Comparison of Three Materials Derived from Waste EPS for Heavy Metal Removal Efficiency

In recent years, a burgeoning scholarly interest has emerged in recycling waste materials. A noteworthy investigation has been directed toward converting waste-expanded polystyrene into three distinct anion exchange resins, enabling their efficacious deployment as lead and copper absorption agents. The viability of modifying expanded polystyrene waste through three distinctive techniques was scrupulously examined, involving the judicious application of sulfuric acid to engender sulfonated polystyrene, subsequently harnessed for extracting heavy metal ions from wastewater. These resins were denoted by the nomenclatures PSS-01, PSS-02, and PSS-03. The modified ion exchange was comprehensively characterized utilizing advanced analytical techniques, including FTIR, XRD, and zero-charge point (pHPZC). To ascertain the kinetics of adsorption, pseudo-second-order models were adroitly employed. The findings evinced a congruence between the adsorption of lead and copper by sulfonated polystyrene and the esteemed Langmuir and Freundlich isotherms. Batch mode heavy metal ion exchange tests were conducted to elucidate the kinetic parameters. The apogee adsorption capacities for copper were 41.25 mg/g for PSS-01, 41.94 mg/g for PSS-02, and 42.1 mg/g for PSS-03. Correspondingly, the paramount adsorption capacities for lead were determined to be 40.38 mg/g for PSS-01, 29.23 mg/g for PSS-02, and 42.01 mg/g for PSS-03. An adsorption/desorption experiment conclusively demonstrated the PSS-03 adsorbent's commendable reusability throughout four cycles.