Several civilian vehicles in China operate in urban traffic conditions and have their motor oil changed every 5,000 km.This study investigates the variations in oil properties after servicing at 5,000 km,based on syst...Several civilian vehicles in China operate in urban traffic conditions and have their motor oil changed every 5,000 km.This study investigates the variations in oil properties after servicing at 5,000 km,based on systematic road tests(including a repeated test,a parallel test,and a new vehicle test).The physicochemical properties,changes in components,oxidation stability,detergent‐dispersant performance,and tribological properties of motor oils were analyzed.The results showed that the total acid number(TAN)of oils increased with the operation mileage,by up to 1.41 mgKOH/g.The total base number(TBN)decreased after the road tests were completed,and the decrease was less than 44.6%.The kinematic viscosity(KV)of most oils decreased initially and then stabilized in the middle stage,before starting to increase later in the experiment.The change in KV at 100℃was less than 15.96%.The oxidation onset temperature(OOT)of the oils diminished gradually with the operation mileage.All OOT values of the used oils were higher than 210℃.A spot test indicated that the used oils retained their detergentdispersant performance to an appropriate extent.The four‐ball wear scar diameters and friction coefficient of the used oils did not increase significantly after the road tests were completed.This study can serve as a reference for end‐users when changing motor oils.展开更多
Widespread contamination by nitrobenzene（NB） in sediments and groundwater requires better understanding of the biogeochemical removal process of the pollutant. NB degradation, coupled with dissimilatory iron reducti...Widespread contamination by nitrobenzene（NB） in sediments and groundwater requires better understanding of the biogeochemical removal process of the pollutant. NB degradation, coupled with dissimilatory iron reduction, is one of the most efficient pollutant removal methods. However, research on NB degradation coupled to indigenous microorganism dissimilatory iron reduction stimulated by electron donors is still experimental. A model for remediation in an actual polluted site does not currently exist.Therefore, in this study, the dynamics was derived from the Michaelis–Menten model（when the mass ratio of emulsified vegetable oil and NB reached the critical value 91：1）. The effect of SO4^（2-）, NO3^-, Ca^（2＋）/Mg^（2＋）, and the grain size of aquifer media on the dynamics were studied, and the NB degradation dynamic model was then modified based on the most significant factors. Utilizing the model, the remediation time could be calculated in a contaminated site.展开更多
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(51575402)the National Natural Science Foundation of Hunan Province of China(No.2020JJ5217).
文摘Several civilian vehicles in China operate in urban traffic conditions and have their motor oil changed every 5,000 km.This study investigates the variations in oil properties after servicing at 5,000 km,based on systematic road tests(including a repeated test,a parallel test,and a new vehicle test).The physicochemical properties,changes in components,oxidation stability,detergent‐dispersant performance,and tribological properties of motor oils were analyzed.The results showed that the total acid number(TAN)of oils increased with the operation mileage,by up to 1.41 mgKOH/g.The total base number(TBN)decreased after the road tests were completed,and the decrease was less than 44.6%.The kinematic viscosity(KV)of most oils decreased initially and then stabilized in the middle stage,before starting to increase later in the experiment.The change in KV at 100℃was less than 15.96%.The oxidation onset temperature(OOT)of the oils diminished gradually with the operation mileage.All OOT values of the used oils were higher than 210℃.A spot test indicated that the used oils retained their detergentdispersant performance to an appropriate extent.The four‐ball wear scar diameters and friction coefficient of the used oils did not increase significantly after the road tests were completed.This study can serve as a reference for end‐users when changing motor oils.
基金funded by the National Natural Science Foundation of China(Nos.41272253,41402206 and 41530636)the National Science Foundation of Jilin Province(No.20130101027JC)+2 种基金 “the 12th Five-Year Plan” science and technology research projects of education department in Jilin Province(No.2014B012)the Graduate Innovation Fund of Jilin University(No.2015065)grateful for the support of the Key Laboratory of Groundwater Resources and Environment,Ministry of Education
文摘Widespread contamination by nitrobenzene（NB） in sediments and groundwater requires better understanding of the biogeochemical removal process of the pollutant. NB degradation, coupled with dissimilatory iron reduction, is one of the most efficient pollutant removal methods. However, research on NB degradation coupled to indigenous microorganism dissimilatory iron reduction stimulated by electron donors is still experimental. A model for remediation in an actual polluted site does not currently exist.Therefore, in this study, the dynamics was derived from the Michaelis–Menten model（when the mass ratio of emulsified vegetable oil and NB reached the critical value 91：1）. The effect of SO4^（2-）, NO3^-, Ca^（2＋）/Mg^（2＋）, and the grain size of aquifer media on the dynamics were studied, and the NB degradation dynamic model was then modified based on the most significant factors. Utilizing the model, the remediation time could be calculated in a contaminated site.
