Optimization of methylene blue using Ca2+ and Zn2+ bio-polymer hydrogel beads: A comparative study

• The bio-polymer used this study is sodium alginate and it is an eco-friendly polymer.
• Polymeric bead preparation was done using Ca2+ and Zn2+ by ionic polymerization method.
• Methylene blue dye has chosen for modeling of optimization studies.
• Isotherms, kinetics, diffusion and thermodynamics equations were assessed for modeling.
• Characterization of bio-polymer beads was done with FTIR, SEM and TGA&DTA analysis.

Recently noted that the methylene blue cause severe central nervous system toxicity. It is essential to optimize the methylene blue from aqueous environment. In this study, a comparison of an optimization of methylene blue was investigated by using modified Ca2+ and Zn2+ bio-polymer hydrogel beads. A batch mode study was conducted using various parameters like time, dye concentration, bio-polymer dose, pH and process temperature. The isotherms, kinetics, diffusion and thermodynamic studies were performed for feasibility of the optimization process. Freundlich and Langmuir isotherm equations were used for the prediction of isotherm parameters and correlated with dimensionless separation factor (RL). Pseudo-first order and pseudo-second order Lagegren's kinetic equations were used for the correlation of kinetic parameters. Intraparticle diffusion model was employed for diffusion of the optimization process. The Fourier Transform Infrared Spectroscopy (FTIR) shows different absorbent peaks of Ca2+ and Zn2+ beads and the morphology of the bio-polymer material analyzed with Scanning Electron Microscope (SEM). The TG & DTA studies show that good thermal stability with less humidity without production of any non-degraded products.