Fabrication of semi-interpenetrated PVA/PAMPS hydrogel as a reusable adsorbent for cationic methylene blue dye: isotherms, kinetics and thermodynamics studies

Abstract

A reusable adsorbent was developed based on semi-interpenetrated hydrogel made of poly(vinyl alcohol) (PVA) and poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) for the adsorptive removal of cationic methylene blue (MB) dye. The developed PVA/PAMPS adsorbent hydrogel was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA) and scanning electron microscope (SEM) analysis tools. Consequence of the variation of AMPS concentration on water uptake profile and polymer add-on (%) was explored. In addition, batch adsorption studies were performed to evaluate the aptitude of the developed adsorbent for MB dye removal under several adsorption conditions. The results showed an increase in the add-on (%) value up to 70% with increasing AMPS content up to 5%. Moreover, the MB dye removal was occurred quickly at the initial stage and recorded 60% after only 5 min from the initial contact time, while it recorded a maximum value of 86% at 25 oC. The experimental adsorption data were well-fitted to the Langmuir isotherm model and followed the pseudo-second-order kinetic model. Moreover, the adsorption of MB dye by the adsorbent hydrogel was an endothermic process. Besides, the PVA/PAMPS adsorbent exhibited better reusability with a maximum removal (%) exceeded 70% after five consecutive cycles. The results obtained from this study infer that the PVA/PAMPS adsorbent hydrogel could be effectually used as an appropriate and reusable adsorbent for removing cationic MB dye molecules from wastewater bodies.