Chitosan (CS) and sodium alginate (SA) were used as the base materials. A Schiff base reaction was successfully conducted between the amino groups in chitosan and benzaldehyde to synthesize benzaldehyde-chitosan (B-CS) with protected amino groups. Subsequently, B-CS was modified with (3-mercaptopropyl)trimethoxysilane to introduce thiol functional groups and remove benzaldehyde, resulting in thiol-functionalized chitosan (CS-SH). CS-SH was crosslinked with a mixture of polyvinyl alcohol (PVA) and sodium alginate (SA) through a calcium chloride solution, and polyvinyl alcohol-sodium alginate/thiol-functionalized chitosan aerogel beads (PVA-SA/CS-SH) were successfully prepared using a gel-vacuum freeze-drying technique. Various technical means such as XRD, TG, SEM, XPS, EDS, and FT-IR were used to analyze the physicochemical properties of PVA-SA/CS-SH. Characterization results showed that PVA-SA/CS-SH has a unique three-dimensional porous structure, high specific surface area, and abundant functional groups, providing favorable conditions for the adsorption of U(VI). Systematic batch adsorption experiments were conducted to explore the adsorption performance of PVA-SA/CS-SH aerogel beads for U(VI) in uranium-containing wastewater and the influencing factors. The experimental results showed that under optimal conditions (pH of 6, t of 300 min, m/v of 0.125 g/L, T of 313 K, C0 of 50 mg·L-1), the maximum adsorption capacity of PVA-SA/CS-SH for U(VI) reached up to 350.33 mg/g. Adsorption kinetics and thermodynamic analysis indicated that the adsorption process fits the Langmuir isotherm adsorption model and the pseudo-second-order kinetic model, indicating that the adsorption is a spontaneous endothermic process dominated by chemical adsorption with a single layer and homogeneous nature. The adsorption mechanism is mainly attributed to the coordination/chelation action of various functional groups such as amino, hydroxyl, and thiol on the material surface with U(VI) to form stable chemical bonds, which together promote the efficient capture of U(VI) ions. In summary, PVA-SA/CS-SH aerogel beads not only exhibit excellent U(VI) adsorption performance but also have good reusability and adsorption selectivity, and are expected to become a new type of efficient uranium removal adsorbent with broad application prospects in the field of nuclear wastewater treatment.

中文翻译：

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新型 PVA-SA/CS-SH 气凝胶微珠的制备及其对 U（VI） 的高效吸附


以壳聚糖 （CS） 和海藻酸钠 （SA） 为基材。壳聚糖和苯甲醛中的氨基之间成功进行席夫碱反应，合成具有受保护氨基的苯甲醛-壳聚糖 （B-CS）。随后，用 （3-巯基丙基）三甲氧基硅烷修饰 B-CS 以引入巯基官能团并去除苯甲醛，得到巯基官能化壳聚糖 （CS-SH）。CS-SH 通过氯化钙溶液与聚乙烯醇 （PVA） 和海藻酸钠 （SA） 的混合物交联，并使用凝胶真空冷冻干燥技术成功制备聚乙烯醇-海藻酸钠/巯基官能化壳聚糖气凝胶珠 （PVA-SA/CS-SH）。采用 XRD、TG、SEM、XPS、EDS 和 FT-IR 等多种技术手段对 PVA-SA/CS-SH 的理化性质进行了分析。表征结果表明，PVA-SA/CS-SH 具有独特的三维多孔结构、高比表面积和丰富的官能团，为U（VI）的吸附提供了有利条件。进行系统的批量吸附实验，探究 PVA-SA/CS-SH 气凝胶珠对含铀废水中 U（VI） 的吸附性能及其影响因素。实验结果表明，在最佳条件下（pH 值为 6，t 为 300 min，m/v 为 0.125 g/L，T 为 313 K，C0 为 50 mg·L-1）中，PVA-SA/CS-SH 对 U（VI） 的最大吸附量高达 350.33 mg/g。 吸附动力学和热力学分析表明，吸附过程符合 Langmuir 等温线吸附模型和准二级动力学模型，表明吸附是一个以化学吸附为主的自发吸热过程，具有单层和均质性质。吸附机理主要归因于氨基、羟基、巯基等各种官能团在材料表面与 U（VI） 的配位/螯合作用，形成稳定的化学键，共同促进 U（VI） 离子的高效捕获。综上所述，PVA-SA/CS-SH 气凝胶珠不仅表现出优异的 U（VI） 吸附性能，而且具有良好的可重用性和吸附选择性，有望成为一种在核废水处理领域具有广阔应用前景的新型高效脱铀吸附剂。