Green Kenaf-Based Adsorbent for Adsorption of Pb (II) Ions in Water

Abstract

Excessive toxic metals are commonly found in polluted water bodies. This study aimed to synthesise kenaf-based adsorbents for the adsorption of lead (II) ions. The physical and chemical characteristics of the kenaf (KNF) core and fibre were determined using field emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR). The further synthesised kenaf-chitosan-alginate (KNF-CHT-ALG) beads were characterised through FESEM and FTIR, while inductively coupled plasma (ICP) was employed to determine the percentage of adsorption. The FESEM analysis demonstrated that the KNF core had a rougher surface morphology than the KNF fibre. The TGA analysis confirmed that the KNF core was coarser and contained a higher residue of approximately 75.91%. The FTIR spectra established intense functional groups in the KNF core, such as hydroxyl and carboxyl, attracting more Pb (II) ions. The KNF core was then used to synthesise KNF-CHT-ALG beads. The beads confirmed the enhancement in surface morphology and the existence of numerous functional groups for Pb (II) ions to bind. The ICP analysis demonstrated 95% of Pb (II) ion adsorption. Additionally, batch adsorption experiments were conducted at pH 2–7 and the contact time was within 5–60 minutes. The kinetic study of the adsorption followed the pseudo-second order model with an R2 value of 0.9999. The KNF is a crop found in abundance in Malaysia, which could reduce the production cost of adsorbents. The significant outcomes would minimise the dependency on chemical adsorbents and accelerate the removal process of heavy metals in natural bodies of water.