UV/ozone degradation of gaseous hexamethyldisilazane (HMDS)

As a carcinogen, hexamethyldisilazane (HMDS) is extensively adopted in life science microscopy, materials science and nanotechnology. However, no appropriate technology has been devised for treating HMDS in gas streams. This investigation evaluated the feasibility and effectiveness of the UV (185+254nm) and UV (254nm)/O(3) processes for degradation of gaseous HMDS. Tests were performed in two batch reactors with initial HMDS concentrations of 32-41mgm(-3) under various initial ozone dosages (O(3) (mg)/HMDS (mg)=1-5), atmospheres (N(2), O(2), and air), temperatures (28, 46, 65 and 80 degrees C), relative humilities (20%, 50%, 65%, 99%) and volumetric UV power inputs (0.87, 1.74, 4.07 and 8.16Wl(-1)) to assess their effects on the HMDS degradation rate. Results indicate that for all conditions, the decomposition rates for the UV (185+254nm) irradiation exceeded those for the UV (254nm)/O(3) process. UV (185+254nm) decompositions of HMDS displayed an apparent first-order kinetics. A process with irradiation of UV (185+254nm) to HMDS in air saturated with water at temperatures of 46-80 degrees C favors the HMDS degradation. With the condition as above and a P/V of around 8Wl(-1), k was approximately 0.20s(-1) and a reaction time of just 12s was required to degrade over 90% of the initial HMDS. The main mechanisms for the HMDS in wet air streams irradiated with UV (185+254nm) were found to be caused by OH free-radical oxidation produced from photolysis of water or O((1)D) produced from photolysis of oxygen. The economic evaluation factors of UV (185+254nm) and UV (254nm)/O(3) processes at different UV power inputs were also estimated.     

Destruction of phenol aqueous solution by photocatalysis or direct photolysis

The photodegradation of phenol has been investigated under a high-pressure mercury lamp with a kind of jacket (glass or quartz) depending on used UV light range and a variety of experimental conditions: UV (lambda > 200 nm) with oxygen or with TiO2 and oxygen or with N2; UV (lambda > 330 nm) with oxygen or with TiO2 and oxygen or with N2. Photocatalysis and direct photolysis of phenol have different reaction pathways. Direct photolysis of phenol yielded a brown-yellow complex organic polymer in both aerobic and anaerobic environments. The polymer cannot be mineralized in an anaerobic environment. The effects of catalyst amount and oxygen concentration in the reaction atmosphere on the destruction of phenol were studied. The results prove that an appropriate catalyst amount can avoid direct photolysis and increase the mineralization rate of phenol.     

Photocatalytic oxidation of toxic organohalides with TiO2/UV: the effects of humic substances and organic mixtures

TiO2/UV photocatalytic oxidation of DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane), 1,2,3-trichlorobenzene and 4-chlorophenol were examined in aqueous solution in the presence of humic substances and organic mixtures to study if the degradation rates were affected. Both commercial and natural humic substances were observed to retard the photodegradation rates, with a greater effect from the natural humic substances. Acetonitrile and isopropanol also caused significant retardation of 4-chlorophenol photodegradation. The overall retardation can be attributed to the combination of light attenuation, inhibition and competition effects. Moreover, the TiO2/UV system favors the decomposition of compounds that have stronger adsorption onto the TiO2 surface. To engineer effective treatment facilities that use the TiO2/UV system for the treatment of toxic substances in wastewater, the methodology must allow for concerns about adventitious species which are present.     

Photooxidation of naphthalenesulfonic acids: comparison between processes based on O(3), O(3)/activated carbon and UV/H(2)O(2)

