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1.
The effect of different chemical parameters on photocatalytic inactivation of E. coli K12 is discussed. Illumination was produced by a solar lamp and suspended TiO 2 P-25 Degussa was used as catalyst. Modifications of initial pH between 4.0 and 9.0 do not affect the inactivation rate in the absence or presence of the catalyst. Addition of H 2O 2 affects positively the E. coli inactivation rate of both photolytic (only light) and photocatalytic (light plus TiO 2) disinfection processes. Addition of some inorganic ions (0.2 mmol/l) like HCO 3−, HPO 42−, Cl −, NO 3− and SO 42− to the suspension affects the sensitivity of bacteria to sunlight in the presence and in absence of TiO 2. Addition of HCO 3− and HPO 42− resulted in a meaningful decrease in photocatalytic bactericidal effect while it was noted a weak influence of Cl −, SO 42− and NO 3−. The effect of counter ion (Na + and K +) is not negligible and can modify the photocatalytic process as the anions. Bacteria inactivation was affected even at low concentrations (0.2 mmol/l) of SO 42− and HCO 3−, but the same concentration does not affect the resorcinol photodegradation, suggesting that disinfection is more sensitive to the presence of natural anions than photocatalytic degradation of organic compounds. The presence of organic substances naturally present in water like dihydroxybenzenes isomers shows a negative effect on photocatalytic disinfection. The effect of a mixture of chemical substances on photocatalytic disinfection was also studied by adding to the bacterial suspension nutrient broth, phosphate buffer and tap water. 相似文献
2.
The effect of oxygen concentration on the pulse and steady-state selective catalytic reduction (SCR) of NO with C 3H 6 over CuO/γ-Al 2O 3 has been studied by infrared spectroscopy (IR) coupled with mass spectroscopy studies. IR studies revealed that the pulse SCR occurred via (i) the oxidation of Cu 0/Cu + to Cu 2+ by NO and O 2, (ii) the co-adsorption of NO/NO 2/O 2 to produce Cu 2+(NO 3−) 2, and (iii) the reaction of Cu 2+(NO 3−) 2 with C 3H 6 to produce N 2, CO 2, and H 2O. Increasing the O 2/NO ratio from 25.0 to 83.4 promotes the formation of NO 2 from gas phase oxidation of NO, resulting in a reactant mixture of NO/NO 2/O 2. This reactant mixture allows the formation of Cu 2+(NO 3−) 2 and its reaction with the C 3H 6 to occur at a higher rate with a higher selectivity toward N 2 than the low O 2/NO flow. Both the high and low O 2/NO steady-state SCR reactions follow the same pathway, proceeding via adsorbed C 3H 7---NO 2, C 3H 7---ONO, CH 3COO −, Cu 0---CN, and Cu +---NCO intermediates toward N 2, CO 2, and H 2O products. High O 2 concentration in the high O 2/NO SCR accelerates both the formation and destruction of adsorbates, resulting in their intensities similar to the low O 2/NO SCR at 523–698 K. High O 2 concentration in the reactant mixture resulted in a higher rate of destruction of the intermediates than low O 2 concentration at temperatures above 723 K. 相似文献
3.
Photocatalysis of a hollandite compound K xGa xSn 8−xO 16 ( x = ca. 1.8) was examined for the reduction of nitrate ion with a reducing agent of methanol in water under UV irradiation. Hollandites have a characteristic one-dimensional tunnel structure. The hollandite powder, which was prepared by the sol–gel method and unloaded with any additives like metals, was used as the photocatalyst and its photocatalytic reaction was analyzed quantitatively by using ion chromatography and on-line mass spectrometry, and its reaction mechanism was analyzed by in-situ FT-IR. The hollandite photocatalyst showed a significant activity for the formation of N 2 from NO 3−. The nitrate was reduced to N 2 and NO 2−, while the reducing agent methanol was partly oxidized to change to formic acid. The conversion of NO 3−was proportional to the yields of N 2, NO 2−, and HCOO −. The present photocatalyzed decomposition of NO 3− to N 2 would be a useful photocatalysis for the environmental protection of water. 相似文献
4.
Oxygen reduction on the Au(100) face was studied by the rotating disk-ring electrode technique in solutions of anions which adsorb strongly on gold (HSO 4−/SO 42− and/or OH −) over the entire pH range. The specific adsorption of OH − anions, which is a pH dependent process, is found to play the key role in determining the reaction pathways. In the absence of OH − adsorption, for pHs below 6, the reduction of O 2 begins as a 2e-process. Due to the increase in local pH during O 2 reduction, the reaction pathway turns into a 4e-reduction at a certain potential depending on the pH of the solution. For pHs higher than 6, O 2 reduction begins as a 4e-process in the potential region where specifically adsorbed OH − anions are present. 相似文献
5.
