Sustainable Production of Hexadecanoic Acid from Gmelina arborea Leaf Biomass via BaCl2-Catalysed Thermal Hydrolysis

Abstract

The valorization of underutilised lignocellulosic biomass into value-added chemicals offers a promising pathway for sustainable production and circular bioeconomy development. This study investigated hexadecanoic acid production from Gmelina arborea leaf biomass through BaCl₂-catalysed thermal hydrolytic processing under mild conditions. The effects of BaCl₂ catalyst loading (0.5 and 1.0 wt.%) and reaction temperature (50-80 °C) were evaluated, with duplicate experiments conducted to assess reproducibility. Products were characterised and quantified using gas chromatography–mass spectrometry (GC-MS), while the effects of catalyst loading and temperature were evaluated using two-way analysis of variance (ANOVA). Both factors significantly affected hexadecanoic acid production, with a highly significant catalyst-loading-temperature interaction (p < 0.0001). At 0.5 wt.% BaCl₂, specific yield decreased progressively with increasing temperature. In contrast, at 1.0 wt.% BaCl₂, specific yield increased from 507.17 mg/g at 50 °C to a maximum average of 599.48 mg/g at 70 °C before declining to 427.65 mg/g at 80 °C. The optimum condition was therefore 1.0 wt.% BaCl₂ at 70 °C, with the highest individual replicate yielding 604.00 mg/g. Experimental reproducibility was satisfactory, with coefficients of variation ranging from 0.99 to 2.72%. The findings demonstrate the potential of BaCl₂-catalysed thermal hydrolysis for converting underutilised G. arborea leaves into a commercially relevant bio-based fatty acid. The process supports SDG 9 through innovative biomass conversion, SDG 12 through waste valorisation and resource efficiency, and SDG 13 through the potential reduction of dependence on non-renewable feedstocks. Further optimisation of process variables is recommended to improve yield, efficiency, and sustainability.