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1.
Sze-Mun Lam Jin-Chung Sin Abdul Rahman Mohamed 《Korean Journal of Chemical Engineering》2010,27(4):1109-1116
P25 powder embedded and TiO2 immobilized on activated carbon (TiO2-P25/AC) was prepared by P25 powder modified sol-gel and dip-coated method. The photocatalysts were characterized by XRD, BET, SEM and their photocatalytic activities were evaluated through phenol degradation in a fluidized bed photoreactor. The addition of P25 in the photocatalysts could significantly enhance the photocatalytic activity, and the optimum loading of P25 was 3 g L?1. The operating parameter results indicated that the optimum pH for phenol degradation was 5.2; the effect of air flow rate gave an optimal value of 2 L min?1; the increasing of UV light intensity led to an increase of degradation efficiency due to more photons absorbed on the surface of the photocatalyst. The kinetics of the phenol degradation fitted well with the Langmuir-Hinshelwood kinetics model. Finally, the photocatalytic ability of TiO2-P25/AC was reduced only 10% after five cycles for phenol degradation. 相似文献
2.
Sayed Javid Royaee Morteza Sohrabi Faezeh Soleymani 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(2):205-212
BACKGROUND: Photocatalysis is one of the advanced oxidation processes that has gained in importance over recent years owing to its ability to decompose a wide range of organic and inorganic pollutants at ambient temperature and pressure. However, there are two essential issues regarding photocatalytic processes, i.e. limitations on photon transfer and on mass transfer. In the present study, a novel photo‐impinging streams reactor, which can minimize such limitations, has been utilized in the photocatalytic degradation of phenol. The design and operating parameters such as type of nozzle, flow rate, catalyst loading, pH, initial phenol concentration and light intensity were found to have the expected impact on the efficiency of the process. The effects of two different co‐oxidants, H2O2 and Na2S2O8 on the photocatalysis were also examined. RESULTS: Results indicated that 100 mg L?1 of phenol in a 750 cm3 solution was completely degraded within 2.5 h reaction time in the presence of TiO2 without a co‐oxidant present; and within 1 h in the presence of a co‐oxidant. CONCLUSION: A comparison between the current data and those available in the literature revealed higher efficiency and increased performance of the present reactor relative to conventional apparatus. Copyright © 2010 Society of Chemical Industry 相似文献
3.
Nitrogen-doped TiO2 (TiO2?xNy) nanoparticles with and without adding Sm3+ were synthesized by thermohydrolysis of TiCl3. The samples were characterized by X-ray diffraction, specific surface area determination, UV–Vis diffuse reflectance spectroscopy. The photocatalytic activity of the sample was investigated by employing the oxidative destruction of nitric oxide as a probe reaction using a flow reactor. Although the doping of Sm3+ in the lattice of titania was not useful to improve the photocatalytic activity, loading of samarium oxides on the surface of titania resulted in an improvement of the photocatalytic activity of the nitrogen-doped TiO2. The beneficial effect was explained by an increased separation efficiency of the photogenerated electron–hole pairs. 相似文献
4.
Jin-Chung Sin Sze-Mun Lam Abdul Rahman Mohamed 《Korean Journal of Chemical Engineering》2011,28(1):84-92
TiO2 deposited on granular activated carbon (TiO2/GAC) was used for photocatalytic degradation of phenol. The effects of photocatalyst loading, initial substrate concentration and addition of an oxidizing agent as H2O2 were investigated using a one-factor-at-a-time experiment. Central composite design, an experimental design for response surface methodology (RSM), was used for the modelling and optimization of the phenol degradation. Analysis of variance (ANOVA) indicated that the proposed quadratic model was in agreement with the experimental case with R2 and R adj 2 correlation coefficients of 0.9760 and 0.9544, respectively. Accordingly, the optimum conditions for phenol degradation were a photocatalyst loading of two layers, initial phenol concentration of 34.44 mg L?1 and H2O2 concentration of 326.90 mg L?1. The TiO2/GAC was used for five cycles with phenol degradation efficiency still higher than 90%. Finally, the phenol that remained adsorbed on GAC was able to migrate to TiO2 and then photocatalytically be degraded. 相似文献
5.
