Mercury Lamp Irradiation Research Articles

Photochemical degradation of triadimefon in seawater

The photochemical degradation of triadimefon in seawater was investigated under different reaction conditions in this study. The results showed that triadimefon could be effectively degraded by the irradiation of a high-pressure mercury lamp and the photodegradation rates were influenced by aquatic media, heavy metal ions and photosensitizers. The photochemical degradation of triadimefon followed the first-order reaction kinetic behavior, with the rate constants ranging from 0.0027 to 0.0128 min−1 under the studied conditions. The photolysis of triadimefon was slower in natural seawater than in distilled water or synthetic seawater. All the heavy metal ions studied in this paper had inhibition effects on the photolysis of triadimefon. Acetone, as a common photosensitizer, could accelerate the photolysis of triadimefon. Three photoproducts were identified by GC-MS analysis. Our study confirmed that photochemical degradation is an effective pathway to remove triadimefon in seawater.

Synthesis of a new photoreactive gelatin with BTDA and HEMA derivatives

AbstractA novel bio‐affinitive, photocuring, and membrane‐forming gelatin derivative was synthesized in this study. This process was based on the amide formation between carboxylic acid and the amine in methanol–water media using dicyclohexyl‐carbodiimide (DCC) as a condenser. Gelatin and glycine were the sources of amine in the model reaction. Since there were two anhydride groups in each 3,3′,4,4′‐benzophenone tetra‐carboxylic dianhydride (BTDA) molecule, two 2‐hydroxyethyl methacrylate (HEMA) molecules were used to induce the ring‐opening reaction of BTDA and release two carboxylic acid groups. The resulting photoreactive gelatin was called GE‐BTHE, of which the photoreactive component was the ketone groups of BTDA and HEMA that played the role of double bond supplier. This photoreactive gelatin could be converted from the transparent liquid phase into swollen membrane by a 6‐min irradiation of high pressure mercury lamp. The most efficient irradiation was at 267 nm and the highest degree of swelling of the cured GE‐BTHE membrane could reach 5.9. The elongation from the dried gel remained 5–10%, i.e., relatively elastic. The properties of this gelatin derivative were investigated using amide formation analysis, calculation of the gel content and the swelling ratio, and monitoring of the photocuring process. The GE‐BTHE synthesized in this study should be very potential in applications such as protective wound dressings and hemostatic absorbents for minimally invasive surgery. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Photolysis of mono-through deca-chlorinated biphenyls by ultraviolet irradiation in n-hexane and quantitative structure-property relationship analysis

The photolysis of 16 polychlorinated biphenyls (PCBs) (including mono- through deca-chlorinated) in n-hexane was investigated under ultraviolet irradiation using a 500-W high-pressure mercury lamp. Photolysis of PCBs follows pseudo-first-order reaction kinetics, with photolysis rate constants ranging between 0.0011 s(-1) for PCB-52 and 0.0574 s(-1) for PCB-118. The degradation rates of PCBs by high-pressure mercury lamp irradiation were remarkably independent with respect to the degree of chlorination. Furthermore, partial least squares (PLS) models were developed to provide insight into which aspect of the molecular structure influenced PCB photolysis rate constants. It was found that the photolysis rates of PCBs increased with an increase in the net charge on the carbon atom (qc), (E(LUMO)-E(HOMO))2, and the Y-axis dipole moment (mu(y)) values, or the decrease in the energy of the second highest occupied molecular orbital (E(HOMO-1)), energy of the lowest unoccupied molecular orbital (E(LUMO)), E(LUMO) + E(HOMO), E(LUMO)--E(HOMO), most positive atomic charge (q+), and the twist angle of the chlorine atom (TA) values.

