活性炭纤维在机动车尾气净化中的研究与应用展望

机动车尾气净化控制的一个难点在于冷启动阶段，此时由于温度较低，催化剂尚未完全起作用，导致排出的污染物浓度较高。阐述了活性炭纤维的基本特性，特别是其低温吸附与催化性能对NO和CO的转化作用，讨论了活性炭纤维作为机动车尾气净化材料所需的改性及方法，并展望了其应用前景。     

活性炭纤维及其在水处理中的应用

介绍了活性炭纤维材料的发展历史、类别、结构性能、制备过程。活性炭纤维比普通活性炭性能优越，吸附量大，机械强度高，吸附、脱附速度快，正逐渐地被用于废水处理和饮用水的净化。其具体方法有常用的吸附法、电解法，以及尚在起步阶段的生物活性炭纤维法。     

九江市机动车尾气污染控制对策

机动车尾气已成为城市重要的空气污染源之一,对城市的环境影响越来越严重.根据《九江市环境保护“十一五”规划》,九江市机动车尾气污染的控制势在必行.因此,为了有利于城市机动车尾气污染的综合整治和科学管理,结合该市特征和机动车尾气污染现状,在分析机动车尾气污染形成原因的基础上,提出了控制城市机动车尾气污染的对策.     

成都市轻型车尾气污染物排放趋势预测

机动车尾气污染物已成为影响城市大气环境质量的主要因素之一,预测未来机动车尾气污染物排放状况可以为城市机动车尾气污染防治提供有力的依据.依据成都市的经济发展趋势,设定了不同阶段的轻型车尾气污染物排放标准,并利用建立的尾气污染物排放趋势预测模型分析了该市轻型车尾气中颗粒物、NOx、总碳氢化合物、CO的排放量和变化趋势,并提出了相应的尾气污染物减排对策.     

重庆市机动车尾气对大气环境的影响分析及减缓措施

在对重庆市机动车保有量、主城区交通状况进行深入调查的基础上，对机动车尾气排放对大气环境的影响进行了细致的分析与评估。阐述了机动车尾气是造成重庆市大气污染的重要因素。同时结合国内外一些先进的预防、控制和处理汽车尾气污染的方法，及近年来的观察、研究和试验，提出了合理减缓、控制机动车尾气污染的措施，以防止机动车尾气污染进一步蔓延。     

杭州市机动车尾气污染和控制对策

随关经济的快速发展,城市道路交通和机动车尾气污染成为人们关注的热点,通过对杭州市机动车行驶现状及路检情况调查,分析了机动车排污分担率及尾气排放的潜在影响,提出控制机动车尾气大大气污染的对策。     

基于GIS城市机动车尾气扩散迁移研究

中国城市大气污染日趋严重，汽车尾气污染所占比重越来越大。交通、道路、管制及气候条件等是影响城市机动车尾气排放的主要因素。本文根据机动车尾气研究的实际，研究了专题MGIS数据库结构， 并以广州为例，建立了基于GIS的城市机动车尾气扩散迁移预报系统，在此基础上实现了机动车尾气污染状况的可视化。     

机动车尾气VOCs排放特征及减排措施研究

分析了机动车尾气挥发性有机物(VOCs)的排放特征,发现尾气VOCs排放具有明显的日变化和季节变化特征。不同区域不同车型机动车尾气VOCs成分谱略有差异,轻型汽油车尾气VOCs中芳香烃和烷烃含量较高,柴油车烷烃含量较高。尾气排放受机动车保有量、行驶里程、维护保养水平、行驶速度和燃油标准、排放标准等因素影响。从优先控制汽油车、加快机动车更新、采取本地化减排措施、加强多元管理措施、提高科研水平等方面提出了针对性的减排措施。     

