Investigation of the Role of Polysaccharide in the Dolomite Growth at Low Temperature by Using Atomistic Simulations

详细信息    查看全文

• 作者：Zhizhang Shen ; Izabela Szlufarska ; Philip E. Brown ; Huifang Xu
• 刊名：Langmuir
• 出版年：2015
• 出版时间：September 29, 2015
• 年：2015
• 卷：31
• 期：38
• 页码：10435-10442
• 全文大小：470K
• ISSN：1520-5827

文摘

Dehydration of water from surface Mg²⁺ is most likely the rate-limiting step in the dolomite growth at low temperature. Here, we investigate the role of polysaccharide in this step using classical molecular dynamics (MD) calculations. Free energy (potential of mean force, PMF) calculations have been performed for water molecules leaving the first two hydration layers above the dolomite (104) surface under the following three conditions: without catalyst, with monosaccharide (mannose), and with oligosaccharide (three units of mannose). MD simulations reveal that there is no obvious effect of monosaccharide in lowering the dehydration barrier for surface Mg²⁺. However, we found that there are metastable configurations of oligosaccharide, which can decrease the dehydration barrier of surface Mg²⁺ by about 0.7鈥?.1 kcal/mol. In these configurations, the molecule lies relatively flat on the surface and forms a bridge shape. The hydrophobic space near the surface created by the nonpolar 鈭扖H groups of the oligosaccharide in the bridge conformation is the reason for the observed reduction of dehydration barrier.