Environmental friendly natural polymers as adsorbents for organic pollutants dyes removal from colored wastewater

Abstract

The Demand for sustainable and effective removal of dye has driven the recent research into the synthesis of innovative material with maximum adsorption capabilities. This research focuses on the development of an innovative crosslinked guar gum/polyvinyl alcohol (PVA) blend for the enhanced removal of methyl red dye. The obtained blend was further characterized with techniques: Fourier transform infrared (FTIR) and scanning electron microscopy (SEM), EDX, XRD, and TGA, which showed the blend formation (functional group), surface morphology, elemental analysis, crystalline nature, and thermal analysis, respectively. Furthermore, to check the mechanical strength of the blend, the swelling study was performed, which shows swelling in deionized water for 105 min, with the swelling ratio of 115.6 g/g, maximum swelling of 276.84–284.16 g/g at neutral pH studied at a range of pH 6–7. In electrolyte solutions, the swelling ratio of the blend decreased with increasing salt concentration. The adsorption of dye onto the prepared blend was optimized at pH 6, contact time 60 min, adsorbent dose of 0.0025 g, and temperature of 25°C. Under these conditions, the maximum adsorption capacity was 82.18 mg/L (80%) achieved. There was a decrease in adsorption with increasing temperature; at 25°C, it was 13.85 mg/L, while at 55°C, it was 11.79 mg/L, indicating an exothermic process. To check the efficiency of the blend, the adsorption data was simulated by applying different adsorption models, which shows Isotherm data closely followed the Langmuir isotherm with R² value of 0.99, and kinetic data best fitted by pseudo-second-order model having R² equal to 0.98. Langmuir isotherm indicated the monolayer adsorption, and the kinetic model showed chemisorption has taken place on the blend. The thermodynamic parameters were calculated, and the data revealed that the process of this adsorption was exothermic and spontaneous. The gel content of the blend was found to be 42%, which shows the crosslinking density of the blend. Regeneration trials showed that the adsorbent could successfully retain methyl red even after four cycles. Synthesized blends can remove dyes from wastewater in sustainable and effective ways. This study examines the unique features of this composite blend, including its better performance, eco-friendliness, efficiency, innovation above traditional blends, and its structural makeup and fabrication method.