Zou Chenglong, Liao Ziwen, Wu Qun, Wu Zixuan, Gong Haoyu, Xiang Sulin, Song Mingyang, Deng Zilong
School of Civil Engineering and Architecture, East China Jiaotong University, 808 East Shuanggang Road, Nanchang 330013, China.
State Key Laboratory for Pollution Control, School of Environmental Science and Engineering, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, 1239 Siping Road, Shanghai 200092, China.
Int J Biol Macromol. 2025 Aug;320(Pt 3):145974. doi: 10.1016/j.ijbiomac.2025.145974. Epub 2025 Jul 12.
The wastewater containing gadolinium ions produced during the rare earth mining process posed a serious threat to the ecosystem and human health. This study provided a novel TEMPO-oxidized cellulose nanocrystals intercalated with magnetic bentonite (TOCNC@M-Bt) via the co-precipitation for effective Gd(III) adsorption from wastewater. TOCNC@M-Bt had a dense lamellar structure, abundant oxygen-containing functional groups (e.g., hydroxyl and carboxyl groups), and large numbers of adsorption sites. Compared with Bt, the specific surface area of TOCNC@M-Bt was expanded from 54.96 m/g to 101.36 m/g. The adsorption experiments showed that at optimal conditions (pH = 7, temperature = 303 K, adsorbent dosage = 0.9 g/L), the removal rate of 97.53 % was achieved for a 30 mg/L Gd(III) solution. Furthermore, the experimental data conformed to the pseudo-second-order kinetic (R = 0.998), the intra-particle diffusion (R = 0.950; R = 0.938; R = 0.977), and Boyd's liquid film diffusion model (R = 0.852), indicating that the adsorption process was influenced by chemical adsorption, intraparticle diffusion and external liquid film diffusion. The equilibrium adsorption data aligned with the Langmuir adsorption isotherm, and the maximum Gd(III) adsorption capacity of 40.85 mg/g, which suggested that the adsorption process followed a monolayer mechanism on a homogeneous surface. Thermodynamic parameters (ΔG < 0, ΔH > 0) showed that the adsorption process was spontaneous and endothermic. Mechanistic studies showed that ion exchange, electrostatic adsorption, complexation, hydrogen bonding, and pore filling predominantly determined the adsorption process. TOCNC@M-Bt also presented selective removal of Gd(III) ions in the presence of multiple ion species and the 79.11 % removal rate after five sorption-desorption cycles, indicating the inherent robustness and reusability.
稀土开采过程中产生的含钆离子废水对生态系统和人类健康构成了严重威胁。本研究通过共沉淀法提供了一种新型的插层有磁性膨润土的 TEMPO 氧化纤维素纳米晶体（TOCNC@M-Bt），用于从废水中有效吸附钆（III）。TOCNC@M-Bt 具有致密的层状结构、丰富的含氧官能团（如羟基和羧基）以及大量的吸附位点。与膨润土相比，TOCNC@M-Bt 的比表面积从 54.96 m²/g 扩大到了 101.36 m²/g。吸附实验表明，在最佳条件（pH = 7，温度 = 303 K，吸附剂用量 = 0.9 g/L）下，对于 30 mg/L 的钆（III）溶液，去除率达到了 97.53%。此外，实验数据符合准二级动力学（R = 0.998）、颗粒内扩散（R = 0.950；R = 0.938；R = 0.977）以及 Boyd 液膜扩散模型（R = 0.852），表明吸附过程受化学吸附、颗粒内扩散和外部液膜扩散的影响。平衡吸附数据符合朗缪尔吸附等温线，钆（III）的最大吸附容量为 40.85 mg/g，这表明吸附过程在均匀表面上遵循单层机制。热力学参数（ΔG < 0，ΔH > 0）表明吸附过程是自发的且吸热的。机理研究表明，离子交换、静电吸附、络合、氢键作用和孔隙填充主要决定了吸附过程。TOCNC@M-Bt 在多种离子共存的情况下还表现出对钆（III）离子的选择性去除，并且在五个吸附 - 解吸循环后去除率为 79.11%，表明其具有内在的稳定性和可重复使用性。
