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Efficient removal of formaldehyde from indoor environments is of significance for human health.In this work,a typical binary transition metal oxide that could provide various oxidation states,β-NiMoO_4,was employed as a support to immobilize the active Pt component(Pt/NiMoO_4) for catalytic formaldehyde elimination at low ambient temperature(15℃).The results showed that the hydrothermal preparation temperature and time had a noticeable impact on the morphology and catalytic activity of the samples.The catalyst prepared with hydrothermal temperature of 150℃ for 4 hr(Pt-150-4) exhibited superior catalytic activity and stability mainly due to its distinctly porous structure,relative abundance of adsorbed surface hydroxyls/water,and high oxidation ability,which resulted from the interaction of Pt with Ni and Mo of the bimetallic NiMoO_4 support.Our results might shed light on the rational design of multifunctional catalysts for removal of indoor air pollutants at low ambient temperature.  相似文献   

3.
The extracellular enzyme secretion and biodegradation of polycyclic aromatic hydrocarbons (PAHs) were studied in agitated and shallow stationary liquid cultures of Phanerochaete chrysosporium. Veratryl alcohol and Tween80 were added to cultures as lignin peroxidase (LIP) and manganese peroxidase (MnP) inducer, respectively. Shallow stationary cultures were suitable for the production of enzyme, whereas agitated cultures enhanced overall biodegradation by facilitating interphase mass transfer of PAHs into aqueous phases. The use of a LIP stimulator, veratryl alcohol, did not increase PAH degradation but significantly enhanced LiP activity. In contrast, Tween80 increased both MnP secretion and PAH degradation in shallow stationary cultures. On the other hand, high PAH degradation was observed in agitated cultures in the absence of detectable LIP and MnP activities. The results suggested that extracellular peroxidase activities are not directly related to the PAH degradation, and the increased solubility rather than enzyme activity may be more important in the promotion of PAH degradation.  相似文献   

4.
In order to explore the biodegradation behavior of nonylphenolic compounds during wastewater treatment processing, two full-scale wastewater treatment plants were investigated and batch biodegradation experiments were conducted. The biodegradation pathways under the various operational conditions were identified from batch experiments: shortening of ethoxy-chains dominated under the anaerobic condition, whereas oxidizing of the terminal alcoholic group prevailed over the other routes under the aerobic condition. Results showed that the anoxic condition could accelerate the biodegradation rates of nonylphenolic compounds, but had no influence on the biodegradation pathway. The biodegradation rates of nonylphenol (NP) and short-chain nonylphenol polyethoxylates (NPnEOs, n: number of ethoxy units) increased from the anaerobic condition, then the anoxic, finally to the aerobic condition, while those of long-chain NPnEOs and nonylphenoxy carboxylates (NPECs) seemed similar under the various conditions. Under every operational condition, long-chain NPnEOs showed the highest biodegradation activity, followed by NPECs and short-chain NPnEOs, whereas NP showed relatively recalcitrant characteristics especially under the anaerobic condition. In addition, introducing sulfate and nitrate to the anaerobic condition could enhance the biodegradation of NP and short-chain NPnEOs by supplying more positive redox potentials.  相似文献   

5.
Quantitative analysis of microbial biomass yield in aerobic bioreactor   总被引:1,自引:0,他引:1  
We have studied the integrated model of reaction rate equations with thermal energy balance in aerobic bioreactor for food waste decomposition and showed that the integrated model has the capability both of monitoring microbial activity in real time and of analyzing biodegradation kinetics and thermal-hydrodynamic properties. On the other hand, concerning microbial metabolism, it was known that balancing catabolic reactions with anabolic reactions in terms of energy and electron flow provides stoichiometric metabolic reactions and enables the estimation of microbial biomass yield (stoichiometric reaction model). We have studied a method for estimating real-time microbial biomass yield in the bioreactor during food waste decomposition by combining the integrated model with the stoichiometric reaction model. As a result, it was found that the time course of microbial biomass yield in the bioreactor during decomposition can be evaluated using the operational data of the bioreactor (weight of input food waste and bed temperature) by the combined model. The combined model can be applied to manage a food waste decomposition not only for controlling system operation to keep microbial activity stable, but also for producing value-added products such as compost on optimum condition.  相似文献   

