药用虎杖剩余物的化学组成与热解特性

为了探索药用虎杖加工剩余物资源的合理化利用途径,以药用虎杖的秸秆、根和药渣为研究对象,利用热重分析法(TGA)研究了三者的热解特性及其动力学规律,利用Py-GC-MS技术研究了秸秆、根和药渣在快速裂解条件下的产物分布及热裂解机理。结果表明:虎杖秸秆、根和药渣的热解过程主要分为干燥、主失重和炭化3个阶段;采用Coats-Redfern法对三者的热解动力学进行了分析,获得了虎杖秸秆、根和药渣的热解动力学机理函数,热解动力学机理分别为三维扩散Jander机理、2级化学反应机理和二维扩散Valensi机理,其热解活化能分别为113.87、64.49和28.16 kJ·mol~(-1)。快速热裂解产物表明,中药加工剩余物在热裂解制备乙酸、糠醛及酚类化合物等精细化学品方面具有一定的开发前景。     

生活垃圾和玉米秆混合热解动力学及产物分布

为探讨生活垃圾和玉米秆共热解过程中的协同关系和产物分布,采用热重分析仪对生活垃圾、玉米秆及其混合物进行了热解实验研究,并进行动力学计算。结果表明,混合热解可分为脱水、热解、炭化、焦催化气化4个阶段,前3个阶段与单独热解过程类似,第4个阶段与单独热解相比失重明显增加,表明混合热解过程中存在协同效应;混合物热解的实际活化能为28.492 k J/mol,低于单独热解及其混合物热解理论活化能,可见混合热解利于热解反应进行。为明晰混合热解对热解反应的促进作用,利用固定床热解实验,研究了混合比例对产物产率和热解气各组分产率的影响。结果表明,在不同混合比例下,固液实际产率低于理论值,而气体实际产率则比理论值高;混合物料热解气中H2、CH4、CO2产量均高于其理论值,而CO产量却相反,低于其理论值。     

催化剂掺混对污泥快速热解产气的影响

将干污泥(DS)与3种催化体系(CaO、焦炭、CaO-焦炭)掺混,经机械化学预处理后制得热解混合样品,考察催化剂掺混对DS快速热解产气的影响。研究表明,CaO可以提高DS热解综合产气效果,促进热解气相产物中的CH4和CO2向H2和CO转化,当CaO和DS质量比为1.00∶1.00时,热解气相产物中H2、CO体积分数之和、气体产率、产气低位热值及H2产量均达到最大值,分别为77.04%、0.412 m3/kg、62.75kJ/kg和6.88 mol/kg;焦炭可以改善DS热解气相产物品质,当焦炭和DS质量比为1.00∶1.00时,热解气相产物中H2体积分数和氢占比(H2与CO的体积比)最优,分别为38.90%和1.23;CaO-焦炭体系可以明显提高DS热解液相产物质量分数,当CaO、焦炭和DS质量比为0.50∶0.50∶1.00时,热解液相产物的质量分数达到最大值50.17%。研究结果为剩余污泥的资源化利用提供数据支持。     

TG-FTIR研究生物质成型燃料热解与燃烧特性

利用热重-红外联用分析仪(TG-FTIR)研究了生物质成型燃料(玉米秸杆)的热解和燃烧特性。结果表明,热解和燃烧反应过程均可分为3个阶段:干燥脱气(100~200℃)、挥发分反应(200~400℃)与碳化反应(400~1 000℃)。热解和燃烧主要失重阶段(200~400℃),燃烧反应速率总体上大于热解反应速率。利用Coats-Redfern方法对玉米秸杆的主要失重阶段进行动力学分析发现,热解和燃烧的反应过程符合一级反应模型;在主要失重阶段(200~400℃),热解和燃烧所需的活化能相差不大。FTIR分析表明,热解的气相产物主要分为轻质类气体(H2O、CO2、CO、CH4、HCl、NH3和HCN)和焦油类(酸类和酚类)物质,而燃烧的气相产物主要以CO2和H2O析出为主。     

O_2/CO_2气氛下市政污泥混煤燃烧及动力学特性

采用差示扫描量热法对市政污泥、神华烟煤和淮北烟煤单独及不同比例混合物在O2/CO2气氛下进行燃烧特性的实验研究,结果表明,市政污泥综合燃烧特性最好,神华烟煤次之,淮北烟煤最差;随着污泥掺混比例的增加,混合试样着火温度和燃尽温度提前,综合燃烧特性得到改善,但燃烧放热量减少。利用Freeman-Carroll法对淮北烟煤、市政污泥及两者混合物的燃烧动力学参数进行计算,得到市政污泥、淮北烟煤和神华烟煤的平均反应活化能E分别为48.34、68.32和51.47 k J/mol。     

