Importance of temperature on the diffusiophoretic behavior of a charge-regulated zwitterionic particle.

Previous theoretical diffusiophoresis analyses were usually based on a fixed temperature, and its influence on the diffusiophoresis behavior of a particle was seldom discussed. Because both the physicochemical properties of the liquid phase and the charged conditions of a particle can be influenced appreciably by the temperature, so is diffusiophoresis behavior. This effect is taken into account in the present study for the first time, along with the possible presence of multiple ionic species in the liquid phase, a factor of practical significance if reactions occur on the particle surface and/or the solution pH is adjusted. Taking an aqueous dispersion of SiO2 particles as an example, a thorough numerical simulation is conducted to examine the behavior of a charge-regulated, zwitterionic particle subject to an applied salt concentration gradient under various conditions. Considering the potential applications of diffusiophoresis, the results gathered provide necessary information for the design of diffusiophoresis devices, and empirical relationships that correlate the scaled particle mobility with key parameters are developed for that purpose.