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1.
WO3-modified TiO2 polyscale crystals were fabricated successfully using the hydrothermal technique. The as-prepared samples were characterized using powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy and UV–vis spectroscopy. The photocatalytic application of these synthesized samples was confirmed by photocatalytic degradation of fast green dye solution under sunlight and UV irradiation. The degradation efficiency was analyzed by measuring the parameters such as percent transmittance, chemical oxygen demand and percent decomposition of the dye solution. It was noted that the photodegradation efficiency of the samples varies with added amounts of WO3 content. The highest photodegradation efficiency was obtained using 2WT sample where the pace of decomposition was 70.5% under UV light and 81.3% under sunlight.  相似文献   

2.
In recent years, traces of acetaminophen, a widely used analgesic and anti-inflammatory and known to be an over-the-counter drug, have been detected unaltered in effluents of conventional wastewater treatment facilities. About 58–68% released through excretion during patient’s therapeutic treatment, and only about 80–86% were removed by the wastewater treatment facility. This study investigated the improved performance of photocatalysis in degrading or removing acetaminophen. The visible light active potassium peroxodisulfate-doped titanium dioxide photocatalysts synthesized via sol–gel method was used to eliminate acetaminophen from aqueous solutions through photocatalytic oxidation. The effects of the amount of dopant, calcination temperature and calcination time on the properties and visible light photocatalytic activity of potassium peroxodisulfate-doped titanium dioxide were also investigated. Increasing the amount of the dopant and calcination temperature up to a certain extent increases removal efficiency while further decreased the removal rate. Potassium peroxodisulfate-doped titanium dioxide photocatalysts were characterized by X-ray diffraction, ultraviolet–visible light diffuse reflectance spectroscopy, Brunauer–Emmett–Teller method and X-ray photoelectron spectroscopy. Potassium peroxodisulfate-doped titanium dioxide with 0.5%w dopant and calcined at 300 °C for 3 h degrades about 100% acetaminophen in aqueous solution within 540 min. The reaction of acetaminophen with the photocatalyst has an apparent rate constant of 8.39 × 10?3 min?1.  相似文献   

3.
It is demonstrated that single titanium dioxide (TiO2) has high potential for photodegradation of pollutants. However, it is still far from becoming an effective photocatalyst system, due to issues of adsorption process, separation, as well as dissolution. Therefore, this study highlights the high adsorption capacity, simplified separation, and the promising stability of TiO2(SY) (synthesized via sol–gel method) photocatalyst, fabricated using chitosan–TiO2(SY) and supported by glass substrate (Cs–TiO2(SY)/glass substrate) photocatalysts. Chitosan (Cs), with abundant –R–NH and NH2 groups, promotes the adsorption sites of methyl orange (MO) and OH groups for major attachment to TiO2(SY). Meanwhile, the glass substrate increases stability and assists separation of the photocatalysts. Initially, nano-TiO2(SY) has been characterized using high-resolution transmission electron microscope. Cs–TiO2(SY)/glass substrate was fabricated via dip-coating. The distribution and interface between the photocatalytic components were characterized by Fourier transform infrared absorption spectroscopy, UV–Vis diffuse reflectance spectroscopy, field emission scanning electron microscopy, and energy-dispersive spectrometer. UV–Vis analysis of the multilayer photocatalyst (2, 4, 6, and 8 layers) was further carried out by the adsorption–photodegradation, with MO as model of pollutant. Seventy percent of the total removal of MO via optimized eight layers of photocatalyst was achieved within 1 h of UV irradiation. The adsorption photocatalyst achieved 50 % with no exposure to UV light for 15 min of irradiation. It is concluded that suitable photocatalytic conditions and sample parameters possessing the multilayer photocatalyst of Cs–TiO2(SY) are beneficial toward the adsorption–photodegradation process in wastewater treatment.  相似文献   

