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1.
SO2在Co—Mo/AC催化剂上的还原   总被引:5,自引:1,他引:4  
刘守军  刘振宇 《环境化学》1999,18(6):519-525
本文研究了活性焦(AC)担载Co-Mo催化剂对SO2还原的催化性能。考查了催化剂不同的预处理方法,H2/SO2摩尔比和还原温度对还原过程硫产率的影响,并就硫化后的Co-Mo和活性焦在催化床不同的构成对硫产率的影响进行了研究。结果表明,经硫化后的催化剂在SO2+2H2→S+2H2O反应有较高的催化活性,在最佳反应温度300℃,H/SO摩尔比为3,空速6000L;kg^-1.h^-1条件下,生成硫的产  相似文献   

2.
二氧化硫与1—己烯的光化学反应动力学   总被引:1,自引:0,他引:1  
郭海忱  杜尧国 《环境化学》1995,14(6):500-507
利用GC/MS方法研究了SO2与1-己烯在无氧和有氧体系中光化学反应动力学,确定了SO2与1-己烯光化学反应的级数,给出了293-333K温度范围内总的反应速度常数K,以及K与温度的关系、反应的活化能和指前因子。另外,对反应物己醛和2-己酮的生成反应速度常数及其活化能也进行了计算和讨论。  相似文献   

3.
NOx分解还原催化研究进展   总被引:1,自引:0,他引:1  
介绍和评价了NO_x分解还原的3类催化剂:贵金属催化剂、氧化物催化剂、金属离子置换的分子筛。在NO_x的碳氢化合物选择性催化还原反应(HC-SCR反应)中,同样有3类催化剂,即金属氧化物、贵金属和分子筛。由于Cu-ZSM-5是目前最有希望投入实际使用的一种,故本文重点介绍了它对NO_x的HC-SCR反应的催化机理,以及温度、O_2含量、Cu~(2+)的置换度、不同种类HC及HC含量等各种因素对Cu-ZSM-5的影响,并对其工作台试验进行了评价,指出了其存在的问题及当前的研究热点。  相似文献   

4.
研究结果表明.酸性红壤施适量石灰,能改善甘蔗的N、P、K养分状况,提高Ca2+-ATP酶和中性转化酶活性,减缓甘蔗在伸长期Ca2+-ATP酶活性降低的幅度,极显著地促进甘蔗生长。石灰施用量与甘蔗叶片N、K含量、Ca2+-ATP酶活性及甘蔗株高里极显著或显著的二次函数曲线相关;与甘蔗叶片含P量、中性转化酶活性亦呈二次函数曲线相关,但相关性未达显著水平。研究结果还表明,施石灰量不同对甘蔗各生长时期株高的影响很大,施用量为1.2t/hm2左右时,甘蔗前、中、后期的株高都极显著的高于对照,小于0.4t/hm2或大于2.0t/hm2时,甘蔗生长后期的株高与对照差异不显著.  相似文献   

5.
添加物对填埋场稳定化时间的影响   总被引:8,自引:0,他引:8  
在垃圾中添加KCl、KH2PO4、(NH4)2CO3,FeCl2时,对垃圾降解和填埋场稳定化时间的缩短有促进作用,而CuSO4、K2C42O7、Na2MoO4、Na2WO4、醋酸的加入则抑制了垃圾的降解,认为KCl是促进垃圾降解,加速填埋场稳定化的最佳添加物。  相似文献   

6.
苯酚、苯胺及其衍生物对斜生栅列藻的急性毒性及QSAR研究   总被引:19,自引:2,他引:17  
陆光华  袁星  赵元慧 《环境化学》2000,19(3):225-229
本文应用OECD标准方法测定了18种酚类胺类化合物对斜生栅列藻的48h-EC60值,选择参数ELUMO和lgKow进行了QSAR分析,得到下列回归方程:-1gEC50=2.541-0.649ELUMO+0.299LgKow,n=18,r=0.903,SE=0.314应用所得方程计算了化合物的毒性,探讨了毒机理。  相似文献   

7.
二氧化氯对水中无机污染物的去除效果研究   总被引:11,自引:1,他引:11  
本文通过模拟水厂混凝沉淀-过滤工艺,研究了ClO2抽量和投加点对水中Fe^2+,Mn^2+,S^2-CN^-污染物的去除效果,并与液氯进行了对比,结果表明,随ClO2投量增大,去除率也增加,且ClO2效果优于液氯;后投ClO2的去除效果好于中间投和预投ClO2,且可省药,这为ClO2在饮用水中的应用提供了科学依据。  相似文献   

8.
对Al2(SO4)3,Ca(OH)2不同反应条件下去除洗涤废水中总磷的情况作了对比试验,结果表明,按Ca(OH)2:TP=3.7:1.0(重量比)投加试剂,回用生成的磷灰石沉淀助凝,TP(总磷)去除率可达95%,CODcr有少量去除。  相似文献   

