The molecular transformations of carboxylic acids in heavy acidic SL crude before and after true boiling point distillation were examined by ultra-high resolution negative-ion electrospray ionization(ESI) Fourier tran...The molecular transformations of carboxylic acids in heavy acidic SL crude before and after true boiling point distillation were examined by ultra-high resolution negative-ion electrospray ionization(ESI) Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS). The acid class(heteroatom number), type(z numbers) and carbon number distributions were positively characterized. It was found out that the total acid number(TAN) of SL crude decreased after true boiling point distillation, and the abundance of O2 class in mass spectra was also found to be reduced from 67.6% to 34.5% in SL TBP mixed crude as measured by MS spectra, indicating to a potential carboxylic acid decomposition. However, it was interesting that the carboxylic acids type distribution in both oils was almost the same although their relative abundance in SL TBP mixed crude turned to be much lower, suggesting that various petroleum carboxylic acid types have the similar thermal decomposition reaction behavior. Furthermore, for each O2 type of acids in SL TBP mixed crude, the abundance of carboxylic acids with carbon number higher than 35 was reduced greatly, especially for those with carbon number higher than 60, the mass peaks of which were nearly totally removed, indicating that the large carboxylic acid molecules in heavy fractions decomposed more significantly because of longer heating time during the true boiling point distillation process. As a result, the reduction of TAN may be caused by the thermal decomposition of carboxylic acids especially those with high carbon number, suggesting that quick distillation or much lower pressure is required to avoid the thermal decomposition.展开更多
High acidity crude oils have an advantage over normal oils in terms of their price,but can cause corrosion and refinery problems.They are the so-called opportunity crudes and likely to be important reserved resources ...High acidity crude oils have an advantage over normal oils in terms of their price,but can cause corrosion and refinery problems.They are the so-called opportunity crudes and likely to be important reserved resources in the 21st century.Researches on high acidity crude oils are becoming more and more profound.Based on the existing research achievements,this article has given an overview of the chemical composition and acid distribution of high acidity oils,and also analyzed their origin types and potential influence factors.展开更多
食源性致病菌一直是我国食品安全的危害之一,如何有效控制食品中食源性致病菌的繁殖一直是研究热点。该研究以等离子体活性乳酸溶液(Plasma-Activated Lactic Acid,PALA)体积分数、活化时间以及反应时间的单因素实验为基础,以大肠埃希...食源性致病菌一直是我国食品安全的危害之一,如何有效控制食品中食源性致病菌的繁殖一直是研究热点。该研究以等离子体活性乳酸溶液(Plasma-Activated Lactic Acid,PALA)体积分数、活化时间以及反应时间的单因素实验为基础,以大肠埃希氏菌、沙门氏菌、金黄色葡萄球菌及单核增生李斯特菌等菌种为模型,菌落总数为响应值,研究PALA对4种食源性致病菌的影响。研究结果表明:在一定范围内,4种食源性致病菌的杀灭率均随PALA体积分数的升高、活化时间以及反应时间的延长而增大;采用活化120 s、体积分数为0.2%的PALA与4种食源性致病菌反应10 min,约可杀灭纯培养大肠埃希氏菌7.71 lg CFU/mL、沙门氏菌4.52 lg CFU/mL、金黄色葡萄球菌4.03 lg CFU/mL、单核增生李斯特菌3.90 lg CFU/mL。对4种纯培养食源性致病菌的杀灭率达99.9%以上(P<0.05),可杀灭3.9个对数值以上菌落总数的致病菌。综上所述,PALA可快速、高效杀灭常见食源性致病菌。展开更多
基金financially supported by the National Key Basic Research Development Program "973" Project (2006CB202501)
文摘The molecular transformations of carboxylic acids in heavy acidic SL crude before and after true boiling point distillation were examined by ultra-high resolution negative-ion electrospray ionization(ESI) Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS). The acid class(heteroatom number), type(z numbers) and carbon number distributions were positively characterized. It was found out that the total acid number(TAN) of SL crude decreased after true boiling point distillation, and the abundance of O2 class in mass spectra was also found to be reduced from 67.6% to 34.5% in SL TBP mixed crude as measured by MS spectra, indicating to a potential carboxylic acid decomposition. However, it was interesting that the carboxylic acids type distribution in both oils was almost the same although their relative abundance in SL TBP mixed crude turned to be much lower, suggesting that various petroleum carboxylic acid types have the similar thermal decomposition reaction behavior. Furthermore, for each O2 type of acids in SL TBP mixed crude, the abundance of carboxylic acids with carbon number higher than 35 was reduced greatly, especially for those with carbon number higher than 60, the mass peaks of which were nearly totally removed, indicating that the large carboxylic acid molecules in heavy fractions decomposed more significantly because of longer heating time during the true boiling point distillation process. As a result, the reduction of TAN may be caused by the thermal decomposition of carboxylic acids especially those with high carbon number, suggesting that quick distillation or much lower pressure is required to avoid the thermal decomposition.
文摘High acidity crude oils have an advantage over normal oils in terms of their price,but can cause corrosion and refinery problems.They are the so-called opportunity crudes and likely to be important reserved resources in the 21st century.Researches on high acidity crude oils are becoming more and more profound.Based on the existing research achievements,this article has given an overview of the chemical composition and acid distribution of high acidity oils,and also analyzed their origin types and potential influence factors.
文摘食源性致病菌一直是我国食品安全的危害之一,如何有效控制食品中食源性致病菌的繁殖一直是研究热点。该研究以等离子体活性乳酸溶液(Plasma-Activated Lactic Acid,PALA)体积分数、活化时间以及反应时间的单因素实验为基础,以大肠埃希氏菌、沙门氏菌、金黄色葡萄球菌及单核增生李斯特菌等菌种为模型,菌落总数为响应值,研究PALA对4种食源性致病菌的影响。研究结果表明:在一定范围内,4种食源性致病菌的杀灭率均随PALA体积分数的升高、活化时间以及反应时间的延长而增大;采用活化120 s、体积分数为0.2%的PALA与4种食源性致病菌反应10 min,约可杀灭纯培养大肠埃希氏菌7.71 lg CFU/mL、沙门氏菌4.52 lg CFU/mL、金黄色葡萄球菌4.03 lg CFU/mL、单核增生李斯特菌3.90 lg CFU/mL。对4种纯培养食源性致病菌的杀灭率达99.9%以上(P<0.05),可杀灭3.9个对数值以上菌落总数的致病菌。综上所述,PALA可快速、高效杀灭常见食源性致病菌。
