Characterization of Cabot BP280 with argon and nitrogen adsorption at temperatures above and below the triple point - Energetic vs Structural Heterogeneities -
Characterization of Cabot BP280 with argon and nitrogen adsorption at temperatures above and below the triple point - Energetic vs Structural Heterogeneities -
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在高于和低于三相点的温度下对卡博特 BP280 进行氩气和氮气吸附的表征 - 能量异质性与结构异质性 -
DOI：
10.1016/j.micromeso.2019.109762
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发表时间：
2020
影响因子：
5.2
通讯作者：
D. Nicholson
中科院分区：
文献类型：
--
作者：
Quang K. Loi; Toshihide Horikawa;Shiliang (Johnathan) Tan;Luisa Prasetyo;D. D. Do;D. Nicholson
表面润湿转变是自然界中普遍存在的现象，因为润湿性取决于吸附物-吸附剂之间的平衡(这又取决于表面的拓扑结构)、吸附-吸附物相互作用和温度。为了了解这些相互作用在特定的吸附物-吸附剂对的润湿转变中的单独贡献，分子模拟是一个宝贵的工具。在这里，我们通过详细的实验和分子模拟研究了在高于和低于各自三点温度的条件下，Ar和N在Cabot BP280上的吸附。我们报道了在60 K、87 K和77 K下的新吸附等温线，证实了以前在该吸附剂上的测量结果。这些结果也被用来计算等温热。我们的透射电子显微镜研究表明，BP280的表面具有几何波纹的石墨化结构，不像Carbopack F等高度石墨化的热炭黑那样平坦。用两种模型进行了模拟：一种是由不同吸附强度的条带构成的能量模型，另一种是由嵌入石墨表面的缝隙组成的结构模型。在三相点以下的温度下吸附有利于探测表面的精细细节，从而能够区分能量和结构分子模型，如本文所提出的。用结构分子模型模拟的等温线和等量热与实验数据符合得很好。对吸附的微观机理进行了分析，包括局域密度分布和分子构型快照，并用局域有序参数来了解吸附层的堆积。
Wetting transitions on surfaces are a ubiquitous phenomenon in nature because the wettability depends on the balance between the adsorbate-adsorbent (which in turn depend on the surface topology), adsorbate-adsorbate interactions and temperature. To understand the separate contributions of these interactions in a wetting transition for a specific adsorbate-adsorbent pair, molecular simulation is an invaluable tool. Here we illustrate this with a detailed experimental and molecular simulation study of argon and nitrogen adsorption on Cabot BP280 at temperatures above and below their respective triple point temperatures. We report new adsorption isotherm data at 60 K and at 87 K and 77 K which confirm previous measurements on this adsorbent. These results were also used to calculate isosteric heats. Our TEM study shows that the surface of BP280 has a geometrically corrugated graphitic structure which is not as planar as highly graphitized thermal carbon black, such as Carbopack F.Simulations were carried out with two models: an energetic model built from strips of different adsorption strength, and a structural model consisting of crevices embedded in a graphite surface. Adsorption at temperatures below the triple point facilitates the probing of the fine details on the surface, enabling the discrimination between the energetic and structural molecular models, as proposed in this paper. The simulated isotherms and the isosteric heats, generated with the structural molecular models, agree very well with experimental data. Analyses of the microscopic mechanism of adsorption include local density distributions and snapshots of molecular configurations, and local order parameters were used to understand the packing of the adsorbate layer.