Versatile fabrication of ordered cellular structures double network composite hydrogel and application for cadmium removal

• Published in: The Journal of chemical thermodynamics 2020-02, Vol.141, p.105918, Article 105918
• Main Authors: Tang, Jianxin, Huang, Jianmin, Zhou, Guiyin, Liu, Sihua
• Format: Article
• Language: English
• Subjects: Adsorbent; Double network composite hydrogel; Graphene oxide
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/j.jct.2019.105918

[Display omitted] •A double network composite gel was successfully synthesized.•The gel has a fast adsorption rate for Cd2+ and a good adsorption effect.•The gel has good mechanical properties and can be easily separated and reused.•The adsorption behavior was discussed in detail. In this paper, a new type of double network composite (DNC) hydrogel adsorbent with good mechanical properties was synthesized using calcium alginate, graphene oxide and acrylic acid. The physical and chemical characteristics of DNC hydrogels were characterized by FTIR, TGA, XPS, SEM. The adsorption properties and adsorption mechanism of Cd2+ on hydrogels also were studied. The adsorption properties were investigated mainly by the effects of pH and ion concentration, adsorption kinetics and adsorption model studies, at the last, the thermodynamic studies also were carried out. The experimental results show that the pH has a good adsorption effect between 5 and 6. In the selective adsorption experiment, the order of adsorption of different metals is as follows: qe(Pb2+) > qe(Cu2+) > qe(Cd2+) > qe(Mn2+). According to the Langmuir isotherm adsorption model, the maximum theoretical adsorption capacity of Cd2+ on hydrogel at 20 °C, 30 °C, 40 °C is 71.93 mg·g−1, 88.05 mg·g−1, 115.65 mg·g−1, respectively and the adsorption equilibrium can be achieved within 120 min. The XPS was used to study the adsorption mechanism of Cd2+ on gel, and adsorption process mainly depends on ion exchange with Ca2+ and coordination of hydroxyl groups.