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61.
Photocatalytic oxidation and ozonation of catechol over carbon-black-modified nano-TiO2 thin films supported on Al sheet 总被引:5,自引:0,他引:5
The photocatalytic activity of the carbon-black-modified nano-TiO2) (CB-TiO2) thin films was 1.5 times higher than that of TiO2 thin films in degrading Reactive Brilliant Red X-3B. Photocatalytic oxidation and ozonation of catechol over CB-TiO2 thin films supported on Al sheet was investigated. The experiments showed that ozone concentrations had an important effect on TOC removal. The combined photocatalysis with UV irradiation and ozonation (TiO2/UV/O3) process considerably increased TOC removal rate compared to combined photocatalysis with UV irradiation and oxygen oxidation (TiO2/UV/O2) process, ozonation alone (O3) process, combined ozonation and UV irradiation (UV/O3) process. The complete mineralization of catechol followed pseudo-zero-order kinetics dependent upon ozone (oxygen) concentration and indicated catechol concentration did not affect the kinetics during UV/O3 and TiO2/UV/O3 (O2) processes. The kinetic study showed that the rate constants in the complete mineralization of catechol with TiO2/UV/O3 are 1.32-1.80 times higher than that of UV/O3 with the same concentration of ozone. The rate constants are 2.56-5.36 times higher than the maximal rate constants of TiO2/UV/O2 and 4.68-9.8 times higher than the maximal rate constants of TiO2/UV. 相似文献
62.
Würtele MA Kolbe T Lipsz M Külberg A Weyers M Kneissl M Jekel M 《Water research》2011,45(3):1481-1489
GaN-based ultraviolet-C (UV-C) light emitting diodes (LEDs) are of great interest for water disinfection. They offer significant advantages compared to conventional mercury lamps due to their compact form factor, low power requirements, high efficiency, non-toxicity, and overall robustness. However, despite the significant progress in the performance of semiconductor based UV LEDs that has been achieved in recent years, these devices still suffer from low emission power and relatively short lifetimes. Even the best UV LEDs exhibit external quantum efficiencies of only 1-2%.The objective of this study was to investigate the suitability of GaN-based UV LEDs for water disinfection. The investigation included the evaluation of the performance characteristics of UV LEDs at different operating conditions as well as the design of a UV LED module in view of the requirements for water treatment applications. Bioanalytical testing was conducted using Bacillus subtilis spores as test organism and UV LED modules with emission wavelengths of 269 nm and 282 nm.The results demonstrate the functionality of the developed UV LED disinfection modules. GaN-based UV LEDs effectively inactivated B. subtilis spores during static and flow-through tests applying varying water qualities. The 269 nm LEDs reached a higher level of inactivation than the 282 nm LEDs for the same applied fluence. The lower inactivation achieved by the 282 nm LEDs was compensated by their higher photon flux. First flow-through tests indicate a linear correlation between inactivation and fluence, demonstrating a well designed flow-through reactor. With improved light output and reduced costs, GaN-based UV LEDs can provide a promising alternative for decentralised and mobile water disinfection systems. 相似文献
63.
64.
The formation of bromate levels exceeding the drinking water standard of 10 microg L-1 may impose the reduction of ozone doses used in the treatment of drinking water. This paper illustrates the procedure of evaluating the use of reduced ozone doses while implementing an additional UV disinfection step for an actual drinking water treatment plant. Ozonation was performed at low ozone doses in bench-scale experiments with a pretreated river water from the Paris area (France). At the low ozone dose of 0.5 mg L-1, bromate formation could be kept below 0.4 microg L-1, while inactivation of vegetative bacteria and UV-resistant viruses was calculated to exceed 5 log units, and a substantial decoloration (31% of the absorption at lambda=254 nm) was achieved. Based on the measured transient ozone and OH radical concentrations, the oxidation of micropollutants was calculated. Fast reacting micropollutants containing phenol, amine or double bond moieties, such as sulfamethoxazole, diclofenac and 17-alpha-ethinylestradiol, were completely oxidized. Slow-reacting synthetic micropollutants, e.g., atrazine, iopromide and methyl tertiary butyl ether (MTBE), were oxidized by only 20%, 20% and 10%, respectively, and the taste and odor compounds 2-methylisoborneol (MIB) and geosmin by 40% and 50%, respectively. The addition of an UV treatment step to the existing treatment train, which should guarantee disinfection of ozone-resistant pathogenic microorganisms, including Cryptosporidium parvum oocysts, has negligible effects on water matrix components but may induce significant transformation of micropollutants. Overall, the combination of ozonation at reduced doses and UV treatment leads to an improved water quality with regard to disinfection, oxidation of micropollutants and minimization of bromate. 相似文献
65.
UV/Fenton光催化氧化法处理液晶显示屏清洗废水 总被引:5,自引:3,他引:5
采用UV/Fenton光催化氧化法处理难生物降解、含高浓度表面活性剂的液晶显示屏清洗废水,考察了反应时间、亚铁盐及双氧水投加量、UV光强、体系pH、有机物初始浓度等对处理效果的影响。结果表明,当初始pH值为3~7.2时,经2 h左右的反应后可将废水的COD值由1 468 mg/L降至100 mg/L以下。对COD的去除率随反应时间的延长而增大并最终趋于平稳,合适的反应时间约为2 h。当H2O2与Fe2+的物质的量之比较低时,对COD的初始去除率较高。合适的FeSO4.7H2O投加量为543.5 mg/L,双氧水投加量为2.5~3 mL/L,且一次性投加即可。增加紫外光光强、投加TiO2等对有机污染物的去除有显著促进作用。 相似文献
66.