6.
Harmful cyanobacterial blooms are a growing environmental problem worldwide in natural waters, the biodegradation is found to be the most efficient method for removing microcystins (MCs) produced by harmful cyanobacteria. Based on the isolation of a promising bacterial strain of Sphingopyxis sp. USTB-05 for biodegrading MCs, we for the first time cloned and expressed a gene USTB-05-A (HM245411) that is responsible for the first step in the biodegradation of microcystin LR (MC-LR) in E. coli DH5αup, with a cloning vector of pGEM-T easy and an expression vector of pGEX-4T-1, respectively. The cell-free extracts (CE) of recombinant E. coli DH5αup containing USTB-05-A had high activity for biodegrading MC-LR. The initial MC-LR concentration of 40 mg/L was completely biodegraded within 1 hr in the presence of CE with a protein concentration of 0.35 mg/mL. Based on an analysis of the liquid chromatogram-mass spectrum (LC-MS), the enzyme encoded by gene USTB-05-A was found to be active in cleaving the target peptide bond between 3-amino-9-methoxy-2,6, 8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda) and arginine of MC-LR, and converting cyclic MC-LR to linear MC-LR as a first product that is much less toxic than parent MC-LR, which offered direct evidence for the first step on the pathway of MC-LR biodegradation by Sphingopyxis sp. USTB-05.  相似文献   

7.
The potential of pennywort(Hydrocotyle vulgaris)for phytoremediation of C.I.Acid Blue 92(AB92)was evaluated.The efects of various experimental parameters including pH,temperature,dye concentration and plant weight on dye removal efciency were investigated.The results showed that the optimal condition for dye removal were pH 3.5 and temperature 25°C.Moreover,the absolute dye removal enhanced with increase in the initial dye concentration and plant weight.Pennywort showed the same removal efciency in repeated experiments(four runs)as that obtained from the first run(a 6-day period).Therefore,the ability of the plant in consecutive removal of AB92 confirmed the biodegradation process.Accordingly,a number of produced intermediate compounds were identified.The efect of treatment on photosynthesis and antioxidant defense system including superoxide dismutase,peroxidase and catalase in plant roots and leaves were evaluated.The results revealed a reduction in photosynthetic pigments content under dye treatments.Antioxidant enzyme responses showed marked variations with respect to the plant organ and dye concentration in the liquid medium.Overall,the increase in antioxidant enzyme activity under AB92 stress in the roots was much higher than that in the leaves.Nevertheless,no significant increase in malondialdehyde content was detected in roots or leaves,implying that the high efciency of antioxidant system in the elimination of reactive oxygen species.Based on these results,pennywort was founded to be a capable species for phytoremediation of AB92-contaminated water,may be efective for phytoremediation dye-contaminated polluted aquatic ecosystems.  相似文献   

8.
The neurotransmitter le vel changes of ducks exposed 8-month in a mercury-polluted site(Wanshan, China) and a reference site ( Shanghai, China) were examined. Chemical analyses showed both higher mercury and selenium concentrations in the organ of Wanshan ducks. An increased content of acetylcholine(ACh) in brain and blood and a decreased activity of acetylcholinesterase(AChE) in blood were observed. Moreover, there was an increasing trend for nitric oxide synthase(NOS) activity and nitric oxide(NO) production in duck brain, but a reduction of NOS activity in duck serum. The possible explanations were due to the interactive effect of selenium accumulation and the sublethal exposure level of mercury in Wanshan area. The present study showed that AChE and NOS were sensitive to mercury contamination of real circumstance, suggesting that these two indexes have the potential to be biomarkers in assessment of health effects by mercury contamination.  相似文献   

9.
Mo/ZSM-5 catalysts with different Mo content were prepared by impregnation method. The effect of Mo content on the property of Mo/ZSM-5 catalysts and their performance for selective catalytic reduction(SCR) of NO with ammonia was investigated by XRD, ICP,XPS and NO-TPD respectively. The results showed that the catalytic activity of Mo/ZSM-5 for SCR of NO is strongly influenced by the Mo loading in HZSM-5 zeolites. The NOx conversion reached the highest value of 64.2% at 375℃ when Mo content is about 10.9%, and the temperatures at which the maximum of NOx conversion obtained were declined with the increase of Mo content. From XRD results, it can be seen that it exhibits the distinct interaction between Mo and HZSM-5 when Mo content is about 10.9%. This may result in a suitable phase structure in Mo/ZSM-5 catalyst, which is advantageous for NO reduction. XPS and NO-TPD results also showed that the catalytic activity of Mo/ZSM-5 may be related to the Mo percent on the surface.  相似文献   

10.
Ag/AgBr/GdVO_4 composite photocatalysts were designed and synthesized in this paper.The physical and chemical structures, as well as optical properties of the synthesized composite were investigated via XRD, XPS, TEM, and UV–vis. It is found that the composite showed a ternary heterojunction structure of Ag, Ag Br and GdVO_4. Meanwhile, it has a high intensity of light current, indicating its high separation efficiency of electron and hole.Photocatalytic oxidation of rhodamine B(RhB) under visible light irradiation was performed to investigate the activity of the Ag/Ag Br/GdVO_4 composite. Result indicates that it shows excellent photocatalytic activity. Under visible light irradiation for 12 min, about 80% of Rh B(30 μmol/L) was degraded. The degradation rate is estimated to be 0.253 min1, which is three times higher than that of pure AgBr. The high photoactivity can be ascribed to the synergetic effect of Ag Br, GdVO_4, and Ag nanoparticle in separation of electron–hole pairs.  相似文献   

