye decolorization approximately follows a pseudo-first order kinetic behavior according to the Langmuir–Hinshelwood model. Ultimately, the observed rate constants, experimental half-times, adsorption constants and decolorization rate constants at surface at buffer and non-buffer media under aerobic conditions were evaluated.

Irradiation of (E)-4-(2-(2-naphthyl)vinyl)pyridine (1a) and (E)-4-(2-(1-naphthyl)vinyl)pyridine (1b) with a 250 W high-pressure mercury lamp in acidic solution afforded synHT dimers in high stereoselectivities. Similar results were obtained by visible light irradiation. On the other hand, when the reactions were carried out under neutral conditions, the stereoselectivities were very low, and the yields were decreased by visible light irradiation. Comparison of the UV-vis spectra between the acidic and the neutral conditions elucidated that the red shift was observed in acidic solutions. These results show that HCl plays essential roles not only in the preorientation of substrates through cation-π interactions, but also in the changes in the absorption properties of substrates that enable visible light reactions.

The present work describes the degradation of natural dye Curcumin in organic-aqueous media upon irradiation by a multi-wavelength source of light like mercury lamp. The presence of anions in the solution leads to degradation of Curcumin and this degradation is especially enhanced in the case of fluoride ion. The degradation of Curcumin is investigated by studying the change in its absorption and fluorescence characteristics in organoaqueous solution upon irradiation. A broad detection range of fluoride ranging from 2.3×10−6−2.22×10−3 M points to the potential of the method of visible light irradiation enabling aqueous based sensing of fluoride using Curcumin.

As one of the most commonly employed UV-filters, 4-methylbenzylidene camphor (4-MBC) has been shown to accumulate in the environment and have endocrine disrupting activity. 4-MBC cannot be degraded completely by common methods in wastewater treatment plants. To prevent the environmental problems caused by 4-MBC from being more serious, finding effective method to degrade 4-MBC is essential. In this research, Fenton reaction and photo-Fenton was employed to degrade the 4-MBC. Orthogonal experimental design was employed to evaluate the influence of factors (Fe2+, H2O2, pH and reaction time) on the degradation of 4-MBC. The degradation rate reached to 66.01% in Fenton process and 96.71% in photo-Fenton process. UV light irradiation was also employed to degrade 4-MBC. After being irradiated by mercury lamp (300W) 90 min, the concentration of the 4-MBC reduced 85.4%, but most of them translated to the isomeride. Compared with the Fenton, photo-Fenton and UV light irradiation processes, we deduces that photo-Fenton can get the better degradation efficiency of 4-MBC, and, Fenton reagents and light irradiation are synergistic.

A 5% albumin aqueous solution has been irradiated with air spark plasma radiation and UV light from a low-pressure mercury lamp, and the concentration of -SH groups has been determined. The unirradiated solution contains on average about 0.2 SH groups per albumin molecule. During the spark discharge treatment of albumin for 15 min, the concentration of -SH groups increases by a factor of ∼2 and then remains unchanged. After UV irradiation, the concentration of -SH groups monotonically increases to become approximately seven times greater for 30 min. The increase in the concentrations of -SH groups is due to the reduction of disulfide bonds. The reducing agents in the case of spark discharge can be degradation products of peroxynitrous acid.

In this work, the degradation of Acid blue 25 (AB25), an anthraquinonic dye and a widely used colorant in many industries, by photoactivated periodate (UV/) process was investigated. Experiments were conducted in batch mode using a low-pressure mercury lamp emitting mainly at 253.7 nm. The effects of the operational conditions such as periodate ions concentration, initial dye concentration, initial pH of the solution, and tert-butanol addition on the degradation of AB25 were examined. The results have shown that the degradation rate was increased in the presence of UV/ compared to UV irradiation alone. The degradation rate increased with the increase in periodate concentration to 1 mM and decreased slightly at higher values (>1 mM). The degradation of AB25 decreased when the dye concentration increased. The extent of degradation was found to be inversely proportional to the initial concentration of dye. AB25 degradation was significantly affected by varying the initial solution pH. The fastest deg...

