Synthesis of hygroscopic sodium alginate-modified graphene oxide: Kinetic, isotherm, and thermodynamic study

Abstract

Herein, 3D-graphene oxide/sodium alginate nanocomposite (3D-GO/SA) with various graphene oxide (GO) contents (0.1875, 0.375, and 0.75 mg/mL) was successfully synthesized using sodium alginate (SA) as a binding agent and Ca2+ as cross-linking agent. The water vapor adsorption performance of the nanocomposite was evaluated. The selected material was characterized via various modern analysis methods for morphological and structural investigation. Its adsorption kinetics, isotherms, and thermodynamics for water vapor adsorption were studied. Afterward, the obtained aerogel was also used for fruit preservation. Accordingly, the prepared aerogel with uniform distribution of pore size exhibited high porosity, adsorption performance. The synthesized aerogel exhibited good thermal stability under 200 °C and strong hydrophilicity with a water contact angle of 0°. Water vapor adsorption of 3D-GO/SA was 35 % higher than that of silica gel. The adsorption kinetics study revealed pseudo-second-order kinetics with a predicted maximum adsorption capacity of 50.35 (mg/g), meanwhile, the Freundlich isotherm model demonstrated the best fit for the adsorption equilibrium of the synthesized aerogel. The thermodynamic results indicated that the aerogel could be recovered at low temperatures. An adsorption mechanism was proposed based on adsorption results. 3D-GO/SA could be used in desiccant dehumidification to process and prolong the lifetime of a grape up to 12 weeks. Furthermore, the obtained adsorption and preservation test results suggested that the material could be used to preserve food products or be utilized in a desiccant dehumidifying system.