Equilibrium and Kinetic Study of Methylene Blue (MB) Adsorption on the Activated East Kalimantan’s Low-Rank Coal

Abstract

Several studies have been conducted on the adsorption of Methylene Blue (MB) dye using carbon-based materials as an adsorbent. However, there has yet to be a reported study investigating MB removal using the activated East Kalimantan's Low-Rank Coal (LRC). This research aims to investigate the MB dye adsorption behavior onto activated East Kalimantan's LRC to develop a novel low-cost adsorbent. Batch experiments were performed on the adsorption of 50, 100, 150, 200, and 250 mg/L MB dye (100 mL) with different adsorbent dosages (60, 80, 100,120, and 140 mg) at room temperature, natural pH (3 – 13) and 5, 10, 20, 30, 40, 50, and 60 min contact time. The findings revealed that the optimum condition of the MB dye adsorption was 100 mg of LRC, 100 mg/L of MB concentration, pH of 12, and 5 min of contact time. The adsorption isotherm modeling result showed that the R2 coefficient was the highest for the model fit provided by the Langmuir isotherm = 0.9474, and the highest possible MB adsorption capacities were 196.08 mg/g. The findings from the experiment fit best by the pseudo-second-order model. The results suggested that an affordable activated LRC from East Kalimantan could remove MB from wastewater.