Influence of operating parameters on photocatalytic degradation of phenol in UV/TiO2 process

Abstract The use of hydrogen peroxide (H 2 O 2 ) for improved photocatalytic degradation of phenol in aqueous suspension of commercial TiO 2 powders (Degussa P-25) was investigated. Photodegradation was compared using direct photolysis (UV alone), H 2 O 2 /UV, TiO 2 /UV, and H 2 O 2 /TiO 2 /UV processes in a batch reactor with high-pressure mercury lamp irradiation. The effects of operating parameters such as catalyst dosage, light intensity, pH of the solution, the initial phenol, and H 2 O 2 concentrations on photodegradation process were examined. It was shown that photodegradation using H 2 O 2 /TiO 2 /UV process was much more effective than using either H 2 O 2 /UV or TiO 2 /UV process. The effect of the initial phenol concentration on TOC removal was also studied, demonstrating that more than 8 h was required to completely mineralize phenol into water and carbon dioxide. For all the four oxidation processes studied, photodegradation followed the first-order kinetics. The apparent rate constants with 400-W UV ranged from 5.0 × 10 −4 min −1 by direct photolysis to 1.4 × 10 −2 min −1 using H 2 O 2 /TiO 2 /UV process. The role of H 2 O 2 on such enhanced photodegradation of phenol in aqueous solution was finally discussed.

Fabrication of Boron-Doped TiO2 Nanotube Array Electrode and Investigation of Its Photoelectrochemical Capability

Boron-doped TiO2 nanotube arrays were produced by forming a nanotube-like TiO2 film in an anodization process on a Ti sheet, followed by chemical vapor deposition treatment using trimethyl borate as the boron source with N2 as the carrier gas, and were characterized by ESEM, XPS, XRD, and UV−vis methods. The highly ordered vertically oriented nanotube arrays were obtained, and the nanotubes were open at the top end with an average diameter of approximately 80 nm. Analysis by XPS indicated that the introduced boron was probably incorporated into TiO2 and that the chemical environmental surrounding boron might be Ti−B−O. The boron-doped sample with a mixture of anatase and rutile was identified by X-ray diffraction. A shift of the absorption edge to a lower energy in the spectrum of the UV−vis absorption was observed. Under both UV and 400−620 nm visible light irradiation, the B-doped TiO2 nanotube array electrode exhibited a higher photoconversion efficiency than the non-doped one, a notable photoconversion efficiency of 31.5% was achieved under high-pressure mercury lamp irradiation, and a photoconversion efficiency of 15.1% on the B-doped electrode was obtained under λ > 290 nm light irradiation. The photoelectrocatalytic activity of the prepared electrode was evaluated using pentachlorophenol as a test substance under UV and visible light irradiation.

Regio‐ and Stereoselective Head‐to‐Head Photo[2 + 2]cycloaddition of 3‐(1‐Methyl‐2‐phenylsulfanyl‐1H‐imidazol‐5‐yl)propenoates.

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Photo-Catalytic Activity of Fe<sup>3+</sup>/Sn<sup>4+</sup> Co-Doped Titanium Dioxide Nano-Crystalline Thin Films for Methyl Orange Degradation

The uniform and transparent nano-crystalline thin films of pure and co-doped with Fe3+/Sn4+ titanium dioxide photo-catalysts were prepared via sol-gel dip-coating process, and were loaded firmly on the surface of glass substrates. The structure and surface morphology of films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). In particular, the photo-catalytic activity of films was measured by ultraviolet-visible (UV-VIS) spectrophotometer. Methyl orange was used as a model compound to study the photo-catalytic activity of films. The effects of the concentrations of doping ions and the number of layers on photo-catalytic degradation of methyl orange solutions were investigated. Experimental results showed clearly that the co-doping of iron and tin ions exhibited a synergistic effect, which increased significantly the photo-catalytic activity of titanium dioxide. Especially, the photo-catalytic activity of nano-crystalline titanium dioxide thin films co-doped with 0.1 mol%Fe3+ and 11.41mol%Sn4+ was 2.0 times higher than that of those un-doped for photo-degradation of methyl orange solutions under the 125W self-ballasted fluorescent high-pressure mercury lamp irradiation.