4.
A low-cost visible light-driven silver/titanium oxide/expanded perlite (Ag/TiO2/EP) as a floating plasmonic photocatalyst is fabricated by a simple hydrolysis method. Photocatalytic properties of Ag/TiO2/EP have been studied by scanning electron microscope, X-ray diffraction, UV–Vis (DRS), EDAX, FTIR, chemiluminescence, photoluminescence and X-ray photoelectron spectroscopy methods. The photocatalytic activity of resulting Ag/TiO2/EP with different Ag contents (3 and 5%) was evaluated by its ability to degrade furfural solution under visible light irradiation. The Ag/TiO2/EP exhibits wide absorption in the visible light region and shows visible light-driven photocatalytic activities in furfural degradation compared with TiO2/EP photocatalyst. The Ag/TiO2/EP (5%) was the best concentration of photocatalyst dosage with almost 80% furfural degradation under visible light. The antibacterial character of Ag/TiO2/EP with different Ag contents has been tested against Escherichia Coli under visible light. The photocatalytic activity of Ag/TiO2/EP can be attributed to the plasmonic effect of silver in the separation of photoinduced electrons and holes in resulting photocatalyst. The Ag/TiO2/EP (5%) as a floating photocatalyst combined with its ability to absorb visible light makes it of significant interest for the purification of industrial wastewater.  相似文献   

5.
The photocatalytic degradation of Indigo Caramine dye using commercial TiO2 and fine grained natural rutile has been carried out. The commercial TiO2 and natural rutile were characterized using powder X- ray diffraction (XRD) and Fourier transformed infra red spectroscopy (FTIR). The study on the photodegradation of Indigo Caramine dye using commercial TiO2 and natural rutile were investigated both under Solar and UV irradiation. The degradation of Indigo Caramine dye was checked by the following parameters like Chemical Oxygen Demand (COD), %T, irradiation time and duration. In both cases using commercial TiO2 and natural rutile, the COD of the dye solution was reduced from 288 mg/L to less than 20 mg/L, and similarly the %T was increased from 76% to 97% and the percentage decomposition upto 97% within the irradiation duration of 3.5 hrs. The preliminary results obtained on the photodegradation of Indigo Caramine dye are highly encouraging and further work is being carried out for the use of the natural rutile or anatase sources for the other organic decomposition and treatment of industrial effluents.  相似文献   

6.
To enhance the overall efficiency of oil and grease removal in wastewater coated N-doped TiO2 photocatalytic polyscales were fabricated through sol–gel technique. The materials fabricated were characterized using powder X-ray diffraction, Fourier transmission infrared spectroscopy, scanning electron microscopy, and UV–Vis spectroscopy. In order to enhance degradation efficiency of organic pollutant under natural sun light, shifting of absorption range of TiO2 to visible spectrum, various modifications such as surface modification and size optimization were carried out by doping of nitrogen under sol–gel processes. To ease recovery of suspended catalysts from aqueous media, the coated N-doped TiO2 were prepared by decorating photocatalytic particles onto suitable substrates. N-doped TiO2 polyscales with desired functionalities were coated onto the spherical supporting substrates using a binding agent. The photocatalytic treatment studies clearly indicated the considerable level of the oil and grease and other organic pollutants removal from wastewater (up to 85–90 % ± 2) using coated N-doped TiO2 under natural sunlight as an alternative driving energy source. Removal of oil and grease along with other organic pollutants in wastewater using coated N-doped TiO2 polyscales is a versatile, economical, and environmental friendly technique due to the ease of handling and recovery, utilization of natural sunlight which is renewable energy source.  相似文献   

7.
Undoped and Ni-doped TiO2 nanoparticles are synthesized using sol–gel technique. The physical, structural, optical and thermal properties of the samples are investigated using X-ray powder diffraction, Fourier transform infrared spectroscopy, transmittance electron microscopy, UV–visible diffuse reflectance and thermogravimetric analysis. The photocatalytic activity of the samples is investigated by the photocatalytic degradation of phthalate esters. Phthalate esters have been considered as endocrine disrupting compounds. Ni-doped TiO2 samples show better photocatalytic activity as compared to undoped TiO2 sample. The greater photocatalytic activity of doped samples as compared to undoped TiO2 can be attributed to the production of more number of electron–hole pairs in doped samples.  相似文献   

