WO3 nanofibers on ACF by electrospun for photo-degradation of phenol solution

Electrospun WO_3 nanofibers were fabricated by coaxial electrospinning and directly annealing WCl_6/polyvinylpyrrolidone(PVP) nanofibers on activated carbon fibres(ACF), and characterized by scanning electron microscopy(SEM) and X-ray diffractometry(XRD). The most suitable condition for electrospinning is the mass ratio of WCl_6 to PVP 0.6, appropriate amount DMF and ethanol, a voltage of 28 kV, the reception distance of 15 cm, the humidity range within 10% and 20% and the moving rate of the pump 0.001 mm/s. The photocatalytic activities of WO_3 nanofibers were evaluated by the photo-degradation of phenol solution under the irradiation of 500 W xenon lamp. The results showed that, the sizes of the fibers are about 100 nm, and after being photodegraded for 210 min, the concentration of phenol decreased from 20.05 mg/L to 8.60 mg/L. Thus, the photo-degradation rate of WO_3 nanofibers for phenol solution is 2.87 mg/(L·h).

Simulated photo-degradation of dissolved organic matter in lakes revealed by three-dimensional excitation-emission matrix with regional integration and parallel factor analysis

Simulated photo-degradation of fluorescent dissolved organic matter(FDOM) in Lake Baihua(BH) and Lake Hongfeng(HF) was investigated with three-dimensional excitationemission matrix(3 DEEM) fluorescence combined with the fluorescence regional integration(FRI),parallel factor(PARAFAC) analysis,and multi-order kinetic models.In the FRI analysis,fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM.Four individual components were identified by use of PARAFAC analysis as humic-like components(C1),fulvic-like components(C2),protein-like components(C3) and unidentified components(C4).The maximum 3 DEEM fluorescence intensity of PARAFAC components C1-C3 decreased by about 60%,70% and 90%,respectively after photo-degradation.The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient(Radj2)(0.963-0.998).The photo-degradation rate constants(kn) showed differences of three orders of magnitude,from 1.09 × 10-6 to 4.02 × 10-4 min-1,and half-life of multi-order model(T1/2n)ranged from 5.26 to 64.01 min.The decreased values of fluorescence index(FI) and biogenic index(BI),the fact that of percent fluorescence response parameter of Region I(PⅠ,n) showed the greatest change ratio,followed by percent fluorescence response parameter of Region II(PⅡ,n,while the largest decrease ratio was found for C3 components,and the lowest T1/2n was observed for C3,indicated preferential degradation of protein-like materials/components derived from biological sources during photodegradation.This research on the degradation of FDOM by 3 DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FD OM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM.

Photo-degradation organic dyes by Sb-based organic-inorganic hybrid ferroelectrics

The organic-inorganic hybrid halide compounds have emerged as one of the most promising photoelectric material for their superior optoelectronic properties and hold great prospects for renewable energy substitutes and environmental protection as photocatalysis.Here,we report the optical properties of the Sb-based organic-inorganic hybrid ferroelectric materials:pyridine-4-aminium tetrachloroantimonate((C_(5)H_(7)N_(2))SbCl_(4),sample 1),piperidin-1-aminium tetrachloroantimonate((C_(5)H_(13)N_(2))SbCl_(4),sample 2)and tris(trimethylammonium)nonachlorodiantimonate(((CH_(3))_(3)NH)_(3)Sb_(2)Cl_(9),sample 3),which are a kind of exploited efficient photocatalysts.Samples 2 and 3 exhibit distinct photoelectric respond,which are mainly ascribed to their minor narrow band-gap compared with sample 1.For the ferroelectrics,the intrinsic of spontaneous polarization of sample 3 at room temperature is favourable for the separation of photogenerated electrons and holes within the photorespond process.Moreover,sample 3 shows the highest efficiency of photo-decomposed Rhodamine B(90.2%within 80 min)and Methyl Orange(MO)(97.4%within 50 min),thanks to the photo-excited electrons and holes promoting the formation of oxidative radical species during the photo-redox progress.These findings prove that the development of a novel Sbbased organic-inorganic hybrid halide compounds with good stability in the degradation of organic dyes paves a way to designing new photocatalyst.

