A novel and cost-effective approach was successfully developed for synthesizing high-performance zeolite 4A encapsulating magnetic particles (magnetic zeolite 4A) using kaolinite and red mud as raw materials one-step combined activation-reduction and subsequent hydrothermal synthesis. The concurrent reduction of iron compounds in red mud to magnetic particles mainly composed of FeO during the thermal activation of kaolinite eliminated the need for a distinct red mud reduction process, thereby streamlining the synthesis and maximizing efficiency. The resulting product comprised highly crystalline zeolite 4A encapsulating magnetic particles derived from the red mud, avoiding oxidation and corrosion of the magnetic material in acidic solutions. A series of magnetic zeolite 4A (MZ) were obtained by introducing varying percentages of red mud and kaolinite, and their morphological, structural, magnetic and adsorption properties were investigated. The BET specific surface area of the obtained MZ-20 is 13.6 m/g. MZ-20 (red mud: kaolinite mass percentage is 20%) displayed the maximum adsorption capacity of 172 mg/g for Sr(II). Within 1 h, 96.4% of the Sr(II) was removed. The adsorption kinetics and isotherms followed the pseudo-second-order and Langmuir models, respectively. Using a mixed 0.1 M NaCl and 0.1 M HCl solution as eluent, the magnetic adsorbent maintained high desorption and regeneration ratios along with stable magnetic properties after four adsorption-desorption cycles. In summary, the MZ-20 adsorbent exhibited high adsorption capacity, recyclability and excellent magnetic properties, making it a decontamination candidate for removing Sr(II) from radioactive wastewater.

中文翻译：

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使用高岭石和赤泥以新颖且经济高效的方式合成磁性沸石 4A 以去除 Sr(II)

以高岭石和赤泥为原料，一步活化-还原联合水热合成，成功开发出一种经济有效的合成高性能4A沸石包覆磁性颗粒（磁性4A沸石）的方法。在高岭石热活化过程中，赤泥中的铁化合物同时还原为主要由 FeO 组成的磁性颗粒，消除了对独特赤泥还原过程的需要，从而简化了合成并最大限度地提高了效率。所得产品包含高度结晶的沸石 4A，其中封装了源自赤泥的磁性颗粒，避免了磁性材料在酸性溶液中的氧化和腐蚀。通过引入不同比例的赤泥和高岭石获得了一系列磁性沸石4A（MZ），并研究了它们的形态、结构、磁性和吸附性能。所得MZ-20的BET比表面积为13.6m 2 /g。 MZ-20（赤泥：高岭石质量分数为20%）对Sr(II)的最大吸附容量为172 mg/g。 1小时内，96.4%的Sr(II)被去除。吸附动力学和等温线分别遵循伪二阶模型和朗缪尔模型。使用0.1 M NaCl和0.1 M HCl混合溶液作为洗脱液，磁性吸附剂在四次吸附-解吸循环后仍保持高解吸率和再生率以及稳定的磁性能。综上所述，MZ-20吸附剂表现出高吸附容量、可回收性和优异的磁性能，使其成为去除放射性废水中Sr(II)的净化候选材料。