Adsorption of cationic dyes in wastewater with magnetic κ-carrageenan nanoparticles

The application of innovative adsorbents with high adsorption capacity and easy recovery in wastewater treatment has always been of great concern. This study employed kappa-carrageenan to enhance the dispersion of magnetic nanoparticles and improve their stability through Ca2+ and Na+ crosslinkinelg. XRD, FTIR, SEM and EDS revealed that the magnetic nanoparticles were coated with kappa-carrageenan. The synthesized M Kappa C@Fe3O4MNPs exhibited a stable structure and multiple adsorption sites, which was beneficial for the treatment of cationic dyes in wastewater. The absorption results indicated that abundant active sites on the surface of the adsorbent efficiently adsorbed the three cationic dyes. Through optimization experiments, the M Kappa C@Fe3O4MNPs demonstrated maximum adsorption capacities of 729.9 mg/g, 184.1 mg/g, and 311.0 mg/g for methylene blue, malachite green, and safranin T, respectively. The adsorbent could maintain excellent adsorption efficiency even after 5 cycles of use. The adsorption mechanisms for the three cationic dyes included electrostatic interactions, n-pi interactions, and hydrogen bonding. Therefore, the M Kappa C@Fe3O4MNPs showed highly efficient adsorption and separation of cationic dyes and are suitable candidates for dye wastewater treatment.