Carboxylated alginate hydrogel beads for methylene blue removal: formulation, kinetic and isothermal studies

In this study, carboxylated alginate beads for methylene blue (MB) removal have developed, and the formulation conditions such as alginate concentration, calcium chloride concentration, cross-linking temperature, and beads size have been studied. The influence of various parameters such as initial MB concentration, contact time and adsorbent dosage on MB adsorption was investigated. The fitness of the adsorption data with different kinetic and isothermal models has been explored. Moreover, the diffusion mechanism of the MB through the adsorbent has been studied using various kinetic models namely; intraparticle diffusion model, D-W diffusion model, and Boyd diffusion model to determine the actual rate-controlling step for MB removal. Finally, the impact of drying the beads to a different degree and the type of water on the adsorption process was studied to evaluate the practicality of the developed adsorbent.