Synthesis of High-Value Oxalic Acid from Sugarcane Bagasse Waste by Alkaline Melting and Nitric Acid Oxidation Process

Abstract

This study aimed to synthesize oxalic acid from sugarcane bagasse using two methods: alkali fusion and direct oxidation with concentrated nitric acid, and to compare the results from both methods. Sugarcane bagasse was selected as the raw material due to its high cellulose content (26-43%), making it a potential alternative source for oxalic acid production. The alkali fusion method utilized 4N sodium hydroxide as the solvent and 4N sulfuric acid for acidification, while the direct oxidation method employed concentrated nitric acid. The results indicated that the alkali fusion method with sulfuric acid produced oxalic acid yields of 1.93% and 1.94%, whereas the alkali fusion method with nitric acid did not yield solid oxalic acid as it decomposed into other compounds, resulting in a water-soluble form of oxalic acid. In contrast, the direct oxidation method with concentrated nitric acid yielded the highest results, at 2.16% and 2.15%. Product characterization using melting point tests, thin-layer chromatography (TLC), and FT-IR confirmed that the synthesized oxalic acid had purity levels approaching the standard, although some variations were observed due to impurities. These findings demonstrate that the direct oxidation method with concentrated nitric acid is more effective and efficient for producing oxalic acid from sugarcane bagasse compared to the alkali fusion method.