The emissions of CO 2, NO x and SO 2 from the combustion of a high-volatile coal with N 2- and CO 2-based, high O 2 concentration (20, 50, 80, 100%) inlet gases were investigated in an electrically heated up-flow-tube furnace at elevated gas temperatures (1123–1573 K). The fuel equivalence ratio, φ, was varied in the range of 0.4–1.6. Results showed that CO 2 concentrations in flue gas were higher than 95% for the processes with O 2 and CO 2-based inlet gases. NO x emissions increased with φ under fuel-lean conditions, then declined dramatically after φ=0.8, and the peak values increased from about 1000 ppm for the air combustion process and 500 ppm for the O 2(20%)+CO 2(80%) inlet gas process to about 4500 ppm for the oxygen combustion process. When φ>1.4 the emissions decreased to the same level for different O 2 concentration inlet gas processes. On the other hand, NO x emission indexes decreased monotonically with φ under both fuel-lean and fuel-rich combustion. SO 2 emissions increased with φ under fuel-lean conditions, then declined slightly after φ>1.2. Temperature has a large effect on the NO x emission. Peak values of the NO x emission increased by 50–70% for the N 2-based inlet gas processes and by 30–50% for the CO 2-based inlet gas process from 1123 to 1573 K. However, there was only a small effect of temperature on the SO 2 emission. 相似文献
6.
The NO, NO/O 2, and NO/O 2/H 2O adsorption on MnO 2/NaY (5 and 15 wt.% MnO 2) composite catalyst and NaY has been studied by means of in situ FTIR and EPR spectroscopy at elevated temperatures and during heating under reaction-like conditions. NO adsorption and co-adsorption of NO and O 2 on NaY and MnO 2/NaY proceeds via oxidation of NO forming NO 2− and NO 3− species. Whereas the manganese dioxide preferably acts as oxidising agent, the zeolite stores the NO x species as nitrite and nitrate ions in the solid. In the presence of oxygen, the nitrate formation is enhanced due to additional oxidation of NO through gaseous oxygen leading to NO 2. Dimerisation of NO 2 to N 2O 4 and following disproportionation of the latter causes the formation of NO + and NO 3− species which are associated with nucleophilic zeolitic oxygen and especially alkali cations of the zeolite, respectively. The presence of oxygen facilitates reoxidation of Mn 2+ which keeps more Mn ions in the active state. Pre-adsorbed water and higher amounts of water vapour in the feed hinder the NO adsorption by blocking the adsorption sites and shift the nitrate formation to higher temperatures. The quantities and thermal stability of the nitrates formed during NO and NO/O 2 adsorption differs which points to a different mechanism of nitrate formation. In the absence of gaseous oxygen, nitrates are formed by participation of only lattice oxygen. In the presence of oxygen, nitrate formation by dimerisation and disproportionation reactions of NO 2 dominates. The manganese component of the composite catalyst supports the oxidation of NO to nitrite and subsequently to nitrate. During this process Mn 4+ is reduced to Mn 2+ as evidenced by in situ EPR measurements. 相似文献
7.
N 2O 5 reacts with O 2− ion in LiCl---KCl eutectic at 450° to give NO 3−. By analogy to the salts of the other oxides of Group V, NO 3− can be considered as metanitrate and is expected to give—under appropriate conditions—the corresponding pyro-salt. Experiments are described in which the O 2− ion in LiCl---KCl melt is potentiometrically titrated with KNO 3. The titration curves show an inflexion at the composition corresponding to pyronitrate, N 2O 74−. The formation of pyronitrate in KNO3 melts is also established. Strong oxide-ion donors, eg Na2O2 or NaOH, or electrolytically generated O2− ion, react slowly with the melt to produce a compound of less basic character. The reaction is zero-order with respect to O2− and has an activation energy of ca 6·17 Kcal/mole. Pyronitrate in molten KNO3 possesses a basicity comparable to that of the carbonate ion in the same melt. It readily lends its oxide ion to strong acids eg, Cr2O72− and PO3−. X-ray diffraction patterns of NO3−-N2O74− mixtures show peaks that can be correlated to the new anion. 相似文献
8.