含油污泥与玉米秸秆共热解协同特性

利用热重-傅里叶变换红外分析仪(TG-FTIR)对含油污泥与玉米秸秆共热解特性进行了研究,分析了各温度段的协同效应。TG分析表明,共热解主要呈现3个阶段:挥发分的析出(210～520℃)、碳酸盐的分解(600～780℃)、长链难分解重质油的热裂解和半焦的气化(900～1100℃),且在不同热解阶段呈现出不同的协同效应。热解动力学分析表明,含油污泥与玉米秸秆共热解后,第1阶段的活化能有所增高,而第2、3阶段的活化能大幅降低。FTIR分析表明,第1、2阶段,共热解与单一物料热解的产物种类基本一致,而在第3阶段,共热解使含油污泥热解产物甲基化合物发生分解和转化。含油污泥与玉米秸秆共热解可促进CO_2、CO、CH_4和C=O化合物的析出,其中添加玉米秸秆质量分数为10%时,对CO_2、CO和CH_4析出的促进作用最强,添加30%时则对C=O化合物的析出更为有利。     

废弃中药渣催化热解制取生物油的研究

利用热重分析仪(TGA)对植物类中药渣的热解特性进行了研究,用Coats-Redfern积分法计算了其热解动力学参数,得出中药渣热解反应符合一级反应动力学方程,其活化能较低,为36.0kJ/mol。考察了热解温度对气体、液体、固体产物的影响,在723K时,液体产物生物油产率最高,为39%。以介孔分子筛SBA-15以及分别负载Al、Sn、Ni、Cu和Mg的SBA-15作为催化剂,研究催化热解对气体、液体、固体产率及生物油组分的影响。研究表明,Al-SBA-15的催化效果较好,液体产率最高,为36%;采用元素分析仪和热值测定仪,得到用Al-SBA-15作为催化剂时生物油的氧质量分数最低,低位热值最高。用GC/MS对生物油组分的分析结果表明,添加Al-SBA-15后,热解产物中脂肪族和芳香族化合物增加,而含氧化合物减少。     

2种烟煤掺混干化污泥中温热解制气

以2种不同产地烟煤和某污水处理厂污水污泥作为研究对象,在实验室预处理,将两者按不同比例掺混后使用管式电阻炉进行中温热解实验,探讨了烟煤与干化污泥掺混热解产气特性。实验结果表明:烟煤掺混干化污泥热解,不改变两者热解产H_2、CO和CH_4的规律。在相同热解温度下,烟煤的掺混比例越高,产生H_2体积百分含量越大。对于CH_4,掺混物料产气峰值热解温度由800℃降低至700℃。混合物料中污泥掺混比例增加会增加CO含量。通过热重实验,随着物料中配入干化污泥质量比重增加,热解反应所需活化能减小。     

茉莉花茶废弃物的热解特性及其产物

为了探讨茉莉花茶废弃物的热解过程及温度对产物的影响,采用固定热解反应器和热重红外联用仪(TG-FTIR)对其进行了研究,结果表明,茉莉花茶废弃物解产生的固体量随温度升高而降低,气体产量随温度升高而增加,热解得到的液体量比例随热解温度不同而不同,表明茉莉花茶热解产物随热解温度不同而不同。热解产物主要有CO_2、水、醇及含C=C的有机物和生物焦固体。500℃下制得的生物焦比表面积较低,仅为0.720 9 m~2·g~(-1),经活化处理后的生物焦比表面积明显增大。经CO_2和H_2O活化后得到的生物焦的BET比表面积分别升至139.503 3 m~2·g~(-1)和122.527 6 m~2·g~(-1)。茉莉花茶热解的质量损失主要由于有机物挥发,用Coats-Redfern法对茉莉花茶废弃物热解过程进行模拟,得热解过程符合气体扩散模型,热解活化能约为60 kJ·mol~(-1);因此,气体扩散是茉莉花茶废弃物热解过程中主要的限制因素。     

罐底含油泥热解动力学参数计算方法的优选

在化学反应设计中反应动力学是较重要的因素。为得到更合理的污泥热解动力学参数计算方法,利用热重分析仪,在氮气气氛下对罐底含油污泥的热解特性进行研究。根据热重实验数据,分别采用Coats-Redfern法、Kissinger法、FWO法和Popescu法计算污泥热解动力学参数,并获取罐底泥热解制油的主要阶段(第2阶段)的反应活化能E、频率因子A并分析各种方法反应机理。通过对比不同计算方法得到动力学参数及拟合曲线与实验曲线的相关性,确定了最佳罐底含油污泥热解动力学参数计算方法。研究表明,Popescu法得到罐底泥的热解过程符合Jander方程,活化能E为101.43 kJ/mol,与FWO法得到的91.20 kJ/mol相近,且预测曲线与实验曲线有较好的相关性(0.9816),说明Popescu法计算罐底泥热解动力学参数更合适。     

