Effects of metal and acidic sites on the reaction by-products of butyl acetate oxidation over palladium-based catalysts

Catalytic oxidation is widely used in pollution control technology to remove volatile organic compounds. In this study, Pd/ZSM-5 catalysts with different Pd contents and acidic sites were prepared via the impregnation method. All the catalysts were characterized by means of N2 adsorption- desorption, X-ray fluorescence （XRF）, HE temperature programmed reduction （H2-TPR）, and NH3 temperature programmed desorption （NH3-TPD）. Their catalytic performance was investigated in the oxidation of butyl acetate experiments. The by-products of the reaction were collected in thermal desorption tubes and identified by gas chromatography/mass spectrometry. It was found that the increase of Pd content slightly changed the catalytic activity of butyl acetate oxidation according to the yield of CO2 achieved at 90%, but decreased the cracking by-products, whereas the enhancement of strong acidity over Pd-based catalysts enriched the by-product species. The butyl acetate oxidation process involves a series of reaction steps including protolysis, dehydrogenation, dehydration, cracking, and isomerization. Generally, butyl acetate was cracked to acetic acid and 2- methylpropene and the latter was an intermediate of the other by-products, and the oxidation routes of typical by-products were proposed. Trace amounts of 3-methylpentane, hexane, 2-methylpentane, pentane, and 2-methylbutane originated from iso4merization and protolysis reactions.     

饮用水消毒副产物控制工艺研究进展

通过对氯、二氧化氯、紫外线等常见消毒工艺以及去除已生成消毒副产物的深度处理工艺进行了分析,探讨了各种消毒工艺的消毒性能和对消毒副产物的控制效果以及各种深度处理工艺对消毒副产物的去除性能,为实际水处理中消毒以及深度处理工艺的选择提供了参考。     

Biodegradation of α and β Endosulfan in Soil as Influenced by Application of Different Organic Materials

Abstract

A laboratory pot experiment was conducted to study the effect of amending soil with four different sources of organic matter on the degradation rate of α and β endosulfan isomers. Poultry by-product meal, poultry manure, dairy manure, and municipal solid waste compost were cured, dried, ground (<1 mm) and thoroughly mixed with a calcareous soil at a rate of 2% and placed in plastic pots. Endosulfan was added at the rate of 20 mg kg^?1. The moisture level was kept near field capacity and the pots were kept at room temperature. Soil sub-samples, 100 g each, were collected from every pot at days 1, 8, 15, 22, 29, 43, and 57 for the measurement of endosulfan isomers. Endosulfan residues were extracted from the soil samples with acetone. The supernatant was filtered through anhydrous sodium sulphate, 5 mL aliquot was diluted to 25 mL with hexane, mixed well, and then two sub-samples from the filtrates were analyzed for α and β endosulfan isomers by gas chromatography. The results indicated that the half-life (T _½) of α-endosulfan in the poultry by-product meal treatment was 15 days compared to about 22 days in the other treatments. The T _½ of β-endosulfan was 22 days in the poultry by-product meal treatment and followed a bi-phasic pattern, 57 days in the municipal solid waste compost treatment and the extrapolated T _½ was about 115 days for the other three treatments.     

Ru/AC催化臭氧氧化难生物降解有机物

研究了臭氧单独氧化和Ru/AC催化臭氧氧化DMP、酚类物质和消毒副产物前体物.结果表明,Ru/AC能显著提高臭氧氧化中有机物的矿化效果.在DMP降解中,反应100 min后TOC的去除率由单独臭氧氧化的28.84%提高到66.13%.在23种酚类物质降解中,反应60min后TOC的去除率由单独臭氧的9.57%~56.08%提高到41.81%~82.32%.相对于单独臭氧,Ru/AC催化臭氧氧化更能有效地降低水源水中消毒副产物的生成势,以卤乙酸生成势的降低最为明显,100 min后卤乙酸生成势由144.02μg/L降到58.50μg/L,低于美国环保局规定的限制浓度60μg/L.而使用单独臭氧处理并不能使卤乙酸生成势降到符合美国EPA的规定.比较了BAC、O3+BAC、O3/AC+BAC以及Ru/AC+O3+BAC工艺处理水源水的效果,TOC平均去除率分别为3.80%、20.14%、27.45%和48.30%;COD平均去除率分别为4.37%、27.22%、39.91%和50.00%;UV254去除率分别为8.16%、62.24%、67.03%和84.95%.Ru/AC+O3+BAC工艺相比其他工艺,更能有效地...     