Photochemical degradation of crude oil in seawater

Photochemical degradation of crude oil in seawater is an important issue in marine environ- mental protection and is studied in this work. Results showed that petroleum hydrocarbons could be ef- fectively degraded by the irradiation of high-pressure mercury light or natural sunlight. Photochemical reaction was controlled by various factors including light source, aquatic medium, heavy metal ion and photo-sensitizer. The rate of photo-degradation was fast at the initial stage of exposure, exhibiting a first-order reaction kinetic behavior. However, after irradiation for a few hours, the concentration of wa- ter-soluble fraction (WSF) of petroleum hydrocarbons stabilized. For all experimental conditions, the range of the photo-degradation rate is from 0.001 3 to 0.005 7/min.

In-situ fabrication SnO2/SnS2 heterostructure for boosting the photocatalytic degradation of pollutants

Heterostructure photocatalysts with a built-in electric field have become one of the most promising strategies to enhance photogenerated electron-hole pair separation. However, close contact between the two active components of heterogeneous photocatalysts remains a problem. Herein, the in-situ fabrication of an SnO2/SnS2 heterostructure photocatalyst was performed;the structure showed enhanced photocatalytic performance resulting from the tight-contact heterostructures. The results of photoelectrochemical measurements further verified that a tight-contact heterostructure improved the separation of photogenerated electron-hole pairs. The results of EIS Bode plots also demonstrated that such in-situ fabricated SnO2/SnS2 samples exhibited the longest carrier lifetime(41.6 μs) owing to the intimate interface of SnO2/SnS2 heterostructures.

Ag-Co3O4：Synthesis,characterization and evaluation of its photo-catalytic activity towards degradation of rhodamine B dye in aqueous medium

Synthesis,characterization of Co_3O_4 and Ag-Co_3O_4 composites and evaluation of their photo-catalytic activities towards photo-degradation of aqueous solution of rhodamine B dye under irradiation of visible light have been described in this paper.Co_3O_4 was prepared by solid phase mechano chemical process using Co(NO_3)_2·6H_2O and NH_4 HCO_3 as precursor materials.Ag was deposited on Co_3O_4 from AgNO_3 using Calotropis gigantea extract as reducing agent.XRD,SEM and FTIR were used for characterization of prepared composites.Photo-catalytic efficiencies of as-prepared Co_3O_4 and Ag-Co_3O_4 were evaluated for aqueous phase photo-degradation of rhodamine B.It was found that deposition of Ag on Co_3O_4 highly enhanced the photo-catalytic activity of Co_3O_4.Photo-catalytic degradation followed the Eley–Rideal mechanism.About 100% and 91% photo-degradation of 40 ml dye solution achieved at 313 K in 90 and 120 min over 0.05 g of Ag-Co_3O_4 as photo-catalyst using 100 and 200 mg·L^(-1) as initial concentration of dye respectively.

Impact of Annealing Treatment on the Behaviour of Titanium Dioxide Nanotube Layers

In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs to be better understood. Nanotube layers were prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then annealed in air atmosphere. In-situ X-ray diffraction analysis, coupled with thermogravimetry, gives us an inside on the oxidation behaviour of titanium dioxide nanotube layers compared to bulk reference samples. Structural studies were performed at 700°C for 12 h in order to follow the time consequences on the oxidation of the material, in sufficient stability conditions. In-situ XRD brought to light that the amorphous oxide layer induced by anodization is responsible for the simultaneous growths of anatase and rutile phase during the first 30 minutes of annealing while the bulk sample oxidation leads to the nucleation of a small amount of anatase TiO2. The initial amorphous oxide layer created by anodization is also responsible for the delay in crystallization compared to the bulk sample. Thermogravimetric analysis exhibits parabolic shape of the mass gain for both anodized and bulk sample;this kinetics is caused by the formation of a rutile external protective layer, as depicted by the associated in-situ XRD diffractograms. We recorded that titanium dioxide nanotube layers exhibit a lower mean mass gain than the bulk, because of the presence of an initial amorphous oxide layer on anodized samples. In-situ XRD results also provide accurate information concerning the sub-layers behavior during the annealing treatment for the bulk and nanostructured layer. Anatase crystallites are mainly localized at the interface oxide layer-metal and the rutile is at the external interface. Sample surface topography was characterized using scanning electron microscopy (SEM). As a probe of the photoactivity of the annealed TiO2 nanotube layers, degradation of an acid orange 7 (AO7) dye solution and 4-chlorophenol under UV irradiation (at 365 nm) were performed. Such titanium dioxide nanotube layers show an efficient photocatalytic activity and the analytical results confirm the degradation mechanism of the 4-chlorophenol reported elsewhere.