The paper preliminary studied the photocatalytic efficiency of the filter residue of the acidolysis of high titanium slag (RAHTS) with hydrochloric acid, and explored the photocatalytic efficiency on the acid methyl orange solution under the mercury lamp irradiation. With RAHTS performing as a raw material to react with hydrochloric acid, and then the substance content, nature and catalytic efficiency of the filter residues were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and photocatalytic reaction apparatus. Through the experimental investigation, the photocatalytic degradation efficiency on the methyl orange of the filter residues increased with the acid-sludge ratio, reaction time, reaction temperature, and the concentration of hydrochloric acid. When the temperature was 100°C, the reaction time was 4 h, the concentration of the hydrochloric acid was 6 mol/L, the acid-sludge ratio was 1, the filter residues showed a best photocatalytic degradation efficiency. Under that experimental condition, the degradation rate was as high as 85.1%.

Cr and La-codoped SrTiO3nanoparticles were successfully prepared by a microwave-assisted hydrothermal synthesis. The products were characterized by XRD, TEM, BET specific surface area, and UV-Vis absorption spectra. The photocatalytic activity was determined by deNOxability under irradiation of a 450 W high-pressure mercury lamp. The products could absorb the visible light and showed high photocatalytic ability for the decomposition of NOxgas. All samples showed the photocatalytic activities superior to that of commercial titania (Degussa P25) in both UV and visible light regions.

Photodegradation is the major dissipation pathway for emamectin benzoate (EB) in water. Therefore, the photolysis of EB was studied in distilled water (DW) and methanol under different irradiation conditions such as natural sunlight, UV tube, and artificially stimulated light (mercury lamp 125 W). The results of the study showed that EB degrades rapidly in DW than in methanol as evidenced by a photodegradation efficiency of about 75 % achieved in DW, after 24 h of irradiation with UV light, while in methanol, it was only 59.3 %. The addition of iron to EB solution in DW further enhanced its photodegradation. The rate of photodegradation of EB was recorded to be increased from 5.5 × 10−2 to 1.0 × 10−1 k/h after amendment with iron. The order for the rate of photodegradation of EB was DW + Fe > DW > methanol, with their respective t 1/2 values of 6.5, 12.6, and 18.7 h. Fe amendment was also found to enhance the degradation efficiency of EB even in the absence of any light (dark).

An ultraviolet (UV) process using a low-pressure mercury lamp is affected by ambient humidity. It is due to strong influence of humidity on the production of ozone and other radicals by the UV light. In this paper, a photochemical reaction model under the irradiation of a low-pressure mercury lamp is developed, and the effect of humidity on the production of ozone and other radicals [O, O ( D 1 ) , O2(a1Δg), O 2 ( b 1 Σ g + ) , OH, HO2, H, and H2O2] by a low-pressure mercury lamp is discussed using the reaction model. The validity of the reaction model is confirmed by comparing the ozone densities calculated using the model with experimentally measured ozone densities, and they showed good agreement. The reaction model shows that the ozone density decreases with increasing humidity for three reasons: (i) attenuation of 185 nm light due to absorption by H2O, leading to a decreased O atom production by O2 + hν(185 nm) ⟶ O + O which is required to produce ozone by O + O2 + M ⟶ O3 + M; (ii) ozone destruction by O 3 + h ν ( 254 nm ) ⟶ O ( D 1 ) + O 2 ( a 1 Δ g ) , where the resulting O ( D 1 ) partly reacts with H2O before converting back to O3 after quenching to O; and (iii) an ozone destruction cycle OH + O3 ⟶ HO2 + O2 and HO2 + O3 ⟶ OH + 2O2. The effect of humidity on the densities of other radicals is also discussed using the reaction model.

This work studied the effect of multi-wavelength UV processing on the ascorbic acid content of aqueous solutions, at different pH values (3, 4, and 5). The source of radiation was a mid-pressure mercury lamp (460 W), emitting between 250 and 740 nm. The samples were treated for 60 min, at 25 °C and 45 °C, with the lamp on and with the lamp off. A radiation balance was performed to estimate the total radiation power absorbed by the whole solution. Ascorbic acid content was reduced, either in irradiated or non-irradiated solutions, due to aerobic oxidation. But, in most cases, irradiation did not accelerate degradation. This can be explained by the fact that ascorbic acid barley absorbs ultraviolet in the interval of wavelengths emitted by the lamp (only 31% of the incident radiation P(0) could be absorbed by the solutions). Therefore, mid-pressure mercury lamps are helpful to avoid Vitamin C photo-degradation.

