Adsorption isotherm and kinetics of methylene blue on gamma radiation assisted Starch/Acrylic acid/4-Styrenesulfonic acid sodium salt hydrogel

Abstract

ABSTRACT Starch/Acrylic acid (AAc)/4-Styrenesulfonic Acid Sodium Salt (SSS) based hydrogels were prepared by using simple and facile Gamma radiation (Cobalt-60 source) technique. The prepared hydrogels were characterized by Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR), Scanning Electron Microscopy (SEM), and Thermogravimetric Analysis (TGA). The influences of different parameters such as radiation dose, constituents of hydrogels, pH, ionic strength on different hydrogel properties like crosslinking density (CD), porosity, gel content, swelling behavior and adsorption kinetics were investigated in detail. Results showed that porous hydrogels were formed with well-interconnected networks. The maximum gel fraction 97.95% was observed for 15% Starch concentration, and the high-water penetration in the hydrogel with a high swelling ratio (3072%) was found at 25% AAc in the hydrogel composition. The dye adsorption capacity of the optimized hydrogel was assessed in terms of different kinetics and isotherm models using methylene blue (MB) as a model dye. Starch/AAc/SSS hydrogel’s adsorption behavior followed pseudo-second order and well-matched with the Langmuir isotherm model with maximum dye adsorption of 136.89 mg/g. Hence, the Starch/AAc/SSS hydrogel could be used as a prospective adsorbent to remove dye from the wastewater.