【作者】 才洪美；

【导师】 张玉贞；

【作者基本信息】 中国石油大学 ， 化学工程与技术， 2010， 博士

【摘要】 近年来,我国乃至全世界面临严重的环境污染问题,其中有机物以其高毒性、成分复杂性和难治理性成为环境检测和治理的一个重点和难点。沥青在加工和使用过程中其组分可以迁移到环境中,是造成环境有机物污染的一个污染源。为了评价沥青组分对环境的危害性,本文针对沥青组分在空气和水体中的危害性进行研究,进而指导沥青材料的使用,来减少或避免沥青组分对环境的危害性。在评价沥青烟对空气的危害性时,在实验室内采用反应釜为主体的沥青烟产生设备,考察拌和条件对沥青烟释放量和化学组成的影响,结果表明沥青烟主要是由粒径大于3μm的颗粒状物质组成(重组分),而粒径低于3μm的颗粒状物质和气态物质(轻组分)含量甚小,远远低于重组分的含量,且随着温度、时间和空速的增加,沥青烟的释放量呈增加的趋势;而未搅拌条件下沥青烟的释放量较搅拌条件下有所增加。对沥青烟的化学组成分析表明,沥青烟中主要是由烷烃化合物、芳烃化合物和含硫、氮、氧的杂环化合物组成,且随着温度、时间和空速的增加,沥青烟中芳烃化合物和杂环化合物所占比例增加,烷烃化合物所占比例降低;相比于搅拌条件而言,未搅拌条件下沥青烟中芳烃化合物和杂环化合物所占比例增加,烷烃化合物比例降低。由此可见,拌和条件对烷烃化合物的影响较小,而对芳烃化合物和杂环化合物的影响较大。在影响因素研究的基础上,在实验室内以沥青四组分分布为指标,来模拟拌和条件下沥青烟的释放量,并对近十年沥青烟释放量进行统算,结果表明近两年每年都有2.5万吨以上的沥青烟释放到空气中。在评价沥青组分对水体的危害性时,采用浸出的实验方法,首先考察常温条件下沥青组分的可浸出性;结果表明沥青的组分可以浸出,但浸出量较小,且都低于地表水限定指标。但在影响因素研究中表明,温度、浸出液pH值和浸出液中氯盐含量都对沥青组分的浸出有影响,这说明沥青组分对水体存在潜在危害性。为了评价沥青组分对水体的潜在危害性,采用正交实验和单因素考察,优化得出五种沥青组分最大浸出量的条件,并对此条件下的浸出的沥青组分进行定量和定性分析,定量分析表明,浸出液中总有机物含量(COD)较大,且都超过了地表水限定指标;定性分析表明,沥青中浸出量较大的组分是一些含有羟基和羰基的化合物,其次是烷烃化合物,经归属得出,这些易浸出且浸出量较大的含有羟基和羰基的化合物主要分布在沥青的胶质和沥青质中。通过对五种沥青中可浸出组分的危害性评价表明,沥青组分中含有危害性较大的环境优先控制物,但对其的定量分析表明,其含量低于仪器检测下限,这说明可浸出的沥青组分中毒害性较大的组分含量很小。在沥青老化程度对沥青组分浸出量的影响中表明,随着沥青老化程度的增加,其组分的浸出量增加,说明沥青在使用过程中,其组分对水体的潜在危害性程度增加。在浸出级数的考察中表明,随着浸出级数的增加,五种沥青的浸出液COD值均呈现降低的趋势,说明随着雨水等的冲刷作用,沥青中可浸出组分的量会越来越少,对水体的潜在危害性程度会不断降低。通过比较沥青组分对空气和水体的危害性程度,表明沥青在热拌和过程中,每千克沥青可以释放0.7g的多环芳烃;而在最大浸出条件下,浸出组分中毒害性较大的邻苯二甲酸脂类化合物的含量低于仪器检测下限,由此说明沥青烟对空气的危害性比较大。为了降低沥青烟对空气的危害性,本文研究了抑制沥青烟产生的方法。首先通过关联载气中氧气含量和沥青烟释放量的关系,以及沥青组分结构和氧元素含量的变化,验证沥青烟产生是由于组分氧化的机理。再通过考察市场上常用的五种自由基抑制剂对A沥青烟的抑制作用,找出了抑制效果较好的抑制剂及其含量。通过考察抑制剂a对五种沥青烟气的抑制效果表明,同一抑制剂可以对同一油源的沥青具有相同的抑制效果,但不可能找出一种对所有沥青的烟气都具有较好的抑制效果的抑制剂。在实验选用的五种沥青中,a和c抑制剂在加入量为4%时,对A、C、D和E四种沥青烟都具有很好的抑制效果,但对B沥青的抑制效果较差,甚至导致沥青烟释放量的增加。通过考察抑制剂对沥青性能的影响得出,当抑制剂对沥青烟的产生具有较好的抑制效果时,抑制剂不会对沥青的性能产生影响,但如果抑制剂的加入导致沥青烟的释放量增加,则抑制剂的加入使得沥青性能向着老化方向进行。通过抑制剂对沥青TFOT老化性能的影响表明,添加抑制剂后沥青的质量变化变小,但老化后各项指标变化不明显,对老化后沥青的组分结构研究表明,添加了c抑制剂的沥青老化后的羰基吸收峰强度较低,这说明,抑制剂的加入抑制了沥青组分和氧气的反应,即抑制了组分的氧化,进而验证了其对沥青烟具有抑制效果。更多还原