Spruce samples (Picea abies Karst.) were irradiated by a strong ultraviolet (UV) light emitter mercury lamp, and another series of specimens were treated with the combination of UV radiation and water leaching. The total duration of UV radiation for both series of specimens was 10 days. One treatment cycle consisted of 24 h of UV irradiation, followed by 6 h of water leaching. This cycle was repeated 10 times. The chemical changes were determined by IR spectroscopy, and the difference spectrum method was used for evaluation. The IR measurement was carried out after each UV radiation as well as after water leaching, to determine the effect of UV radiation and water leaching separately. The lignin degradation was more significant for the leached samples than for the pure UV treated samples. The chemical components most sensitive to leaching were the unconjugated carbonyl groups generated by the photodegradation. As a consequence of photodegradation, two absorption bands of unconjugated carbonyl groups emerged at 1714 and 1750 cm−1 wavenumbers. The band at 1750 cm−1 was much more sensitive to leaching by water than the band at 1714 cm−1. This band almost disappeared after eight cycles. The water was able to leach out carbonyl groups (absorbing at 1741 cm−1) that had been present in the wood originally as well.

Bisphenol A (BPA) is a typical environmental endocrine disrupting chemicals. Photodegradation of BPA was catalyzed by magnetic nano-Fe3O4 under irradiation of medium pressure mercury lamp (500W, λ ≥ 290nm). Effects of pH value, initial concentration of BPA and magnetic Fe3O4 dosage were discussed respectively. The research results show that the photodegradation of BPA can be enhanced by Fe3O4. The removal rate decreased with the increase of initial concentration of BPA, and the reaction was in accordance with the first-order reaction kinetics. The removal rate is over 98% under acidic (pH ≤ 3) and alkaline (pH ≥ 9) conditions. The removal rate of BPA increased with the increase of magnetic nano-Fe3O4 dosage at the beginning of the reaction, and when the removal rate of BPA was more than 95% after 60min irradiation, the effects of dosage were small.

Photolysis of oxyfluorfen, an herbicide of the nitrodiphenyl ether class, was studied in aqueous methanol under UV and sunlight. UV irradiation was carried out in a borosilicate glass photoreactor (containing 250 ppm oxyfluorfen in 50% aqueous methanol) equipped with a quartz filter and 125 watt mercury lamp (maximum output 254 nm) at 25 ± 1°C. Sunlight irradiation was conducted at 28 ± 1°C in borosilicate Erlenmeyer flasks containing 250 ppm oxyfluorfen in 50% aqueous methanol. The samples from both the irradiated conditions were withdrawn at a definite time interval and extracted to measure oxyfluorfen content by gas chromatography-flame ionization detector for rate study. The half-life values were 20 hours and 2.7 days under UV and sunlight exposure, respectively. Photolysis of oxyfluorfen yielded 13 photoproducts of which three were characterized by infrared spectrophotometer and (1)H NMR and (13)C NMR spectroscopy. The rest of the photoproducts were identified by gas chromatography-mass spectrometry (GC-MS) and thin layer chromatography (TLC). An ionization potential 70 eV was used for electron impact-mass spectrometry (EI-MS) and methane was used as reagent gas for chemical ionization-mass spectrometry (CI-MS). Two of the photoproducts were also synthesized for comparison. The main phototransformation pathways of oxyfluorfen involved nitro reduction, dechlorination, and hydrolysis as well as nucleophiles displacement reaction.

The kinetics of Tartrazine decay through photo-Fenton process, which has not reported in literature, was explored. Tartrazine is a synthetic azo dye used in food colorants industry, cosmetic and textile industry. There are very few studies in the literature concerning Tartrazine degradation but they did not lead to a total mineralization. Fotooxidative degradation of Tartrazine (E102) by UV/Fe2+/H2O2 was investigated using a laboratory scale photoreactor equipped with a low pressure mercury lamp. The degradation kinetics under irradiation (200–280 nm) was optimized in respect to H2O2 concentration (6 × 10−4 M) and Fe2+ concentration (8.28 × 10−5 M) at a constant Tartrazine concentration (1.035 × 10−5 M) at pH 3. The degradation rate was influenced by the temperature with an optimum value of 323 K and thermodynamic parameters were calculated. Application of photo-Fenton system also assures total organic carbon removal with 80% efficiency after 2 h irradiation.