机动车尾气中氮氧化物的分析检测技术

为了分析机动车尾气氮氧化物净化催化剂的催化性能 ,建立了一套尾气模拟评价体系 ,分别使用电化学法、化学发光法和比色法 3种氮氧化物分析手段进行检测。结果表明 ,3种方法都能在一定精度范围内测量机动车尾气中的氮氧化物 ,化学发光法测量精度高 ,响应时间短 ,能够及时地反映发动机运转过程中的氮氧化物浓度变化情况 ,是一种较好的分析手段。电化学法随着使用时间推移 ,响应时间变长 ,灵敏度降低 ,需要及时更换传感器。比色法通过化学吸收可以测定氮氧化物的浓度 ,不能实现连续在线分析 ,只能采样测量。在分析中 ,还尝试利用一些辅助设备 ,将尾气中的NO和NO2转化后再通入测量仪器 ,实现测量总氮氧化物或其中某一气体的功能     

改性活性炭吸附净化黄磷尾气中的PH_3

通过钢瓶配气模拟和气相色谱GC-14C测定的方法,研究了改性活性炭吸附净化黄磷尾气中PH3的相关问题。得到了吸附反应的最佳吸附温度、氧含量、气体流量、改性液浓度、活性炭粒径和焙烧温度。再生方法可行,可通过再生液回收磷酸。热重差热分析和孔径分布初步证明吸附质为磷和磷氧化物。     

活性炭吸附和脱附-等离子体氧化净化有机废气的研究

根据滑动弧放电等离子体适于降解高浓度有机物废气的特性,结合活性炭吸附法,提出了吸附器的吸附浓缩和热脱附-等离子体氧化净化有机废气的方法。在活性炭吸附过程中,最初2 h内甲苯净化率达到100%,随着时间的增加净化率下降;在热脱附滑动弧放电等离子体净化过程中,甲苯降解效率最高为97.3%。将滑动弧放电等离子体反应器出口气相产物收集进行FT-IR检测,发现放电后有CO2、CO、H2O和NO2产生,并分析了甲苯的降解机理。     

Selection and Substantiation of an Organic Solvent Removal Apparatus at a Print Shop by Comparative Experiments Using the Activated Carbon Adsorption and Catalytic Oxidation Methods

ABSTRACT

The investigation of an appropriate organic solvent removal apparatus for installation in a newly reconstructed print shop as a countermeasure for preventing the exhaust of organic solvents was conducted.

The selection of an organic solvent removal apparatus was made after bench-scale tests of the activated carbon adsorption method and the catalytic oxidation method, both of which are effective for the removal of organic solvents, were performed on the actual exhaust gas at the print shop. The results showed that both methods were efficient enough to be applied to the removal of organic solvents, but the activated carbon adsorption method had many drawbacks, such as the need for frequent replacement of activated carbon and complex maintenance. For the catalytic oxidation method, running costs are high, but there are many merits, such as that the catalysts do not have to be replaced as often and maintenance is simple. After considering these factors, a catalytic oxidation removal apparatus was installed at the new print shop. In the results of the substantiation test on the actual apparatus using mixed catalysts of platinum and manganese plus copper, the removal efficiency was 97.998.7% and the concentration of the outlet exhaust gas was about 10 ppm (the average concentration of the inlet exhaust gas was 528 ppm) at a space velocity of 30,000 hr^-1 and a reaction temperature of 200 °C. The results of this study were substantiated.     

Exhaust temperature profiles for application of passive diesel particulate filters to solid waste collection vehicles in California

