Sintesis Fe3O4/ZIF-8 dari Pasir Besi untuk Adsorpsi Logam Pb(II): Studi Pengaruh Variasi pH Larutan terhadap Kapasitas Penyerapan Adsorben

Abstract

The rapid rate of population growth is accompanied by the intensification of human activities, especially in the industrial sector. Increased industrial activity leads to high production of toxic pollutants that can contaminate aquatic environments. Water is a basic necessity for living organisms, especially humans. Lead (Pb) is a heavy metal that is abundant and generally originates from industrial activity byproducts. Fe3O4/ZIF-8 presents a suitable solution for mitigating heavy metal Pb pollution due to its large surface area, ease of material handling, and recyclability. The aim of this research is to combine Fe3O4 synthesized from iron sand with ZIF-8 to adsorb heavy metal Pb by examining pH conditions. This research is divided into 3 stages: synthesis of Fe3O4 nanoparticles using the coprecipitation method, synthesis of Fe3O4/ZIF-8 using the mixing method, and the effectiveness of Fe3O4/ZIF-8 in Pb adsorption at various pH levels. The XRD results show characteristic peaks at 2θ = 30.21°, 35.56°, 43.19°, 57.10°, and 62.67° and peaks from ZIF-8, indicating the successful synthesis of Fe3O4 and Fe3O4/ZIF-8; VSM analysis of Fe3O4 and Fe3O4/ZIF-8 yielded Ms values of 70.08 emu/g and 52.05 emu/g, with an Hc value of 88.29 Oe for Fe3O4, demonstrating superparamagnetic properties and confirming the nanoparticle size of Fe3O4; FESEM-EDX analysis of Fe3O4/ZIF-8 revealed a rhombic dodecahedral crystal morphology with a structure that became more rounded, losing its original edges and corners. EDX analysis showed the presence of Zn and Fe in Fe3O4/ZIF-8 at 12.53 wt% and 22.52 wt%, respectively. TEM analysis of Fe3O4/ZIF-8 shows the crystalline morphology of ZIF-8 with Fe3O4 nanoparticles integrated into ZIF-8 BET analysis showed that Fe3O4 has a surface area of 74.34 m²/g, while Fe3O4/ZIF-8 has a surface area of 140.88 m²/g. AAS analysis showed optimal Pb metal adsorption at pH 5 with a capacity of 298.44 mg/g (separation efficiency up to 99.48%); FTIR analysis confirmed the successful synthesis of Fe3O4/ZIF-8 and showed a shift in the absorption peak between 670-688 cm⁻¹, corresponding to Zn-O vibrations, due to the adsorption of Pb metal ions.