Monica, C.P., Anggraeni, V.P. C., Sumada, K. , Sari, N.K. and Pujiastuti, C. 2025. Optimization of Acetone Concentration and Reflux Ratio for Enhanced Oil Extraction from Spent Bleaching Earth: A Response Surface Methodology Approach. Indonesian Journal of Environmental Management and Sustainability. 9, 4 (Dec. 2025), 183-191. DOI:https://doi.org/10.26554/ijems.2025.9.4.183-191.