南方某水源水中天然有机物的特点及氯胺对氯化消毒副产物的控制

在对天然有机物分类的基础上进行了水体中有机物的特性研究，并采用氯胺对不同特性有机物的氯化消毒副产物进行了控制研究。结果表明，疏水酸占有机物总量的24%，疏水中性物质占41%，疏水性有机物占67%；对于三卤甲烷类消毒副产物生成势，疏水酸所产生的最多，疏水碱次之，亲水酸最少；对于卤乙酸类消毒副产物生成势，疏水碱产生的三卤乙酸最多，其次为疏水酸，亲水酸最少。氯胺对不同类有机物氯化消毒副产物控制程度不同，氯胺对疏水中性物质控制三卤甲烷类消毒副产物最好，其次是疏水碱和亲水碱；对疏水酸的三卤甲烷生成量控制较弱，对亲水酸的控制效果最差；氯胺对亲水碱氯化产生卤乙酸的控制效果最好，其次是疏水碱，控制效果最差的为疏水中性物质。     

脉冲放电等离子体烟气脱硫脱硝工业试验

40000—50000Nm^3／h工业试验结果表明：烟气温度75℃-80℃，脱硫效率大于90％，脱硝效率大于40％，烟气温度90℃-95℃，脱硫效率大于80％，脱硝效率大于50％；能耗小于3.0Wh／Nm^2；随着温度升高，SO2热化学反应效率逐渐降低；随着氨硫化学计量比增大，氨泄漏逐渐增加，烟气温度90℃。95％，氨泄漏增加更为迅速。并分析了副产物的成分，阐述了脱硫脱硝的机理，探讨了烟气排放的温度。     

AAO-MBR工艺污水处理系统中消毒副产物前体物变化规律

为探究DBPs（消毒副产物）前体物在污水处理过程中的变化情况,采用超滤膜和XAD大孔吸附树脂将AAO-MBR工艺沿程出水中DOM（溶解性有机物）进行分离,并利用3D-EEM（三维荧光光谱）对分离前后水样进行表征,同时测定DBPFP（消毒副产物生成势）.结果表明:①沉砂池出水具有较低的C-DBPFP（含碳消毒副产物生成势）;经过AAO和MBR后,由于微生物代谢作用生成的疏水性SMPs（微生物代谢产物）类物质（为主要的C-DBPs前体物质）包含较多不饱和键,导致C-DBPFP增加.②沉砂池出水的N-DBPFP（含氮消毒副产物生成势）较低,但经过AAO后生成的小分子物质（为主要的N-DBPs前体物）导致N-DBPFP增加;经过MBR后由于SRT（污泥停留时间）和污泥浓度的增加造成小分子物质减少,致使N-DBPFP降低.③市政污水经过AAO后,C-DBPs和N-DBPs前体物分别增加了90.9%和7.3%;而MBR具有较高的DOC去除率（74.4%）,去除了56.8%的C-DBPs前体物和78.1%的N-DBPs前体物.研究显示,AAO-MBR工艺对市政污水中C-DBPs和N-DBPs前体物有较好地去除效果.      

河流型水源地源水典型氯化消毒副产物及其前体物的强化去除工艺

以长三角某典型河流型水源地源水为研究对象,设计了传统工艺及基于凹凸棒土处理单元的6种强化工艺,对各工艺及其处理单元应用于典型氯化消毒副产物(三卤甲烷和卤乙酸)及其前体物控制的技术和经济可行性进行了系统分析。结果表明,预O3+凹土强化混凝+O3-GAC强化的工艺对上述2种消毒副产物及其前体物的控制效果最佳;在传统工艺中单纯增加O3处理也能在一定程度上提高其对消毒副产物前体物的去除效果;KMnO4控制消毒副产物的效果一般,但KMnO4处理可强化后续单元对消毒副产物前体物的去除效果。各工艺处理出水中三卤甲烷和卤乙酸单项指标均能达标,但传统工艺和经凹土强化混凝+GAC强化的工艺出水三卤甲烷4种化合物的实测浓度与其各自限值的比值之和均大于1.0,不能满足水质要求,必须进行强化处理。凹土强化混凝单元在6种强化工艺条件下对三卤甲烷生成潜能(THMFP)和卤乙酸生成潜能(HAAFP)的去除率较传统混凝单元平均提高15.99%和4.92%;各强化工艺对THMFP和HAAFP的去除率较传统工艺均提高20%以上(除凹土强化混凝+GAC强化的工艺外),消毒副产物产生量降低40%以上,工艺成本降低20%以上。     

开化县外向型创汇林业的战略模式

我国森林资源少,消耗量大,林业建设资金短缺。如何发展当前的林业生产、筹集林业建设资金,开化县的外向型创汇林业为我们走出了一条具有中国特色的外向型林业建设道路。本文就开化县发展外向型创汇林业的优点、出口创汇的主要对策、主要商品、发展潜力及其前景进行了论述,对目前正在探索适合我国国情的、解决我国林业“两危”的战略对策提供了现实的典型范例。     

苯甲酸重副产物的脱色处理

为了有效去除苯甲酸重副产物中含有的交联大分子和碳化物等有色杂质，降低有用组分资源化处理的难度，分别采用吸附和蒸馏两种方法对苯甲酸重副产物进行脱色处理。实验结果表明：大孔树脂、硅藻土、活性炭等作脱色剂不能有效去除苯甲酸重副产物中的有色杂质；在真空度0．093～0．095MPa、蒸馏温度220～240℃条件下进行蒸馏脱色，当温度出现回落时停止蒸馏，平均馏出率为66．99％；蒸馏脱色得到的轻组分颜色呈黄色，可满足中和、酸化、结晶、回收苯甲酸的要求；釜残物可作为燃料通过焚烧利用其热能。