Multicomponent interpenetrating metal based Alginate-Carrageenan biopolymer hydrogel beads substantiated by graphene oxide for efficient removal of methylene blue from waste water

Abstract

Sodium alginate beads are usually prepared in the presence of Ca2+ ions. Here we prepared Graphene oxide based Sodium Alginate-Carrageenan (Ala-Car) hydrogel beads using copper metal ions as ionic crosslinker. The hydrogel beads were prepared by injecting bio-polymers into a beaker containing Cu2+ ions following rapid magnetic bead strategy. The shape and mechanical properties of hydrogel beads were influenced by concentration of copper ions and amount of the biopolymers used. Rheological and textural analysis was carried to investigate the mechanical and deformation studies of the hydrogel beads and the concentration of copper ions was optimized accordingly. Structural and morphological characterization was done by using FTIR and FESEM analysis. The hydrogels showed high removal capacity than the reported hydrogels of sodium alginate for methylene blue (MB) removal. Keeping the dosage of the adsorbent concentration constant (Ala:Car:GO = 2:2:1) and pH 9.2 conditions, percent removal ranged between 70% and 80% at lower concentrations and went upto about 90% at 60 mg/L of the initial dye concentration. As per Langmuir model, maximum adsorption was observed to be 132 mg/g for Ala: Car: GO ratio of 2:2:1. The dye absorption followed langmuir adsorption isotherm. The synthesized hydrogel beads show multi-functionalities (double network of polymers and graphene oxide) as such may potentially be used for removal of harmful dyes from the waste water as well as from aqueous waters.