Photocatalytic conversion of benzene to phenol using modified TiO2 and polyoxometalates 总被引:1,自引:0,他引:1
The application of photocatalytic reactions to organic synthesis has attracted interests in view of the development of environmentally benign synthetic processes. This study investigated the effects of various parameters (electron acceptor, surface modification, and the combination of photocatalysts) on the direct synthesis of phenol from benzene using photocatalytic oxidation processes. The OH radicals generated on UV-illuminated TiO2 photocatalyst directly hydroxylate benzene to produce phenol, hydroquinone, and catechol. The addition of Fe3+, H2O2, or Fe3+ + H2O2 highly enhanced the phenol production yield and selectivity in TiO2 suspension. Surface modifications of TiO2 had significant influence on the phenol synthetic reaction. Depositing Pt nanoparticles on TiO2 (Pt/TiO2) markedly enhanced the yield and selectivity. Surface fluorination of TiO2 (F-TiO2) increased the phenol yield two-fold because of the enhanced production of mobile (free) OH radicals on F-TiO2. Polyoxometalate (POM) in phenol synthesis played the dual role both as a homogeneous photocatalyst and as a reversible electron acceptor in TiO2 suspension. POM alone was as efficient as TiO2 alone in the phenol production. In particular, the addition of POM to the TiO2 suspension increased the phenol yield from 2.6% to 11% (the highest yield obtained in this study). Reaction mechanisms for each photocatalytic system were discussed in relation to the phenol synthesis. 相似文献
6.
Lili Zhang Jianquan Liu Cao Tang Jinshun Lv Hui Zhong Yijiang Zhao Xin Wang 《Applied Clay Science》2011,51(1-2):68-73
The photocatalytic removal of phenol was studied using palygorskite-SnO2–TiO2 composites (abbreviated as Paly-SnO2–TiO2) under ultraviolet radiation. The photocatalysts were prepared by attachment of SnO2–TiO2 oxides onto the surface of the palygorskite by in situ sol–gel technique. The products were characterized by XRD, TEM and BET measurements. SnO2–TiO2 nanoparticles, with an average diameter of about 10 nm, covered the surface of the palygorskite fibers without obvious aggregation. Compared with palygorskite-titania (Paly-TiO2), palygorskite-tin dioxide (Paly-SnO2), and Degussa P25, Paly-SnO2–TiO2 and SnO2–TiO2 exhibited much higher photocatalytic activity. The photodecomposition of phenol was as high as 99.8% within 1.5 h. The apparent rate constants (kapp) for Paly-SnO2–TiO2, TiO2, and P25 were measured. Paly-SnO2–TiO2 showed the highest rate constant (0.03435 min?1). The chemical oxygen demand (COD) of the phenol solution was reduced from 220.2 mg/L to 0.21 mg/L, indicating the almost complete decomposition of phenol. Reusability of the photocatalyst was proved. 相似文献
7.
Archis A Yawalkar Dhananjay S Bhatkhande Vishwas G Pangarkar Anthony A
C
M Beenackers 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2001,76(4):363-370
Photocatalytic (TiO2, air and solar radiation) and photochemical (H2O2 and solar radiation) mineralizations of phenol solutions (up to 500 mg dm?3) in a batch reactor using concentric solar radiation were studied. A compound parabolic reflector as a concentrating reflector was used to obtain concentrated solar radiation in both cases. Considerable enhancement (Five‐fold) in the rate of degradation was obtained when concentrated solar radiation was used instead of plain solar radiation in photocatalytic degradation. The effect of initial phenol concentration, intensity and presence of anions has been studied in both the cases. Low concentrations of intermediates were observed, during the reaction, over the entire range of phenol concentrations studied in the case of photocatalytic degradation using Degussa‐P25 TiO2 as photocatalyst and in the absence of anions; whereas significant quantities of intermediates were observed in the case of the photochemical degradation. The presence of anions generally had a detrimental effect on the mineralization process in both cases. Different anions showed different effects. Total organic carbon (TOC) variations with time were also studied. A rational explanation has been given for the decrease in the rate in the presence of anions. © 2001 Society of Chemical Industry 相似文献
8.