Partial conductivities in the SrCe(Y)O 3−δ system have been studied in oxidising conditions in the temperature range 923–1273 K. Compositions with variable Y content (5 and 10 at.%), Sr deficiency (3 at.%), and with the addition of Fe 2O 3 as sintering aid (2 mol%) were analysed. A modified Faradaic efficiency method and oxygen permeation measurements were employed to appraise the oxide-ionic transport. Oxide-ion transference numbers in air lie in the range 0.19–0.80 and decrease with increasing temperature in the range 973–1223 K. Modelling of total conductivity as a function of oxygen partial pressure ( p(O 2)) confirmed that protonic transport is minor under the studied conditions. SrCe 0.95Y 0.05O 3−δ exhibits greater oxide-ion conductivity than SrCe 0.9Y 0.1O 3−δ, indicative of dopant–vacancy association at high dopant contents. Conversely, oxygen permeability is slightly higher for SrCe 0.9Y 0.1O 3−δ as a result of faster surface-exchange kinetics. The oxygen flux through Fe-free membranes is dominated by the bulk in low p(O 2) gradients, when the permeate-side p(O 2) is higher than 0.03 atm, but surface exchange plays an increasing role with increasing p(O 2) gradient. Addition of Fe 2O 3 to SrCe(Y)O 3−δ lowers the sintering temperature by 100 K but results in the formation of intergranular second phases which block oxide-ionic and electronic transport, and thus oxygen permeation. The average thermal expansion coefficients (TECs) are (10.8–11.6) × 10 −6 K −1 in the temperature range 373–1373 K for all studied compositions. 相似文献
9.
Selective catalytic reduction of NO x (SCR-NO x) with decane, and for comparison with propane and propene over Cu-ZSM-5 zeolite (Cu/Al 0.49, Si/Al 13.2) was investigated under presence and absence of water vapor. Decane behaves in SCR-NO x like propene, i.e. the Cu-zeolite activity increased under increasing concentration of water vapor, as demonstrated by a shift of the NO x–N 2 conversion to lower temperatures, in contrast to propane, where the NO x–N 2 conversion is highly suppressed. In situ FTIR spectra of sorbed intermediates revealed similar spectral features for C 10H 22– and C 3H 6–SCR-NO x, where –CH x, R–NO 2, –NO 3−, Cu +–CO, –CN, –NCO and –NH species were found. On contrary, with propane –CH x, R–NO 2, NO 3−, Cu +–CO represented prevailing species. A comparison of the in situ FTIR spectra (T–O–T and intermediate vibrations) recorded at pulses of propene and propane, moreover, under presence and absence of water vapor in the reaction mixture, revealed that the Cu 2+–Cu + redox cycle operates with the C 3H 6–SCR-NO x reactions in both presence/absence of water vapor, while with C 3H 8–SCR-NO x, the redox cycle is suppressed by water vapor. It is concluded that decane cracks to low-chain olefins and paraffins, the former ones, more reactive, preferably take part in SCR-NO x. It is concluded that formation of olefinic compounds at C 10H 22–SCR-NO x is decisive for the high activity in the presence of water vapor, while water molecules block propane activation. The increase in NO x–N 2 conversion due to water vapor in C 10H 22–SCR-NO x should be connected with the increased reactivity of intermediates. These are suggested to pass from R–NO x → –CN → –NCO → NH 3; the latter reacts with another activated NO x molecule to molecular nitrogen. The positive effect of water vapor on the NO x–N 2 conversion is attributed to increased hydrolysis of –NCO intermediates. 相似文献
10.
The swelling features of gelatine gels in water (good solvent) were studied as a function of thermodynamic conditions of sol—gel transition and ripening. It is shown that the degree of equilibrium swelling Qe varies with the volume fraction of the polymer in a casting solution φ o in accordance with the prediction of the classic theory: Qe φ o−0.4. Qc, as a function of the gelation temperature Tg, the ripening time tr and φ o, can be rescaled and described by the single empirical equation: Qe Tg−x tr−yφ o−0.4, where x = 0.1, y = 0.15 for wet gels and X = −0.5, y = 0.04 for dried gels. The kinetics of macroscopic swelling is described by the equation of Peters and Candau, with values of collective diffusion coefficients being in good agreement with values obtained by other workers via photon correlation spectroscopy. 相似文献
11.
