Metal Halide Lamp Irradiation Research Articles

Investigation on the photocatalytic degradation properties of BiOX on carbendazim and its mechanism

AbstractBismuth Oxyhalide (BiOX, X=Cl, Br, I) has been widely used in water purification, environmental remediation and other fields due to its special layered structure and good photocatalytic performance. In this work, BiOCl, BiOBr and BiOI photocatalysts were successfully synthesized by a simple solvothermal method and first applied to the mineralization and degradation of carbendazim (CBZ). The degradation performance of BiOX to CBZ was studied under different light sources and different pH conditions. And the influence mechanism of the degradation performance of the three catalysts were revealed by analyzing the structure, morphology, specific surface area, optical performance, energy band structure, and electronic density of state of the materials. The results showed that, under the irradiation of metal halide lamp, the photocatalytic activity of BiOBr was the best when the pH was at 7. The degradation efficiency reached 99 % after 3 h and more than 90 % CBZ molecules could be mineralized. The BiOBr catalyst had good stability in four cycles. Furthermore, it was found that the main active species were h+ and ⋅O2− in the photodegradation process by free radical trapping experiment. Based on the density functional theory (DFT) calculation, it was demonstrated that different halogen atoms had different density of state contribution intensity in atomic orbitals, different band gap width and different light response capabilities by the analysis of its energy band structure and partial wave density of state (PDOS), resulting in different photocatalytic performance under different energy light irradiation.

ZnO nanoparticles photocatalytic activity toward atmospheric toluene under simulated sunlight

In this study, the photocatalytic degradation of toluene through zinc oxide (ZnO) nanoparticles coated on glass plates was examined under simulated sunlight. Heat attachment procedure was employed to immobilize ZnO nanoparticles on glass plates. Removal performance of these prepared plates for toluene degradation was evaluated in a rectangular reactor under irradiation of metal halide lamp. The effects of operational parameters including initial toluene concentration, temperature, relative humidity, irradiation time, and concentration of zinc oxide suspension on the removal of toluene were investigated. The structural properties of ZnO nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The concentration of toluene was analyzed by gas chromatography with flame ionization detector (GC-FID). The results of the present study indicated that ZnO-coated glass plates resulted in removal of 67% toluene for concentration of 50 ppm at temperature 45 °C, and relative humidity of 40% after 240 min irradiation of metal halide light. As the glass plates coated by ZnO have relatively good performance under experimental conditions, it concluded that coating ZnO nanoparticles on surfaces can be considered as an environmentally friendly method to eliminate low concentration of toluene from polluted air under sunlight.

Photocatalytic oxidation of benzene by ZnO coated on glass plates under simulated sunlight

The photocatalytic oxidation of benzene by ZnO nanoparticles coated on glass plates was studied under simulated sunlight. ZnO nanoparticles were coated on three glass plates by heat attachment method. To evaluate the photocatalytic removal of benzene, coated plates were irradiated by metal halide lamp in a rectangular reactor in batch mode. The effect of initial pollutant concentration, temperature, relative humidity, irradiation time, concentration of zinc oxide suspension, were assessed. The surface morphology and structure of ZnO nanoparticles and ZnO coated on glass plates were characterized by scanning electron microscopy, X-ray diffraction and field emission scanning electron microscopy. Sampling and analysis of benzene were performed according to NIOSH method. To analyze the concentration of benzene, gas chromatography with flame ionization detector (GC-FID) was used. Results indicated that photocatalytic process by ZnO under irradiation of metal halide lamp could remove benzene at optimum experimental conditions. Coating of glass plates by ZnO suspension, resulted in 57% removal of benzene as concentration of 50 ppm at 45 °C, and relative humidity of 40% after 240 min irradiation of metal halide lamp. Results indicated that photocatalytic oxidation process by ZnO nanoparticles can be used as a proper and environmentally friendly method for removing low concentrations of benzene from polluted air under simulated sunlight.

