Department of Environmental Science, Zhejiang University, Hangzhou, 310058, China; Key Laboratory of Environmental Pollution and Ecological Health of Ministry of Education, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, 310058, China.
Department of Environmental Science, Zhejiang University, Hangzhou, 310058, China; Key Laboratory of Environmental Pollution and Ecological Health of Ministry of Education, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, 310058, China.
Environ Pollut. 2020 Dec;267:115563. doi: 10.1016/j.envpol.2020.115563. Epub 2020 Aug 31.
Nonlinear sorption and isotherm nonlinearity of organic compounds by widely used porous resins such as XAD-7 are commonly interpreted as adsorption due to their large surface area. However, through displacement experiments using saturated 4-nitrophenol as the displacer, we observed that the nonlinear sorption and isotherm nonlinearity of selected organic compounds (i.e., naphthalene, nitrobenzenes, phenols and anilines) by XAD-7 was captured by a nonlinear partition mechanism rather than the adsorption mechanism. Nonlinear sorption of organic compounds by XAD-7 includes a nonlinear/displaced fraction and a linear/non-displaced fraction. A dual-mode (DM) model, including a nonlinear Dubinin-Ashtakhov (DA) model component and a linear model component, was developed to describe the nonlinear/displaced fraction and the linear/non-displaced fraction, respectively. The capacity of these two fractions are dependent on their solubility in water or octanol with positively linear relationships but not their molecular size, supporting the nonlinear partitioning mechanism. Besides van-der-waals force, hydrogen-bonding is primarily responsible for the nonlinear partitioning of phenols and anilines into XAD-7, while π-π interaction is responsible for the nonlinear partitioning of naphthalene and nitrobenzenes. The explored nonlinear partitioning mechanism for XAD-7 implies that the nonlinear sorption of organic compounds by porous resins should be recognized for their recovery and applications as sorbents.
广泛使用的多孔树脂（如 XAD-7）对有机化合物的非线性吸附和解吸非线性通常被解释为由于其大的表面积而发生的吸附。然而，通过使用饱和 4-硝基苯酚作为置换剂的置换实验，我们观察到 XAD-7 对选定有机化合物（即萘、硝基苯、苯酚和苯胺）的非线性吸附和解吸非线性是由非线性分配机制而不是吸附机制捕获的。有机化合物通过 XAD-7 的非线性吸附包括非线性/置换部分和线性/非置换部分。开发了一种双模式（DM）模型，包括非线性 Dubinin-Ashtakhov（DA）模型组分和线性模型组分，分别用于描述非线性/置换部分和线性/非置换部分。这两个部分的容量取决于它们在水中或辛醇中的溶解度，与正线性关系，但不取决于它们的分子大小，支持非线性分配机制。除范德华力外，氢键主要负责酚类和苯胺通过 XAD-7 的非线性分配，而π-π相互作用则负责萘和硝基苯的非线性分配。XAD-7 探索的非线性分配机制表明，多孔树脂对有机化合物的非线性吸附应被视为其作为吸附剂的回收和应用的认识。
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