CH_3COO^-与Ca^(2+)的络合效应对方解石溶蚀的影响  

Complex effect of CH_3COO^- and Ca^(2+) on dissolution of calcite

作　　者：李美蓉 安波 李晨初 孙秀婷 操应长[3] LI Meirong;AN Bo;LI Chenchu;SUN Xiuting;CAO Yingchang(College of Science in China University of Petroleum(East China), Qingdao 266580, China;College of Chemical Engineering in China University of Petroleum(East China), Qingdao 266580, China;School of Geosciences in China University of Petroleum(East China), Qingdao 266580, China)

机构地区：[1]中国石油大学(华东)理学院,山东青岛266580 [2]中国石油大学(华东)化学工程学院,山东青岛266580 [3]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《中国石油大学学报（自然科学版）》2019年第2期156-162,共7页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家科技重大专项(2016ZX05006-007);国家自然科学基金(青年)项目(41602138)

摘　　要：为探究不同温度下CH_3COO^-与Ca^(2+)的络合效应对方解石的影响以及方解石解理面的溶蚀过程,以方解石为研究对象,在静态条件下开展乙酸溶蚀方解石实验,利用Gaussian模拟软件从量子化学的角度计算络合反应的结合能,并结合SEM等表征手段,分析结合能与溶蚀量之间的关系,观测解理面上次生孔—带—锥的演化过程。结果表明:100℃时,CH_3COO^-与Ca^(2+)的络合效应最强,与溶液中离子的自由扩散以及氢质子的交换作用相结合,使得乙酸对方解石的溶蚀最为剧烈;温度升高或降低,络合反应的结合能均呈现不同程度的减小,络合效应被削弱,使得方解石的溶蚀量减少;晶体解理面上的CO_3^(2-)与Ca^(2+)在不同方向上的排列方式存在差异,造成活性位点沿各个方向的溶解速率不同,导致溶蚀晶锥的形成;晶锥只是方解石溶蚀过程中的一种阶段性产物,随着反应的进行,其规模会逐渐变小甚至消失直至裸露出下方新的晶面。The complex effect of CH3COO^- and Ca^2+on the dissolution of calcite at different temperatures and the dissolution process of cleavage plane of calcite were investigated. The calcite was corroded by acetic acid under static conditions. And the Gaussian simulation software was used to calculate the binding energy of the complex reaction from the perspective of quantum chemistry to analyze the relationship between the binding energy and the corrosion amount. The SEM as well as other characterization methods was conducted to observe the evolution of secondary pore-band-cone on cleavage plane. The results show that the complex effect between acetate and calcium ion is the strongest at 100 ℃, which is combined with the free diffusion of ions in the solution and the exchange function of hydrogen protons to make acetic acid corroding calcite most intense. Increasing or decreasing temperature reduces the binding energy of complex reaction in various extents, which weakens the complex effect and decreases the erosion amount. The arrangement of CO3^2- and Ca^2+ in different directions on crystal cleavage plane shows the difference, which results in different dissolution rates of active sites in all directions and leads to corrosion cones eventually. However, the cones were merely phased products in the dissolution process of calcite. With the progress of reaction, the scale of crystal cone would become smaller and even disappear until new crystal plane below is exposed.

关 键 词：方解石 络合效应 溶蚀量 晶锥 

分 类 号：P168[天文地球—天文学]