8.
A simple one-step synthetic approach using rice husk has been developed to prepare magnetic Fe3O4-loaded porous carbons composite (MRH) for removal of arsenate (As(V)). The characteristics of adsorbent were evaluated by transmission electron microscope, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, and thermogravimetric analysis. On account of the combined advantages of rice husk carbons and Fe3O4 nanoparticles, the synthesized MRH composites showed excellent adsorption efficiency for aqueous As(V). The removal of As(V) by the MRH was studied as a function of contact time, initial concentration of As(V), and media pH. The adsorption kinetics of As(V) exhibited a rapid sorption dynamics by a pseudo-second-order kinetic model, implying the mechanism of chemisorption. The adsorption data of As(V) were fitted well to the Langmuir isotherm model, and the maximum uptake amount (q m ) was calculated as 4.33 mg g?1. The successive regeneration and reuse studies showed that the MRH kept the sorption efficiencies over five cycles. The obtained results demonstrate that the MRH can be utilized as an efficient and low-cost adsorbent for removal of As(V) from aqueous solutions.  相似文献   

9.
Transition metal-doped TiO2 nanoparticles are synthesized by sol–gel method. The as-prepared samples are characterized by various techniques to correlate structural and optical properties with chemical nature of dopants and their effect on photocatalytic degradation of diethyl phthalate esters. X-ray diffraction (XRD) reveals that all the samples are crystalline and exhibit anatase as a major phase. Chemical nature of dopants could not affect the formation of anatase and its volume fraction. The crystallite size of undoped and doped TiO2 nanoparticles varies between 10 and 12 nm as confirmed by XRD and transmission electron microscope. The lowest optical band gap observed is 2.47 eV in Mn-doped TiO2. Among all the samples, Ni-doped TiO2 sample shows better photocatalytic activity and degradation of diethyl phthalate due to its lower crystallite size and higher surface area than those of Mn- and Co-doped TiO2 samples.  相似文献   

10.
The present study highlights the synthesis of CuO–ZnO nanocomposite via facile hydrothermal method at 150 °C and autogenous pressure. The structural and textural features of prepared composite material was characterized by several characterization techniques such as X-ray powder diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The optimized prepared nanocomposite was utilized for photocatalytic degradation of aromatic Direct Blue 71 dye (DB71) under natural sunlight conditions. The catalytic activity results by CuO–ZnO nanocomposite were observed to be higher than the reagent-grade zinc oxide under visible light conditions. The response surface methodology protocol (RSM) with central composite design was optimized by different photodegradation operational parameters such as pH, dye concentration, catalyst amount, and reaction time. The optimized RSM results demonstrated that a quadratic polynomial model was found suitable to define the relation between the photocatalytic activity and operational parameters. Moreover, the observed high R 2 value (0.9786) confirms a strong evaluation of experimental data. To achieve maximum DB71 degradation, optimized condition was found at 177.13 min of contact time, 3.93 solution pH, and 24.34 mg/L of dye concentration with 1.85 g/L of catalyst dose The identical optimum conditions resulted maximum 89.58% DB71 degradation.  相似文献   

11.
In this study, a series of RE3+:YVO4 catalysts were successful synthesized by environmentally friendly mild hydrothermal and supercritical hydrothermal techniques. The rare earth-doped YVO4 photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy. The X-ray diffraction analysis reveals that the as-prepared YVO4 crystals are of tetragonal phase. Further, the Fourier transform infrared spectroscopy result shows the absence of OH– molecules. The photoluminescence spectroscopy curves and UV–Vis spectra suggest that the band gap energy of YVO4 is shifted to lower energy level due to doping of Nd3+ and Er3+ ions. The catalytic activities of the as-prepared RE3+:YVO4 samples were tested for the photodegradation of amaranth aqueous dye solution under sunlight irradiation. Remarkably, the rare earth-doped YVO4 nanocrystal sample showed outstanding photocatalytic degradation activities than undoped YVO4 nanocrystal sample with good reusability. Under full spectrum irradiation, the as-prepared Nd3+-doped YVO4 nanocrystals exhibited about 83% degradation efficiency. The apparent rate constant k for as-prepared Nd3+-doped YVO4 nanocrystals with 50 mg of photocatalyst exhibits highest k value (0.32 min?1), which is 2.9% higher than pure YVO4 nanocrystals (0.11 min?1).  相似文献   