【Abstract】 In recent years, China and the world face serious environmental pollution problems, especially for the organic pollutants, with high toxicity and complexity, it is difficult bring that under control, so organic pollutants become a key and difficult problem in environment monitoring and governance. The components of asphalt can migrate into the environment in the processing and using, which can cause environment pollution, so asphalt is one of the organic pollution sources. In order to evaluate the harmful of asphalt components to environment, this paper studied the harmful of asphalt components to air and water, then by guiding the use of asphalt material to reduce or avoid the harmful of asphalt components to the environment.In evaluation the harmful of asphalt fumes to air, the laboratory asphalt fumes generation system composed mainly by a reactor was used to study the effect of mixing conditions on the asphalt fumes emission and their chemical composition. The results showed that the asphalt fumes were mainly composed by the particles which diameter are larger than 3μm, but the particles which diameter are less than 3μm and the gaseous substances were very small, and the contents were far below the levels of the particles with diameter larger than 3μm. The emission of asphalt fumes increased with the increasing of temperature, time and air volume, but the asphalt fumes under stirring were less than that under no stirring. The composition analysis meaned asphalt fumes were mainly composed by alkane compounds, aromatic compounds and heterocyclic compounds with sulfur, nitrogen or oxygen. With the increase of temperature, time and air volume, the aromatic and heterocyclic compounds increased, but the changing trend of alkane compounds was contrary. Comparing to the stirring, the aromatic compounds and heterocyclic compounds under no stirring were larger, and the ratio of alkane compounds was less. All the results showed that mixing conditions had less effect on the alkane compounds, while on the aromatic compounds and heterocyclic compounds which had more effect. Taking the distribution of asphalt four components as the index in laboratory, the asphalt fumes emissions under mixing conditions was simulated under the basis of influencing factors, then calculation the asphalt fumes emission of nearly a decade, and the results showed the annual emissions of asphalt fumes in recent years were all over 25000 t. In evaluation the harmful of asphalt components to water, the leaching test was taken to study the leachability of asphalt at room temperature first. The results showed that the components could be leached from asphalt and into water, but the contents were very small and below the limit of surface water. However, the study on influencing factors showed that temperature, pH value and chlorate of leachate could effected the leaching of asphalt components, which indicated asphalt component had the potential harmful to water.To evaluate the potentially harmful of asphalt components to water, this paper taked the methods of orthogonal and single factor to get the conditions under which the contents of components leaching from five asphalt were the largest, then quantitative and qualitative analysis were taken to analyse the components leaching from asphalt. Quantitative analysis showed that the COD values of leachate were more than the limited of surface water; and qualitative analysis showed that the components leaching from asphalt mainly composed by the compounds containing hydroxyl and carbonyl which mainly distributed in resin and asphaltene, followed by the alkane compounds. The hazard assessment of components leaching from asphalt showed that the components contained some hazardous compounds priority controlled by environmental, but the quantitative analysis showed that the content was below the instrument detection limit, which indicated the high toxic components leaching from asphalt were very small. The effect of asphalt aged on the leaching of components showed that with he aging of asphalt the content of components leaching from asphalt increased, which indicated the potential harmful of asphalt to water enhanced with the use of asphalt. The study of leaching series indicated that the leachate COD values showed a decreasing trend with the increase in the leaching times, which meaned that as the erosion of rain, the components leaching from asphalt would be less and less, so the potential harmful of asphalt to water decreased with the increase of leaching times.Comparing the harmful of asphalt components to air and water, one kilogram asphalt could released 0.7g of polycyclic aromatic hydrocarbons under the conditions of asphalt mixing; but the content of phthalate was less than the limit of surface water under the maximum leaching condition, all which meaned the harmful of asphalt components to air was larger than the harmful of components to water.In order to reduce the harmful of asphalt fumes to air, this paper studied the asphalt fumes retraining methods. First, the correlation between the kinds of carrier gas and the asphalt fumes emission was studied, as well as the analysis of functional groups and oxygen element content of asphalt, the results showed that asphalt fumes generation mechanism was the oxidation of its components. By examining the inhibitory effect of five free radical inhibitors on A asphalt, a good inhibitor and its content were got. The inhibitory effect of a inhibitor on five asphalt showed that one inhibitor had the same effect on the asphalt from the same crude oil, but it was impossible to find one inhibitor that has good inhibitory effect to all asphalt. For the five asphalt this paper used, a and c inhibitors in dosage of 4% both had the good inhibitory effect to A, C, D and E asphalt, while there was not one inhibitor had good inhibitory effect to B asphalt, even the adding of inhibitors let to an increase in asphalt fumes emission.The effect of inhibitors on the performance of asphalt showed that when the inhibitor had a good inhibitory effect on the asphalt fumes emission, the adding of inhibitor could not affect the performance of asphalt. However, if the inhibitors could not inhibit the emission of asphalt fumes, even lead to the increasing of asphalt fumes emissions, then the inhibitors would affect the performance of asphalt and led the performance of asphalt accession towards the asphalt aging direction.Inhibitors on the effects of performance of TFOT aged asphalt indicated that the adding of inhibitor led to the decrease in the quality changing of asphalt, however they almost not affected the performances of TFOT aged asphalt. The studies on the components structure of asphalt after TFOT aged showed that the adding of c inhibitor lead to the reduction on the strength of caibonyl absorption peak, which showed that the adding of inhibitor inhibited the reaction between the asphalt components and oxygen, which inhibited the oxidation of components, and thus validated its inhibitory effect on the asphalt fumes emission.更多还原