67.
Advanced oxidation treatment using low pressure UV light coupled with hydrogen peroxide (UV/H2O2) was evaluated for the oxidation of six pharmaceuticals in three wastewater effluents. The removal of these six pharmaceuticals (meprobamate, carbamazepine, dilantin, atenolol, primidone and trimethoprim) varied between no observed removal and >90%. The role of the water quality (i.e., alkalinity, nitrite, and specifically effluent organic matter (EfOM)) on hydroxyl radical (OH) exposure was evaluated and used to explain the differences in pharmaceutical removal between the three wastewaters. Results indicated that the efficacy of UV/H2O2 treatment for the removal of pharmaceuticals from wastewater was a function of not only the concentration of EfOM but also its inherent reactivity towards OH. The removal of pharmaceuticals also correlated with reductions in ultraviolet absorbance at 254 nm (UV254), which offers utilities a surrogate to assess pharmaceutical removal efficiency during UV/H2O2 treatment. 相似文献
68.
T. S. C. GROSS BSc CEng DipEM MICE M. K. DAVIS BSc CEng MICE 《Water and Environment Journal》1991,5(6):649-658
In March 1990 a pilot ultra-violet disinfection plant was installed at the sewage-treatment works in Bellozanne, Jersey. The pilot plant was set up to test the ability of the process to meet certain defined objectives and, ultimately, to enable the island authorities to satisfy stringent water quality objectives in the receiving waters of St Aubins Bay.
The pilot study simulated an open channel installation using medium pressure ultra-violet lamps parallel to the direction of flow. The pilot plant was supplied by Trojan Technologies Inc.
The pilot study met its objectives and confirmed the design parameters for a full-scale plant installation to follow. 相似文献
The pilot study simulated an open channel installation using medium pressure ultra-violet lamps parallel to the direction of flow. The pilot plant was supplied by Trojan Technologies Inc.
The pilot study met its objectives and confirmed the design parameters for a full-scale plant installation to follow. 相似文献
69.
Kent FC Montreuil KR Brookman RM Sanderson R Dahn JR Gagnon GA 《Water research》2011,45(18):6173-6180
French River water (Nova Scotia, Canada) was separated into six different natural organic matter (NOM) fractions, including hydrophobic acids, bases and neutrals and hydrophilic acids, bases and neutrals. The raw water, as well as each of the NOM fractions were analysed for disinfection by-product (DBP) formation potential before and after advanced oxidation with UV/TiO2 to determine the efficacy of this treatment for the removal of DBP precursors. The UV/TiO2 treatment was carried out with a nanostructured thin film (NSTF), coated with TiO2 which is compared with the use of a TiO2 suspension. For the raw river water, removals of total trihalomethane formation potential (TTHMFP) and total haloacetic acid formation potential (THAA9FP) were found to be approximately 20% and 90%, respectively, with 50 mJ/cm2 UV exposure and 1 mg/L TiO2. For the fractionated samples, approximately 75% of both trihalomethane (THM) and haloacetic acid (HAA) precursors were found to be associated with the hydrophobic acid fraction. For this individual fraction the same UV/TiO2 treatments exhibited approximately 20-25% removal of both TTHMFP and THAA9FP, suggesting that the fractionation process may have affected the treatability of HAA precursors or may have altered the results of the oxidation processes. 相似文献
70.
Kinetics and mechanisms of DMSO (dimethylsulfoxide) degradation by UV/H(2)O(2) process 总被引:1,自引:0,他引:1
The objective of this study was to elucidate the degradation pathways of dimethylsulfoxide (DMSO) during its mineralization caused by UV/H(2)O(2) treatment. In order to accomplish this, we measured the concentration time-profiles of DMSO and its degradation intermediates during the UV/H(2)O(2) treatment. In addition, we proposed a kinetic model that could account for the degradation pathways of DMSO during its UV/H(2)O(2) treatment. The results show that the degradation of DMSO by the UV/H(2)O(2) treatment can be classified into two major pathways, and this is supported by both the analysis of the intermediates and total organic carbon (TOC) measurements. Firstly, DMSO was degraded into sulfate (SO(4)(2-)) through the formation of methansulfinate (CH(3)SO(2)(-)) and methansulfonate (CH(3)SO(3)(-)) as sulfur-containing intermediates. One of the two carbon constituents of DMSO was highly resistant to mineralization, due to the formation of methansulfonate, which reacted very slowly with (.-)OH k = 0.8 x 10(7) M(-1)s(-1)). Secondly, the other carbon constituent of DMSO was relatively easily mineralized through the formation of formaldehyde (HCHO) and formate (HCO(2)(-)) as non-sulfur-containing intermediates. The kinetic model proposed in this study for the degradation of DMSO by (.-)OH in the UV/H(2)O(2) process was able to successfully predict the patterns of concentration time-profiles of all components during the UV/H(2)O(2) treatment of DMSO. 相似文献