Microwave-assisted activated carbon from oil palm trunk waste for lead removal: Characterization, equilibrium, and kinetic studies
Miftahul Khair (a*), Rozia Elina (a), Delviana Dwi Jaya (a), Desy Kurniawati (a), Ardi (b)

(a) Department of Chemistry, Universitas Negeri Padang, Padang, 25131, Indonesia
*miftah[at]fmipa.unp.ac.id
(b) Department of Biology, Universitas Negeri Padang, Padang, 25131, Indonesia

Abstract

The economic value of oil palm trunk waste can be enhanced by converting it into activated carbon. This study aims to produce activated carbon from oil palm trunk waste using microwave activation, following green chemistry principles. The study involved two stages: carbonization at varying temperatures (250, 300, and 350 C) for different durations (60, 90, 120, and 150 minutes) and microwave activation. The activation stage was conducted with and without deionized water (5:1 ratio) at different microwave powers (150, 300, and 450 watts) and radiation times (1, 2, 3, 4, and 5 minutes).

The optimum carbonization conditions were 250 C for 60 minutes, resulting in a fixed carbon content of 74.88% and an iodine number of 401.6537 mg/g. The optimum microwave activation conditions were 450 watts for 3 minutes, which increased the iodine number to 813.5856 mg/g, indicating the potential of the material as an adsorbent. The characteristics of the produced carbon met the Indonesian National Standard (SNI) 06-3730-1995. Fourier Transform Infrared (FTIR) spectroscopy confirmed the presence of hydroxyl (-OH), carbonyl (C-O), alkene (C=C), and alkane (C-H) functional groups in the activated carbon. X-Ray Diffraction (XRD) analysis revealed the crystalline graphitic structure of the carbon.

The optimum conditions for lead (Pb2+) adsorption were determined as pH 4, an initial Pb2+ concentration of 100 ppm, and a contact time of 160 minutes. The adsorption isotherm followed the Langmuir model with a high regression coefficient (R2 = 0.9932) and a maximum adsorption capacity of 3.1806 mg/g. The pseudo-second-order kinetic model best described the adsorption process, with a rate constant (K) of 0.0003 g/mg min and R2 = 0.9119.

This study demonstrates the successful production of activated carbon from oil palm trunk waste using microwave activation. The produced activated carbon exhibited high efficiency for Pb2+ removal, making it a promising adsorbent for wastewater treatment.

Keywords: Oil palm trunk waste, microwave activation, activated carbon, lead removal, adsorption isotherm, adsorption kinetics

Topic: Chemistry