12.
The Claus process has been used for the conversion of H2S and SO2 to elemental sulfur. These two sulfur compounds need special attention because they are very poisonous with negative impact on both the environment and human health. Here, highly active Fe–Ni/TiO2 catalyst has been prepared and shaped by three different binders (bentonite, polyethylene glycol and carboxymethyl cellulose) into extrudes. Comparing the mechanical strength and surface area of prepared extrudes, the optimal shaped catalyst was selected with 20% of bentonite, 2% of PEG and 2% of CMC. The optimal catalyst was characterized by X-ray powder diffraction, temperature-programmed reduction, Brunauer–Emmett–Teller specific surface area, Barrett–Joyner–Halenda, scanning electron microscopy and energy-dispersive X-ray techniques and used for sulfur recovery process. The performance of this product for sulfur recovery via Claus process was excellent with the conversion of hydrogen sulfide of 76.77% and sulfur dioxide of 97.83%. The catalyst also provides high hydrolysis activity of CS2 (83.06%). Therefore, a highly active TiO2-supported shaped catalyst with 85.62% of conversion efficiency has been prepared successfully to convert the small amounts of H2S, SO2 and CS2 to elemental sulfur.  相似文献   

13.
In this paper, the adsorption and degradation phenomenon involved in the photocatalytic degradation of dimethyl phthalates (DMPs) by titanium dioxide (TiO2) was studied. A variety of operating variables were selected firstly. Then, it was proved that even for such weak adsorption properties molecules as DMP, adsorption was still an important prerequisite for photolysis. A surface-mediated reaction process was proposed that the photodegradation of DMP assisted by TiO2 particles occurred primarily at the surface of the photocatalyst rather than in the homogeneous phase. According to Langmuir–Hinshelwood model, the adsorption constant determined from the dark adsorption was far less than that obtained in the light condition. Enhanced DMP adsorption on the surface of TiO2 under irradiation was the possible reason for the improvement of photodegradation efficiency. Under the irradiation of light, a synergistic mechanism of adsorption and photocatalysis was responsible for DMP degradation. The quantitative analysis by adding scavengers indicated that ·OH radical was primarily responsible for the photodegradation of DMP. It was further verified that ·OH was produced much more from conduction band electrons rather than valance band holes toward photodegradation of DMP by adding foreign Cu2+.  相似文献   

14.
This study investigated the performance of UV light active TiO2 and UV–visible light active WO3/TiO2 nanoparticles as air purifying materials that can be potentially applied to urban green infrastructures such as rain gardens and pervious pavements. Using a laboratory-scale continuous gas flow photoreactor, the removal efficiency of gaseous nitrogen oxide (NO x ) by two different photocatalytic nanoparticles coated on natural zeolites and pervious concrete blocks was evaluated. The results showed that the TiO2- and WO3/TiO2-coated zeolites are excellent photoactive materials providing enhanced air purification function (~95% removal efficiency of NO x ) under UV and UV–visible light irradiation, respectively. In contrast, both of the TiO2- and WO3/TiO2-coated pervious concrete blocks showed a measurable NO x removal (~60%) only under UV irradiation, whereas the visible light activity of the WO3/TiO2-coated concrete block was significantly reduced (~20%) mainly due to the decrease in the photocatalytic reaction sites for visible light. This study revealed the potential utility of photocatalytic nanoparticles in improving urban air quality, in the form of the surface component of various urban infrastructures.  相似文献   