Layered Li[Ni (1−x)/3Mn (1−x)/3Co (1−x)/3Cr x]O 2 materials with x = 0, 0.01, 0.02, 0.03, 0.05 are prepared by a solid-state pyrolysis method. The oxide compounds were calcined with various Cr-doped contents, which result in greater difference in morphological (shape, particle size and specific surface area) and the electrochemical (first charge profile, reversible capacity and rate capability) differences. The Li[Ni (1−x)/3Mn (1−x)/3Co (1−x)/3Cr x]O 2 powders were characterized by means of X-ray diffraction (XRD), charge/discharge cycling, cyclic voltammetry, and SEM. XRD experiment revealed that the Li[Ni (1−x)/3Mn (1−x)/3Co (1−x)/3Cr x]O 2 ( x = 0, 0.01, 0.02, 0.03, 0.05) were crystallized to well layered -NaFeO 2 structure. The first specific discharge capacity and coulombic efficiency of the electrode of Cr-doped materials were higher than that of pristine material. When x = 0.02, the sample showed the highest first discharge capacity of 241.9 mAh g −1 at a current density of 30 mA g −1 in the voltage range 2.3–4.6 V, and the Cr-doped samples exhibited higher discharge capacity and better cycleability under medium and high current densities at room temperature. 相似文献
12.
The production and decay of singlet molecular oxygen ( 1O 2) in TiO 2 photocatalysis were investigated by monitoring its phosphorescence under various reaction conditions. First, the effects of additives such as KBr, KSCN, KI, H 2O 2, and ethanol on the amount of 1O 2 produced by photo excitation of P25 TiO 2 were measured. The same additives were employed to investigate the effect on the amount of O 2− produced. Comparison between the effects on 1O 2 and O 2− suggested that 1O 2 is formed by the electron transfer mechanism, the reduction of molecular oxygens to O 2− by photogenerated electrons and the subsequent oxidation of O 2− to 1O 2 by photogenerated holes. The formation of 1O 2 decreased at pH < 5 and pH > 11, indicating that the intermediate O 2− is stabilized at the terminal OH site of the TiO 2 surface in the pH range of 5 < pH < 11. Eighteen commercially available TiO 2 photocatalysts were compared on the formation of 1O 2 and O 2− in an aqueous suspension system. The formation of 1O 2 was increased with decreasing size of TiO 2 particles, indicating that a large specific surface area causes a higher possibility of reduction producing O 2− and then a large amount of 1O 2 is formed. The difference in the crystal phase (rutile and anatase) did not affect the formation of 1O 2. 相似文献
13.
Hydroxyapatite (Ca 10(PO 4) 6(OH) 2: HAP) was co-substituted with Ti(IV) and antibacterial ions (Ag +, Cu 2+ or Zn 2+) (HAPTiM), by coprecipitation and ion-exchange methods. Both HAPTiAg and HAPTiCu coated on porous spumous nickel film showed high efficiency for killing Escherichia coli and Staphylococcus aureus in the dark and under weak UVA irradiation, respectively. Moreover, their bactericidal activities were much higher than that of P25-TiO 2 film. The studies of ESR revealed that not only O 2− was formed on HAPTiM, HAPTi, HAP and P25-TiO 2 films under weak UVA irradiation, but also at ambient temperature without light O 2− was generated on HAPTiCu, HAPTiAg, and HAPTi. The redox couples of Cu 0/Cu 2+ and Ag 0/Ag + in the structure of HAPTiCu (Ag) caused the transfer of electron leading to the O 2− generation under the above conditions. The higher bactericidal activities of HAPTiM were due to the synergy of the oxidation role of the O 2− and the bacteriostatic action of antibacterial ions. The process of the damage of the cell wall and the cell membrane was directly observed by TEM, and further confirmed by the determination of potassium ion (K +) leakage from the killed bacteria. 相似文献
14.
Pulse reaction method and in situ IR spectroscopy were used to characterize the active oxygen species for oxidative coupling of methane (OCM) over SrF 2/Nd 2O 3 catalyst. It was found that OCM activity of the catalyst was very low in the absence of gas phase oxygen, which indicated that lattice oxygen species contributed little to the yield of C 2 hydrocarbons. IR band of superoxide species (O 2−) was detected on the O 2-preadsorbed SrF 2/Nd 2O 3. The substitution of 18O 2 isotope for 16O 2 caused the IR band of O 2− at 1128 cm −1 to shift to lower wavenumbers (1094 and 1062 cm −1), consistent with the assignment of the spectra to the O 2− species. A good correlation between the rate of disappearance of surface O 2− and the rate of formation of gas phase C 2H 4 was observed upon interaction of CH 4 with O 2-preadsorbed catalyst at 700 °C. The O 2− species was also observed on the catalyst under working condition. These results suggest that O 2− species is the active oxygen species for OCM reaction on SrF 2/Nd 2O 3 catalyst. 相似文献
15.