Bromate is a potential carcinogen that forms during the treatment of bromide-containing water using ozone-based technologies. A study of humic acid (HA) removal and bromate formation in UV/O3 and ozone processes was conducted relative to a variety of operational conditions, such as ozone dosage, pH and initial concentrations of HA and Br−. Additionally, UV irradiation with the addition of ozone, which was generated by the same low-pressure mercury lamp (emitting 254 nm and 185 nm), was studied. Bromate concentrations during the UV/O3 process were 17.1–77.6 μg/L, which was 2.1–2.9 times the concentration for the O3 process, when ozone at concentrations ranging from 1.5 to 6.3 mg/L was continuously applied to water to which no HA was added. UV radiation reduced the concentration of the residual ozone, which was important for the formation of bromate. HA inhibited bromate formation, which was especially dramatic in UV/O3 process, and increasing the initial concentration of Br− accelerated the bromate formation in both processes; however, enhancement of bromate formation after increasing the pH was only observed for O3 process. Reducing the ozone dosage in UV/O3 process lessened both residual ozone concentration and hydroxyl radical ( OH) exposure; changing this parameter led to a slight drop in the rate of HA removal but also caused a significant decrease in the bromate formation. Therefore, the combination of UV irradiation and low doses of ozone represented a promising method for the simultaneous control of bromate formation and HA removal. Because the UV lamp can also generate a low concentration of ozone, combining UV irradiation with the internally generated ozone is recommended.

In order to improve the cooling effect of cable ultraviolet cross-linking irradiation box, the structure of spreader plate, reflector and outlet were improved. Then the 3D solid model of the irradiation box was established and the numerical simulation of turbulent flow field was performed due to the principle of Computational Fluid Dynamics (CFD). On this basis, the flow fields characteristics inside the irradiation box of original and improve programs were analyzed. The results showed that volume air flow of the new program increased by 36.6% and air velocity around the mercury lamp and XLPE cable surface was increased, so the better cooling effect can be achieved in the new program.

Ultraviolet light emitting diodes(UV-LEDs)presenting the advantages of high efficiency,small size,energy saving and without mercury,are gradually replacing mercury lamps in disinfection systems.This study focused 280nm wavelength of UV-LEDs,the Escherichia coli was served as objective in wastewater,the inactivation efficiency and photoreactivation percentage were examined compared with traditional mercury lamps.A series of UV-LEDs dose caused different inactivationefficiency and photoreactivation percentage of E.coli.When UV dose was 1.8 mJ/cm2, inactivation efficiency reached 2.7-lg,then under a 40w sunlight lamp irradiation,the photoreactivation percentage was up to 2.7%;at 3.6 mJ/cm2, inactivation efficiency reached 3-lg,photoreactivation percentage was up to 0.98%.In advanced wastewater treatment,a threshold dose 3.6 mJ/cm2 is suggested of 280nm UV-LEDS.UV dose higher than 3.6 mJ/cm2 can achieve the depth of sterilization effect,that reaches the effect of mercury lamp 40mJ/cm2.The results indicate great advantages of UV-LEDs compared with mercury lamps.

A novel sol-gel method was implied to prepare CuO-doped ZnO nanoparticles. XRD and SEM techniques were used to characterize the CuO-doped ZnO sample. The photocatalytic degradation of Lidocaine HCl was investigated by two methods. The degradation was studied under different conditions such as the amount of photocatalyst, pH of the system, initial concentration, presence of electron acceptor, and presence of anions. The results showed that they strongly affected the photocatalytic degradation of Lidocaine HCl. The photodegradation efficiency of drug increased with the increase of the irradiation time. After 6 h irradiation with 400-W mercury lamp, about 93% removal of Lidocaine HCl was achieved. The degree of photodegradation obtained by Taguchi method compatible with the trial-and-error method showed reliable results.