The aim of the present study was to analyze and compare the efficacy of UV photodegradation with that of different advanced oxidation processes (O(3), UV/H(2)O(2), O(3)/activated carbon) in the degradation of naphthalenesulfonic acids from aqueous solution and to investigate the kinetics and the mechanism involved in these processes. Results obtained showed that photodegradation with UV radiation (254 nm) of 1-naphthalenesulfonic, 1,5-naphthalendisulfonic and 1,3,6-naphthalentrisulfonic acids is not effective. Presence of duroquinone and 4-carboxybenzophenone during UV irradiation (308-410 nm) of the naphthalenesulfonic acids increased the photodegradation rate. Addition of H(2)O(2) during irradiation of naphthalenesulfonic acids accelerated their elimination, due to the generation of ()OH radicals in the medium. Comparison between UV photodegradation 254 m and the advanced oxidation processes (O(3), O(3)/activated carbon and UV/H(2)O(2)) showed the low-efficacy of the former in the degradation of these compounds from aqueous medium. Thus, among the systems studied, those based on the use of UV/H(2)O(2) and O(3)/activated carbon were the most effective in the oxidation of these contaminants from the medium. This is because of the high-reactivity of naphthalenesulfonic acids with the *OH radicals generated by these two systems. This was confirmed by the values of the reaction rate constant of *OH radicals with these compounds k(OH), obtained by competitive kinetics (5.7 x 10(9) M(-1) s(-1), 5.2 x 10(9) M(-1) s(-1) and 3.7 x 10(9) M(-1) s(-1) for NS, NDS and NTS, respectively).     

Decolorizing of lignin wastewater using the photochemical UV/TiO2 process

Studies on applying the photochemical UV/TiO2 oxidation process to treat the lignin-containing wastewater for dissolved organic carbon (DOC), color and reducing A254 (the absorption at the wavelength of 254 nm) have been carried out. The data obtained in this study demonstrate that the UV/TiO2 process is effective in oxidizing the lignin thus reducing the color and DOC of the wastewater treated. The combined UV/TiO2 treatment can achieve better removal of DOC and color than the UV treatment alone. Color removal, based on American Dye Manufacture Index (ADMI) measurement, is greater than 99% if the pH is maintained at 3.0 with the addition of 1 g l(-1) TiO2. When 10 g l(-1) TiO2 is applied, the oxidation reduction potential (ORP) value is reached to result in an 88% removal of both DOC and color. A model was developed based on the variation of ORP during the photochemical reaction to simulate the decoloring process. The proposed model can be used to predict the color removal efficiency of the UV/TiO2 process.     

亚甲基蓝表面修饰纳米TiO2降解造纸废水动力学

以亚甲基蓝(MB)作为表面修饰剂,采用简单的化学吸附法制备亚甲基蓝表面修饰的纳米TiO2光催化剂(TiO2-MB)。经表面修饰后,TiO2-MB光催化剂波长响应范围红移至可见光区575 nm处。探讨了光催化剂量、光照时间和溶液pH值对TiO2-MB光催化降解造纸废水的影响;研究了纳米TiO2-MB对造纸废水的暗吸附规律和光降解性能。结果表明:纳米TiO2-MB对造纸废水的吸附规律都较好地符合Langmuir和Freundlich吸附等温模型,属于吸热反应;光催化降解动力学符合Langmuir-Hinshelwood动力学模型。在160 W高压汞灯光照80 min,3.0 g/L纳米TiO2-MB光催化降解pH=2.0的造纸废水(COD:2 069.8 mg/L),COD去除率可达94.7%,处理效果远高于避光条件下。光催化剂经8次使用仍具有较高的催化活性。     

Abiotic degradation of imazethapyr in aqueous solution

The photodegradation of imazethapyr [2-(4,5-dihydro-4-méthyl-4-(1-méthylethyl)-5-oxo-1H-imidazol-2-yl)-5-ethyl-3-pyridinecarboxylic acid] in aqueous solution in the presence of titranium dioxide (TiO2) and humic acids (HA) at different ratios of herbicide/TiO2 and herbicide/humic acids was studied at pH 7.0. Irradiation was carried out with polychromatic light using Heraeus apparatus equipped with xenon lamp to simulate sunlight having a spectral energy distribution similar to solar irradiation (>290 nm). The concentration of remaining herbicide was followed using a High Pressure Liquid Chromatograph (HPLC) equipped with UV detector at 230 nm. In pure aqueous solution imazethapyr degrades slowly and the photodegradation leads to the formation of two metabolites labelled A and B. The presence of TiO2 caused enhancement of the degradation rate. The presence of HA induced an increase of the photodegradation of the pesticide with respect to pure aqueous solution.     

