Laktionov Mikhail, Nová Lucie, Rud Oleg V
Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, 12800 Prague, Czech Republic.
Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, 197101 Saint-Petersburg, Russia.
Gels. 2022 Oct 15;8(10):656. doi: 10.3390/gels8100656.
Polyelectrolyte hydrogels can absorb a large amount of water across an osmotic membrane as a result of their swelling pressure. On the other hand, the insoluble cross-linked hydrogel network enables dewatering under the influence of external (thermal and/or mechanical) stimuli. Moreover, from a thermodynamic perspective, a polyelectrolyte hydrogel is already an osmotic membrane. These properties designate hydrogels as excellent candidates for use in desalination, at the same time avoiding the use of expensive membranes. In this article, we present our recent theoretical study of polyelectrolyte hydrogel usage for water desalination. Employing a coarse-grained model and the Gibbs ensemble, we modeled the thermodynamic equilibrium between the coexisting gel phase and the supernate aqueous salt solution phase. We performed a sequence of step-by-step hydrogel swellings and compressions in and systems, i.e., in equilibrium with a large and with a comparably small reservoir of aqueous solution. The swelling in an removes ions from the large reservoir, whereas the compression in a decreases the salt concentration in the small reservoir. We modeled this stepwise process of continuous decrease of water salinity from seawater up to freshwater concentrations and estimated the energy cost of the process to be comparable to that of reverse osmosis.
由于其溶胀压力，聚电解质水凝胶能够通过渗透膜吸收大量水分。另一方面，不溶性交联水凝胶网络能够在外部（热和/或机械）刺激的影响下实现脱水。此外，从热力学角度来看，聚电解质水凝胶本身就是一种渗透膜。这些特性使水凝胶成为海水淡化的理想候选材料，同时避免了使用昂贵的膜。在本文中，我们展示了我们最近关于聚电解质水凝胶用于海水淡化的理论研究。采用粗粒度模型和吉布斯系综，我们对共存的凝胶相和上层盐水溶液相之间的热力学平衡进行了建模。我们在大体积和小体积系统中进行了一系列逐步的水凝胶溶胀和压缩操作，即在与大量和相对少量的水溶液储库达到平衡的情况下。在大体积系统中的溶胀从大储库中去除离子，而在小体积系统中的压缩降低小储库中的盐浓度。我们对从海水到淡水浓度的水盐度持续降低的这一逐步过程进行了建模，并估计该过程的能量成本与反渗透相当。
