| With the continuous development of transportation,asphalt pavement accounts for more than 90%of the highway mileage in China.As the product with the most complex composition in petroleum,asphalt contains heteroatoms,aromatic compounds,polycyclic aromatic hydrocarbons and their derivatives.As early as the early 18th century,PAHs were listed as priority pollutants in many countries due to their carcinogenic,teratogenic,and mutagenic risks.Asphalt was used in fields such as transportation,housing construction and water conservancy engineering coating according to its composition.Therefore,harmful PAHs in asphalt components will migrate to various fields and cause a large area of damage.At present,a considerable part of the analysis of PAHs is related to the environment,such as the atmosphere,water body,soil and sediment,etc.,and the analysis of PAHs content in petroleum asphalt is less.With the increasing awareness of environmental protection,scholars at home and abroad begin to pay attention to the study of inhibiting the volatilization of PAHs in bituminous smoke.The inhibitor effect is characterized by the thermogravimetric results before and after heating.This characterization method is controversial because hydrocarbons in asphalt are easy to combine to form PAHs under high temperature and hypoxia,so it is of great importance to directly detect PAHs in petroleum asphalt samples.The purpose of this thesis is to establish a set of mature and complete detection system that researches the content of PAHs on petroleum asphalt,which provides a high theoretical guidance for the future development of environmentally friendly petroleum asphalt in the traffic road market,and for the study of the suppression of the inhibitory effects of toxic PAHs have laid a theoretical foundation.In this study,benzo[b]fluoranthene,benzo[a]pyrene,dibenzo[a,h]anthracene,and benzo[g,h,i]perylene in petroleum asphalt was analyzed.Through pretreatment exploration and the optimization of experimental conditions,the four target PAHs get good separation effect and finally establishes a detection system that can simultaneously detect the content of four PAHs components in petroleum asphalt:alumina column chromatography-molecular imprinting solid-phase extraction-high performance liquid chromatography with ultraviolet detection system,and investigates the method recovery and precision analysis system,the research work are as follows:(1)Through the exploration,this paper obtains the optimal chromatographic conditions about the qualitative and quantitative analysis of four target PAHs in asphalt by HPLC:use the Athena PAHs special chromatography column(4.6×250 mm,5?m),go concentration gradient elution with acetonitrile-water system for the mobile phase,column temperature set at 25?,the velocity of mobile phase is 1.0 m L·min-1and the procedure of gradient elution is:the initial flow is matched for acetonitrile concentration 60%,0?10 min 60%acetonitrile concentration,concentration of 10?15 min acetonitrile to the flow rate of 1.0 m L/min had risen to 80%,15?20 min acetonitrile concentration in the same flow rate increased to 100%,keep for 10 min.The detection wavelength of benzo[b]fluoranthene and benzo[a]pyrene was250 nm,and that of dibenzo[a,h]anthracene and benzo[g,h,i]perylene was 280 nm.The four kinds of polycyclic aromatic hydrocarbons were well separated and detected within 20 min.The peak sequence and retention time of each target were:10.32 min for benzo[b]fluoranthene,12.00 min for benzo[a]pyrene,15.12 min for dibenzo[a,h]anthracene,and 17.58 min forbenzo[g,h,i]perylene.In order to ensure the accuracy and accuracy of the test results,the optimal storage time of standard solution is 5 weeks.(2)The asphalt samples were pretreated by liquid phase extraction,alumina column chromatography,and silica column chromatography.Simple liquid phase extraction could not remove the interference of impurities.Compared with silica column,alumina column was more suitable for removing the interference and enrichment of the target,and the separation effect of the target was better.The optimal pretreatment method was preliminarily determined as follows:(1)n-heptane extracted asphalt to obtain supernatant soft asphalt,and the interference components of asphaltene were discarded:90 m L n-heptane,centrifuged for 15min,and supernatant was taken;(2)soft asphalt through alumina column chromatography for component separation,discard saturated,combined with aromatic and colloid as the intermediate phase,to be further purified and separated;(3)when the mobile phase acetonitrile is used to dissolve the intermediate sample,the optimal conditions are:ultrasonic extraction for 1 h,and the temperature at 40?.(3)Finally,a set of complete qualitative and quantitative detection system for the determination of four trace PAHs components in petroleum asphalt was established:column chromatography-molecular imprinting extraction-HPLC-UV.The results showed that the mass fractions of benzo[b]fluoranthene,benzo[a]pyrene,dibenzo[a,h]anthracene and benzo[g,h,i]perylene in SK90 matrix asphalt were 0.54±0.2 mg·kg-1,0.67±0.1 mg·kg-1,0.24±0.02 mg·kg-1and 0.31±0.07 mg·kg-1,respectively.The standard recovery rate of the four polycyclic aromatic hydrocarbons(PAHs)was between 94%and 98%,and the precision of the methods was less than 5%,indicating that the established analytical detection method had good separation effect,high reproducibility and high recovery rate for the four targets.The analysis and detection system established in this paper provides theoretical guidance for the future development of environmentally friendly petroleum asphalt in the traffic road market and lays a theoretical foundation for the study on the inhibition of toxic pahs volatilization in asphalt. |
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