Statistical Optimization of Operational Parameters on Congo Red Adsorption Using Upscaled Polystyrene

Abstract

Plastic pollution, particularly from non-biodegradable materials like polystyrene waste, remains a significant environmental concern. Additionally, water contamination with toxic dyes poses a grave threat to nature. To address these issues, waste polystyrene (thermocol) was chemically modified to create an effective dye adsorbent capable of removing harmful Congo Red (CR) dye from water-based media. Utilizing Box Behnken Design-Response Surface methodology (BBD-RSM), adsorption parameters such as adsorbent dose, pH, and contact duration were optimized. Remarkably high levels of adsorption were achieved under the following conditions: adsorbent dosage (0.02 g), pH (4), and contact duration (120 min), resulting in a removal efficiency of 98.9%. The pseudo-second-order model best described adsorption kinetics, and Langmuir isotherm analysis indicated a maximum adsorption capacity of 189.2 mg/g, with thermodynamic experiments confirming the endothermic nature of adsorption. Possible adsorption mechanisms for CR dye on adsorbent were suggested from the characterization results. To minimize solid waste from the CR-loaded adsorbent, it was processed with commercial Acrylonitrile Butadiene Styrene (ABS) through extrusion, yielding 3D printing filaments. Remarkably, these filaments maintained tensile strength and exhibited no dye leaching in aqueous environments. The synthesized adsorbent is effective in removing toxic dyes from water and offers a potential solution for managing Expanded Polystyrene (EPS) solid waste. This research contributes to sustainable practices by recovering waste materials and presents a promising approach for environmental remediation.