Hou Tianyu, Zhang Hongjiao, He Dongliang, Liu Qingye, Zhang Zhijun, Xiao Longqiang, Li Wei, Barnes Melanie
School of Chemical Engineering and Technology, North University of China No. 3 Xueyuan Road, Jiancaoping District Taiyuan 030051 China
CSIRO Agriculture and Food GPO Box 1600, ACT 2601 Canberra Australia.
RSC Adv. 2018 Oct 31;8(64):36858-36868. doi: 10.1039/c8ra06110f. eCollection 2018 Oct 26.
Chitosan hydrogel microspheres derived from the LiOH/KOH/urea aqueous system demonstrate great characteristics of high mechanical strength, relative chemical inertness, renewability and 3-D fibrous network, making them promising functional supports. This work aims to investigate the tunable Co adsorption behaviors on these robust chitosan microspheres in detail, providing the theoretical basis for optimizing the preparation procedure of chitosan microspheres supported CoO catalysts in the future. The experimental results revealed that the fabricated original chitosan microspheres with more extended chain conformation could display enhanced adsorption capacity for Co at determined concentration both in water and alcohol solutions, which is about 2-7 times higher than that of the conventional chitosan hydrogel microspheres prepared from the acetic acid solution. The kinetic experiments indicated that the adsorption process in water solution agreed with the pseudo-second-order kinetic equation mostly, while the chemical and physical adsorptions commonly contribute to the higher Co adsorption on chitosan microspheres in alcohol solution. Moreover, in both cases, the film diffusion or chemical reaction is the rate limiting process in the initial adsorption stage, and the adsorption of Co on chitosan microspheres can well fit to the Langmuir isotherm. Thermodynamic analysis demonstrated that such adsorption behaviors were dominated by an endothermic (Δ° > 0) and spontaneous (Δ° < 0) process.
由LiOH/KOH/尿素水溶液体系制备的壳聚糖水凝胶微球具有高机械强度、相对化学惰性、可再生性和三维纤维网络等优异特性，使其成为有前景的功能载体。本工作旨在详细研究这些坚固的壳聚糖微球对钴的可调吸附行为，为未来优化负载氧化钴催化剂的壳聚糖微球制备工艺提供理论依据。实验结果表明，制备的具有更伸展链构象的原始壳聚糖微球在水和醇溶液中对特定浓度的钴具有增强的吸附能力，比由乙酸溶液制备的传统壳聚糖水凝胶微球高约2-7倍。动力学实验表明，水溶液中的吸附过程大多符合准二级动力学方程，而化学吸附和物理吸附共同导致壳聚糖微球在醇溶液中对钴的较高吸附。此外，在两种情况下，膜扩散或化学反应是初始吸附阶段的速率限制过程，钴在壳聚糖微球上的吸附能很好地符合朗缪尔等温线。热力学分析表明，这种吸附行为由吸热（Δ°>0）和自发（Δ°<0）过程主导。
