Daud, Zawawi, Baharin Ahmad, Halizah Awang, Mahmoud Hijab Abubakar, Mohd Baharudin Ridzuan, and Husnul Azan Tajarudin. “Removal of COD Using Delonix Regia Pods Activated Carbon Adsorbent for Natural Rubber Wastewater Treatment”. International Journal of Integrated Engineering 10, no. 9 (January 1, 2019). Accessed June 15, 2021. https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/3634.