To reduce public exposure to diesel particulate matter (DPM), the California Air Resources Board has begun adoption of a series of rules to reduce these emissions from in-use heavy-duty vehicles. Passive diesel particulate filter (DPF) after-treatment technologies are a cost-effective method to reduce DPM emissions and have been used on a variety of vehicles worldwide. Two passive DPFs were interim-verified in California and approved federally for use in most 1994--2002 engine families for vehicles meeting min engine exhaust temperature requirements for successful filter regeneration. Some vehicles, however, may not be suited to passive DPFs because of lower engine exhaust temperatures. The purpose of this study was to determine the applicability of two types of passive DPFs to solid waste collection vehicles, the group of vehicles for which California recently mandated in-use DPM reductions. We selected 60 collection vehicles to represent the four main types of collection vehicle duty cycles--rolloffs, and front-end, rear, and side loaders--and collected second-by-second engine exhaust temperature readings for one week from each vehicle. As a group, the collection vehicles exhibited low engine exhaust temperatures, making the application of passive DPFs to these vehicles difficult. Only 35% of tested vehicles met the temperature requirements for one passive DPF, whereas 60% met the temperature requirements for the other. Engine exhaust temperatures varied by vehicle type. Side and front-end loaders met the engine exhaust temperature requirements in the greatest number of cases with approximately 50-90% achieving the required regeneration temperatures. Only 8-25% of the rear loader and roll-off collection vehicles met the engine exhaust temperature requirements. Solid waste collection vehicles represent a diverse fleet with a variety of duty cycles. Low engine exhaust temperatures will need to be addressed for successful use of passive DPFs in this application.     

Exhaust Temperature Profiles for Application of Passive Diesel Particulate Filters to Solid Waste Collection Vehicles in California

Abstract

To reduce public exposure to diesel particulate matter (DPM), the California Air Resources Board has begun adoption of a series of rules to reduce these emissions from in-use heavy-duty vehicles. Passive diesel particulate filter (DPF) after-treatment technologies are a cost-effective method to reduce DPM emissions and have been used on a variety of vehicles worldwide. Two passive DPFs were interim-verified in California and approved federally for use in most 1994–2002 engine families for vehicles meeting min engine exhaust temperature requirements for successful filter regeneration. Some vehicles, however, may not be suited to passive DPFs because of lower engine exhaust temperatures. The purpose of this study was to determine the applicability of two types of passive DPFs to solid waste collection vehicles, the group of vehicles for which California recently mandated in-use DPM reductions. We selected 60 collection vehicles to represent the four main types of collection vehicle duty cycles—roll-offs, and front-end, rear, and side loaders—and collected second-by-second engine exhaust temperature readings for one week from each vehicle. As a group, the collection vehicles exhibited low engine exhaust temperatures, making the application of passive DPFs to these vehicles difficult. Only 35% of tested vehicles met the temperature requirements for one passive DPF, whereas 60% met the temperature requirements for the other. Engine exhaust temperatures varied by vehicle type. Side and front-end loaders met the engine exhaust temperature requirements in the greatest number of cases with ～50–90% achieving the required regeneration temperatures. Only 8–25% of the rear loader and roll-off collection vehicles met the engine exhaust temperature requirements. Solid waste collection vehicles represent a diverse fleet with a variety of duty cycles. Low engine exhaust temperatures will need to be addressed for successful use of passive DPFs in this application.     

A Characterization of Emissions from an Early Model Flexible-Fuel Vehicle

An emission study was conducted on a 1987 Ford Crown Victoria flexible-fuel vehicle, an early prototype which had been driven about 25,000 miles. The vehicle was run on both gasoline and a blend of 85 percent methanol and 15 percent gasoline. Emission rates of regulated pollutants (hydrocarbons, carbon monoxide, nitrogen oxides, formaldehyde, and methanol) and nonregulated pollutants (speciated organic materials) were determined for both exhaust and evaporative emissions. Tests were run varying the driving cycle, ambient temperature and catalytic converter. In general, hydrocarbon composition of exhaust emissions was significantly affected by catalyst replacement and cold starts, slightly affected by driving schedule, and unaffected by ambient temperature and test fuel. Hydrocarbon composition of evaporative emissions was only sensitive to the type of evaporative test being performed: diurnal tests typically had larger fractions of lower molecular weight paraffins than hot soak tests.     