Solar photocatalytic decolorization of methylene blue in water

In this study, a photocatalytic decolorization system equipped with immobilized TiO2 and illuminated by solar light was used to remove the color of wastewater. To examine the decoloring efficiency of this system, photocatalytic decolorization of an organic dye such as methylene blue was studied as an example. The effects of light source, pH, as well as the initial concentration of dye were also investigated. It was observed that the solution of methylene blue could be almost completely decolorized by the solar light/TiO2 film process while there was about 50% color remaining with solar irradiation only. In addition, it was found that the decoloring efficiency of solution was higher with solar light irradiation than with artificial UV light irradiation, even though the artificial UV light source supplied higher UV intensity at 254 nm. The color removal rate of methylene blue with solar light irradiation was almost twice that of artificial UV light irradiation. This phenomena was mainly attributed to that some visible light range of solar light was useful for exciting the methylene blue molecules adsorbed on TiO2 film, leading to a photosensitization process undergoing and decoloring efficiency promoted. This solar-assisted photocatalytic device showed potential application for decoloring organic dyes in wastewater.     

Phototransformation of ibuprofen and ketoprofen in aqueous solutions

The UV (254 nm) and UV/VUV (254/185 nm) photolysis of two anti-inflammatory drugs, ibuprofen and ketoprofen, have been studied in aqueous solutions as a possible process for the removal of non-biodegradable compounds.We have examined the effects of dissolved oxygen and initial target concentration. Upon irradiation at 254 nm, the decomposition rate of ketoprofen is almost forty times higher as it of ibuprofen whilst VUV irradiation only increased the ibuprofen decomposition rate. The presence of dissolved oxygen accelerated the photodegradation of ibuprofen, whereas no effect was observed on the degradation of ketoprofen. The maximum quantum yield for the phototransformation was 0.2. The rate of mineralization in both cases was ∼60%, even after 1 h of treatment and this suggests the formation of stable by-products which were identified using GC-MS and HPLC-MS, respectively.     

Photocatalytic degradation of p-nitrophenol on nanometer size titanium dioxide surface modified with 5-sulfosalicylic acid

The surface of nanometer size TiO(2) was simply and fast modified by chemical adsorption in saturated solution of 5-sulfosalicylic acid. After surface modification, a stable, yellow surface complex was formed quickly, the wavelength response range of TiO(2) was expanded, it has obvious absorption in the region from 320 to 450 nm; the adsorption efficiency of p-nitrophenol (PNP) by TiO(2) was enhanced from 42% to 84%. The photocatalytic activity was tested on the degradation of PNP. The influences of catalyst and its dosage, pH value, and PNP concentration on the degradation were investigated. On optimal photodegradation conditions, including initial pH 4.0, PNP 5 mg l(-1), catalyst 100 mg, irradiation time 120 min with 160 W high-pressure mercury lamp, the degradation efficiency of PNP was increased from 40% to 88% after surface modification. Surface modification led not only to an increase in the light utilization, but also improved the surface coverage of PNP in comparison with the pure TiO(2). Both of these factors are crucial for the photocatalytic activity of heterogeneous photocatalysis, especially for photodegradation of benzenoid pollutants.     

CdS-TiO2/MWCNTs结构表征及其光催化性能

采用溶胶-凝胶法,制备了多壁碳纳米管（MWCNTs）负载的双组分复合半导体光催化剂CdS-TiO2/MWCNTs。通过透射电镜（TEM）、比表面分析（BET）、X射线衍射（XRD）和紫外-可见吸收光谱（UV-vis）等分析方法对光催化剂进行了结构表征,并考察了CdS-TiO2/MWCNTs对甲苯降解的光催化性能。结果表明：纳米活性粒子CdS-TiO2均匀负载于MWCNTs上,比表面积、光吸收阈值和强度增大,活性粒子间以及活性粒子与载体之间具有协同作用,有利于光催化性能的提高,CdS-TiO2/MWCNTs在主波长为254 nm紫外光照射下对甲苯的降解效果较好,去除率可达55.3%。     

Study on the indoor volatile organic compound treatment and performance assessment with TiO2/MCM-41 and TiO2/quartz photoreactor under ultraviolet irradiation

