Preparation of waterborne polyurethane/β-cyclodextrin composite nanosponge by ion condensation method and its application in removing of dyes from wastewater

• Published in: Chinese journal of chemical engineering Vol. 58; no. 6; pp. 124 - 136
• Main Authors: Ma, Shanghong, Zhang, Haitao, Qu, Jianbo, Zhu, Xiuzhong, Hu, Qingfei, Wang, Jianyong, Ye, Peng, Sai, Futao, Chen, Shiwei
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2023; State Key Laboratory of Biobased Material and Green Papermaking,Qilu University of Technology,Shandong Academy of Sciences,Jinan 250353,China%Institute of Material Science and Technology,Qilu University of Technology,Shandong Academy of Sciences,Jinan 250353,China
• Subjects: Adsorption; Composites; Ion condensation; Nanomaterials; Waterborne polyurethane (WPU); β-Cyclodextrin (β-CD); Ion condensation; Nanomaterials; Composites; β-Cyclodextrin (β-CD); Adsorption; Waterborne polyurethane (WPU)
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/j.cjche.2022.10.003

When the emulsion is added into the mixture of hydrochloric acid and anhydrous ethanol, negative charges on the emulsion particles' surfaces are neutralized, the repulsive force between the emulsion particles vanishes, and the emulsion rapidly agglomerate into larger clusters. In addition, when the emulsion particles are aggregated, the emulsion particles are disassembled, the chain segment shrinks and aggregates to generate internal stress, then a large number nanopore are generated to overcome the internal stress. The nanosponge adsorbents prepared by ion condensation method have a certain removal effect on methylene blue, among which WPU-4,4.62 has the best adsorption capacity. [Display omitted] Currently, polymer nanosponges have received extensive attention. However, developing new synthetic techniques for novel nanosponges remains a challenge. Furthermore, to date, composite nanosponge adsorbents based on waterborne polyurethane (WPU) and β-cyclodextrin (β-CD) have not been reported. Herein, a novel green method, ion condensation method, was developed in this study for the preparation of polymer nanosponge adsorbents for efficient removal of dyes from wastewater. Based on the principle of charge repulsion between nanoparticles to maintain emulsion stability, waterborne polyurethane/β-cyclodextrin composite nanosponges (WPU-x,y) were prepared by coagulating the emulsions synthesized from 2,2-dimethylolpropionic acid, polypropylene glycol and hexamethylene diisocyanate as raw materials in a mixture of hydrochloric acid and anhydrous ethanol. The structure and appearance of WPU-x,y were characterized by attenuated total reflectance Fourier transform infrared spectroscopy, thermal gravimetric analyzer, scanning electron microscope and mercury intrusion porosimetry. The adsorption capacity of WPU-x,y was tested by parameters such as cross-linking degree, β-CD dosage, contact time, initial dye concentration and pH value. The study found that WPU-4,4.62 had the best adsorption effect on methylene blue (MB), the maximum removal rate was 93.42%, and the maximum adsorption capacity was 136.03 mg·g−1. Moreover, the Sips isotherm and pseudo-second-order-model were suitable for MB adsorption. Therefore, this study provides some perspectives for the fabrication of nanosponge adsorbents.