Synthesis and catalytic properties of calcium oxide obtained from organic ash over a titanium nanocatalyst for biodiesel production from dairy scum by Walid Nabgan, Walid Nabgan, Bahador Nabgan, Bahador Nabgan, Muhammad Ikram, Muhammad Ikram, Jadhav, Arvind H., Ali, Mohamad Wijayanuddin, Ul-Hamid, Anwar, Nam, Hyungseok, Lakshminarayana, Parashuram, Kumar, Ankit, Bahari, Mahadi B., Khusnun, Nur Farahain