《Ceramics International》2023,49(4):5977-5985
The efficient TiO2 NTs/Sn3O4 photocatalysts were synthesized by the hydrothermal deposition of Sn3O4 on TiO2 nanotube arrays (TiO2 NTs), and the morphology, microstructure and photocatalytic property were adjusted by changing the alkali kind. The TiO2 NTs/Sn3O4 prepared with NaOH exhibited the outstanding photoelectric conversion and photocatalytic environment remediation/H2 evolution. The methylene blue (MB) dye and Cr(VI) could be removed by the as-prepared photocatalysts under visible light irradiation, and ?O2?/?OH radicals were the main active species for MB photodegradation. Furthermore, the high photocatalytic H2 evolution rate was as high as 6.49 μmol cm?2 h?1. The outstanding photocatalytic activity and stability of TiO2 NTs/Sn3O4 photocatalysts would exhibit attractive prospect in the wastewater remediation and electric energy/hydrogen generation. 相似文献
9.
Preparation of aerochitin‐TiO2 composite for efficient photocatalytic degradation of methylene blue
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An aerochitin–titania (TiO2) composite was successfully synthesized and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, and N2 adsorption isotherms. The photocatalytic activity of the composite was investigated on the degradation of the model organic pollutant, methylene blue (MB) dye, under UV irradiation. The aerochitin–TiO2 composite showed excellent adsorptive and photocatalytic activity with a degradation degree of 98% for MB. The first‐order rate constants for the photodegradation MB by TiO2 nanoparticles and aerochitin–TiO2 composite were found to be (3.49 ± 0.04) × 10?3 and (1.82 ± 0.02) × 10?2 min?1. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45908. 相似文献
10.
Titanium dioxide (TiO2) and powdered activated carbon (PAC) were fabricated via a layer by layer arrangement on a glass plate using a dip-coating technique for the photocatalytic-adsorptive removal of phenol. Thinner TiO2 layer coated on PAC sub-layer has larger surface area and better phenol removal than the thicker TiO2 layer. The system obeyed the Langmuir isotherm model, which exhibited a homogeneous and monolayer adsorption with a maximum capacity of 27.8 mg g-1. The intra-particle diffusion was the rate-limiting step as the linear plot crossed the origin, while the adsorption was unfavorable at elevated temperature. Under light irradiation, the TiO2/PAC system removed phenol two-times more effectively than the TiO2 monolayer due to the synergistic effect of photocatalysis by TiO2 top layer and adsorption by PAC sub-layer. The COD removal of phenol was rapid for 10mg L-1 of concentration and under solar light irradiation. It was shown that the PAC sub-layer plays a significant role in the total removal of phenol by providing the adsorption sites and slowing down the recombination rate of charge carriers to improve the TiO2 photocatalytic oxidation performance. 相似文献
11.
Weihong Li Changsheng Guo Bin Su Jian Xu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(5):643-650
BACKGROUND; In this study, simultaneous photocatalytic degradation of four fluoroquinolone (FQ) compounds (i.e. ofloxacin, norfloxacin, ciprofloxacin and enrofloxacin) was investigated in TiO2 suspensions under simulated solar light irradiation. Effects of experimental variables including pH, TiO2 dosage, initial substrate concentration and hydrogen peroxide (H2O2) on the degradation processes were also investigated. RESULTS: The antibiotics degradation was pH‐influenced. The photocatalytic reaction followed the pseudo‐first‐order model, with reaction rate constants (k) 0.026, 0.027, 0.022 and 0.026 min?1 for ofloxacin, norfloxacin, ciprofloxacin and enrofloxacin, respectively. Complete elimination of four FQs was achieved in a reaction system composed of 0.5 g L?1 of TiO2 and 82.5 mg L?1 of H2O2 at pH 6 after 90 min irradiation. Mineralization of FQs during TiO2 photocatalysis was slower than the FQs conversion, and the antibacterial activity of the four FQs was completely removed by TiO2 under simulated solar light irradiation. CONCLUSION: The four FQs can be simultaneously degraded and mineralized with commercially available TiO2 under simulated solar light irradiation. Microbiological analysis showed that the antibacterial activity of the four FQs was completely removed. These results are helpful for antibiotics removal in the environment, and for exploring new technology for wastewater treatment. Copyright © 2012 Society of Chemical Industry 相似文献
12.
