Roles of K2O on the CaO-ZnO Catalyst and Its Influence on Catalyst Basicity for Biodiesel ProductionLuqman Buchori, I. Istadi, P. Purwanto, Louis Claudia Marpaung and Rahmatika Luthfiani SafitriE3S Web Conf., 31 (2018) 02009DOI: https://doi.org/10.1051/e3sconf/20183102009