DOI: https://doi.org/10.55373/mjchem.v27i5.1

Keywords: Glycerol; esterification; acetins; sulfonated polydivinylbenzene; sulfonation; biodiesel

Abstract

The abundance of glycerol as a by-product of biodiesel production has led to an oversupply in the global market and a consequent decline in its price. Given the potential of glycerol as a valuable resource, it is essential to convert it into value-added derivatives through various processes. This research involves preparing sulfonated polydivinylbenzene (PDVB-SO₃H) catalysts by synthesizing PDVB, followed by sulfonation with sulfuric acid (H₂SO₄) at different concentrations (0.5%wt/wt, 1.0%wt/wt, 1.5%wt/wt, 2.0%wt/wt, and 2.5%wt/wt). The characterization of PDVB-SO₃H was carried out using acid-base titration, CHNS elemental analysis, ATR-FTIR, XRD, TGA, BET, and BJH to assess structural and functional properties. The results showed that the optimum H₂SO₄ concentration was 2.0%wt/wt, balancing catalytic activity and structural integrity. Acid-base titration revealed an increase in total acid content with higher H₂SO₄ concentrations. CHNS analysis indicated that sulfur content increased with increasing acid addition (up to 8.06%), whereas ATR-FTIR confirmed the presence of sulfonic functional groups with characteristic peaks at 1712 cm⁻¹. XRD analysis indicated crystallinity with distinct peaks at 38.50°, 44.97°, 65.10°, and 78.88°. TGA demonstrated high thermal stability, with significant weight loss beginning at 250 °C, and BET analysis revealed an increase in surface area with higher acid concentrations, from 268.12 m²/g to 364.38 m²/g at 2.0%wt/wt sulfonation. The esterification results highlighted that 0.5%wt/wt and 1.0%wt/wt acid concentrations achieved the highest selectivity for diacetin and triacetin, with 100% glycerol conversion. These findings demonstrate the efficiency of PDVB-SO₃H in converting glycerol to valuable acetins, enhancing the sustainability of the biodiesel industry.