Mesoporous TiO2 frameworks incorporated with diverse percentages of Cr2O3 nanoparticles (NPs) were achieved through the one-step sol-gel approach for photocatalytic H2 evolution under visible-light exposure. The obtained isotherms could be classified as type IV, indicating mesopore 2D-hexagonal symmetry. The H2 evolution rate over mesoporous Cr2O3/TiO2 photocatalyst was observably promoted employing glycerol as a sacrificial agent, providing a comparatively high H2 yield of 14300 μmolg?1. The highest photocatalytic efficiency was achieved with an optimal 4% Cr2O3/TiO2 photocatalyst, and the evolution rate was enhanced 1430-fold compared to pristine TiO2. The eminent photocatalytic performance of mesoporous Cr2O3/TiO2 was ascribable to different key factors such as the narrow bandgap, wide visible light photoresponse, Cr2O3 as photosensitizer, synergistic effect and high surface area. The recycle tests for five times over synthesized photocatalyst revealed excellent durability and stability without loss in H2 evolution. The photocatalytic mechanisms for H2 evolution over Cr2O3/TiO2 photocatalyst were proposed according to the photocurrent transient and photoluminescence measurements and photocatalytic H2 evolution results. 相似文献
13.
In this study, TiO2‐loaded wooden‐activated carbon fibers (TiO2/WACFs) were prepared by sol–gel method. TiO2/WACFs were detected by scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. The results showed that TiO2 was deposited on almost each WCAF with a coating thickness. All the TiO2 films on the surface of WACFs were composed of anatase with high photocatalytic property. The characteristic adsorption peaks of nano‐TiO2 emerged at 1,402 and 471 cm−1 on the infrared spectrum of TiO2/WACFs. It was also found that Ti was in the binding state of Ti4+ (TiO2) in the TiO2/WACFs. As the calcination temperature increased, the content of elements Ti and Ti O bond of lattice oxygen on the surface of TiO2/WACFs increased and then decreased, but the loaded nano‐TiO2 did not affect the formation of graphite structure of WACFs. It is suggested that TiO2/WACFs obtained at 450°C have the best photocatalytic property. POLYM. COMPOS., 36:62–68, 2015. © 2014 Society of Plastics Engineers 相似文献
14.
《Ceramics International》2023,49(18):29870-29878
The construction of ternary TiO2 NTs/Ag3PO4–AgBr photocatalysts was carried out by the SILAR deposition of Ag3PO4 and AgBr on TiO2 nanotube arrays (TiO2 NTs) for enhancing the photocatalytic application in H2 evolution and dyeing wastewater remediation. The adjustment of Ag3PO4/AgBr deposition cycles was used to optimize the optical absorption and photocatalytic property. The TiO2 NTs/Ag3PO4–AgBr (5) prepared with 5 cycle deposition of Ag3PO4 and AgBr exhibited the optimal photoelectric activity and photocatalytic performances. The photocatalytic rate constants for the degradation of MO, RhB and MB dyes achieved 1.35 × 10−2, 3.30 × 10−2 and 4.47 × 10−2 min−1, respectively, and the visible light-driven photocatalytic H2 evolution rate achieves 46.87 μmol cm−2 h−1. •O2− radicals exhibited the key influence on the organic dye degradation, and the as-prepared photocatalysts showed exceedingly high photocatalytic activity and stability. Furthermore, the photocatalytic mechanism was proposed based on the ESR result. 相似文献
15.
