DOI: https://doi.org/10.55373/mjchem.v27i3.48

Keywords: Coal desulfurization; potassium tert-butoxide; sulfur; ultrasonics; response surface methodology

Abstract

The research investigates an effective reductive desulfurization method of high-sulfur coal using a combination of potassium tert-butoxide and tetrahydrofuran (KOtBu/THF), strengthened by ultrasonic waves. This study aims to extract organic sulfur from coal by disrupting the chemical bonds that bind sulfur to the coal's macromolecular structure with ultrasonic waves, facilitating its separation with the influence of concentration, time, and temperature. Fourier transform infrared spectroscopy (FTIR) investigation indicated a decrease in the relative abundance of aliphatic sulfur compounds, including thiol, thiophene, and sulfone, as well as the organic matter of the treated coal. Optimal conditions, including concentration, temperature, and processing time, were identified using the Central Composite Design-Response Surface Methodology (CCD-RSM). This method improves the inefficiencies and imprecision of traditional techniques. A maximum decrease of 66.76% of organic sulfur removal was achieved by sonicating the coal at 70 °C for 30 minutes with a 25% w/v solution of KOtBu/THF. The chemical effects were assessed by measuring hydroxyl radical production under ultrasonic conditions using the iodine release method. The experimental results indicated a correlation between hydroxyl radical production and the degree of desulfurization. Afterward, the formation of low molecular weight fragments from aliphatic carbons resulted in enhanced mass loss during thermogravimetric analysis (TGA). These findings confirm that the synergistic physical and chemical effects of ultrasound are crucial to the desulfurization process, offering a foundation for further optimization of coal desulfurization techniques.