9.
氧化热处理对活性炭纤维吸附转化SO2能力的影响   总被引:5,自引:0,他引:5  
李开喜  凌立成 《环境化学》1999,18(3):210-215
本文研究了经O2,空气或HNO3氧化后,高温下热处理改性的活性炭纤维(ACF)在O2和水蒸气存在下脱除SO2的能力。结果表明,氧化热处理改性后,ACF的脱硫能力都有明显提高,其中O2改性的ACF脱硫活性最高,HNO3改性的ACF最低,空气改性的ACF居中。并对改性ACF具有不同脱硫活性的原因进行了分析。TPD实验表明,H2SO4从O2改性ACF上脱除最容易。  相似文献   

10.
水处理氧化还原过程的电化动化学特性   总被引:1,自引:0,他引:1  
曲久辉 《环境化学》1997,16(2):178-184
以流动电流为参数。研究了水处理条件下氧还还原过程的电动化学特性,考察了水中KMnO4及其与MnO2+,Fe^2+之间氧化还原作用的流动电流(SC)规律,探讨了氧化还原的初始条件,水处理环境、原水水质、氧化剂与还原剂的投加方式等对流动电流的影响。结果表明,不中约0.5mg.l^-1的KMnO4可产生SC的峰值,而且当它与Mn^2+和Fe^2+经不同条件进行氧化还原作用时,可通过SC值的变化表现出更为  相似文献   

11.
This paper reviews the application of meso- porous transitional metal oxides in water treatment on basis of the catalysis and adsorption. Mesoporous transitional metal oxides are characterized by their intrinsic features, such as a high surface area, a highly ordered array of unidimensional pores with a very narrow pore size distribution, and highly dispersed active sites. Finally, the suggestions of further study on application are proposed.  相似文献   

12.
柳葛贤  吕功煊 《环境化学》2007,26(5):626-629
研究了过渡金属硝酸盐及Al2O3为载体担载催化剂在罗丹明B臭氧氧化过程中的催化作用,考察了温度、pH值以及催化剂浓度等因素对反应的影响.结果表明,过渡金属离子可显著地提高罗丹明B的脱色速率,而担载型过渡金属氧化物催化剂活性较低.较低的pH值和反应温度有利于罗丹明B的催化臭氧化.罗丹明B溶液经过催化臭氧氧化后COD去除率可提高24%.  相似文献   

13.
在V2O5-WO3/TiO2催化剂上负载碱金属氧化物(K2O,Na2O),通过BET,XRD和SEM等方法对微观结构进行表征,研究不同含量碱金属氧化物对催化剂脱硝活性、N2O生成率和SO2氧化率的影响.结果发现,较大含量的碱金属对催化剂微观结构有一定影响.碱金属氧化物与催化剂表面V物种的结合生成部分碱金属盐(如KVO3),改变了催化剂的表面结构,使催化剂中有效活性位的数量大大降低,从而导致催化剂活性降低.两种碱金属氧化物对催化剂的毒性顺序为K2O〉Na2O.  相似文献   

14.
In sludge incineration, the thermal behavior of heavy metal is a growing concern. In this work, the combined analysis of metal partitioning behavior between vapor phase and condensed phase, speciation redistribu- tion in condensed phase and the difference of metal species in binding energy was carried out to investigate the possible volatilization-condensation mechanism of heavy metals in high-temperature sludge incineration. It was found that there were two steps in metal volatilization. The initial volatilization of heavy metal originated from their exchangeable (EXC), carbonate bound (CAR) and iron- manganese bound (FM) fractions, which is primarily composed of simple substance, chlorides, oxides and sulfides. With the increase of chlorine and sulfur in sludge, the inner speciation redistribution of heavy metals occurred in condensed phase, which was an important factor affecting the potential volatility of heavy metals. A partial of metal species with complexed (COM) and residual (RES) fractions gradually decomposed into simple substance or ions, oxides and carbonates, which signifi- cantly strengthened the second volatility. In presence of chlorine, about 46% of Cd with the RES fraction disappeared when the volatility rate of Cd increased by 44.89%. Moreover, about 9% of Pb with COM fraction disappeared when there was an increase of nearly 10% in the volatilization rate. Thus, the second volatilization was mainly controlled by the decomposition of metal species with COM and RES fractions. By virtue of XRD analysis and the binding energy calculation, it was found that metal complex and silicates were inclined to decompose under high temperature due to poor thermo stability as compared with sulfates.  相似文献   