Polymethyl substituted [2.2]metaparacyclophanes were synthesized via the corresponding 2,11-dithia [3.3]metaparacyclophanes. Photooxygenation reaction of 4,5,6,12,13,15,16-heptamethyl[2.2]metaparacyclophane using a high pressure mercury lamp led to the mono-endoperoxidation of only the para benzene ring; this was attributed to the much larger degree of deformation of the para-benzene ring than of the meta-benzene ring. On the other hand, whilst irradiation of the photoreaction of 4,5,6,8,12,13,15,16-octamethyl[2.2]metaparacyclophane under the same reaction conditions produced only the bis-endoperoxide (on both the meta- and para-benzene rings).

Morphological changes in hair surface are undesirable, since they cause shine loss, roughness increase and split ends. These effects occur more frequently in the cuticle, which is the outermost layer of the hair strand, and thus the most exposed to the environmental damages. Sunlight irradiation contributes significantly to these morphological alterations, which motivates the investigation of this effect on hair degradation. In this work, the influence of irradiation and hand-washing steps on the morphology of pigmented and non-pigmented hair cuticle was investigated using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). To simulate daily conditions, where hair is hand-washed and light exposed, samples of dark brown and gray hair underwent three different conditions: 1) irradiation with a mercury lamp for up to 600h; 2) irradiation with the mercury lamp combined with washes with a sodium lauryl sulphate solution; and 3) only washing. A new preparation procedure was applied for TEM samples to minimize natural variations among different hair strands: a single hair strand was cut into two neighbouring halves and only one of them underwent irradiation and washing. The non-exposed half was used as a control, so that the real effects caused by the controlled irradiation and washing procedures could be highlighted in samples that had very similar morphologies initially. More than 25images/sample were analysed using FESEM (total of 300 images) and ca. 150images/sample were obtained with TEM (total of 900 images). The results presented herein show that the endocuticle and the cell membrane complex (CMC) are the cuticle structures more degraded by irradiation. Photodegradation alone results in fracturing, cavities (O≈20-200nm) and cuticle cell lifting, while the washing steps were able to remove cuticle cells (≈1-2 cells removed after 60 washes). Finally, the combined action of irradiation and washing caused the most severe damages, resulting in a more pronounced cuticle extraction (≈1-4 cuticle cells after a 600h irradiation and a 60 times washing). This irradiation dose corresponds to ca. 2months of sunlight exposure (considering 5h/day) in Campinas-SP, Brazil, during the day period of maximum irradiation intensity. The combined action of irradiation and washing can be explained by the creation of fragile photodegraded spots in the endocuticle and in the CMC, where the mechanical stress associated to the washing steps are more prone to induce rupture.

The photochemical behavior of methyl-substituted aromatic γ,δ-epoxy ketones was investigated by irradiation with a 500 W high-pressure mercury lamp in benzene which led to the formation of 4-methyleneisochromanols through δ-hydrogen abstraction–epoxy rearrangement–1,5-biradical cyclization reactions.

When O-(4-acyloxyanilinocarbonylmethyl)-4-tert-butylcalix[8]arene films were irradiated for 60 min with 254-nm UV light from a low-pressure mercury lamp, the calixarene derivative 1 underwent a highly selective photo-Fries rearrangement in the film state to yield the corresponding Fries-rearranged product 2 along with a minor amount of the fragmentation product 3. This photochemical rearrangement enhanced the refractive index of the films by as much as 0.015.

The modifications of properties of some semi-interpenetrating polymer networks based on aromatic polyurethane and a crosslinked epoxy resin, during UV irradiation with a mercury lamp ( λ > 300 nm), were investigated. Variation of some properties, such as colour, gloss, contact angle, mass variations and water retention were monitored according to the irradiation time. Photochemical reactions that occurred during irradiation were monitored by FT-IR. The results demonstrated that polyurethane-epoxy resin semi-interpenetrating polymer structures showed a higher photo-stability than the polyurethane sample.

