Influence of Soil Sulfur Content and Other Edaphic Factors on Sulfur Levels in Calophyllum inophyllum L. Biodiesel

Abstract

Aims: This study investigates the sulfur content in biodiesel produced from Calophyllum inophyllum L. seeds collected from various regions in Southern Karnataka. Place and Duration of Study: The study area selected was Southern Karnataka region viz., Bengaluru (Plateau), Hassan (Plain) and Udupi (Coast). Methodology: Calophylum kernels collected at four different places in each district were subjected to the oil extraction process and an acid-base catalyzed transesterification process produced biodiesel due to the high acid value in oil. NaOH was used as a catalyst, and methanol served as the analytical solvent for transesterification reaction. During the process, a 1: 6 oil to methanol ratio was used at 60ºC reaction temperature. The sulfur content in soil, oil and biodiesel was analyzed using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) through the CaCl2  extractant method(turbidimetry). Results: The study revealed better biodiesel quality was observed in the Udupi region, followed by Bengaluru and Hassan, as Udupi (coast) is native to this species and rainfall determines the growth performance. Also, biodiesel produced in these three regions met ASTM D6751 and BIS (ISO 15607) standards. The sulphur content in CIME was 7 ppm, 46 ppm and 46 ppm in Bengaluru, Hassan, and Udupi regions, respectively. The soil samples reveal that the total sulfur in the study area ranged from 10.31 ppm to 53.47 ppm. The samples collected from the Udupi region have shown higher sulfur content (42.49 to 53.47 ppm). The higher concentration of sulfur in biodiesel is due to the influence of edaphic factors. Conclusion: Calophyllum is found to be a suitable feedstock for biodiesel production by developing methods for purifying the elements that hinder its quality. The study highlights regional differences in sulfur content, which could impact biodiesel quality standards. These predictions, however, need further work to validate reliability.