Removal of Herbicides from Water Using Heterogeneous Photocatalysis Case Study: MCPA Sodium Monohydrate

In this study, the herbicide MCPA sodium salt monohydrate (sodium (4-chloro-2 methylphenoxy) acetate has been studied as are presentative compound used in the agricultural field. Accordingly, direct photolysis and photocatalytic experiments under artificial irradiation simulating solar light in laboratorial conditions were performed. Photocatalytic experiments were performed using TiO2 dispersed powder and as an immobilized thin layer on the surface of blue glasses. The obtained results of photolysis showed a poor efficacy toward degradation of MCPA sodium monohydrate, with half-life (t1/2) 6931.5 min. While, the addition of TiO2 dispersed powder to the photocatalytic process enhances the process dramatically with (t1/2) equal to 36.5 min;furthermore, complete mineralization had been reached after approximately 4 hours, whereas the addition of TiO2 through immobilized system led to enhance the degradation rate with 2236 min. as t1/2. In spite of this, using TiO2 supported on glass substrates with more improvements could be a promising alternative to conventional TiO2 suspension, and provides a clean treatment method.

Removal of Carbonyl-Containing Effluents by Photodegradation Using β-Carotene Embedded onto Zinc Oxide Particles

Environmental pollution especially in the form of effluent wastewater from industries has been a major challenge. Carbonyl-containing organic standards and sewage sample were effectively photo degraded. ZnO nanoparticles were prepared by emulsification of zinc-carbamate solution using 1 N NaOH and grafted chemically by Molecular Layer Doping method at 180 °C with β-carotene extracted using methanol by refluxing at 50 °C at varying concentrations. Intrinsic and grafted β-carotene ZnO were characterized using FTIR (Fourier transform infrared spectroscopy) and their spectra differed in an additional peak at around 1,435 nm corresponding to the organ metallic bond Zn-C. UV-Vis spectra of the two composites indicated a blue shift in the grafted samples. This translated to a reduced band gap from 3.5 eV to 3.4 eV. Comparison in the rates of photodegradation of pure organic compounds, organic effluents and color change of dyes was in the order 1% grafted, 0.5% grafted, intrinsic ZnO and blank sample. When 10.0 mL of sewerage water was photo degraded using both sunlight and UV-Lamp for 40 minutes, the amount of carbonyls present decreased by 28.5% for β-carotene grafted ZnO, 24.5% for intrinsic ZnO and 0.6% for a blank sample.

Nd-doped NiFe_(2)O_(4) and its composite with CNTs to tune photocatalytic activity

Rare earth-doped spinel nano ferrites are attaining importance as heterogeneous nanocatalysts for the degradation of organic effluents.Rare earth metal doping increases the electrical and optical properties,as well as the surface-to-volume ratio of the bare sample.In this work,NiFe_(2)O_(4)(NF) and Nd-NiFe_(2)O_(4)(NF-1) were successfully synthesized via the co-precipitation route.Carbon nanotubes(CNT)-based nanocomposite(NF-2) was prepared using the ultra-sonication method.The prepared materials were analyzed via various physiochemical approaches.The degradation efficiency of these materials was analyzed for the degradation of Rhodamine B,methylene blue,and benzoic acid,NF-2 shows the highest efficiency among all the prepared catalysts.NF-2 shows 83.87%,90.80%,and 66.96% degradation of Rhodamine B,methylene blue,and benzoic acid,respectively.The reason for the superior activity of NF-2 is the existence of rare earth Nd ions and CNTs.The surface area of NF increases due to the presence of carbon nanotubes and enhanced surface area provides more active sites for the degradation reaction.

Photocatalytic oxidation of phenol in aqueous solutions with oxygen catalyzed by supported metallophthalocyanine catalyst

In this paper, zinc tetraaminophthalocyanine (Zn-APc) was immobilized on cellulosic fiber by covalent bond to obtain a novel cellulosic fiber supported metallophthalocyanine, named Zn-TDTAPc-F. At pH 11, upon visible light irradiation for 6 h in the presence of O2, Zn-TDTAPc-F was found to be highly effective for the degradation of phenol in aqueous solution, and the degradation rate of phenol was more than 95%. HPLC was used to confirm formic acid, fumaric acid and maleic acid as its main degradation products.

