Soybean biodiesel production using synergistic CaO/Ag nano catalyst: Process optimization, kinetic study, and economic evaluation

•Silver performs synergistic effects with CaO for biodiesel production.•CaO/Ag exhibited strong basicity, superior pore structure and catalytic activity.•Process optimization was performed using response surface methodology.•Kinetic and thermodynamic studies were undertaken to deepen understanding.•Economic evaluation was performed to provide insights of industrial application.