Sintesis Fe3O4/ZIF-8 dari Pasir Besi sebagai Adsorben Logam Berat Pb(II): Studi Efektivitas Adsorpsi terhadap Waktu Kontak

Abstract

The rapid industrialization and urbanization have increased environmental pollution, particularly by toxic heavy metals like Pb(II), which pose serious health risks. WHO reports that Pb(II) exposure causes over 1.5 million deaths worldwide. Conventional methods for addressing Pb(II) pollution still have limitations, such as high costs and secondary pollutant formation. Adsorbents based on Fe₃O₄ nanoparticles have become a viable option due to their excellent regeneration, and enhanced capacity when combined with ZIF-8. This study aims to combine Fe₃O₄ with ZIF-8 to form Fe₃O₄/ZIF-8 for the adsorption of Pb(II) in solution. The study consists of three stages: the synthesis of Fe₃O₄ nanoparticles from iron sand using the coprecipitation method, the synthesis of Fe₃O₄/ZIF-8 via a mixing method, and the performance of Fe₃O₄/ZIF-8 in adsorbing Pb(II) with varying contact times from 10 to 60 minutes, along with kinetic modeling. XRD analysis confirms the successful synthesis of Fe₃O₄ and Fe₃O₄/ZIF-8, with peaks at 2θ = 30.21°; 35.56°; 43.19°; 57.10°; and 62.67°. VSM measurements show ms values of 70.08 emu/g for Fe₃O₄ and 52.05 emu/g for Fe₃O₄/ZIF-8, confirming the soft ferrimagnetic. FESEM-EDX and TEM of Fe₃O₄/ZIF-8 show a rhombic dodecahedral crystal morphology, with the structure becoming more rounded and successful encapsulation achieved. while EDX results show Zn and Fe contents of 26.1 wt% and 17.57 wt%, respectively. SAA surface area measurements reveal values of 74.34 m²/g for Fe₃O₄ and 140.88 m²/g for Fe₃O₄/ZIF-8. AAS analysis indicates that the optimal Pb metal adsorption occurs at 30 minutes, reaching 296.88 mg/g (98.96% of the maximum capacity). Kinetic modeling suggests that the pseudo-second-order model is the most suitable. FTIR analysis confirms the successful synthesis of Fe₃O₄/ZIF-8 and shows changes in the peak at 670-688 cm⁻¹, due to Pb adsorption. Fe₃O₄ demonstrates a chemical adsorption, which is confirmed by the kinetic model and FTIR analysis.