Green Production of Biodiesel from High Acid Value Oil via Glycerol Esterification and Transesterification Catalyzed by Nano Hydrated Eggshell-Derived CaO oleh Zhenghui Weng, Yuanzhe Tao, Haotian Fei, Weishan Deng, Yiyao Chen, Zhiqi Zhao, Xiaojiang Liang, Yong Nie