Performance and Economic Assessment of the Treatment of Phenol with TiO2 Photocatalysis,Photo‐Fenton,Biological Aerated Filter,and Wetland Reactors
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José Alejandro Ortega-Méndez José Alberto Herrera-Melián Javier Araña María Rocío Espino-Estévez José Miguel Doña-Rodríguez 《化学工程与技术》2017,40(6):1165-1175
The performance and economic cost of the removal of phenol with TiO2 photocatalysis, photo‐Fenton reactions, biological aerated filter (BAF), and constructed wetland (CW) reactors has been studied. The BAF achieved complete removal with a maximum phenol concentration of 200 mg·L?1. The BAF‐CW combination provided a phenol‐free effluent with a maximum phenol concentration of 650 mg·L?1. In both cases, a complete detoxification of the treated water was achieved at the concentrations studied. The efficiency of TiO2 photocatalysis was limited to concentrations below 50 mg L?1 to minimize removal reduction and toxicity of the intermediates. Photo‐Fenton was more efficient, but also more expensive because of the high cost of H2O2. The photo‐Fenton‐BAF combination is proposed to be the most suitable one. 相似文献
16.
Hana Žabová Vladimír Církva 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(11):1624-1630
BACKGROUND: Mercury electrodeless discharge lamps (Hg‐EDLs) were used to generate UV radiation when exposed to a microwave field. EDLs were coated with doped TiO2 in the form of thin films containing transition metal ions Mn+ (M = Fe, Co, Ni, V, Cr, Mn, Zr, Ag). Photocatalytic degradation of mono‐chloroacetic acid (MCAA) to HCl, CO2, and H2O, and decomposition of Rhodamine B on the thin films were investigated in detail. RESULTS: Polycrystalline thin doped TiO2 films were prepared by dip‐coating of EDL via a sol–gel method using titanium n‐butoxide, acetylacetone, and a transition metal acetylacetonate. The films were characterized by Raman spectroscopy, UV/Vis absorption spectroscopy, X‐ray photoelectron spectroscopy (XPS), electron microprobe analysis and by atomic force microscopy (AFM). The photocatalytic activity of doped TiO2 films was monitored in the decomposition of Rhodamine B in water. Compared with the pure TiO2 film, the UV/Vis spectra of V, Zr and Ag‐doped TiO2 showed significant absorption in the visible region, and hence the photocatalytic degradation of MCAA had increased. The best apparent degradation rate constant (0.0125 min?1), which was higher than that on the pure TiO2 film by a factor of 1.7, was obtained with the Ag(3%)/TiO2 photocatalyst. The effect of doping level of vanadium acetylacetonate on the photocatalytic efficiency of the V‐doped TiO2 was determined. CONCLUSIONS: Transition metal ion‐doped TiO2 thin films showed significant absorption in the visible region. The metal doped TiO2 photocatalyst (with an appropriate amount of V, Zr and Ag) on the Hg‐EDLs increased the degradation efficiency of MCAA in a microwave field. Copyright © 2009 Society of Chemical Industry 相似文献
17.
Porous ultrahigh‐molecular‐weight polyethylene (UHMWPE)‐based composites filled with surface‐modified Ce‐doped TiO2 nanoparticles (Ce–TiO2/UHMWPE) were prepared by template dissolution. The composites were characterized by Fourier transform infrared spectroscopy, ultraviolet (UV)–visible spectroscopy, diffuse reflectance spectra, and scanning electron microscopy); the photocatalytic activity was also evaluated by the decomposition of methyl orange under UV exposure. The results demonstrate that the severe aggregation of Ce–TiO2 nanoparticles could be reduced by surface modification via a silane coupling agent (KH570). The Ce–TiO2/UHMWPE porous composites exhibited a uniform pore size. Doping with Ce4+ effectively extended the spectral response from the UV to the visible region and enhanced the surface hydroxyl groups of the TiO2 attached to the matrix. With a degradation rate of 85.3%, the 1.5 vol % Ce–TiO2/UHMWPE sample showed the best photocatalytic activity. The excellent permeability of the porous composites is encouraging for their possible use in wastewater treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
18.