Volatile organic compounds (VOCs) are the cause of indoor air pollution and are readily emitted from furniture and cleaning agents. In Taiwan, the concentrations of indoor VOCs range roughly from 1 to 10 ppm. It is important to effectively reduce indoor VOC emissions and establish the implementation of long-term, low-cost, controlled techniques such as those found in the ultraviolet/titanium dioxide (UV/TiO2) control systems. This study evaluates the performance of a photoreactor activated by visible irradiation and packed with TiO2/quartz or TiO2/mobile catalytic material number 41 (MCM-41). The photocatalysts tested include commercial TiO2 (Degussa P-25) and synthesized TiO2 with a modified sol-gel process. The UV light had a wavelength of 365 nm and contained an 8-W, low-pressure mercury lamp. Reactants and products were analyzed quantitatively by using gas chromatography with a flame-ionization detector. It is important to understand the influence of such operational parameters, such as concentration of pollutant, temperature, and retention time of processing. The indoor concentrations of VOCs varied from 2 to 10 ppm. Additionally, the temperatures ranged from 15 to 35 degrees C and the retention time tested from 2 to 8.2 sec. The results show that quartz with TiO2 had a better photoreductive efficiency than quartz with MCM-41. The toluene degradation efficiency of 77.4% with UV/TiO2/quartz was larger than that of 54.4% with the UV/TiO2/MCM-41 system under 10-min reaction time. The degradation efficiency of the UV/TiO2 system decreased with the increasing concentrations of indoor VOCs. The toluene degradation efficiency at 2 ppm was approximately 5 times greater than that at 10 ppm. The photoreduction rate of the VOCs was also evaluated with the Langmuir-Hinshewood model and was shown to be pseudo-first-order kinetics.     

The direct photolysis and photocatalytic degradation of alachlor at different TiO2 and UV sources

Direct photolysis and photocatalytic degradations of alachlor, a widely used herbicide, were studied using three different monochromatic UV lamps (254, 300 and 350 nm) and two TiO(2) sources. Both the direct photolysis and photocatalytic degradations of alachlor follow pseudo-first-order decay kinetics. TiO(2)-P25 was found to be an effective photocatalyst compared to TiO(2)-BDH. The direct photolysis of alachlor was dominant at 254 nm even if TiO(2) was present in the solution. Among the three UV wavelengths used, the highest photocatalysis quantum yield was obtained at 300 nm. The photocatalytic degradation rate of alachlor increased with the dosages of TiO(2), but an overdose of TiO(2) would retard the reaction due to light attenuation. Photocatalytic reactions were slightly enhanced in an alkaline medium, and the different proton sources causing various degrees of rate retardation were due to the presence of the corresponding counter anions. This effect was diminished at a later stage after the reaction intermediates were formed.     

Photocatalytic degradation of dyes on a magnetically separated photocatalyst under visible and UV irradiation

A novel kind of magnetically separable photocatalyst of TiO2/SiO2/gamma-Fe2O3 (TSF) is prepared. Scanning tunnel microscope (STM) and X-ray diffractometer (XRD) were used to characterize the structure of the photocatalyst. In the TSF photocatalyst, a TiO2 shell is for photocatalysis, a gamma-Fe2O3 core as a carrier is for separation by the magnetic field and a SiO2 membrane between the TiO2 shell and the gamma-Fe2O3 core is used to weaken the adverse influence of gamma-Fe2O3 on the photocatalysis of TiO2. Three kinds of dyes, Fluoresein, Orange II and Red acid G, were used to examine the photocatalytic activity of TSF. Due to strong UV adsorption of the gamma-Fe2O3, the photocatalytic activity of TSF was lower than that of the pure TiO2. Deducting the light absorption of the gamma-Fe2O3 particles, the photocatalytic activity of TSF was found to be higher than that of the P25 under UV irradiation. On the other hand, the photocatalytic activity of TSF under visible irradiation was much lower than that of the P25 TiO2 even deducting the visible light absorption of the gamma-Fe2O3 particles. Differences in the photocatalytic mechanisms under UV and visible irradiation lead to the differences in the photodegradation characteristics of dyes on TSF. The recycled TSF exhibited a good repeatability of photocatalytic activity.     