15.
The present study deals with the effect of Fe2+ on degradation kinetics of imidacloprid in moist soil under UV system. The moist soil samples were spiked with imidacloprid and irradiated in specially designed UV-photoreactor. The analysis of imidacloprid was carried out by using HPLC–DAD system. UV irradiation caused about ten fold increase in photodegradation rate of the pesticide. Amendment of soil with Fe2+ at concentrations of 30 mg/kg led to a further increase in the rate of photodegradation, i.e., a 98 % degradation of imidacloprid was observed in the presence of iron after 32 days of irradiation. Moreover, the half-life of imidacloprid in Fe2+ -amended soil was observed to be reduced to 7 days that in the absence of Fe2+ was recorded to be 21 days. Iron was also observed to affect the half-life of imidacloprid in dark. When compared with unsterilized Fe2+-amended batch treatments, the t 1/2 in sterilized Fe2+-amended batch treatments increased from 58 to 96 days. Imidacloprid-urea was detected by HPLC as the only stable photodegradation byproduct of imidacloprid in the soil.  相似文献   

16.
A pyroxene with composition LiNiSi2O6 was synthesized at T = 1,473 K and P = 2.0 GPa; the cell parameters at T = 298 K are a = 9.4169(6) Å, b = 8.4465(7) Å, c = 5.2464(3) Å, β = 110.534(6)°, V = 390.78(3) Å3. TEM examination of the LiNiSi2O6 pyroxene showed the presence of h + k odd reflections indicative of a primitive lattice, and of antiphase domains obtained by dark field imaging of the h + k odd reflections. A HT in situ investigation was performed by examining TEM selected area diffraction patterns collected at high temperature and synchrotron radiation powder diffraction. In HTTEM the LiNiSi2O6 was examined together with LiCrSi2O6 pyroxene. In LiCrSi2O6 the h + k odd critical reflections disappear at about 340 K; they are sharp up to the transition temperature and do not change their shape until they disappear. In LiNiSi2O6 the h + k odd reflections are present up to sample deterioration at 650 K. A high temperature synchrotron radiation powder diffraction investigation was performed on LiNiSi2O6 between 298 and 773 K. The analysis of critical reflections and of changes in cell parameters shows that the space group is P-centred up to the highest temperature. The comparative analysis of the thermal and spontaneous strain contributions in P21/c and C2/c pyroxenes indicates that the high temperature strain in P-LiNiSi2O6 is very similar to that due to thermal strain only in C2/c spodumene and that a spontaneous strain contribution related to pre-transition features is not apparent in LiNiSi2O6. A different high-temperature behaviour in LiNiSi2O6 with respect to other pyroxenes is suggested, possibly in relation with the presence of Jahn–Teller distortion of the M1 polyhedron centred by low-spin Ni3+.  相似文献   

17.
A new organic hybrid of silicotungstic acid was prepared by means of an easily available, very cheap, and non-toxic amine via a facile precipitation method. Characterization of hybrid was carried out by elemental analyses, Fourier transform infrared spectroscopy, powder X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Dye adsorption and photocatalytic properties of the prepared water-insoluble hybrid were examined by studying the decolorization of model dyes such as methylene blue and methyl, orange and their mixture solutions under ultraviolet, visible, and sunlight irradiation. The effect of different factors containing the initial concentration, pH, catalyst dosage, H2O2 dosage, and salt adding was investigated on the decolorization of dyes. The results showed that the hybrid is a good heterogeneous photocatalyst in the degradation of methylene blue, methyl orange and their mixture and can be recovered and reused. The methylene blue is removed via combination of adsorption and photocatalytic degradation under ultraviolet, visible, and sunlight through direct oxidation by hybrid. The methyl orange is removed via ultraviolet and solar photocatalytic degradation through indirect oxidation by ·OH radicals. While the visible light is not able to degrade methyl orange solution alone in the presence of hybrid, it degrades the methyl orange mixed with methylene blue solution.  相似文献   

