Preparation of low-cost metal-loaded adsorbent using post-consumer waste plastics: Experimental and modelling studies

Abstract

Fluoride contamination in drinking water is a world-wide problem which causes dangerous irreversible diseases called fluorosis. The present study highlighted the efficacy of metals (Al and Zn) impregnated thermally degraded products of polyethylene terephthalate (PET) towards the removal of fluoride from the solution. Synthesized metal impregnated carbonaceous materials was characterised by pHzpc, proximate analysis, SEM, EDX and FTIR studies. A batch adsorption study with operating variables such as initial concentration, pH, adsorbent dose, contact time, temperature and agitation speed were undertaken. Then an optimization study was performed through Response Surface Methodology (RSM). The results revealed that the adsorption isotherm and kinetics followed Langmuir Isotherm model (R² = 0.968) and pseudo-second order kinetics (R² = 0.995), respectively with adsorption capacity 6.793 mg/g. The thermodynamics of fluoride adsorption reveal that the adsorption was spontaneous and endothermic in nature. The RSM results demonstrated the optimization of operating parameters such as initial concentration (9.95 mg/L), adsorbent dose (0.01 g/50 mL), contact time (11.42 min) and temperature (331 K). The result from perturbation plot indicate that the most influential parameters are initial concentration followed by temperature and adsorbent dose and the least influential parameter is contact time. Finally, it can be concluded that waste PET plastics could be a valuable adsorbent for decontamination of pollutants from aqueous medium.