NO removal efficiency of high-yield carbon nitride irradiated under various light sources

Graphitic carbon nitride (g-C3N4) is a well-known photocatalyst. In this work, the NO removal efficiency of g-C3N4 irradiated under various light sources is explored. For achieving high productivity and activity photocatalyst, the pyrolysis temperature is adjusted from 450°C to 600°C. All prepared g-C3N4 are put into a transparent reaction box one by one to remove the NO with the initial concentration of 1000 ppb level in air flow under real indoor illumination of three light resources: metal halide lamp, LED lamp and high pressure sodium lamp. According to the photocatalytic reaction results, the NO removal ratio of g-C3N4 synthesized under 500°C can reach to 29.26% under the irradiation of metal halide lamp, overwhelming that of g-C3N4 irradiated under other light sources. Several characterization methods were adopt to analyze the photocatalytic reaction mechanism and the micro structures of g-C3N4 prepared from melamine. Because of the conduction band potential difference between g-C3N4 and melem, heterojunction of melem and g-C3N4 can form the convention-type charge transfer, which greatly reduce the combination ratio of photogenerated electrons and holes, thus enhance the photocatalytic activity of g-C3N4 under the irradiation of metal halide lamp indicating why the g-C3N4 synthesized under 500°C possesses the best NO removal efficiency among these samples. In addition, compared with other lamps, metal halide lamp is proved to be the most suitable light resource to motivate g-C3N4 because of its relatively concentrated light intensity. The present work provide us new perspectives for selecting suitable light resources and proper synthesis conditions for the generation of g-C3N4 to achieve better air purification performance in tunnels and indoors.

Preparation of a Novel Zinc Zirconate Nanocomposite Coated on Glass for Removal of a Textile Dye (Reactive Brilliant Red X8B) From Water

In the present work, zinc zirconate nanocomposite (ZZN) thin film was coated on glass surface by sol-gel spin-coating technique via zirconium acetylacetonate, zinc acetate, monoethanolamine, and 1,3-propanediol. The product was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive analysis of X-ray, and UV-vis spectroscopy. XRD data confirmed the formation of nanostructure zinc zirconate (ZnZrO3) layer. The photocatalytic activity of the ZZN thin film was estimated on the degradation and mineralization of Reactive Brilliant Red textile dye under metal halide lamp irradiation. Effects of some parameters such as pH of solution, irradiation time, cycles of use and initial dye concentration were studied and obtained results demonstrated that the degradation efficiency was affected by initial concentration of the dye. Total organic carbon of aqueous dye solution after 180 min irradiation showed 95% decrease in carbon.

Natural montmorillonite induced photooxidation of As(III) in aqueous suspensions: Roles and sources of hydroxyl and hydroperoxyl/superoxide radicals

Photooxidation of arsenite(As(III)) in a suspension of natural montmorillonite under the irradiation of metal halide lamp (λ≥313nm)has been investigated. The results showed that the natural montmorillonite induced the photooxidation of As(III) by generating hydroxyl radicals (HO) and hydroperoxyl/superoxide radicals (HO2/O2−). HO which was responsible for the As(III) photooxidation. Approximately 38% of HO was generated by the photolysis of ferric ions, and the formation of the remaining 62% was strongly dependent on the HO2/O2−. The presence of free ironions (Fe2+ and Fe3+), made significant contributions to the photogeneration of these reactive oxygen species (ROS). The photooxidation of As(III) in natural montmorillonite suspensions was greatly influenced by the pH values. The photooxidation of As(III) by natural montmorillonite followed the Langmuir–Hinshelwood equation. In addition, the photooxidation of As(III) could be enhanced by the addition of humic acid. This work demonstrates that photooxidation may be an important environmental process for the oxidation of As(III) and may be a way to remove As(III) from acidic surface water containing iron-bearing clay minerals.

