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971.
972.
对苯二甲酸臭氧化降解的动力学及机制研究 总被引:3,自引:1,他引:2
研究了臭氧化对苯二甲酸(TA)的降解效率,并对该过程的动力学特性和降解机制进行了探讨.结果表明,TA与臭氧的
反应速率常数ko3-TA为(0.047±0.001)L·(mol·s)-1,与羟基自由基的kOH-TA为2.28╳109L·(mol·s)-1以上结果与TA臭氧化降解的表观反应速率常数相一致.采用高效液相色谱(HPLC)和离子色谱(IC)分析了TA降解过程的中间产物,主要包括苯甲酸、酒石酸、甲酸和草酸,在此基础上提出了臭氧化TA的可能降解历程. 相似文献
973.
结合气浮溶剂浮选和双水相萃取(ATPE)的优点,建立了一种新的分离/富集的方法,双水相气浮溶剂浮选(ATGS),并用于环境中痕量Cd(Ⅱ)的分离/富集.同时,以火焰原子吸收光谱(FAAS)检测Cd(Ⅱ),考察了浮选时间、N2流速、丙醇的分相条件、pH和配合剂用量等因素对浮选Cd(Ⅱ)的影响.最后优化出最佳浮选条件和测定条件,并探讨了共存离子对Cd(Ⅱ)浮选的干扰情况.结果表明,2mol·L-1的KI 9.5mL,1g·L-1的罗丹明B 2.5mL,盐体积分数为46%,缔合时间17min,气浮流速20 mL·min-1,浮选率可达100%,富集倍数为10,优于单一的双水相萃取.cd(Ⅱ)含量在0.050~5.000 mg·L-1与吸光度呈线性关系,线性方程为F=2.8967C-0.1474,可决系数为0.9996,检出限为0.0113mg·L-1,相对标准偏差RSD为1.8%(n=15).该方法在痕量/超痕量分析的样品前处理中有较好的应用前景. 相似文献
974.
The accumulation of organic matter in substratum pores is regarded as an important factor causing clogging in the subsurface flow constructed wetlands.In this study,the developing process of clogging separately caused by biofilm growth and organic particles accumulation instead of total organic matter accumulation was investigated in two groups of lab-scale vertical flow constructed wetlands (VFCWs) fed with glucose (dissolved organic matter) and starch (particulate organic matter) influent.Results showed that the growth of biofilms within the substratum pores certainly caused remarkable reduction of effective porosity,especially for the strong organic wastewater,whereas its influence on infiltration rate was negligible.It was implied that the most important contribution of biofilm growth to clogging is accelerating the occurrence of clogging.In comparison with biofilm growth,particles accumulation within pores could rapidly reduce infiltration rate besides effective porosity and the clogging occurred in the upper 0-15 cm layer.With approximately equal amount of accumulated organic matter,the effective porosity of the clogged layer in starch-fed systems was far less than that of glucose-fed systems,which indicated that composition and accumulation mode of the accumulated organic matter played an important role in causing clogging besides the amount.According to the results,some related methods to prevent and recover the clogging phenomenon were suggested. 相似文献
975.
H_2O和SO_2对Cr-Ce/TiO_2催化氧化NO性能的影响 总被引:3,自引:1,他引:2
采用浸渍法在最佳制备条件下制备了新型Cr-Ce/TiO2催化剂,并对催化剂进行了BET和XRD表征.同时,考察了反应温度、H2O和SO2对该催化剂催化氧化NO性能的影响,并对中毒催化剂进行了FT-IR分析,讨论了中毒机理.结果表明,Cr-Ce/TiO2催化剂具有良好的NO氧化活性,在空速为10000h-1、O2体积分数8%(φ)、NO进口体积分数700×10-6条件下,反应温度250℃时NO转化率可达到59.7%,330℃时NO转化率可达到最大值80.7%.单独加入10%(φ)H2O或300×10-6(φ)SO2都可使催化剂活性降低,但在较高温度时影响较小.330℃下单独通入SO2和同时通入H2O与SO210h后,由于催化剂表面生成了少量硫酸盐和亚硫酸盐,活性下降并维持在62.4%左右,能够满足对NOx进行高效吸收的要求;停止通入H2O和SO2后,催化剂活性恢复到71.6%,加热处理后活性能进一步恢复到78.5%.该催化剂具有比文献中报道的其它NO氧化催化剂更强的抗H2O和SO2毒化能力. 相似文献
976.
