Carrageenan@Graphene Oxide Nanocomposites for the Adsorption of Trivalent Arsenic, Hexavalent Chromium, and Fluoride Ions from Aqueous Solutions: Conceptualization Modeling of Adsorptive Interfacial Interactions, Kinetics, and Swelling

Anastasia D Meretoudi; Athanasia K Tolkou; Ramonna I Kosheleva; Maria Xanthopoulou; Nikolaos M Tzollas; Margaritis Kostoglou; Ioannis A Katsoyiannis; George Z Kyzas

doi:10.1021/acs.langmuir.5c01927

Carrageenan@Graphene Oxide Nanocomposites for the Adsorption of Trivalent Arsenic, Hexavalent Chromium, and Fluoride Ions from Aqueous Solutions: Conceptualization Modeling of Adsorptive Interfacial Interactions, Kinetics, and Swelling

Langmuir. 2025 Jul 1;41(25):16529-16547. doi: 10.1021/acs.langmuir.5c01927. Epub 2025 Jun 23.

Authors

Anastasia D Meretoudi¹, Athanasia K Tolkou¹, Ramonna I Kosheleva¹, Maria Xanthopoulou², Nikolaos M Tzollas², Margaritis Kostoglou², Ioannis A Katsoyiannis², George Z Kyzas¹

Affiliations

¹ Hephaestus Laboratory, School of Chemistry, Faculty of Sciences, Democritus University of Thrace, GR-65404 Kavala, Greece.
² Laboratory of Chemical and Environmental Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.

Abstract

This research aims to develop low-toxicity, cost-effective, and reusable biobased materials by combining natural biopolymers with graphene oxide. Therefore, chitosan/kappa carrageenan (CS/kCar) and chitosan/kappa carrageenan/graphene oxide (CS/kCar@GO) nanocomposites were synthesized and applied for the effective removal of As(III), Cr(VI), and F^- from aqueous solutions. The results showed that the maximum removal for As(III) (79%), Cr(VI) (99%), and F^- (36%) was achieved at pH 5.0, 7.0, and 3.0, respectively. The data were best fitted by pseudo-second-order (PSO) kinetics and the Langmuir isotherm model, indicating adsorption capacities of 2.44 for As(III), 2.82 for Cr(VI), and 32.63 mg/g for F^- from the optimal CS/kCar@GO composite. According to the thermodynamic analysis, the adsorption of heavy metals and fluoride ions on the CS/kCar@GO nanocomposite was endothermic and spontaneous in all cases. Reuse of CS/kCar@GO for up to 10 cycles after regeneration demonstrated the effectiveness of this adsorbent.