11.
含氮农药的好氧生物降解性能及废水治理对策   总被引:5,自引:0,他引:5  
从动力学角度出发,利用长期驯化的菌种,对乙草胺,阿特拉津,西草净,赛克津等4种含氮农药的好氧生物降解性能进行了研究,并对含氮农药废水提出了治理对策,结果表明,4种含氮农药的好氧生物降解性能都很差,均属于难生物降解有机物,降解过程均符合一级降解动力学模式,它们的生物降解速率常数分别为0.00353L(g.h),0.00577L/(g.h),0.00160L/(g.h),0。0456L/(g.h)进一  相似文献   

12.
单歧藻对烷基酚类化合物的生物降解性研究   总被引:1,自引:0,他引:1  
以4-乙基酚为研究对象,研究其在单歧藻作用下的可降解性及其影响因素,然后对邻甲酚,间甲酚,4-辛基酚的生物降解动力学进行了比较,最后运用生物降解数据logK对8种烷基酚类化合物进行了结构-生物降解性(QSBR)的研究。研究结果表明:单歧藻对烷基酚类化合物的降解速率与藻细胞浓度和有机物初始浓度有关,化合物的降解动力学常数K值由污染物的初始浓度所决定,化合物的疏水性参数logKOW、分子量MW、一级价键连接指数1XV、二级价键连接指数2XV、生成热ΔHf和分子偶极距μ能够较好地拟合烷基酚类化合物的生物降解速率,其中2XV拟合效果最好。并在此基础上,初步分析了烷基酚类化合物的生物降解机理,认为空间参数是决定其生物降解的主要因素,化合物的生成热和电性参数μ、Ehomo的影响也不可忽视。  相似文献   

13.
酚类化合物好氧生物降解的QSBR研究   总被引:9,自引:0,他引:9  
 采用多种软件计算了酚类化合物的11种理化参数.应用SPSS统计软件,采用回归分析的方法,对3组生物降解数据-logKb、BOD、CO2进行了结构-生物降解性(QSBR)的研究.结果发现,分子最低空轨道能(Elumo)、偶极矩-μ-、分子摩尔质量(Mw)、分子表面积(TSA)、一阶分子连接性指数(1X)、生成热(Hf)等能够较好地拟合酚类化合物的生物降解速率或程度.在此基础上,初步分析了酚类化合物的生物降解机理,认为电性参数与立体参数是决定酚类化合物生物降解的主要因素,化合物的生成热对生物降解最终产物的影响也不可忽视.  相似文献   

14.
松花江中取代苯酚和苯胺类的生物降解性及QSBR研究   总被引:9,自引:0,他引:9       下载免费PDF全文
以松花江水细菌为接种源,用碘量法分别测定了28种苯酚及苯胺类化合物的BOD5值,采用QSBR程序软件计算分子量Mw,分子体积Mv,及电离常数pKa,用ClogP程序计算了疏水性参数logP.对28种取代苯的BODT值与其物化参数间进行了回归分析,得到如下最佳回归方程,BODT=87.5571+5.958pKa-0.73W,n=28,R^2=0.874,SE=10.33,F=86.85,P=0.应用所得QSBR模型,预测了28种化合物的BODT值,计算了残差,并初步探讨了生物降解机理。  相似文献   

15.
饱和带有机污染物的厌氧反硝化微生物降解   总被引:4,自引:0,他引:4  
以卤代烃和芳香烃为代表,通过室内实验模拟饱和带厌氧反硝化环境,对地下饱和带中有机污染物的厌氧反硝化可生物降解性,降解机理,降解动力学方程等进行了研究。实验结果表明,芳香烃较卤代烃易被微生物降解,在有低学葡萄糖存在时有 机物的最大生物降解速率C6H6:Lmax=17mg/(m^2.d),C7H8:Lmax=46mg/(m^2.d),CCl4;Lmax=7mg/(m^2.d),CHCl3:Lmax=6  相似文献   

16.
温度对汞抑制土壤脲酶动力学影响研究   总被引:10,自引:0,他引:10  
以不同施肥方式、不同有机质含量的草甸棕壤和黑土4个土样为对象,研究了不同温度条件下,汞(Hg)对土壤脲酶动力学特征的影响.结果表明,同一类型、有机质含量高的土壤脲酶活性、酶促最大反应速度(Vmax)和Vmax/Km均高于有机质含量低的土壤,表明有机质对脲酶的吸附能力较强;黑土VmaxVmax/Km值总体上大于草甸棕壤,但酶活性和米氏常数(Km)值在不同土壤类型之间规律性较差,反映出酶活性由总酶量和酶-底物亲和力等因素共同决定;黑土Km值大小与有机质含量相一致,而草甸棕壤则相反,表明有机质含量和施肥方式均会对Km值产生影响;在最适温度以下,随温度升高,土壤的脲酶活性、VmaxVmax/Km值均增加;Hg对土壤脲酶表现出典型的反竞争性抑制现象;Hg对脲酶活性的抑制作用及对KmVmaxVmax/Km的负效应均随温度升高而有增加的趋势,揭示出土壤对脲酶的保护能力随温度升高而有所下降.  相似文献   