Ferrioxalate-mediated photodegradation and mineralization of 4-Chlorophenol

INTENTION, GOAL, SCOPE, BACKGROUND: Advanced oxidation processes are powerful methods which are capable of transforming refractory, nonbiodegradable and/or toxic organic compounds into harmless end products such as carbon dioxide and water. However, one commen problem of all advanced oxidation processes is the high demand of electrical energy for ultraviolet lamps, which causes high operational costs. Minimization of the required irradiation time, and therefore the energy consumption, by optimization of other reaction conditions such as catalyst-oxidant type and concentration, pH, temperature, pollutant/oxidant ratio etc., therefore continues to gain importance. OBJECTIVE: The main objective of this study was the minimization of the required irradiation time through optimization of the use of a newly patented catalyst, ferrioxalate, and also to compare the performance of this catalyst with the performance of other AOPs. METHODS: Oxidation of 4-chlorophenol by photo-Fenton process using potassium ferrioxalate as a mediator was studied in a lab scale photoreactor. The influence of parameters such as hydrogen peroxide and ferrioxalate concentrations, initial pH, power-output, oxalate/iron ratio and different iron sources was evaluated. An upflow photoreactor equipped with a 1000 Watt high-pressure mercury vapour lamp and operating in a recirculation mode was used during photodegradation experiments. The extent of the reduction of 4-chlorophenol, Total Organic Carbon and Chemical Oxygen Demand was used to evaluate the photodegradation reaction. RESULTS AND DISCUSSION: The optimum pH range observed was found to be 2.7-3. The efficiency of 4-chlorophenol oxidation increased with increasing concentrations of hydrogen peroxide and ferrioxalate, reaching a plateau after the addition of 10 and 0.072 mM of those reagents, respectively. Using an Oxalate/iron ratio of 12 was 18% less efficient than using a ratio of 3:1. The efficiency increased with increasing radiation power. However, this increase was not linear. The UV/ferrioxalate/H2O2 process, by which complete mineralization of 100 mg l(-1) 4-chlorophenol was achieved in 20 min of total reaction time, was the most efficient process among the alternatives applied. CONCLUSIONS: The use of ferrioxalate as the catalyst was found to be more efficient than the use of Fe(II) and Fe(III) iron species. It was possible to completely mineralize 4-chlorophenol. RECOMMENDATION AND OUTLOOK: The results of this study demonstrate that the ferrioxalate-mediated degradation of 4-chlorophenol requires less irradiation times than other advanced oxidation processes. There are mainly 19 phenol isomers and other toxic and nonbiodegradable organic compounds. We recommend that similar studies should be performed on many such compounds in order to attain a clear understanding of the performance of this catalyst. Because of its light sensitivity, this catalyst should be used immediately after its preparation. The use of low pressure mercury vapour lamps in this process should also be considered, since low power outputs may be enough for the process.     

Photodegradation of bisphenol Z by UV irradiation in the presence of beta-cyclodextrin

In this work, the formation of the inclusion complex of bisphenol Z (1,1-bis(4-hydroxyphenyl)cyclohexane, abbreviated as BPCH) with beta-cyclodextrin (beta-CD) has been studied, 1:1 inclusion complex can be obtained, the formation constant of the beta-CD/BPCH complex is 5.94x10(3)M(-1). The photodegradation behavior of BPCH was investigated under monochromatic UV irradiation (lambda=254 nm). The photodegradation rate constant of BPCH in aqueous solutions with beta-CD showed a 9.0-fold increase, and simultaneously the mineralization of BPCH can be enhanced by beta-CD. The influence factors on photodegradation of BPCH were also studied and described in details, such as concentration of beta-CD, initial concentration of BPCH, organic solvent and pH. The photodegradation of BPCH in the presence of beta-CD includes the direct photolysis and the photooxidation of BPCH during the photochemical process. Some predominant photodegradation products are 4-(2,4,5-trihydroxy-phenyl)-4-(4-hydroxyphenyl) butanoic acid, 5,5-bis(4-hydroxyphenyl)pentanoic acid, meta-hydroxylated BPCH, ortho-hydroxylated BPCH and 4-(1-(4-hydroxyphenyl)pentyl)phenol respectively. The enhancement of photodegradation of BPCH mainly results from moderate inclusion depth of BPCH molecule in the beta-CD cavity. This kind of inclusion structure allows BPCH molecule sufficient proximity to secondary hydroxyl groups of the beta-CD cavity, and these hydroxyl groups could be activated and converted to hydroxyl radicals under UV irradiation, which can enhance the photooxidation of BPCH.     

