Removal of Heavy Metals from Their Solution Using Polystyrene Adsorbent (Foil Take-Away Disposable Plates)

The presence of heavy metal ions, viz. Cr(vi), Mn(ii) and Cu(ii), in aquatic systems pose heavy risks to human health. Therefore, removal of such metal ions from water bodies may be considered an interesting and important research activity. This is a research work on the removal of heavy metals from their solution with the use of polystyrene. Polystyrene (Foil take-away disposable plates) was sourced locally. The Plates were ground to fine particles to increase the surface area for adsorption and then serial dilution was performed. The adsorption isotherm models used were Langmuir, Freundlich and Dubinin-Radushkevich (DR). The result from the models showed that Langmuir fits better for Cr(vi) and Cu(ii) while DR fits in better for Mn(ii). Results obtained showed that adsorption followed second order kinetics. Equilibrium was obtained at 30 minutes. Thermodynamic data for enthalpy (ΔH) for Cr, Cu, and Mn are 2036.986 J/mol, 24276.88 J/mol and 27469 J/mol respectively and showed that adsorption was found to be endothermic. Entropy results were -49.21888 J/K, -117.97566 J/K and 66.7828 J/K for Cr(vi), Cu(ii) and Mn(ii) respectively, showing a decrease in entropy. Free energy change showed that adsorption for Chromium and Manganese at temperatures 323, 343 and 363K were spontaneous, while Copper was non spontaneous. pH result showed maximum adsorption at pH of 6. This study showed that polystyrene fits better for the adsorption of Chromium and Copper ion in the Langmuir Isotherm model. While that of Manganese was described better by the Dubinin-Radushkevich Isotherm Model. It is hereby recommended that polystyrene wastes are good adsorbents for the removal of heavy metals from aqueous solutions. Therefore, should be employed for the removal of heavy metals in the environment, as it can be easily gotten even at a low cost