15.
纳米金属氧化物对土壤酶活性的影响研究进展   总被引:1,自引:0,他引:1  
纳米金属氧化物的大量生产和广泛应用使其不可避免地进入环境中,土壤是其释放到环境中主要的汇。纳米颗粒由于尺寸效应,具有许多独特的物理化学性质,其进入环境后潜在的生态和健康风险问题日益受到研究者的关注。土壤酶是土壤生物化学过程的主要参与者,也是生态系统物质循环和能量流动过程中最活跃的生物活性物质。土壤酶活性的变化能反映土壤中生化反应的情况,可作为评价土壤中纳米材料污染状况的生物学指标。本文较系统地回顾和总结了纳米金属氧化物对土壤酶活性的影响及可能的影响途径,探讨了纳米金属氧化物作用于土壤酶的主要影响途径,并展望了未来研究主要发展方向。  相似文献   

16.
红壤胶体铁氧化物界面有机氯的非生物转化研究进展   总被引:7,自引:0,他引:7  
综述了红壤胶体铁氧化物的结构、形态及其转化;铁氧化物界面有机氯的非生物转化过程及其影响因素;异化铁还原作用下的有机氯转化过程。有机氯的非生物转化主要包括氧化转化与脱氯转化过程。氧化转化包括暗态下的化学氧化与光化学氧化过程;脱氯转化包括脱氢卤化、加氢脱氯、脱双卤、二聚脱氯与亲核置换脱氯等反应过程。有机氯的非生物转化主要受胶体界面pH、Eh、水溶性有机物、金属离子、铁氧化物形态与铁还原细菌等的显著影响。有机氯非生物转化的化学-微生物耦合机制、复合污染条件下重金属对界面有机氯非生物转化过程的影响机制、红壤胶体界面有机氯污染的综合调控技术方法等三个方面值得关注,有助于推动土壤胶体界面环境化学的发展。  相似文献   

17.
A five‐step extraction procedure for metal speciation studies (copper, lead, nickel, manganese and zinc) was applied to the analysis of lake sediments characterised by different environmental features. A different partition of metals into the several metal forms was observed. Both the metal fraction sorbed or co‐precipitated on hydrous Mn‐oxides (especially lead and zinc) and that bound to organic matter (especially copper) are high in some samples. A prevalently anthropogenic origin of these metals may be hypothesised on the basis of existing knowledge of the equilibrium and change phenomena occurring among water, particulate and sediments. Conversely, the non‐solubilised forms of metals are abundant in the sediments of lakes that are certainly not polluted. The concentration of manganese is very high in the sediments of Antarctic lakes; sequential extractions show its lithogenic origin. In conclusion, a knowledge of the different types of metal associations in sediments and their percentage can facilitate understanding of both natural and anthropogenic metal enrichment of aquatic systems.  相似文献   

18.
土壤重金属化学形态的生物可利用性评价   总被引:59,自引:0,他引:59  
雷鸣  廖柏寒  秦普丰 《生态环境》2007,16(5):1551-1556
重金属化学形态是近年来土壤化学、植物营养和环境科学研究领域的一个热点和难点,利用重金属的化学形态分布和含量变化来评价重金属的生物可利用性,有利于全面研究重金属的危害性和治理重金属污染土壤。结果表明,水溶态和交换态的重金属易被生物吸收利用,而残留态重金属一般不被生物利用,其它形态如碳酸盐结合态、铁锰氧化物结合态和有机物结合态的生物可利用性主要取决于外界环境的变化。  相似文献   

19.
Mesoporous silicas such as MCM-41 and SBA-15 possess high surface areas, ordered nanopores, and excellent thermal stability, and have been often used as catalyst supports. Although mesoporous metal oxides have lower surface areas compared to mesoporous silicas, they generally have more diversified functionalities. Mesoporous metal oxides can be synthesized via a soft-templating or hard-templating approach, and these materials have recently found some applications in environmental catalysis, such as CO oxidation, N2O decomposition, and elimination of organic pollutants. In this review, we summarize the synthesis of mesoporous transition metal oxides using mesoporous silicas as hard templates, highlight the application of these materials in environmental catalysis, and furnish some prospects for future development.  相似文献   

20.
In recent years, heavy metal contamination has become a major environmental issue in many parts of the world. Fe and Mn oxides, oxyhydroxides and hydroxides have long been recognized as scavengers playing an important role in controlling the location, mobility and bioavailability of metal contaminants in soils. Fe–Mn concretions and nodules are discrete bodies made of soil or sediment materials cemented together under the influence of Fe and Mn oxides. Here metals sorption by Fe–Mn concretions and nodules are surveyed and critical reviewed. Valuable available literature data demonstrate that the formation of Fe–Mn concretions and nodules is the most efficient and durable process for metal contaminants sequestration in the soils. The papers discussed in this review show that the application of Fe–Mn concretions and nodules, as geochemical scavengers for remediating metal contaminated soils, is strongly recommended.  相似文献   

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