Methylene blue uptake by gum arabic/acrylic amide/3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt semi-IPN hydrogel.

In this study, the capacity of methylene blue (MB) uptake from aqueous solution was investigated using acrylic amide-co-3-Allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt/Gum Arabic semi-IPN hydrogel. The semi-IPN hydrogels were prepared by the classical free radical solution technique. The swelling experiments were carried out gravimetrically and the swelling kinetics parameters were calculated. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) confirmed the semi-IPN hydrogel formation. The MB uptake was studied by the batch technique and the impact of different conditions was investigated. It was found that the obtained semi-IPN hydrogels gave adsorption capacity for the dye within a range of 101-187 mg g-1 at the initial dye concentration of 100 mg/L. The adsorption kinetics (pseudo-first-order and pseudo-second-order) and the adsorption isotherms (Langmuir, Freundlich, and Temkin equations) were tested and the adsorption data was well described by the pseudo-second-order and Freundlich models, respectively. The maximum adsorption capacity calculated by the Langmuir model (R2 = 0.8718) was 655.2 mg g-1. The thermodynamic study indicated the spontaneity and the endothermic nature of MB adsorption. Furthermore, the usability study showed that the prepared adsorbents could be employed repeatedly for successive 5 cycles of adsorption and desorption.