The chemist found PM2.5 haze particles initially formed mechanism of news – Sohu sexhu

The chemist found PM2.5 haze particles initially forming mechanism of Sohu news Technology Daily News February 22nd, School of chemistry and materials science University of Science & Technology China and energy materials collaborative center has professor Xiao Cheng and former chairman of the American Chemical Society academician Joseph Francisco research group, found ammonium hydrogen sulfate in the atmosphere of a new formation mechanism. The results were recently published in the Journal of the American Chemical Society, and were selected as the focus of science by chemical and engineering news of the American Chemical society. Ionic compounds composed of ammonium ion generation — Ammonium ammonia reacts with the acid, such as ammonium sulfate (subsequent ammonium hydrogen sulfate), is an important component of PM2.5 haze particles, and the view that the PM2.5 of the initial formation of haze particles plays a vital role. The first principles molecular dynamics simulations of ammonia and sulfur dioxide were first found in the reactions of three sulfur oxides with water by Ceng Xiaocheng and Francisco. They are directly observed in the simulation process of ammonia molecules and three sulfur molecules in water clusters spontaneously formed by reaction of ammonium hydrogen sulfate, ammonia and sulphur dioxide and three water clusters form a special ring structure, the ring structure has greatly promoted the water molecules in the hydrogen atom transfer to ammonia molecules, resulting in the formation of ammonium ions. And the formation of hydrogen sulfate and hydroxide with root quickly and three sulfur dioxide molecules. Through further research, they confirm the reaction path, that the three molecular clusters in third water molecules contribute to the ring structure, and the annular structure can be the reaction barrier (chemical reaction process must exceed the energy, as the bar in the high hurdles) dropped to almost zero, thereby greatly increase the formation rate of ammonium hydrogen sulfate in water clusters in the atmosphere. They also observed the same reaction mechanism on the surface of nano water droplets. The discovery of a new reaction mechanism with almost zero energy barrier indicates that ammonia can directly participate in and accelerate the formation of ammonium hydrogen sulfate and ammonium sulfate in the atmosphere, thus playing a crucial role in the formation of haze particles in the atmosphere.

中美化学家联合发现PM2.5雾霾颗粒最初形成机制-搜狐新闻  科技日报2月22日消息,中国科学技术大学化学与材料科学学院及能源材料协同中心曾晓成教授和美国化学学会前主席Joseph Francisco院士研究组合作,发现了硫酸氢铵在大气中一种全新的形成机制。该成果近日发表在《美国化学会志》上,并被美国化学学会《化学与工程新闻》选为科学焦点报道。  铵盐――氨与酸反应生成的由铵离子和酸根离子构成的离子化合物,如硫酸铵(硫酸氢铵的后续物),是PM2.5雾霾颗粒的重要组成成分,并有观点认为其对PM2.5雾霾颗粒的最初形成起着至关重要的作用。  曾晓成和Francisco小组利用第一性原理分子动力学模拟研究首次发现,氨气可直接参与到三氧化硫与水的反应中。他们在模拟中直接观测到氨气分子和三氧化硫分子在水团簇中自发反应形成硫酸氢铵的过程:氨气和三氧化硫与水团簇形成一种特殊的环状结构,该环状结构极大地促进了水分子中氢原子向氨气分子的转移,从而形成铵根离子。而同时氢氧根则很快与三氧化硫分子结合形成硫酸氢根。  通过进一步研究,他们确认了反应路径,发现三分子水团簇中第三个水分子的存在有助于环状结构的形成,而该环状结构能将反应能垒(化学反应过程中必须超过的能量,有如跨栏中的栏高)降至几近为零,从而大大增加了硫酸氢铵在大气水团簇中的形成速度。他们在纳米水滴表面也观测到同样的反应机理。  这种能垒近乎为零的新型反应机理的发现,表明氨气可以直接参与并加速大气中硫酸氢铵及硫酸铵的形成,从而对大气中雾霾颗粒的形成起到至关重要的作用。相关的主题文章: