Forced Migration of Nonsoluble and Soluble Metallic Pollutants ahead of a Liquid−Solid Interface during Unidirectional Freezing of Dilute Clayey Suspensions

Abstract

To test whether suspended and dissolved forms of metallic pollutants in water can be simultaneously separated by freezing, we subjected water initially at 0 °C and containing (0.69−1.03) × 10-2 mol of dissolved lead nitrate and 0.83−1.68 g of suspended clay (Na−montmorillonite) per kilogram of suspension to unidirectional freezing. Less suspended and dissolved forms of lead remained behind the freezing interface as compared to that in the initial suspension. The greatest reduction of total lead behind the freezing interface was obtained when the pH was between 5 and 9 and when −2 °C cooling was used: i.e., for a mean rate of freezing front advance on the order of 1 μm s-1.

Freeze‐Casting of Porous Ceramics: A Review of Current Achievements and Issues

“…This effect is being used in the purification of pollutants. [60] However, to form porous structures, particles redistribution must occur; the particles must be rejected from the solidification front and collected between the arms of the solidification front. The morphology of the front will then dictate the architecture of the final materials.…”

Force of a gas bubble on a foreign particle in front of a freezing interface

“…When an ice front advances in a suspension containing particles, the ice may repel, pierce, break, or entrap the solid particles ahead of it [1][2][3]. Uhlmann et al [4] proposed the first systematic analysis on the solid-solidifying front interaction, demonstrating the existence of a critical velocity (V c ) above which all particles would be trapped in the moving front, since a liquid bridge was not maintainable between the particle and the ice front by the surrounding liquid.…”

Morphological instability induced by the interaction of a particle with a solid-liquid interface

“…Ni, 81.30.Fb, 81.10.Mx,81.10.Dn, 81.20.Dn The freezing of a liquid with a dispersed phase takes place in numerous natural and industrial processes. Some examples include the formation of ice lenses that result from the freezing of soil water [1], the freezing of biological cell suspensions in a cryopreservation experiment [2], the decontamination of metallic pollutants from soils [3], the growth of Y123 superconductors by the undercooling method [4] and the manufacture of particulate reinforced metal matrix composites (PMMC) [5]. The properties of these composite materials are enhanced by the addition of the dispersed elements.The freezing of a liquid suspension is associated with the interaction of the constituents of the dispersed phase with a solidifying interface.…”