Investigation of the photocatalytic degradation of organochlorine pesticides on a nano-TiO 2 coated film

The photocatalytic degradation of organochlorine pesticides including α-, β-, γ-, δ-hexachlorobenzene (BHC), dicofol and cypermethrin were carried out on a nano-TiO 2 coated films under UV irradiation in the air. The photocatalytic conditions, including the amount of TiO 2, irradiation time and the intensity of light were optimized. The pesticides were most effectively degraded under the condition of 2.24 mg/cm 2 on TiO 2 film and a 400 W UV irradiation of high-pressure mercury lamp with a wavelength of 365 nm. A typical organochlorine pesticide, 20 μg α-BHC, was dipped onto the TiO 2 film surface and degraded completely within 20 min. In addition, the photocatalytic degradation pathways on the nano-TiO 2 coated film were discussed.

Regio- and Stereoselective Head-to-Head Photo[2+2]cycloaddition of 3-(1-Methyl-2-phenylsulfanyl-1H-imidazol-5-yl)propenoates

Head-to-head photo[2+2]cycloaddition of 1, ω -di[3-(1-methyl-2-phenylsulfanyl-1H-imidazol-5-yl)propenoyloxy]alkylenes smoothly proceeded under irradiation of a high-pressure mercury lamp to give cyclobutane compounds regio- and stereoselectively. The stereochemistry of these cyclobutanes was determined as β-form.

Photocatalysis effect of nanometer TiO 2 and TiO 2-coated ceramic plate on Hepatitis B virus

The photocatalysis effect of nanometer TiO 2 particles and TiO 2-coated ceramic plate on Hepatitis B virus surface antigen (HBsAg) was investigated. The ELISA (enzyme-linked immunosorbent assay) standard method was used to assess the efficiency of TiO 2 material to destroy the HBsAg. The research has shown that the suspension of TiO 2 (0.5 g/L) can destroy most of the HBsAg under the irradiation of mercury lamp, with the light intensity of 0.6 mW/cm 2 at 365 nm wavelength, or under the sunlight irradiation for a few hours. TiO 2-coated ceramic plates can also destroy the HBsAg under the irradiation of mercury lamp, with the light intensity of 0.05 mW/cm 2 at 365 nm wavelength or under the room daylight for a few hours.

Fluorescence and bioluminescence analysis of sequential UV‐biological degradation of p‐cresol in water

The photolysis and Penicillium tardum H-2 degradation of p-cresol in water containing humic acids was investigated by fluorescence and bioluminescence methods. Humic acids extracted from peat (the Vasuygan bog, Tomsk region of Russia) induce the phototransformation of p-cresol. The influence of humic acids on the phototransformation of p-cresol under different irradiation conditions was investigated. Comparison of the data on the KrCl* (lambda = 222 nm) and XeCl* (lambda = 308 nm) excilamps light showed that the most effective p-cresol degradation was observed with mercury lamp irradiation in the presence of humic acids.

The preparation of porous nano-TiO 2 with high activity and the discussion of the cooperation photocatalysis mechanism

The material of porous nano-TiO 2 was prepared with a new preparation method. The relations between the crystalloid and the size of TiO 2 nanograin and the technics conditions were studied. The control of TiO 2 nanograin was discussed initially. It has very high photocatalytic activity. The degradation rate of the methyl orange solutions (50 mg L −1) which were decomposed by nano-TiO 2 in the irradiation of the ultraviolet high-voltage mercury lamp whose main wavelength is 365 nm only in 17 min was above 99.6%. After stopping irradiation, there is a degradation dark-reaction whose reaction rate is rapid at first and then slow down. The standpoint that in the anatase TiO 2 there are thimbleful rutile TiO 2 which could bring the cooperation photocatalysis degradation and improve its photocatalytic activity was first put forward.