Non-crystalline, transparent methylsilsesquioxane–titania hybrid films for application in micropatterning were prepared from methyltriethoxysilane and titanium tetrabutoxide by the sol–gel method. The hybrid films were heat-treated at 100 8C for 1 h and then irradiated with UV light using an ultrahighpressure mercury lamp. The refractive index of the film increased as the amount of incorporated TiO2 increased. No changes in hardness were observed for the films lacking TiO2 during UV irradiation, whereas adding a small amount of TiO2 caused the hardness to increase significantly following UV irradiation. These changes in the physical properties of the films with UV irradiation were caused by the cleavage of Si–C bonds in the films induced by the photocatalytic effect of TiO2. On the basis of the changes in surface profiles, and optical, chemical, and mechanical properties induced by UV irradiation, it is concluded that the methylsilsesquioxane–titania films are promising for micropatterning by photolithography.

Using magnetic nanoparticles as cores we successfully fabricated magnetic TiO2 composite by sol-gel method, which was simple and effective. The morphologies and structure of the products were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The photocatalytic activity of magnetic TiO2 composite was investigated by decomposing reactive orange under the mercury lamp irradiation. In the presence of magnetic TiO2 composite the degradation rate of reactive orange was studied and the effects of various experimental factors on the photocatalytic performance were investigated. Compared with that of TiO2 sample, magnetic TiO2 composite expressed the higher photocatalytic activity.

In order to study the influence of UV irradiation, treat temperature of nano-titanium dioxide and intensity of UV irradiation on the mercury removal performance, experiments were carried out on a photocatalytic oxidization system to find the best experimental conditions. Commercial Degussa P25 was used as a photocatalyst loading on titanium mesh, and the mercury removal efficiency was stable at 8% in the absence of UV irradiation. Under the UV irradiation of 300W mercury lamp, the mercury removal efficiency surged to 100%. With the same light intensity, the same removal time, the mercury removal efficiency of nano-titanium dioxide calcinated at 100°C reached 92.2% after 0.5h while the mercury removal efficiency of nano-titanium dioxide calcinated at 500°C reached 93.6%. Intensity of UV irradiation has a positive impact on the mercury removal performance.

The photochemistry of para-chlorophenol (4-CP) was studied under simulated sunlight (λ > 300 nm) and UV irradiation by using a 125 W high-pressure mercury lamp with or without a hard glass as light source in an ice matrix. The experiments were carried out in a photochemical cold chamber reactor at −14 to −12 °C. The photoconversion rate, photoproducts and photoconversion mechanism of 4-CP were all inspected and compared. The results show that the 4-CP photoconversion obeys the first order kinetic model and its photoconversion rate is highly affected by the initial concentration of 4-CP, light intensity and water quality. It is found that the conversion rate of 4-CP under UV irradiation is higher than that under simulated sunlight irradiation. The intermediate products of 4-CP were characterized by GC-MS, HPLC-ESI-MS and HPLC techniques and the possible photoconversion mechanism was proposed accordingly. It is concluded that the mechanism and photoproducts of 4-CP photolysis in ice are different from those in water, and the photoproducts and photoconversion pathways of 4-CP in ice varied with different light sources.

A research study has been performed to determine the ultraviolet (UV) fluence-response of several target non-pathogenic microorganisms to UV light emitting diodes (UV-LEDs) by performing collimated beam tests. UV-LEDs do not contain toxic mercury, offer design flexibility due to their small size, and have a longer operational life than mercury lamps. Comsol Multiphysics was utilized to create an optimal UV-LED collimated beam design based on number and spacing of UV-LEDs and distance of the sample from the light source while minimizing the overall cost. The optimized UV-LED collimated beam apparatus and a low-pressure mercury lamp collimated beam apparatus were used to determine the UV fluence-response of three surrogate microorganisms (Escherichia coli, MS-2, T7) to 255 nm UV-LEDs, 275 nm UV-LEDs, and 254 nm low-pressure mercury lamps. Irradiation by low-pressure mercury lamps produced greater E. coli and MS-2 inactivation than 255 nm and 275 nm UV-LEDs and similar T7 inactivation to irradiation by 275 nm UV-LEDs. The 275 nm UV-LEDs produced more efficient T7 and E. coli inactivation than 255 nm UV-LEDs while both 255 nm and 275 nm UV-LEDs produced comparable microbial inactivation for MS-2. Differences may have been caused by a departure from the time-dose reciprocity law due to microbial repair mechanisms.