Nanometer perovskite-type oxides La 1−xSr xMO 3−δ (M = Co, Mn; x = 0, 0.4) have been prepared using the citric acid complexing-hydrothermal-coupled method and characterized by means of techniques, such as X-ray diffraction (XRD), BET, high-resolution scanning electron microscopy (HRSEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and temperature-programmed reduction (TPR). The catalytic performance of these nanoperovskites in the combustion of ethylacetate (EA) has also been evaluated. The XRD results indicate that all the samples possessed single-phase rhombohedral crystal structures. The surface areas of these nanomaterials ranged from 20 to 33 m 2 g −1, the achievement of such high surface areas are due to the uniform morphology with the typical particle size of 40–80 nm (as can be clearly seen in their HRSEM images) that were derived with the citric acid complexing-hydrothermally coupled strategy. The XPS results demonstrate the presence of Mn 4+ and Mn 3+ in La 1−xSr xMnO 3−δ and Co 3+ and Co 2+ in La 1−xSr xCoO 3−δ, Sr substitution induced the rises in Mn 4+ and Co 3+ concentrations; adsorbed oxygen species (O −, O 2−, or O 22−) were detected on the catalyst surfaces. The O 2-TPD profiles indicate that Sr doping increased desorption of the adsorbed oxygen and lattice oxygen species at low temperatures. The H 2-TPR results reveal that the nanoperovskite catalysts could be reduced at much lower temperatures (<240 °C) after Sr doping. It is observed that under the conditions of EA concentration = 1000 ppm, EA/oxygen molar ratio = 1/400, and space velocity = 20,000 h −1, the catalytic activity (as reflected by the temperature ( T100%) for EA complete conversion) increased in the order of LaCoO 2.91 ( T100% = 230 °C) ≈ LaMnO 3.12 ( T100% = 235 °C) < La 0.6Sr 0.4MnO 3.02 ( T100% = 190 °C) < La 0.6Sr 0.4CoO 2.78 ( T100% = 175 °C); furthermore, there were no formation of partially oxidized by-products over these catalysts. Based on the above results, we conclude that the excellent catalytic performance is associated with the high surface areas, good redox properties (derived from higher Mn 4+/Mn 3+ and Co 3+/Co 2+ ratios), and rich lattice defects of the nanostructured La 1−xSr xMO 3−δ materials. 相似文献
16.
Fine powders of submicron-sized crystallites of BaTiO 3 were prepared at 85–130°C by the hydrothermal method, starting from TiO 2.ξH 2O gel and Ba(OH) 2 solution. The products obtained below 110°C incorporated considerable amounts of H 2O and OH − in the lattice. As-prepared BaTiO 3 is cubic and converts to the tetragonal phase after heat treatment at 1200°C, accompanied by the loss of residual OH − ions. Hydrothermal reaction of SnO 2.ξH 2O gel with Ba(OH) 2 at 150–260°C gives rise to the hydrated phase, BaSn(OH) 6.3H 2O, due to the amphoteric nature of SnO 2.ξH 2O which stabilises Sn(OH) 62− anions in basic media. On heating in air or releasing the pressure in situ at 260°C, BaSn(OH) 6.3H 2O converts to BaSnO 3 through an intermediate, BaSnO(OH) 4. Solid solutions of Ba(Ti,Sn)O 3 are directly formed from (TiO 2 + SnO 2)..ξH 2O gel up to 35 mol% SnO 2. At higher Sn contents, the hydrothermal products are mixtures of BaSn(OH) 6.3H 2O and BaTiO 3, which on annealing at 1000°C result in monophasic Ba(Ti,Sn)O 3. The sintering characteristics and the dielectric properties of the ceramics prepared out of these fine powders are presented. The dielectric properties of fine-grained Ba(Ti,Sn)O 3 ceramics are explained on the basis of the prevailing diffuse phase transition behaviour. 相似文献
17.