Evolution of vehicle exhaust particles in the atmosphere

Aerosol mass spectrometer (AMS) measurements are used to characterize the evolution of exhaust particulate matter (PM) properties near and downwind of vehicle sources. The AMS provides time-resolved chemically speciated mass loadings and mass-weighted size distributions of nonrefractory PM smaller than 1 microm (NRPM1). Source measurements of aircraft PM show that black carbon particles inhibit nucleation by serving as condensation sinks for the volatile and semi-volatile exhaust gases. Real-world source measurements of ground vehicle PM are obtained by deploying an AMS aboard a mobile laboratory. Characteristic features of the exhaust PM chemical composition and size distribution are discussed. PM mass and number concentrations are used with above-background gas-phase carbon dioxide (CO2) concentrations to calculate on-road emission factors for individual vehicles. Highly variable ratios between particle number and mass concentrations are observed for individual vehicles. NRPM1 mass emission factors measured for on-road diesel vehicles are approximately 50% lower than those from dynamometer studies. Factor analysis of AMS data (FA-AMS) is applied for the first time to map variations in exhaust PM mass downwind of a highway. In this study, above-background vehicle PM concentrations are highest close to the highway and decrease by a factor of 2 by 200 m away from the highway. Comparison with the gas-phase CO2 concentrations indicates that these vehicle PM mass gradients are largely driven by dilution. Secondary aerosol species do not show a similar gradient in absolute mass concentrations; thus, their relative contribution to total ambient PM mass concentrations increases as a function of distance from the highway. FA-AMS of single particle and ensemble data at an urban receptor site shows that condensation of these secondary aerosol species onto vehicle exhaust particles results in spatial and temporal evolution of the size and composition of vehicle exhaust PM on urban and regional scales.     

Preparation of activated carbon using low temperature carbonisation and physical activation of high ash raw bagasse for acid dye adsorption

Activated carbons were prepared from bagasse through a low temperature (160 degrees C) chemical carbonisation treatment and gasification with carbon dioxide at 900 degrees C. The merit of low temperature chemical carbonisation in preparing chars for activation was assessed by comparing the physical and chemical properties of activated carbons developed by this technique to conventional methods involving the use of thermal and vacuum pyrolysis of bagasse. In addition, the adsorption properties (acid blue dye) of these bagasse activated carbons were also compared with a commercial activated carbon. The results suggest that despite the high ash content of the precursor, high surface areas (614-1433 m2 g(-1)) and microporous (median pore size from 0.45 to 1.2 nm) activated carbons can be generated through chemical carbonisation and gasification. The micropore area of the activated carbon developed from chars prepared by the low temperature chemical carbonisation provides favourable adsorption sites to acid blue dye (391 mg g(-1) of carbon). The alkalinity of the carbon surface and total surface area were shown to have complementary effects in promoting the adsorption of acid blue dye. Adsorption of the anionic coloured component of the acid dye was shown to be promoted in carbon exhibiting alkaline or positively charged surfaces. This study demonstrates that activated carbons with high acid dye adsorption capacities can be prepared from high ash bagasse based on low temperature chemical carbonisation and gasification.     

活性碳纤维吸附甲苯废气吸附等温方程的研究

研究了固定床吸附器中粘胶基活性碳纤维(viscose rayon-based ACFs)吸附甲苯废气的特性,通过实验测定活性碳纤维吸附不同浓度甲苯废气的穿透曲线,作出等温吸附曲线,根据实验数据拟合出几个吸附平衡方程,并与实验结果进行比较.实验结果可为工业设备设计提供参考.     

活性碳纤维吸附甲苯废气吸附等温方程的研究

研究了固定床吸附器中粘胶基活性碳纤维（viscose rayon-based ACFs）吸附甲苯废气的特性，通过实验测定活性碳纤维吸附不同浓度甲苯废气的穿透曲线，作出等温吸附曲线。根据实验数据拟合出几个吸附平衡方程，并与实验结果进行比较。实验结果可为工业设备设计提供参考。