Bentonite/Sesbania Gum Hydrogel for Effective Removal of Cationic Dyes: Network Structure Construction and the Role of Multiple Hydroxyl and Carboxyl Adsorption Sites

• Published in: International Journal of Environmental Research Vol. 18; no. 5
• Main Authors: Jiang, Luying, Yu, Sishan, Zhang, Jingwei, Xu, Zisong, Tang, Rui, Wang, Yinlong, Liang, Ke, Zhai, Chen, Tong, Zhangfa, Zhang, Hanbing
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.10.2024; Springer Nature B.V
• Subjects: Acrylamide; Acrylic acid; Adsorbents; Adsorption; Amino groups; Aqueous environments; Bentonite; Cationic dyes; Color removal; Dyes; Earth and Environmental Science; Elastic recovery; Environment; Environmental Engineering/Biotechnology; Environmental Management; Geoecology/Natural Processes; Hydrogels; Isotherms; Landscape/Regional and Urban Planning; Malachite green; Mechanical properties; Methylene blue; Natural Hazards; Polysiloxanes; Research Paper; Synthesis; Bentonite; Mechanical properties; Sesbania gum; Adsorption mechanism; Cationic dyes
• ISSN: 1735-6865; 2008-2304
• DOI: 10.1007/s41742-024-00624-3

Effective hydrogel adsorbents are widely used in toxic dyes removal, but weak toughness and inferior adsorption performance limit their actual application. Herein, a dual-functionalized epoxy and amino groups hyperbranched polysiloxane (HPSi) cross-linker was initially developed, bentonite (BT) was incorporated with sesbania gum (SG), acrylic acid/acrylamide (AA/AAm) was utilized as monomers to synthesize hydrogel adsorbent H-SG/BT(AA/AAm) for the adsorption of methylene blue (MB) and malachite green (MG). Various characterization techniques, adsorption parameters test and mechanism analysis demonstrated that HPSi and BT endowed H-SG/BT(AA/AAm) with enhanced mechanical strength (tentative extensibility of 2645% and elastic recovery was over 90%). The hydroxyl of BT and SG was completely insert into the hydrogel then significantly enhanced the swelling and adsorption capacity. H-SG/BT(AA/AAm) exposed a promising adsorption capacity towards MB and MG with maximum adsorption capacity of 1226 mg/g and 783 mg/g. Kinetic and isotherm studies indicated that the adsorption of MB and MG onto H-SG/BT (AA/AAm) closely followed the pseudo-second-order kinetic model and Langmuir isotherm. The adsorption efficiency of H-SG/BT (AA/AAm) for MB and MG could still reach 80% after five adsorption–desorption cycles. Clearly, H-SG/BT(AA/AAm) composites can be effectively utilized as an eco-friendly adsorbent for dyes adsorption in aqueous environments. Highlights H-SG/BT(AA/AAm) was successfully synthesized by hyperbranched polysiloxane (HPSi) crosslinker. HPSi and BT enhanced the mechanical properties of H-SG/BT(AA/AAm). SG and BT synergistically enhance the adsorption performance of H-SG/BT(AA/AAm). H-SG/BT(AA/AAm) exhibits high adsorption capacity for MB and MG. The adsorption mechanism of H-SG/BT(AA/AAm) was proposed.