Sources and fate of PCDD and PCDF

PCDD and PCDF were found in urban air particulates from St. Louis and Washington, D.C., and in sediments from the Great Lakes and Siskiwit Lake, Isle Royale. The similarity between the PCDD and PCDF found in air particulates and sediment samples and the presence of PCDD and PCDF in sediment from Siskiwit Lake (a location which can receive only atmospheric inputs) suggest that these compounds are emitted to the atmosphere from combustion sources. The historical input of PCDD and PCDF to dated sediment cores shows a strong increase since 1940, and this suggests that the incineration of chlorinated organic compounds is an important source of PCDD and PCDF to the environment.     

Field and laboratory studies of the fate and enantiomeric enrichment of venlafaxine and O-desmethylvenlafaxine under aerobic and anaerobic conditions

The stereoselectivity of R,S-venlafaxine and its metabolites R,S-O-desmethylvenlafaxine, N-desmethylvenlafaxine, O,N-didesmethylvenlafaxine, N,N-didesmethylvenlafaxine and tridesmethylvenlafaxine was studied in three processes: (i) anaerobic and aerobic laboratory scale tests; (ii) six wastewater treatment plants (WWTPs) operating under different conditions; and (iii) a variety of wastewater treatments including conventional activated sludge, natural attenuation along a receiving river stream and storage in operational and seasonal reservoirs. In the laboratory and field studies, the degradation of the venlafaxine yielded O-desmethylvenalfaxine as the dominant metabolite under aerobic and anaerobic conditions. Venlafaxine was almost exclusively converted to O-desmethylvenlafaxine under anaerobic conditions, but only a fraction of the drug was transformed to O-desmethylvenlafaxine under aerobic conditions. Degradation of venlafaxine involved only small stereoisomeric selectivity. In contrast, the degradation of O-desmethylvenlafaxine yielded remarkable S to R enrichment under aerobic conditions but none under anaerobic conditions. Determination of venlafaxine and its metabolites in the WWTPs agreed well with the stereoselectivity observed in the laboratory studies. Our results suggest that the levels of the drug and its metabolites and the stereoisomeric enrichment of the metabolite and its parent drug can be used for source tracking and for discrimination between domestic and nondomestic wastewater pollution. This was indeed demonstrated in the investigations carried out at the Jerusalem WWTP.     

Meta-analysis of time-series studies of air pollution and mortality: effects of gases and particles and the influence of cause of death,age, and season

A comprehensive, systematic synthesis was conducted of daily time-series studies of air pollution and mortality from around the world. Estimates of effect sizes were extracted from 109 studies, from single- and multipollutant models, and by cause of death, age, and season. Random effects pooled estimates of excess all-cause mortality (single-pollutant models) associated with a change in pollutant concentration equal to the mean value among a representative group of cities were 2.0% (95% CI 1.5-2.4%) per 31.3 microg/m3 particulate matter (PM) of median diameter < or = 10 microm (PM10); 1.7% (1.2-2.2%) per 1.1 ppm CO; 2.8% (2.1-3.5%) per 24.0 ppb NO2; 1.6% (1.1-2.0%) per 31.2 ppb O3; and 0.9% (0.7-1.2%) per 9.4 ppb SO2 (daily maximum concentration for O3, daily average for others). Effect sizes were generally reduced in multipollutant models, but remained significantly different from zero for PM10 and SO2. Larger effect sizes were observed for respiratory mortality for all pollutants except O3. Heterogeneity among studies was partially accounted for by differences in variability of pollutant concentrations, and results were robust to alternative approaches to selecting estimates from the pool of available candidates. This synthesis leaves little doubt that acute air pollution exposure is a significant contributor to mortality.     

Sorption and desorption of Cu and Cd by macroalgae and microalgae

The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment.     