17.
研究了间歇试验条件下,2,4-二硝基酚(2,4-DNP)与葡萄糖共基质时的厌氧降解动力学.结果表明:2,4-DNP与葡萄糖能同时被微生物降解;葡萄糖浓度高低对2,4-DNP的降解影响不大,而2,4-DNP的存在明显影响COD的降解.当2,4-DNP浓度<225 mg/L时,其比降解速率随浓度增大而增大,浓度为225 mg/L时比降解速率达到最大;由于底物抑制,当2,4-DNP浓度>225 mg/L时,其比降解速率呈下降趋势.选用Andrews非竞争性抑制模型描述2,4-DNP厌氧降解动力学,对实验数据进行非线性拟合,求得模型参数qmaxKsKi分别为3.24 mg/(h·g)、196.23 mg/L和165.91mg/L,实验数据与该动力学方程拟合较好.  相似文献   

18.
小麦秸杆对水中Pb(2+)和Cd(2+)的吸附特性   总被引:8,自引:2,他引:6       下载免费PDF全文
谭光群  袁红雁  刘勇  肖丹 《环境科学》2011,32(8):2298-2304
以农业废弃物小麦秸杆为吸附材料,探讨了小麦秸杆对Pb2+、Cd2+的吸附特性,重点研究了吸附时间、离子浓度、溶液pH值等对小麦秸杆吸附Pb2+、Cd2+的影响.结果表明,溶液pH值对吸附的影响大,在pH 2.0~6.0范围内,吸附量随溶液初始pH值的升高而升高.小麦秸杆吸附Pb2+、Cd2+的速度快,吸附动力学过程可以...  相似文献   

19.
高岭石、针铁矿及其二元体对胡敏酸的吸附特性   总被引:1,自引:1,他引:0       下载免费PDF全文
牛鹏举  魏世勇  方敦  但悠梦 《环境科学》2016,37(6):2220-2228
研究了高岭石、针铁矿及其混合物(KGM)和复合物(KGC)的表面性质及吸附胡敏酸的特性.结果表明,4种物质的比表面积(SSA)表现为针铁矿KGCKGM高岭石,KGM的SSA接近两种纯物质的平均值,而KGC的SSA明显升高.高岭石、针铁矿、KGM和KGC的等电点(IEP)分别为3.2、7.9、6.1和6.7;初始p H=5.0时,其表面Zeta电位分别为-13.9、38.2、14.3和19.7 m V.4种样品对胡敏酸的动力学吸附过程适合用准二级动力学模型描述,表明化学吸附是主要作用机制.一、二位Langmuir模型可较好地拟合等温吸附数据(R~2为0.962~0.993),其中二位Langmuir模型对KGM和KGC吸附数据的拟合度R~2分别为0.989和0.993;Freundlich模型对等温吸附数据的拟合度较低,但两种二元体的拟合度高于两种纯物质.初始p H=5.0时,高岭石、针铁矿、KGM和KGC对胡敏酸的吸附容量(q_(max))分别为6.02、61.83、35.13和42.10 mg·g~(-1);两种二元体的q_(max)都高于两种纯物质q_(max)的平均值,其中KGC的q_(max)明显升高.热力学参数表明,4种样品对胡敏酸的吸附均属于吸热反应,其中高岭石的吸附为非自发过程,其余样品的吸附为自发过程.  相似文献   

20.
微生物碳源利用效率(CUE)是指微生物将吸收的碳(C)转化为自身生物量C的效率,土壤微生物CUE的研究对深入认识土壤C循环过程十分重要.利用18 O-H2 O-DNA标记法,研究戴云山不同海拔(980~1765 m)天然林土壤微生物CUE、微生物生长速率(Cgrowth)和呼吸速率(Crespiration)的变化特征和影响机制.结果表明,微生物CUE在0.1~0.4之间变化,并随海拔升高而增加;微生物CUE与CgrowthCrespiration和单位微生物生长正相关,而与呼吸熵负相关,说明随海拔的增加,微生物通过增加个体生长和抑制个体呼吸来提高CUE;温度是影响CUE的主要因素,微生物CUE与温度负相关,说明随海拔增加,温度下降是促进土壤微生物CUE升高的关键因素.  相似文献   

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