In this study, the ability of cationic poly(acrylamide-co-(3-acrylamidopropyl)trimethylammonium chloride) hydrogels to desalinate seawater is explored, where the salt separation is based on the partial rejection of mobile salt ions by the fixed charges along the polymer backbone. Water absorbency measurements reveal that artificial seawater-containing divalent ions (Mg$^{2+}$, Ca$^{2+}$, and SO$_{4}$$^{2-}$) drastically decrease the swelling capacity of previously employed anionic poly(acrylic acid-co-sodium acrylate) hydrogels, whereas no influence on the swelling behavior of the synthesized cationic hydrogels is found. The swelling behavior and mechanical properties are studied by varying the degree of crosslinking and degree of ionization systematically in the range of 1–5 and 25–75 mol%, respectively. Finally, artificial seawater (c$_{sea}$= 0.171 mol L$^{-1}$) is desalinated in a custom-built press setup with an estimated efficiency of E$_{m³}$= 17.6 kWh m$^{-3}$ by applying an external pressure on the swollen hydrogels.

中文翻译：

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使用阳离子聚（丙烯酰胺）水凝胶和机械力分离海水淡化

在这项研究中，阳离子聚（丙烯酰胺-共-（3-丙烯酰胺丙基）三甲基氯化铵）水凝胶对海水淡化的能力进行了探索，其中盐分离是基于沿聚合物的固定电荷部分排斥移动盐离子骨干。吸水率测量表明，人工海水中含有二价离子（Mg$^{2+}$、Ca$^{2+}$ 和 SO$_{4}$$^{2-}$）显着降低了膨胀先前使用的阴离子聚（丙烯酸-共-丙烯酸钠）水凝胶的容量，而对合成的阳离子水凝胶的溶胀行为没有影响。通过分别在 1-5 和 25-75 mol% 范围内系统地改变交联度和电离度来研究溶胀行为和机械性能。最后是人工海水（c$_{sea}$= 0.