Optimization of solid alcohol production from waste cooking oil using response surface methodology–Box-Behnken design: Process parameters, combustion performance, and FTIR validation - Heri Septya Kusuma; Muhammad Redo Ramadhan; Dyan Hatining Ayu Sudarni; Debora Engelien Christa Jaya; Dwi Kurnia Afifah; Safinah Annajah Nasution; Deva Meida Fachri; Ratu Kalya Mongilong; Andrew Nosakhare Amenaghawon (Process Safety and Environmental Protection, 2026)