Optimization of Gelatin-based 3D hydrogel scaffold for effective removal of Methylene Blue and Alizarin Red S from aqueous solutions and food samples: kinetic and isotherm investigations

Abstract

The extensive use of organic dyes reduces the quality of the water and adversely affects aquatic organisms. In recent years, researchers have become more interested in the adsorptive removal of dyes. Herein, biodegradable gelatin-based 3D hydrogels are cross-linked with epichlorohydrin, named as gelatin hydrogel under acidic conditions (GHA) and gelatin hydrogel under basic conditions (GHB). The synthesis of the desired hydrogels were confirmed using Fourier transformation infrared spectroscopy and scanning electron microscopy. They were used successfully for the adsorptive removal of dyes such as methylene blue (MB) and alizarin red S (ARS) from aqueous solutions and food samples. The optimization study shows that maximum adsorptive removal of MB and ARS were obtained at pH range of 4 to 9. The maximum adsorption capacities in the case of GHA for MB and ARS were 19.5 mgg⁻¹ and 19.9 mgg⁻¹, respectively. Whereas, in the case of GHB, the maximum adsorption capacities for MB and ARS were 18.9 mgg⁻¹ and 19.7 mgg⁻¹, respectively. The percent adsorption values in the range of 72 ± 2‒100 ± 2 shows that the developed methods can be successfully applied to water and food samples. Furthermore, both adsorbents follow the Freundlich adsorption isotherm and pseudosecond-order kinetics. Gelatin-3D hydrogels have significant adsorption capacity and are environmentally friendly, low-cost, and easy to synthesize. These qualities make them excellent platforms for the adsorptive removal of dyes from wastewater.