Photocatalytic degradation of coking wastewater by nanocrystalline (Fe,N) co-doped TiO_2 powders

The yellowish nitrogen and iron co-doped nanocrystalline titanium dioxide ((Fe,N) co-doped TiO2) powders have been prepared by hydrothermal method using TiOSO4 and CO(NH2)2 as starting materials.The grain size of the synthesized powders was estimated as 11 nm by Scherrer's method.The UV-Vis diffuse reflectance spectra indicated that the light absorption edge of the powders was red-shifted up to 605 nm.And the doped TiO2 powders exhibited good photocatalytic activities during the photo-degradation of coking wastewater under sunshine irradiation.The biotreatability of the coking wasterwater after photocatalytic degradation was improved greatly and it is more suitable to be further treated by biochemical method.

Research progress of photocatalysis based on highly dispersed titanium in mesoporous SiO_2

With the development of the human economy and green chemistry, people pay much more attention to environmental safety. Correspondingly, mesoporous TiO_2 and its correlated photocatalysts are able to help people seek for better life. In this review, first of all, we briefly introduce the preparations and applications of mesoporous TiO_2-SiO_2 materials, which exhibit excellent performance in pollutants decomposition and H_2 evolution in photocatalysis. Then, we review the mesoporous composites of TiSiO_2 materials, which are ideal materials used in the photoreduction of air pollutants such as CO_2, NO and NO_2. It is powerfully evident from the literature surveys that these TiO_2 based mesoporous photocatalysts possess a large potential in environment and energy development.

Gadolinium doped tin dioxide nanoparticles: an efficient visible light active photocatalyst

Photocatalytic degradation of phenol with sol-gel prepared rare earth doped tin dioxide （SnO2） nanoparticles was reported. Gadolinium doped tin dioxide （SnO2：Gd） nanoparticles were found to absorb higher visible light compared to lanthanum, neodymium and cerium doped materials that were studied in detail. Photocatalytic degradation of phenol under artificial white light and sunlight in the presence of SnO2：Gd nanoparticles was studied with high performance liquid chromatography （HPLC）, capillary electrophoresis （CE）, total organic carbon （TOC） measurements and the determination of chemical oxygen demand （COD）. Clear correlations be- tween the results obtained from these multiple measurements were found, and a kinetic pathway for the degradation process was pro- posed. Within 150 min of solar irradiation, the TOC of a 10 ppm phenol solution in water was reduced by 95%-99%, thus demon- strating that SnO2：Gd nanoparticles are efficient visible light photocatalysts.

Asymmetric Structure Awakened n-π*Electron Transition in Sulfur and Selenium Co-doped g-C_(3)N_(4) with Efficient Photocatalytic Performance

Sulfur and selenium co-doped graphitic carbon nitride(SSCN)with efficient photocatalytic activity was synthesized by synchronously introducing sulfur and selenium atoms into the melon structure of g-C_(3)N_(4)(GCN)via a facile solid-phase thermal reaction of GCN and SeS_(2).The as-prepared SSCN possesses a larger specific surface area with a richer pore structure that provides more active centers for catalytic reaction.More importantly,the asymmetric structure of SSCN due to introducing sulfur and selenium not only maintains an easier activation ofπ-π*electron transition but also awakens the n-π*electron transition in g-C_(3)N_(4).Moreover,the n-π*electron transition of SSCN can be controlled through changing the amount of SeS_(2),which can greatly extend the photo-response range to 600 nm.As a result,the SSCN samples show an excellent photo-degradation performance for typical antibiotic of tetracycline hydrochloride(TC).The specific degradation route and main intermediates of TC based on liquid chromatograph mass spectrometer(LC-MS)analysis are also investigated and discussed.

Hollow TiO_2 spheres with improved visible light photocatalytic activity synergistically enhanced by multi-stimulative: Morphology advantage,carbonate-doping and the induced Ti^(3+)

Great efforts have been devoted to improve the photocatalytic activity of TiO2 in the visible light region. Rational design of the external structure and adjustment of intrinsic electronic status by impurity doping are two main effective ways to achieve this purpose. A facile onepot synthetic approach was developed to prepare C-doped hollow TiO2 spheres, which simultaneously realized these advantages. The synthesized TiO2 exhibits a mesoporous hollow spherical structure composed of fine nanocrystals, leading to high specific surface area（~180 m^2/g） and versatile porous texture. Carbonate-doping was achieved by a postthermal treatment at a relatively low temperature（200°C）, which makes the absorption edge red-shifted to the visible region of the solar spectrum. Concomitantly, Ti^（3＋） induced by C-doping also functions in improving the visible-light photocatalytic activity by reducing the band gap. There exists a synergistic effect from multiple stimulatives to enhance the photocatalytic effect of the prepared TiO2 catalyst. It is not out of expectation that the asprepared C-doped hollow TiO2 spheres exhibits an improved photocatalytic activity under visible light irradiation in organic pollutant degradation.