Jing Wang Guangfei Liu Hong Lu Ruofei Jin Jiti Zhou 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(5):970-974
BACKGROUND: Traditional treatment systems failed to achieve efficient degradation of anthraquinone dye intermediates at high loading. Thus, an airlift internal loop reactor (AILR) in combination with the TiO2‐photocatalytic ozonation (TiO2/UV/O3) process was investigated for the degradaton of 1‐amino‐ 4‐bromoanthraquinone‐2‐ sulfonic acid (ABAS). RESULTS: The AILR using Sphingomonas xenophaga as inoculum and granular activated carbon (GAC) as biocarrier, could run steadily for 4 months at 1000 mg L?1 of the influent ABAS. The efficiencies of ABAS decolorization and chemical oxygen demand (COD) removal in AILR reached about 90% and 50% in 12 h, respectively. However, when the influent ABAS concentration was further increased, a yellow intermediate with maximum absorbance at 447 nm appeared in AILR, resulting in the decrease of the decolorization and COD removal efficiencies. Advanced treatment of AILR effluent indicated that TiO2/UV/O3 process more significantly improved the mineralization rate of ABAS bio‐decolorization products with over 90% TOC removal efficiency, compared with O3, TiO2/UV and UV/O3 processes. Furthermore, the release efficiencies of Br? and SO42? could reach 84.5% and 80.2% during TiO2/UV/O3 treatment, respectively, when 91.5% TOC removal was achieved in 2 h. CONCLUSION: The combination of AILR and TiO2/UV/O3 was an economic and efficient system for the treatment of ABAS wastewater. © 2012 Society of Chemical Industry 相似文献
19.
Photocatalytic degradation of polyvinylpyrrolidone (PVP) by titanium dioxide and ozone in an annular reactor was investigated using a 125-W mercury vapor lamp as the light source. It was observed that the TiO2/O3/UV process presented a greater efficiency than the TiO2/UV process. In fact, around 90% of the mineralization was obtained in 1 h of reaction, reflecting the synergistic effect of the combination of O3 and TiO2 under UV light, because the sum of the rate constants of the individual processes is less than the rate constant of the combined process. The effects of the initial PVP concentration, photocatalyst dosage, ozone input flow rate and pH on the PVP degradation rate were studied. In general, the results suggest that PVP can undergo a cross-linking process when the TiO2/O3/UV treatment is applied. The reaction rate was increased when the photocatalyst dosage was increased up to 2.0 g L?1; however, increasing the initial PVP concentration led to a drop in the reaction rate. The efficiency also decreased at basic pH, because ozone is decomposed under alkaline conditions. In addition, it was noted that most of the nitrogen atoms of the macromolecules of PVP can be transformed into nitrate and ammonia during photocatalytic ozonation. 相似文献
20.
The oxidative polycondensation reaction conditions of 2‐(morpholinoiminomethyl)phenol were studied with H2O2, air O2, and sodium hypochloride (NaOCl) oxidants in an aqueous alkaline medium between 40 and 90°C. The structure of oligo‐2‐(morpholinoiminomethyl)phenol was characterized with 1H‐ and 13C‐NMR, Fourier transform infrared, ultraviolet–visible, size exclusion chromatography, and elemental analysis techniques. Under the optimum reaction conditions, the yield of oligo‐2‐(morpholinoiminomethyl)phenol was 28% for the H2O2 oxidant, 12% for the air O2 oxidant, and 58% for the NaOCl oxidant. According to the size exclusion chromatography analysis, the number‐average molecular weight, weight‐average molecular weight, and polydispersity index of oligo‐2‐(morpholinoiminomethyl)phenol were 2420 g/mol, 2740 g/mol, and 1.187 with H2O2, 1425 g/mol, 2060 g/mol, and 1.446 with air O2, and 1309 g/mol, 1401 g/mol, and 1.070 with NaOCl, respectively. Thermogravimetry/dynamic thermal analysis showed that the oligo‐2‐(morpholinoiminomethyl)phenol–lead complex compound was more stable than 2‐(morpholinoiminomethyl)phenol and oligo‐2‐(morpholinoiminomethyl)phenol against thermal degradation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3795–3804, 2006 相似文献