SrBi<sub> 4</sub>Ti<sub> 4</sub>O<sub> 15</sub>的Pechini法制备及其光催化性能*

以硝酸锶、硝酸铋和钛酸丁酯为原料，柠檬酸为配位剂，乙二醇为溶剂，用Pechini溶胶–凝胶法制备了SrBi4Ti4O15粉体。研究了柠檬酸量、溶液pH值、乙二醇用量、煅烧温度对产物物相的影响。对所合成粉体进行形貌分析和光催化性能测试。经多组对比试验表明，在pH = 7.0、金属离子：柠檬酸 = 1:3、柠檬酸：乙二醇 = 1:2、干凝胶在650℃煅烧3 h可以得到单相SrBi4Ti4O15粉体。产物SrBi4Ti4O15的结构较疏松，带宽为3.01 eV，在金卤灯下照射3.5 h对甲基橙的降解率可达96.6%。 SrBi4Ti4O15 was prepared by a Pechini sol-gel method, using strontium nitrate, bismuth nitrate penthydrate and tetrabutyl titanate as raw materials, citric acid as ligand, and ethylene glycol as solvent. The influences of the amount of citric acid, pH, ethylene glycol and calcining temperature on the phases of the product were researched. The morphology and photocatalytic properties of the as-synthesized powders were measured. The multiple comparison tests showed single phase of SrBi4Ti4O15 was obtained under the conditions of pH = 7, metals:citric acid = 1:3, citric acid:glycol = 1:2, calcining the dry gel at 650C for 3 h. The as-synthesized SrBi4Ti4O15 had a loose structure with a bandwidth of 3.01 eV. The degradation ratio of methyl orange reached up to 96.6% under the metal halide lamp irradiation for 3.5 h.

The Effect of Operational Parameters on the Photocatalytic Mineralization of Indocorn Brilliant Red M5B Using Sol–gel Derived Nanostructured Zinc Titanate as an Efficient Photocatalyst

AbstractNanostructured zinc titanate (NZT) was synthesized in high yield via a one-step and template-free sol-gel route. The prepared nanocomposite exhibited good size uniformity and regularity. The enhanced photocatalytic activity of the NZT was evaluated in the degradation and mineralization of Indocorn Brilliant Red (M5B) under metal halide lamp irradiation. The effects of different parameters such as pH of the solution, and initial dye concentration on photodegradation of M5B were analyzed. The degradation of M5B follows pseudo-first order kinetics according to the Langmuir-Hinshelwood model. The experimental results showed that the initial concentration of azo dye in the dye mixture greatly affected the degradation efficiency. At M5B concentrations of 10 mg/L, the optimum conditions for the highest degradation efficiency (94%) of azo dye were a photocatalyst dosage of 0.01 g/L and an initial solution pH of 9. This study provided new insight into the design and preparation of nanomaterial demonstrated an excellent ability to remove organic pollutants in wastewater.

Induction of chronic skin changes in intraperitoneally hematoporphyrin-injected mice with metal halide lamp irradiation.

AbstractTo induce chronic skin changes simulating human porphyria, mice which had been injected intraperitoneally with hematoporphyrin dihydrochloride were exposed to metal halide lamps. Clinical and histopathological findings in the mice were observed. Clinically, erythema, edema, erosion, necrosis and crust formation were initially seen in all of the mice treated. Hypertrophy of the skin, scarring, and deformities of the ear lobes followed gradually. Histopathological findings in these skin changes were mainly seen in the dermis and included infiltration of lymphocytes, proliferation of mast cells, dilatation and hyperemia of blood vessels in the upper dermis, and swelling and proliferation of connective tissues. PAS positive materials were deposited in the dermo‐epidermal junction and around the small blood vessels in the upper dermis. Using the direct immunofluorescent technique, the deposition of immunoglobulin G (IgG) was confirmed in the same areas, and some deposition of IgM, IgA and C3 was also observed. These findings are similar to those seen in patients with erythropoietic protoporphyria and porphyria cutanea tarda.

Photoelectrochemical sterilization of microbial cells by semiconductor powders

We report the novel concept of photochemical sterilization. Microbial cells were killed photoelectrochemically with semiconductor powder (platinum-loaded titanium oxide, TiO2/Pt). Coenzyme A, (CoA) in the whole cells was photo-electrochemically oxidized and, as a result, the respiration of cells was inhibited. Inhibition of respiratory activity caused death of the cells. Lactobacillus acidophilus, Saccharomyces cerevisiae and Escherichia coli (103 cells/ml respectively) were completely sterilized when they were incubated with TiO2/Pt particles under metal halide lamp irradiation for 60–120 min.