Sayed Alshaima, El-Sherbeeny Ahmed M, Abdel-Gawad Gouda Ismail, Mohamed Essam A, Al Zoubi Wail, Abukhadra Mostafa R
Faculty of Earth Science, Beni-Suef University, Beni-Suef, Egypt.
Materials Technologies and their applications Lab, Geology Department, Faculty of Science, Beni-Suef University, Beni Suef, Egypt.
Front Chem. 2025 Apr 16;13:1550726. doi: 10.3389/fchem.2025.1550726. eCollection 2025.
A mesoporous calcium-bearing siliceous framework (Ca-MCM-41) was synthesized using natural coral reef carbonate rocks as precursors. The structural characterization, confirmed through XRD, SEM, FT-IR, and BET analyses, validated the formation of the MCM-41 framework with well-defined mesoporous properties and a high surface area of 159.6 m/g. The developed Ca-MCM-41 was evaluated as a potential adsorbent for the removal of Sr and B ions from both aqueous solutions and real seawater samples collected from the Gulf of Suez, Egypt. The adsorption capacity at saturation reached 285.9 mg/g for Sr and 86.1 mg/g for B, demonstrating the framework's high affinity for these contaminants. The adsorption mechanisms were elucidated using steric and energetic parameters, as derived from statistical physics-based isotherm models. The Ca-MCM-41 framework exhibited a higher active site density (148.9 mg/g) for Sr compared to B (54.8 mg/g), explaining its superior sequestration performance for strontium ions. Each receptor site was capable of accommodating up to three Sr ions and 2 B ions, indicating a multi-ionic interaction process and preferential vertical alignment during adsorption. Energetic analysis revealed that the sequestration process occurred via physical adsorption with interaction energies below 7 kJ/mol, alongside exothermic and spontaneous behavior, as evidenced by calculated internal energy, entropy, and enthalpy values. The developed Ca-MCM-41 structure demonstrated notable efficiency in real seawater applications, achieving sequestration percentages of 80% for Sr and 64% for B, considering their average concentrations (24.2 mg/L for Sr and 12.85 mg/L for B) in a 1-L volume. These findings highlight the high potential of Ca-MCM-41 as an effective and sustainable adsorbent for Sr and B removal in environmental water treatment applications.
以天然珊瑚礁碳酸盐岩为前驱体合成了一种介孔含钙硅质骨架（Ca-MCM-41）。通过XRD、SEM、FT-IR和BET分析证实的结构表征验证了具有明确介孔性质和159.6 m²/g高比表面积的MCM-41骨架的形成。所制备的Ca-MCM-41被评估为从水溶液和从埃及苏伊士湾采集的实际海水样品中去除Sr和B离子的潜在吸附剂。Sr的饱和吸附容量达到285.9 mg/g，B的饱和吸附容量达到86.1 mg/g，表明该骨架对这些污染物具有高亲和力。利用基于统计物理等温线模型得出的空间和能量参数阐明了吸附机制。Ca-MCM-41骨架对Sr的活性位点密度（148.9 mg/g）高于对B的活性位点密度（54.8 mg/g），这解释了其对锶离子的优异螯合性能。每个受体位点最多可容纳三个Sr离子和两个B离子，表明吸附过程中存在多离子相互作用过程和优先垂直排列。能量分析表明，螯合过程通过相互作用能低于7 kJ/mol的物理吸附发生，同时伴随着放热和自发行为，计算出的内能、熵和焓值证明了这一点。考虑到1升体积中它们的平均浓度（Sr为24.2 mg/L，B为12.85 mg/L），所制备的Ca-MCM-41结构在实际海水应用中表现出显著效率，Sr的螯合百分比达到80%，B的螯合百分比达到64%。这些发现突出了Ca-MCM-41作为环境水处理应用中去除Sr和B的有效且可持续吸附剂的巨大潜力。