Meta-Analysis of Time-Series Studies of Air Pollution and Mortality: Effects of Gases and Particles and the Influence of Cause of Death,Age, and Season

Abstract

A comprehensive, systematic synthesis was conducted of daily time-series studies of air pollution and mortality from around the world. Estimates of effect sizes were extracted from 109 studies, from single- and multipollutant models, and by cause of death, age, and season. Random effects pooled estimates of excess all-cause mortality (single-pollutant models) associated with a change in pollutant concentration equal to the mean value among a representative group of cities were 2.0% (95% CI 1.5-2.4%) per 31.3 μg/m³ particulate matter (PM) of median diameter <10 μm (PM₁₀); 1.7% (1.2-2.2%) per 1.1 ppm CO; 2.8% (2.1-3.5%) per 24.0 ppb NO₂; 1.6% (1.1-2.0%) per 31.2 ppb O₃; and 0.9% (0.7-1.2%) per 9.4 ppb SO₂ (daily maximum concentration for O₃, daily average for others). Effect sizes were generally reduced in multipollutant models, but remained significantly different from zero for PM₁₀ and SO₂. Larger effect sizes were observed for respiratory mortality for all pollutants except O₃. Heterogeneity among studies was partially accounted for by differences in variability of pollutant concentrations, and results were robust to alternative approaches to selecting estimates from the pool of available candidates. This synthesis leaves little doubt that acute air pollution exposure is a significant contributor to mortality.     

剩余污泥浓缩脱水投药量优化和模型建立

应用高分子阳离子絮凝剂（CPF-100）和聚丙烯酰胺（PAM）对污水厂剩余污泥进行浓缩脱水实验,研究表明：CPF-100的浓缩脱水效果优于PAM;当CPF-00投加量为1．16‰时,污泥沉降性能改善程度为37．51％;且在CPF-100投加量逐渐增大的初始阶段,污泥沉降性能改善程度随投加量的增加而增大,但CPF-100投加量也不宜过大,当CPF-100投加量超过1．16‰后,反而会使浓缩脱水效果变差。同时,建立了污泥沉降性能改善程度与絮凝剂CPF-100投加量、沉降时间之间的数学模型,其能较好地反映污水厂剩余污泥的浓缩脱水效果。     

骆马湖富营养化和生态状况调查与评价

为了了解骆马湖水质状况，在2005年对骆马湖富营养化状态和生态特性进行了调查，并结合“十五”期间的监测资料进行了分析。2005年骆马湖水体中总氮和总磷的平均值超《地表水环境质量标准》（GB3838-2002）中Ⅲ类，超标情况分别为0．78倍和0．54倍，达到湖库特定项目Ⅳ类水标准，骆马湖处于轻度富营养化状态。对骆马湖生态特征分析表明，由于该湖泊的形态以及“藻型浊水状态”和“泥沙型浊水状态”交替出现，遏制了湖水从高营养盐含量向全面富营养化状态演变，保障了底栖动物的良好生长环境，从而形成了骆马湖独特的环境生态平衡。     

Experimental and statistical validation of SPME-GC-MS analysis of phenol and chlorophenols in raw and treated water

A procedure based on solid-phase microextraction (SPME) and gas chromatography coupled with mass spectrometry (GC-MS) was developed and validated in order to analyse 10 phenols in water samples. The optimised conditions were obtained using polyacrylate fibre (PA), 20ml of sample volume, 10% NaCl, pH 4.0 and direct extraction at 35 degrees C and 1000rpm, for 40min. The linear range and quantification limits for these compounds by SPME-GC-MS were defined. An evaluation of the main uncertainty sources of this method is included, which allows expanded uncertainties in the 9.4-35% range for the majority of the compounds. The main source of uncertainty is associated with matrix effects. The validated method is suitable for monitoring the production and distribution of potable water and was used, in field trials, for the analysis of samples from main intakes of water (surface or underground) and from water supply system of a large area (Lisbon and neighbour municipalities).     

Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene

The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C₂ through C₈ organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene.     

Aerobic and anaerobic degradation of profluralin and trifluralin

Abstract

The degradation of profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐]p‐toluidine] and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was studied under aerobic and anaerobic soil conditions. Three soils (Goldsboro loamy sand, Cecil loamy sand, Drummer clay loam) were each treated with 1 ppmw herbicide; anaerobic conditions were maintained by flooding. Soil samples were extracted monthly and subjected to TLC analysis. No degradation was detected in sterile controls. Aerobic degradation of both herbicides was greatest in the Cecil loamy sand soil over the entire incubation period. Degradation of profluralin in Cecil soil under aerobic conditions was 86 percent after 4 months with three products detected; 83 percent of the trifluralin was degraded with two products detected. Anaerobic degradation accounted for 72 percent of the profluralin and 78 percent of the trifluralin after 4 months. Degradation of both herbicides increased with incubation time for the first 3 months and decreased slightly thereafter. Generally there was more extensive degradation (percent and in number of products formed) of profluralin than trifluralin under the conditions tested. More degradation products were detected for both herbicides under aerobic conditions than under anaerobic conditions.