Photocatalytic oxidation of organic pollutants on titania-clay composites

TiO2/Ca-montmorillonite composites were prepared by wet grinding in an agate mill. Positively charged TiO2 nanoparticles are bound to the surface of the negatively charged montmorillonite layers via heterocoagulation; the clay mineral is used as adsorbent and support for the photooxidation process. Aquatic solution of 0.5mM phenol was degraded by irradiation with UV-VIS light (lambda=250-440 and 540-590 nm) in suspensions of TiO2-clay composites and significant photodegradation was observed at 40-60% TiO2/Ca-montmorillonite compositions. Synergistic effect was detected at solid/liquid interface for degradation of phenol and at solid/gas interface in the recycling flow reactors for photooxidation of ethanol and toluene vapors.     

Photocatalytic degradation of the herbicide erioglaucine in the presence of nanosized titanium dioxide: comparison and modeling of reaction kinetics

The present work mainly deals with photocatalytic degradation of a herbicide, erioglaucine, in water in the presence of TiO2 nanoparticles (Degussa P-25) under ultraviolet (UV) light illumination (30 W). The degradation rate of erioglaucine was not so high when the photolysis was carried out in the absence of TiO2 and it was negligible in the absence of UV light. We have studied the influence of the basic photocatalytic parameters such as pH of the solution, amount of TiO2, irradiation time and initial concentration of erioglaucine on the photodegradation efficiency of erioglaucine. A kinetic model is applied for the photocatalytic oxidation by the UV/TiO2 system. Experimental results indicated that the photocatalytic degradation process could be explained in terms of the Langmuir-Hinshelwood kinetic model. The values of the adsorption equilibrium constant, K, and the second order kinetic rate constant, k, were 0.116 ppm-1 and 0.984 ppm min-1, respectively. In this work, we also compared the reactivity between the commercial TiO2 Degussa P-25 and a rutile TiO2. The photocatalytic activities of both photocatalysts were tested using the herbicide solution. We have noticed that photodegradation efficiency was different between both of them. The higher photoactivity of Degussa P-25 compared to that of rutile TiO2 for the photodegradation of erioglaucine may be due to higher hydroxyl content, higher surface area, nano-size and crystallinity of the Degussa P-25. Our results also showed that the UV/TiO2 process with Degussa P-25 as photocatalyst was appropriate as the effective treatment method for removal of erioglaucine from a real wastewater. The electrical energy consumption per order of magnitude for photocatalytic degradation of erioglaucine was lower with Degussa P-25 than in the presence of rutile TiO2.     

Photocatalytic oxidation of gaseous DMF using thin film TiO2 photocatalyst

The heterogeneous photocatalytic oxidation of gaseous N,N'-dimethylformamide (DMF) widely used in the manufacture of synthetic leather and synthetic textile was investigated. The experiments were carried out in a plug flow annular photoreactor coated with Degussa P-25 TiO2. The oxidation rate was dependent on DMF concentration, reaction temperature, water vapor, and oxygen content. Photocatalytic deactivation was observed in these reactions. The Levenspiel deactivation kinetic model was used to describe the decay of catalyst activity. Fourier transform infrared (FTIR) was used to characterize the surface and the deactivation mechanism of the photocatalyst. Results revealed that carbonylic acids, aldehydes, amines, carbonate and nitrate were adsorbed on the TiO2 surface during the photocatalytic reaction. The ions, NH4+ and NO3-, causing the deactivation of catalysts were detected on the TiO2 surface. Several treatment processes were applied to find a suitable procedure for the regeneration of catalytic activity. Among these procedures, the best one was found to be the H2O2/UV process.     

炼化企业中水紫外线消毒及其影响因素简

研究水质对254 nm紫外线透射率的影响,通过动态实验考察了照射时间、254 nm紫外线透射率以及紫外线剂量对炼化企业中水消毒效果的影响并同时考察异养菌、硫酸盐还原菌和铁细菌的光复活及暗修复现象。结果表明,有机物是影响炼化企业中水紫外线消毒的重要因素;紫外线对炼化企业中水中的异养菌具有良好的灭活作用;增加照射时间对消毒效果的提升作用受254 nm紫外线透射率的影响;紫外线透射率在较低的范围内时对消毒效果的影响相对较大,在较高的范围内时影响较小;紫外线剂量-响应曲线受254 nm紫外线透射率的影响;剂量的“成分”,即照射时间和透射率的不同组合,也会对消毒效果产生影响;在80 mJ/cm²的剂量下,20 h内异养菌出现了较强烈的光复活和暗修复现象,铁细菌仅出现了明显的光复活现象,硫酸盐还原菌没有表现出明显的复活。