Efficient dechlorination of chlorinated solvent pollutants under UV irradiation by using the synthesized TiO_2 nano-sheets in aqueous phase

Titanium dioxide （TiO2）, which is the widely used photo-catalyst, has been synthesized by simple hydrothermal solution containing tetrabntyl titanate and hydrofluoric acid. The synthesized product has been applied to photo-degradation in aqueous phase of chlorinated solvents, namely tetra- chloroethene （PCE）, tdchloroethene （TCE） and 1,1,l-trichloroethane （TCA）. The photo-degradation results revealed that the degradation of these harmful chemicals was better in UV/synthesized TiO2 system compared to UV/commerciai P25 system and UV only system. The photo-catalytic efficiency of the synthesized TiO2 was 1.4, 1.8 and 3.0 folds higher compared to the commercial P25 for TCA, TCE and PCE degradation, respectively. Moreover, using nitrobenzene （NB） as a probe of hydroxyl radical （.OH）, the degradation rate was better over UV/synthesized TiO2, suggesting the high concentration of .OH generated in UV/synthesized TiO2 system. In addition, .OH concentration was confirmed by the strong peak displayed in EPR analysis over U~/synthesized TiO2 system. The characterization result using XRD and TEM showed that the synthesized TiO2 was in anatase form and consisted of well-defined sheet-shaped structures having a rectangular outline with a thickness of 4 rim, side length of 50 nm and width of 33 nra and a surface 90.3 m^2/g. XPS analysis revealed that ≡Ti-F bond was formed on the surface of the synthesized TiO2. The above results on both photocatalytic activity and the surface analysis demonstrated the good applicability of the synthesized TiO2 nano-sheets for the remediation of chlorinated solvent contaminated groundwater.

Band gap engineered polymeric-inorganic nanocomposite catalysts:Synthesis, isothermal stability, photocatalytic activity and photovoltaic performance

Polymeric-inorganic nanocomposite catalysts were synthesized by facile one-pot chemical polymerization of pyrrole in the presence of titanium dioxide nanoparticles. The electrical, optical, photovoltaic performance of dye sensitized solar cell（DSSC） and visible light driven photocatalytic activities of the nanocomposite were investigated. The prepared nanocomposite displays excellent photo-activity, attaining 100% degradation of methyl orange dye in 60 min under visible light source while 55% for pure TiO_2 under similar experimental conditions. The photovoltaic performance of the polypyrrole-titanium dioxide（PPy-TiO_2） nanocomposite has a 51.4% improvement with a photo-conversion efficiency of 8.07% as compared to pure TiO_2 based DSSC. By comparing the physical mixture of the PPy-TiO_2 nanocomposite and pristine TiO_2, the enhanced activity of the PPy-TiO_2 nanocomposite can be attributed to the reduced charge transfer resistance, outstanding electrical conductance of the PPy, the nano-sized structure of TiO_2 and their synergetic effect. Furthermore, the PPy-TiO_2 nanocomposite shows excellent electrical conductivity and isothermal stability under ambient conditions below 110？C.

Ilmenite:Properties and photodegradation kinetic on Reactive Black 5 dye

Ilmenite is natural mineral ore made up with titanium and iron mineral; including small portion of magnesium and manganese. To the best of our knowledge, photo-degradation of Reactive Black 5 dye（RB5） using ilmenite under solar irradiation is still lacking. In the present study, the physicochemical properties of ilmenite were characterized by using X-ray diffraction（XRD）, Scanning electron microscope（SEM）, BET and Raman Spectroscopy. Based on our results obtained, 73% solar-driven photo-degradation of RB 5 was successfully obtained when the catalyst loading increased up to 2.0 g/L for 20 min. In general,the photo-degradation of RB 5 by ilmenite followed first-order kinetics. The p H had a significant effect,with the most rapid degradation occurring at p H less than 7.