Alotaibi Alya M, Elsayed Nadia H
Department of Chemistry, College of Science and Humanities in Al-Kharj, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia.
Department of Chemistry, Faculty of Science, University of Tabuk, Tabuk 71491, Saudi Arabia.
Int J Biol Macromol. 2025 Apr;303:140564. doi: 10.1016/j.ijbiomac.2025.140564. Epub 2025 Feb 2.
This study involved the creation of AlCu-layered double hydroxide (LDH) encapsulated in carboxymethyl cellulose (CMC) and alginate (Alg), which was then crosslinked with epichlorohydrin to form hydrogel beads (AlCu-LDH/CMC-Alg hydrogel beads) used for the removal of diquat (DQ) herbicide. The resulting material, AlCu-LDH/CMC-Alg hydrogel beads, underwent a comprehensive analysis of its properties using XRD, FT-IR, XPS, EDX, N adsorption/desorption isotherm, and FESEM to determine its textural characteristics. The AlCu-LDH/CMC-Alg hydrogel beads was analyzed using nitrogen adsorption/desorption isotherms to assess its textural properties. The hydrogel beads of AlCu-LDH/CMC-Alg showed a surface area of 114.22 m/g, a pore volume of 0.35 cc/g, and a pore radius of 3.62 nm, indicating a mesoporous structure with a notable adsorption capacity. Following the adsorption of DQ, these measurements decreased to 65.145 m/g, 0.2 cc/g, and 2.4 nm, respectively, suggesting that the DQ had filled or blocked the pores. This study also analyzed the impact of dose, pH, temperature, and initial concentration on the adsorption process. Equilibrium and adsorption kinetics were used to examine the adsorption characteristics. The process followed the pseudo-second-order and Langmuir isotherm models. The primary adsorption mechanism identified was chemisorption, with an adsorption energy of 29.6 kJ.mol. The rise in DQ absorption at higher temperatures suggests an endothermic and spontaneous adsorption process. The optimal adsorption parameters, as determined by the Box-Behnken design software, are a pH of 8, a dosage of 0.02 g of AlCu-LDH/CMC-Alg hydrogel beads per 25 mL, and an adsorption capacity of 302.6 mg/g for the DQ solution. Through careful testing and utilization of the Box-Behnken design and response surface technique in the Design-Expert software, significant enhancements were made to the adsorption process. The stability of the adsorbent was assessed by conducting six successive cycles of adsorption and desorption, revealing that its reusability remained steady with no noticeable decline in removal efficiency. Furthermore, it preserved its original chemical makeup both before and after being reused, demonstrated steady effectiveness, and kept consistent X-ray diffraction (XRD) results.
本研究涉及制备包裹在羧甲基纤维素（CMC）和海藻酸盐（Alg）中的AlCu层状双氢氧化物（LDH），然后将其与环氧氯丙烷交联形成用于去除敌草快（DQ）除草剂的水凝胶珠（AlCu-LDH/CMC-Alg水凝胶珠）。使用X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、X射线光电子能谱（XPS）、能量散射X射线光谱（EDX）、氮吸附/解吸等温线和场发射扫描电子显微镜（FESEM）对所得材料AlCu-LDH/CMC-Alg水凝胶珠的性质进行了全面分析，以确定其结构特征。使用氮吸附/解吸等温线对AlCu-LDH/CMC-Alg水凝胶珠进行分析，以评估其结构性质。AlCu-LDH/CMC-Alg水凝胶珠的比表面积为114.22 m²/g，孔体积为0.35 cc/g，孔半径为3.62 nm，表明其为具有显著吸附能力的介孔结构。在吸附DQ后，这些测量值分别降至65.145 m²/g、0.2 cc/g和2.4 nm，这表明DQ填充或堵塞了孔。本研究还分析了剂量、pH值、温度和初始浓度对吸附过程的影响。使用平衡和吸附动力学来研究吸附特性。该过程遵循准二级和朗缪尔等温线模型。确定的主要吸附机制是化学吸附，吸附能为29.6 kJ/mol。较高温度下DQ吸附量的增加表明吸附过程是吸热和自发的。由Box-Behnken设计软件确定的最佳吸附参数为pH值8、每25 mL使用0.02 g AlCu-LDH/CMC-Alg水凝胶珠以及DQ溶液的吸附容量为302.6 mg/g。通过在Design-Expert软件中仔细测试和利用Box-Behnken设计和响应面技术，吸附过程得到了显著改善。通过进行六个连续的吸附和解吸循环来评估吸附剂的稳定性，结果表明其可重复使用性保持稳定，去除效率没有明显下降。此外，它在重复使用前后保持了其原始化学组成，表现出稳定的有效性，并保持了一致的X射线衍射（XRD）结果。
