Optimization of adsorption parameters of anionic dye on polyvinyl alcohol hydrogel-based adsorbents

Synthetic polymer hydrogel for dye removal application faces low dye removal efficiency and weak mechanical strength. In this project, polyvinyl alcohol (PVA) hydrogels-based adsorbents were prepared by grafting its matrices with oil palm biowaste (OPB) and carbon nanotubes (CNT). The synthesized hydrogels, namely PVA, PVA-g-OPB, PVA-g- CNT and PVA-g-OPB/CNT were immersed in methyl orange (MO) solutions to study their adsorption ability at different adsorption parameters. UV-Vis was used throughout the adsorption and regeneration studies. PVA-g-OPB/CNT recorded the highest percentage of MO dye adsorption (81.84) at the parameters of pH 4, the solution temperature at 60?°C and the initial concentration 10mg/L. The acidic solution at a lower pH value led to fewer -OH ions, enhancing the interaction between the hydrogels and the anionic dye. The optimized temperature is at a high temperature as the active site of the adsorbent gets activated and increased the pore size, thus enhancing the adsorption of MO ions on the hydrogels. The PVA- g-OPB/CNT had an excellent sustainability property by having the highest dye removal percentage at 80.05, even after five cycles of adsorption and desorption. This research showed the potential to supersede other adsorption methods for dye removal. © 2022 Author(s).