In practical applications of surface-modified nanoparticles (NPs), the washing stage has a number of challenges, such as insufficient washing, long treatment time, and various waste liquors. Cosolvent-enhanced supercritical CO₂ (scCO₂) is an appealing solvent system for complete, rapid, and eco-friendly washing owing to its high diffusivity and recyclability. In this paper, we report a rapid washing guideline for surface-modified NPs using ethanol-enhanced scCO₂. Kinetic analysis was performed on the washing behavior of oleic acid-modified NPs mixed with various modifiers (C10 to C18 fatty acids) at 40 °C and 20.0 MPa while designing scCO₂ media based on rationally estimated modifier solubilities. Notably, the scCO₂ medium showed superior washing rates to that of ethanol for various modifiers with a wide range of solubilities in scCO₂. The washing rate was dependent on solubility and could be organized into two regions, with a threshold value of 0.016 mol kg^–1: solubility/diffusivity-controlled and diffusivity-controlled washing. These findings provide valuable guidelines for designing cosolvent-enhanced scCO₂ media for the rapid washing of surface-modified NPs.

中文翻译：

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使用合理设计的超临界 CO2 介质对表面改性纳米颗粒进行速率控制清洗


在表面改性纳米颗粒 （NPs） 的实际应用中，洗涤阶段存在洗涤不充分、处理时间长、废液种类繁多等诸多挑战。助溶剂增强型超临界 CO₂ （scCO₂） 具有高扩散性和可回收性，是一种极具吸引力的溶剂系统，可实现完整、快速和环保的清洗。在本文中，我们报告了使用乙醇增强 scCO₂ 的表面改性 NPs 的快速清洗指南。在基于合理估计的改性剂溶解度设计 scCO₂ 介质时，对油酸改性 NPs 与各种改性剂 （C10 至 C18 脂肪酸） 混合在 40 °C 和 20.0 MPa 下的洗涤行为进行了动力学分析。值得注意的是，scCO₂ 培养基对各种改性剂的洗涤速率优于乙醇，在 scCO₂ 中具有广泛的溶解度。洗涤速率取决于溶解度，可以分为两个区域，阈值为 0.016 mol ^kg-1：溶解度/扩散率控制洗涤和扩散率控制洗涤。这些发现为设计助溶剂增强的 scCO₂ 介质以快速清洗表面改性 NP 提供了有价值的指导。