New hybrid adsorbent based on APTES functionalized zeolite W for lead and cadmium ions removal: Experimental and theoretical studies

Abstract

Water pollution remains a primary worldwide concern, requiring various treatment technologies for efficient and effective remediation. In recent years, zeolites have gained extensive attention as promising materials and approaches for removing heavy metals from wastewater. This study presents a new hybrid adsorbent based on zeolite W (ZW) chemically modified with aminopropyltriethoxysilane (APTES), demonstrating excellent Pb(II) and Cd(II) removal efficiency, was developed. The prepared zeolites were characterized using several advanced techniques. XPS, NMR, FTIR spectroscopy, elemental analysis and TGA confirmed the successful functionalization via covalent bonds between the zeolite W inorganic surface and the available APTES silanol groups. The adsorption behavior of both metal ions onto the prepared zeolites was well-fitted by the Redlich-Peterson and Langmuir isotherms, and the Pseudo-second order model. Results showed that ZW@APTES provides a larger adsorption capacity than ZW under all studied experimental conditions. The maximum adsorption capacity of ZW@APTES for Pb(II) and Cd(II) reached 421.7 and 253.5 mg/g, respectively. Moreover, batch experiments indicated that ion exchange and surface complexation with weak chemical bonds were the main adsorption mechanisms for Pb(II) and Cd(II). This study demonstrates that APTES-modified zeolite W could be a valuable and promising material for removing heavy metal ions from contaminated water in real-world applications.