Aurora M. Castilla Stefan Van Dongen Anthony Herrel Amadeu Francesch Juan Martínez de Aragón Jim Malone Juan José Negro 《Die Naturwissenschaften》2010,97(2):143-151
We compared membrane thickness of fully developed eggs with those of non-developed eggs in different endangered falcon taxa.
To our knowledge, membrane thickness variation during development has never been examined before in falcons or any other wild
bird. Yet, the egg membrane constitutes an important protective barrier for the developing embryo. Because eggshell thinning
is a general process that occurs during bird development, caused by calcium uptake by the embryo, eggs are expected to be
less protected and vulnerable to breakage near the end of development. Thus, egg membranes could play an important protective
role in the later stages of development by getting relatively thicker. We used linear mixed models to explore the variation
in membrane thickness (n = 378 eggs) in relation to developmental stage, taxon, female age, mass and identity (73 females), egg-laying sequence (105
clutches) and the study zone. Our results are consistent with the prediction that egg membranes are thicker in fully developed
eggs than in non-developed eggs, suggesting that the increase in membrane thickness during development may compensate for
eggshell thinning. In addition, our data shown that thicker membranes are associated with larger, heavier and relatively wider
eggs, as well as with eggs that had thinner eggshells. Egg-laying sequence, female age and the study zone did not explain
the observed variation of membrane thickness in the falcon taxa studied. As we provide quantitative data on membrane thickness
variation during development in falcons not subjected to contamination or food limitation (i.e. bred under captive conditions),
our data may be used as a reference for studies on eggs from natural populations. Considering the large variation in membrane
thickness and the multiple factors affecting on it and its importance in the protection of the embryo, we encourage other
researchers to include measurements on membranes in studies exploring eggshell thickness variation. 相似文献
977.
978.
研究了蜂窝陶瓷对臭氧化降解苯乙酮效率的影响.结果表明,蜂窝陶瓷显著提高了臭氧化降解苯乙酮的效率,叔丁醇的试验表明该体系遵循.OH氧化机理.蜂窝陶瓷催化臭氧化降解苯乙酮的动力学可分为2个阶段,第一阶段的表观动力学常数为8.77×10-4s-1,Rct为10.34×10-10;第二阶段的表观动力学常数为4.63×10-3s-1,Rct为172.34×10-10.基于降解过程的色度变化和水样原子吸收的分析结果,结合降解动力学可以推测:降解过程中蜂窝陶瓷催化剂中Ti4+的溶出是苯乙酮降解效率提高的主导因素. 相似文献
979.
The toxicity of methyl tert-butyl ether (MTBE) to Chlorella ellipsoidea and Aphanizomenon flos-aquae was tested and assessed for a 15-d incubation with concentrations of MTBE from high (2.00×104 mg/L) to low (2 mg/L). The results showed that the toxicity was low when the concentration of MTBE was in the range 1.00×104-2.00×104 mg/L (the greatest inhibition of growth-rate was 70%-71%, occurred during the day 1-5). Low concentrations (2-500 mg/L) stimulated algal growth up to the greatest effect of 85%-200% w... 相似文献
980.
The traditional locomotive diesels are usually designed for the performance of rated condition and much fuel will be consumed. A new plunger piston matching parts of fuel injection pump and injector nozzle matching parts were designed. The experimental results of fuel injection pump test and diesel engine show that the fuel consumption rate can be decreased a lot in the most of the working conditions. The forced lubrication is adopted for the new injector nozzle matching parts, which can reduce failure rate and increase service life. The design has been patented by Chinese State Patent Office. 相似文献