Utilizing a sustainable surfactant from Cucurbita pepo seeds for eco-friendly flotation of non-coking coal in sustainable energy applications

Abstract

Fatty acids are being explored as promising collectors in coal flotation as they consist of both polar heads and non-polar aliphatic tails. In the present study, the fatty acid-rich oil extracted from Cucurbita pepo (Cp) seeds by Soxhlet extraction was used as a bio-based surfactant to reduce ash in non-coking coal by flotation. The FTIR and GCMS were used to investigate the functional groups and free fatty acid composition of the extracted oil respectively. The molecular conformation was identified using NMR spectroscopy. The extracted Cp oil was primarily composed of linoleic acid (64.17%) and oleic acid (11.54%). The extracted oil was utilized as a bio-based surfactant to float high ash non-coking coal, taking advantage of the oil's fatty acid content. Taguchi's design of experiments was used to optimize flotation process parameters such as collector dosage (extracted Cp oil), frother dosage (MIBC), and airflow rate. ANOVA analysis was conducted to determine the significance of the process parameters. It was observed that frother dosage played the most significant role in achieving optimal ash rejection, followed by collector dosage and airflow rate. The optimized conditions for combustible recovery were an airflow rate of 2.0 lpm, collector dosage of 3.5 ml, and frother dosage of 0.35 ml. For optimal combustible recovery (92.15) and separation efficiency (67.77), the airflow rate had the highest impact, followed by collector and frother dosages. From the XRD analysis, it was found that the major gangue, namely, quartz and kaolinite present in the non-coking coal, were significantly reduced in the final concentrate (float). Thus, the oil extracted from the seeds of Cucurbita pepo can be used as a bio-based surfactant in high ash, non-coking coal flotation.