Photolysis Behavior of Herbicide Propisochlor in Water Media and Preliminary Analysis of Photoproducts Under Different Light Sources

Photolysis behavior of a new herbicide propisochlor in water media as well as the effects of light sources, initial concentration of propisochlor, pH value, dissolved oxygen (DO) level, and salinity on the photolysis process was investigated. It was found that the relationship between initial concentration of propisochlor and its photodegradation rate was negatively correlated. The changes in acidity and alkalinity of the reaction medium influenced the photoreaction rate evidently. In the alkaline solution the degradation was accelerated. In the reaction media with different pH values, the photolysis followed the first-order kinetics. The presence of dissolved oxygen may promote the photolysis and there existed an optimum of dissolved oxygen concentrations. Increasing the DO level can weaken the promotion and even have an adverse effect. It was demonstrated that with dissolved oxygen the photodegradation of propisochlor followed the first-order kinetics equation. The addition of salt ions Ca2+ and Mg2+ changed the ionic strength and solvent polarity, resulting in the effect on propisochlor photolysis. The photoproducts were detected by both HPLC and GC-MS methods. It was found that photolysis products varied under different light sources. Conclusions may be reached that in the photodegradation of propisochlor, the benzene ring remained intact under irradiation of both solar light and high-pressure mercury lamp, and the amido link was relatively stable, while dechlorination was liable to take place; moreover, α-hydrogen at the substituent of benzene ring was active.

Photocatalytic Degradation of Brilliant Red Dye and Textile Wastewater

The degradation of textile wastewater and brilliant red dye solutions in a coil photoreactor provided with recirculation, assisted by powdered TiO2 and medium-pressure mercury lamp irradiation, was investigated. Factorial design was used for the attainment of the best conditions for COD and color abatement. pH and TiO2 loading showed to be critical variables for the photocatalytic degradation process for both textile wastewater and aqueous reactive dye solutions (25 mg L−1). For both substrates, the optimized process conditions by factorial design were almost the same (pH 2–3, 444 mg TiO2 L−1 loading, 5 L h−1 recirculation flow-rate). A 41% COD abatement for textile wastewater was obtained with a 120 min treatment. For the Brilliant Red dye solutions, a 20 min treatment resulted in about 90% decolorization (517 nm, pH 5), as well as in a reduction of 66% of the integrated absorbance (200–600 nm, pH 5).

Fluorescence analysis of photoinduced degradation of ecotoxicants in the presence of humic acids

The photolysis of humic acids and phenols in water containing humic acids was investigated. Humic acids extracted from peat (Vasuygan Bog, Tomsk Region, Russian Federation) induce the phototransformation of 4-chlorophenol at 365 and 222 nm. Humic acids were characterized by UV-, fluorescence-, IR- and EPR-spectroscopy and laser-induced fluorescence. The influence of humic acids on the phototransformation of phenols in different irradiation conditions was investigated. Comparison of the data on mercury lamp irradiation showed that the most effective phenols degradation was observed under exposure to KrCl* exilamp light (lambda = 222 nm) in the presence of humic acids.

The effect of operational parameters on the photocatalytic degradation of three textile azo dyes in aqueous TiO 2 suspensions

Photocatalytic degradation of three commercial textile diazo dyes, called (C.I. Direct 80, 3BL, C.I. Direct Blue 160, RL and C.I. Reactive Yellow 2, X6G) were investigated using commercial TiO 2 in aqueous solution under 400 W high-pressure mercury lamp irradiation. The effect of oxygen, temperature, catalyst loading, UV-light irradiation time, solution pH and inorganic ions such as SO 4 2−, Cl − and NO 3 − were studied and optimized values were obtained. Results show that the employment of efficient photocatalyst and selection of optimal operational parameters may lead to complete decolorization and to substantial decrease of the chemical oxygen demand (COD) of dye solutions.

