We present a microfluidic crossflow separation of colloids enabled by the dissolution of CO₂ gas in aqueous suspensions. The dissolved CO₂ dissociates into H⁺ and HCO₃^– ions, which are efficient candidates for electrolytic diffusiophoresis, because of the fast diffusion of protons. By exposing CO₂ gas to one side of a microfluidic flow channel, a crossflow gradient can be created, enabling the crossflow diffusiophoresis of suspended particles. We develop a simple two-dimensional model to describe the coupled transport dynamics that is due to the competition of advection and diffusiophoresis. Furthermore, we show that oil nanoemulsions can be effectively separated by utilizing highly charged particles as a carrier vehicle, which is otherwise difficult to achieve. These results demonstrate a portable, versatile method for separating particles in broad applications including oil extraction, drug delivery, and bioseparation.

中文翻译：

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通过CO2诱导的扩散电泳进行胶体分离。

我们提出了通过将CO ₂气体溶解在水性悬浮液中而实现的胶体微流错流分离。将溶解的CO ₂离解成H ⁺和HCO ₃ ^-离子，其是用于电解diffusiophoresis有效候选者，因为质子的快速扩散。通过暴露CO ₂气体流向微流通道的一侧时，会产生错流梯度，从而实现悬浮颗粒的错流扩散电泳。我们开发了一个简单的二维模型来描述由于对流和扩散电泳竞争引起的耦合的运输动力学。此外，我们表明，通过利用带高电荷的颗粒作为载体，可以有效地分离油纳米乳液，否则很难实现。这些结果证明了一种便携式，多功能的方法可以在广泛的应用中分离颗粒，包括油提取，药物输送和生物分离。