Oxalic acid is more efficient than sulfuric acid for rock phosphate solubilization. (15th August 2020)

• Record Type: Journal Article
• Authors: Mendes, Gilberto de Oliveira; Murta, Hiunes Mansur; Valadares, Rafael Vasconcelos; Silveira, Wendel Batista da; Silva, Ivo Ribeiro da; Costa, Maurício Dutra
• Is Part Of: Minerals engineering. Volume 155(2020)
• Publication Date: 2020-08-15
• Subjects: Phosphorus -- Fertilizer -- Bioleaching; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2020.106458
• Languages: English
• ISSNs: 0892-6875

Abstract

Highlights: Oxalic acid extracts 100% of P from rock phosphates. Compared to sulfuric acid, lower amount of oxalic acid is required to solubilize P. Oxalic acid is a biotechnological alternative to produce P fertilizer. Abstract: Organic acids produced by microorganisms have been proposed as a biotechnological tool to release phosphorus (P) from sparingly soluble rock phosphates (RPs). In this work, organic acids commonly associated with microbial P solubilization (citric, gluconic, itaconic, malic, and oxalic) were applied at increasing doses to solubilize RPs with distinct reactivity grades. P solubilization by organic acids was compared to sulfuric acid, the traditional reagent applied in RP solubilization for fertilizer production. The acid type and its concentration had more influence on solubilized P than RP reactivity. In general, the efficiency of organic acids was oxalic > citric ≥ malic > itaconic > gluconic. Oxalic and sulfuric acids solubilized 100% of the P contained in all RPs composed by apatite [Ca5 (PO4 )3 (OH, F, Cl)]. However, oxalic acid was superior to sulfuric acid, releasing more P per mmol of acid applied. In average, each mmol of oxalic acid released 21 mg P, while sulfuric acid solubilized 14 mg P mmol −1 . Thus, microorganisms producing oxalic acid appear as a promising alternative to process RP via a biotechnological route.