Preliminary study on photoproduction of hydroxyl radicals in aqueous solution with Aldrich humic acid, algae and Fe(III) under high‐pressure mercury lamp irradiation

AbstractUnder a high‐pressure mercury lamp (HPML) and using an exposure time of 4 h, the photoproduction of hydroxyl radicals (*OH) could be induced in an aqueous solution containing humic acid (HA). Hydroxyl radicals were determined by high performance liquid chromatography using benzene as a probe. The results showed that *OH photoproduction increased from 1.80 to 2.74 μM by increasing the HA concentration from 10 to 40 mg L−1 at an exposure time of 4 h (pH 6.5). Hydroxyl radical photoproduction in aqueous solutions of HA containing algae was greater than that in the aqueous solutions of HA without algae. The photoproduction of *OH in the HA solution with Fe(III) was greater than that of the solution without Fe(III) at pH ranging from 4.0 to 8.0. The photoproduction of *OH in HA solution with algae with or without Fe(III) under a 250 W HPML was greater than that under a 125 W HPML. The photoproduction of *OH in irradiated samples was influenced by the pH. The results showed that HPML exposure for 4 h in the 4‐8 pH range led to the highest *OH photoproduction at pH 4.0.

Cross-photodimerization of 4-(2-phenylethenyl)pyridine, 2-(2-phenylethenyl)benzoxazole and 5-phenyl-2-(2-phenyl-ethenyl) oxazole

Three cross-photodimers were synthesized by irradiation of each two monomers of 4-(2-phenylethenyl) pyridine, 2-(2-phenylethenyl) benzoxazole and 5-phenyl-2-(2-phenylethenyl) oxazole in H2SO4 solution using medium-pressure Mercury lamp (λ＞300nm) as light source. The cross-photodimerization was monitored by HPLC titration. The results showed that three photodimers were produced in each reaction, two of them were the self-photodimers and the other one was the cross-photodimer. The cross-photodimers were isolated by column chromatography and their structures with syn-head-to-tail configurations were determined by UV, IR, 1H NMR, 13C NMR and MS. The photolysis of the cross-photodimer was performed in dilute methanol solution upon the irradiation of low-pressure Mercury lamp (λ=254nm) and monitored by HPLC and UV titration. It was found that the cross-photodimer was photolyzed into trans-monomers at first, and then the new formed trans-monomers were converted into cis-ones by the trans-cis isomerization.

Preliminary study on the photoproduction of hydroxyl radicals in aqueous solution with Aldrich humic acid, algae and Fe(III) under high-pressure mercury lamp irradiation.

Under a high-pressure mercury lamp (HPML) and using an exposure time of 4 h, the photoproduction of hydroxyl radicals (*OH) could be induced in an aqueous solution containing humic acid (HA). Hydroxyl radicals were determined by high-performance liquid chromatography using benzene as a probe. The results showed that *OH photoproduction increased from 1.80 to 2.74 microM by increasing the HA concentration from 10 to 40 mg L(-1) at an exposure time of 4 h (pH 6.5). Hydroxyl radical photoproduction in aqueous solutions of HA containing algae was greater than that in the aqueous solutions of HA without algae. The photoproduction of *OH in the HA solution with Fe(III) was greater than that of the solution without Fe(III) at pH ranging from 4.0 to 8.0. The photoproduction of *OH in HA solution with algae with or without Fe(III) under a 250 W HPML was greater than that under a 125 W HPML. The photoproduction of *OH in irradiated samples was influenced by the pH. The results showed that HPML exposure for 4 h in the 4-8 pH range led to the highest *OH photoproduction at pH 4.0.

Growth and characterization of boron carbon nitride films with low dielectric constant

Polycrystalline boron carbon nitride (BCN) films are synthesized by plasma-assisted chemical vapor deposition. Effect of the mercury (Hg) lamp irradiation and annealing processes on the dielectric constant of the BCN films are investigated. The dielectric constant is estimated from the accumulation region of the capacitance–voltage characteristics of Cu/BCN/p-Si samples. It is found that the dielectric constant is reduced by the Hg lamp irradiation or by the annealing process. In comparison with the as-grown BCN film, the BC bond increases by the irradiation. On the other hand, the CH and C=C bonds decrease after annealing. A dielectric constant as low as 2.1 is achieved for the BCN film, which is treated by the annealing process.