18.
High pressure in situ synchrotron X-ray diffraction experiment of strontium orthophosphate Sr3(PO4)2 has been carried out to 20.0 GPa at room temperature using multianvil apparatus. Fitting a third-order Birch–Murnaghan equation of state to the P–V data yields a volume of V 0 = 498.0 ± 0.1 Å3, an isothermal bulk modulus of K T  = 89.5 ± 1.7 GPa, and first pressure derivative of K T ′ = 6.57 ± 0.34. If K T ′ is fixed at 4, K T is obtained as 104.4 ± 1.2 GPa. Analysis of axial compressible modulus shows that the a-axis (K a  = 79.6 ± 3.2 GPa) is more compressible than the c-axis (K c  = 116.4 ± 4.3 GPa). Based on the high pressure Raman spectroscopic results, the mode Grüneisen parameters are determined and the average mode Grüneisen parameter of PO4 vibrations of Sr3(PO4)2 is calculated to be 0.30(2).  相似文献   

19.
A new synchrotron X-ray diffraction study of chromium oxide Cr2O3 (eskolaite) with the corundum-type structure has been carried out in a Kawai-type multi-anvil apparatus to pressure of 15 GPa and temperatures of 1873 K. Fitting the Birch–Murnaghan equation of state (EoS) with the present data up to 15 GPa yielded: bulk modulus (K 0,T0), 206 ± 4 GPa; its pressure derivative K′0,T , 4.4 ± 0.8; (?K 0,T /?T) = ?0.037 ± 0.006 GPa K?1; a = 2.98 ± 0.14 × 10?5 K?1 and b = 0.47 ± 0.28 × 10?8 K?2, where α 0,T  = a + bT is the volumetric thermal expansion coefficient. The thermal expansion of Cr2O3 was additionally measured at the high-temperature powder diffraction experiment at ambient pressure and α 0,T0 was determined to be 2.95 × 10?5 K?1. The results indicate that coefficient of the thermal expansion calculated from the EoS appeared to be high-precision because it is consistent with the data obtained at 1 atm. However, our results contradict α 0 value suggested by Rigby et al. (Brit Ceram Trans J 45:137–148, 1946) widely used in many physical and geological databases. Fitting the Mie–Grüneisen–Debye EoS with the present ambient and high-pressure data yielded the following parameters: K 0,T0 = 205 ± 3 GPa, K′0,T  = 4.0, Grüneisen parameter (γ 0) = 1.42 ± 0.80, q = 1.82 ± 0.56. The thermoelastic parameters indicate that Cr2O3 undergoes near isotropic compression at room and high temperatures up to 15 GPa. Cr2O3 is shown to be stable in this pressure range and adopts the corundum-type structure. Using obtained thermoelastic parameters, we calculated the reaction boundary of knorringite formation from enstatite and eskolaite. The Clapeyron slope (with \({\text{d}}P/{\text{d}}T = - 0.014\) GPa/K) was found to be consistent with experimental data.  相似文献   

20.
The crystal structure of Pb6Bi2S9 is investigated at pressures between 0 and 5.6 GPa with X-ray diffraction on single-crystals. The pressure is applied using diamond anvil cells. Heyrovskyite (Bbmm, a = 13.719(4) Å, b = 31.393(9) Å, c = 4.1319(10) Å, Z = 4) is the stable phase of Pb6Bi2S9 at ambient conditions and is built from distorted moduli of PbS-archetype structure with a low stereochemical activity of the Pb2+ and Bi3+ lone electron pairs. Heyrovskyite is stable until at least 3.9 GPa and a first-order phase transition occurs between 3.9 and 4.8 GPa. A single-crystal is retained after the reversible phase transition despite an anisotropic contraction of the unit cell and a volume decrease of 4.2%. The crystal structure of the high pressure phase, β-Pb6Bi2S9, is solved in Pna2 1 (a = 25.302(7) Å, b = 30.819(9) Å, c = 4.0640(13) Å, Z = 8) from synchrotron data at 5.06 GPa. This structure consists of two types of moduli with SnS/TlI-archetype structure in which the Pb and Bi lone pairs are strongly expressed. The mechanism of the phase transition is described in detail and the results are compared to the closely related phase transition in Pb3Bi2S6 (lillianite).  相似文献   

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