Phosphoric Acid Treated Oil Palm Trunk Waste for Removal of Malachite Green – Kinetics and Isotherm Investigations

Abstract

Dyeing operations in industries like textiles, paper, and leather are significant contributors to environmental pollution due to the release of harmful dyes. The current study aimed to examine the use of oil palm trunk (OPT) treated with phosphoric acid (PAOPT) to remove malachite green (MG) dye from aqueous solutions through batch adsorption experiments. Spectroscopic and quantitative tests were used to characterise the PAOPT adsorbent. The effects of initial solution pH (3–6), PAOPT dosage (0.02–0.10 g), and adsorption duration (0–120 min) were studied. The adsorption rate of MG followed a pseudo-second-order kinetic model with a high regression correlation (R2) and a low chi-squared value (χ2). The single-layer adsorption of PAOPT for MG was determined to be 217.23 mg/g at a pH of 6, 0.02 g PAOPT mass, 20 min contact time, and 298 K. The percentage of MG desorption from the loaded PAOPT using distilled water and 0.01 M HCl was 0% and 19.65%, respectively, indicating the possible involvement of electrostatic interactions between the dye and PAOPT, π-π interaction and hydrogen bonding. The experimental results of the current study and the assessment with other stated adsorbents indicate that PAOPT could be used as a cost-effective alternative adsorbent for MG removal.