CeO 2 and CeReO x_ y catalysts are prepared by the calcination at different temperatures ( y = 500–1000 °C) and having a different composition (Re = La 3+ or Pr 3+/4+, 0–90 wt.%). The catalysts are characterised by XRD, H 2-TPR, Raman, and BET surface area. The soot oxidation is studied with O 2 and NO + O 2 in the tight and loose contact conditions, respectively. CeO 2 sinters between 800–900 °C due to a grain growth, leading to an increased crystallite size and a decreased BET surface area. La 3+ or Pr 3+/4+ hinders the grain growth of CeO 2 and, thereby, improving the surface catalytic properties. Using O 2 as an oxidant, an improved soot oxidation is observed over CeLaO x_ y and CePrO x_ y in the whole dopant weight loading and calcination temperature range studied, compared with CeO 2. Using NO + O 2, the soot conversion decreased over CeLaO x_ y catalysts calcined below 800 °C compared with the soot oxidation over CeO 2_ y. CePrO x_ y, on the other hand, showed a superior soot oxidation activity in the whole composition and calcination temperature range using NO + O 2. The improvement in the soot oxidation activity over the various catalysts with O 2 can be explained based on an improvement in the external surface area. The superior soot oxidation activity of CePrO x_ y with NO + O 2 is explained by the changes in the redox properties of the catalyst as well as surface area. CePrO x_ y, having 50 wt.% of dopant, is found to be the best catalyst due to synergism between cerium and praseodymium compared to pure components. NO into NO 2 oxidation activity, that determines soot oxidation activity, is improved over all CePrO x catalysts. 相似文献
18.
The Randles circuit well represents impedance measurements carried out with activated Pt electrodes. This enables us to study the variation of jo for redox reactions with concentration of the reactants, at constant potential, and also the variation of jo with potential, keeping constant the concentration of one of the reactants. The results thus obtained indicate that the step Br 2 + e Br 2− is rate-determining; it is followed or preceded by the rapid equilibria Br 2− Br − + Br 2Br Br 2. The mechanisms proposed hitherto for the electrochemical behaviour of the halogen/halide systems at inert electrodes are discussed, and it is reasoned that the ‘reversibility’ of these systems increases in the order Cl 2/Cl − < Br 2/Br − < I 2/I. 相似文献
19.
Co/ZSM-5 catalysts were prepared by several methods, including wet ion exchange (WIE), its combination with impregnation (IMP), solid state ion exchange (SSI) and sublimation (SUB). FTIR results show that the zeolite protons in H-ZSM-5 are completely removed when CoCl 2 vapor is deposited. TPR shows peaks for Co 2+ ions at 695–705°C and for Co 3O 4 at 385–390°C, but a peak in the 220–250°C region appears to indicate Co 2+ oxo-ions. The catalysts have been tested for the selective reduction of NOx with iso-C4H10 under O2-rich conditions and in the absence of O2, both with dry and wet feeds. A bifunctional mechanism appears to operate at low temperature: oxo-ions or Co3O4 clusters first oxidize NO to NO2, which is chemisorbed as NOy (y≥2) and reduced. In this modus operandi catalyst SUB shows the highest N2 yield 90% near 390°C for dry and wet feeds. It is found to be quite stable in a 52 h run with a wet feed. In contrast, the WIE catalyst, which mainly contains isolated Co2+ ions and has poor activity below 400°C, excels at T>430°C. This and the observation that, at high temperature, NO is reduced in O2-free feeds over Co/MFI catalysts, suggest that NO can be reduced over Co2+ ions without intermediate formation of NO2. The bifunctional mechanism at low temperature is supported by the fact that a strongly enhanced performance is obtained by mixing WIE with Fe/FER, a catalyst known to promote NO2 formation. 相似文献
20.
The hydroxyapatite (HAP) is prepared by precipitation method and examined for the photocatalytic degradation of calmagite, a toxic and non-biodegradable azo-dye compound. The physicochemical properties of hydroxyapatite material were characterized using BET surface area, XRD, FT-IR, and SEM analysis. The FT-IR analysis of the hydroxyapatite revealed that the peak intensity due to absorbance of surface PO 43− group centered at wave number 1030 cm −1 is drastically decreased upon exposure to UV for 1 h. The study includes dark adsorption experiments at different pH conditions, influence of the amount of catalyst, and effect of pH on photocatalytic degradation of dye, chemical oxygen demand (COD) removal, biological oxygen demand (BOD 5) increase and SO 42− and NO 3− ions evolution during the degradation. At optimum photocatalytic experimental conditions the same is compared with commercial degussa P-25 TiO 2. The photocatalytic treatment significantly reduced the COD (92% removal) and increased the BOD 5/COD ratio to 0.78. Considerable evolution of SO 42− (8.5 mg L −1) and NO 3− (12.2 mg L −1) ions are achieved during the degradation process, thus reflecting the usefulness of the hydroxyapatite photocatalytic treatment in calmagite removal in wastewater. 相似文献
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