Influence of ionic strength and temperature on adsorption of tetrakis-N-methylpyridyl porphyrin onto mesoporous silica
Influence of ionic strength and temperature on adsorption of tetrakis-N-methylpyridyl porphyrin onto mesoporous silica
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DOI：
10.1016/j.colsurfa.2022.130262
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发表时间：
2022-12
期刊：
影响因子：
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通讯作者：
Akira Yamaguchi;Ami Ishii;T. Kamijo
中科院分区：
文献类型：
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作者：
Akira Yamaguchi;Ami Ishii;T. Kamijo
在本研究中，我们研究了离子强度和温度对四甲基- n -甲基吡啶卟啉（TMPyP）在孔径为7.0 nm的介孔二氧化硅上吸附的影响。TMPyP在含0 ~ 150 mM NaCl的10 mM磷酸盐缓冲溶液中的吸附表现为TMPyP吸附量与TMPyP平衡溶液浓度成反比的线性等温线。通过静电修正Langmuir模型对吸附等温线的分析可知，随着离子强度的增加，表观吸附常数的减小归因于电解质离子对表面电荷的屏蔽作用。在温度对TMPyP吸附的依赖关系中，分析了包括吸附过程中热容变化在内的非线性范霍夫图。van 't Hoff分析结果表明，TMPyP在低温下的吸附为放热焓驱动反应，而随着温度的升高，其吸附为吸热熵驱动反应。此外，表面扩散率是影响TMPyP在介孔二氧化硅上最大吸附量的主要因素。
In the present study, we examined the effects of ionic strength and temperature for adsorption of tetrakis-N-methylpyridyl porphyrin (TMPyP) on mesoporous silica with 7.0 nm in pore diameter. The adsorption of TMPyP in 10 mM phosphate buffer solutions containing 0–150 mM NaCl showed linear adsorption isotherm plotted as inverse of the adsorption amount of TMPyP versus inverse of the equilibrium solution concentration of TMPyP. From the analysis of the adsorption isotherm by electrostatically modified Langmuir model, decrease in apparent adsorption constant with increasing the ionic strength was ascribed to the surface charge screening by electrolyte ions. In the temperature dependence on the TMPyP adsorption, non-linear van’t Hoff plots were analyzed by including heat capacity change during adsorption. The results of the van’t Hoff analysis indicated that the TMPyP adsorption at low temperature was exothermic and enthalpy-driven reaction, whereas it became endothermic and entropy-driven reaction with temperature elevation. In addition, the surface diffusivity was suggested as a primary factor to govern the maximum adsorption amount of TMPyP on mesoporous silica.