Department of Physical Sciences, University of Embu, P.O Box 6-60100, Embu, Kenya.
School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg Campus, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa.
Environ Sci Pollut Res Int. 2024 Nov;31(54):63374-63392. doi: 10.1007/s11356-024-35443-8. Epub 2024 Nov 1.
The Schiff base chelating ligands; (E)-2-(3,3-dimethoxy-2-oxa-7,10-diaza-3-silaundec-10-en-11-yl)phenol (L1), (E)-N-(2-((pyridine-2ylmethylene)amino)ethyl)-3-(trimethoxysilyl)propan-1-amine (L2) and (E)-N-(2-((thiophen-2-ylmethylene)amino)ethyl)-3-(trimethoxysilyl)propan-1-amine (L3) were immobilized on FeO magnetic nanoparticles (MNPs) and utilized in the extraction of Cr(VI), Cd(II) and Pb(II) metal cations from aqueous solutions. The compounds synthesized, denoted as L1@ FeO, L2@FeO, and L3@FeO, were characterized using FT-IR spectroscopy, TEM-SEM, VSM, and BET/BHJ techniques for analysis of functional groups, surface morphology, magnetic properties, and degree of porosity of the adsorbents, respectively. BET/BHJ technique confirmed the mesoporous nature of the compounds as their pore diameters ranged between 15 and 17 nm. The initial optimization conditions of pH, adsorbent dosage, initial metal concentration, and contact time on adsorption were studied using L1@ FeO. The optimum efficiencies recorded were 68% and 46% for Cr(VI) and Cd(II), respectively, obtained at pH 3, and a metal concentration of 20 ppm while an efficiency of 99% was recorded for Pb(II) cations at pH 7 and a metal concentration of 100 ppm. Compounds L2@FeO and L3@ FeO were also used in the extraction of metal cations from aqueous solution and gave efficiencies of 22%, 56%, and 78% for L2@ FeO and 19%, 90%, and 59% using L3@ FeO for Cr(VI), Cd(II), and Pb(II), respectively. The maximum adsorption capacities of L1@ FeO for Cr(VI), Cd(II), and Pb(II) cations were obtained from the Langmuir isotherm as 32.84, 41.77, and 450.45 mg/g, respectively. The experimental data was analyzed using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models. Both linear and non-linear forms of kinetic isotherms; Langmuir, Freundlich, Redlich-Peterson, and Temkin were utilized to investigate the nature of adsorption on L1@FeO. The mechanistic studies deduced that the Langmuir isotherm and pseudo-second-order kinetic model better described the adsorption process both yielding high correlation coefficient values (R > 0.98).
席夫碱基螯合配体; (E)-2-(3,3-二甲氧基-2-氧杂-7,10-二氮杂-3-硅十一-10-烯-11-基)苯酚 (L1), (E)-N-(2-((吡啶-2 基亚甲基)氨基)乙基)-3-(三甲氧基硅基)丙-1-胺 (L2) 和 (E)-N-(2-((噻吩-2-基亚甲基)氨基)乙基)-3-(三甲氧基硅基)丙-1-胺 (L3) 被固定在 FeO 磁性纳米粒子 (MNPs) 上，并用于从水溶液中萃取 Cr(VI)、Cd(II) 和 Pb(II) 金属阳离子。合成的化合物，分别表示为 L1@FeO、L2@FeO 和 L3@FeO，分别通过 FT-IR 光谱、TEM-SEM、VSM 和 BET/BHJ 技术进行表征，用于分析功能基团、表面形态、磁性和吸附剂的多孔度。BET/BHJ 技术证实了化合物的中孔性质，因为它们的孔径在 15 到 17nm 之间。使用 L1@FeO 研究了 pH、吸附剂用量、初始金属浓度和吸附时间对吸附的初始优化条件。在 pH 3 和金属浓度为 20ppm 时，Cr(VI)和 Cd(II)的最佳效率分别为 68%和 46%，而在 pH 7 和金属浓度为 100ppm 时，Pb(II)阳离子的效率为 99%。化合物 L2@FeO 和 L3@FeO 也用于从水溶液中萃取金属阳离子，L2@FeO 的效率分别为 22%、56%和 78%，而 L3@FeO 的效率分别为 19%、90%和 59%。L1@FeO 对 Cr(VI)、Cd(II)和 Pb(II)阳离子的最大吸附容量是从 Langmuir 等温线得到的，分别为 32.84、41.77 和 450.45mg/g。实验数据分别使用伪一阶、伪二阶、内扩散和 Elovich 动力学模型进行分析。线性和非线性形式的动力学等温线;Langmuir、Freundlich、Redlich-Peterson 和 Temkin 都被用来研究在 L1@FeO 上吸附的性质。机理研究推断，Langmuir 等温线和伪二阶动力学模型更好地描述了吸附过程，两者都产生了高相关系数值 (R>0.98)。
