Efrillia FS, Fajar M. Preparation of Activated Carbon From Kluwek (Pangium Edule) Shells as An Adsorbent for Effective Removal of Free Fatty Acid (FFA) from used cooking oil. greensusmater [Internet]. 2025 Jul. 2 [cited 2025 Jul. 7];2(1):12-6. Available from: https://greensusmater.com/index.php/gsm/article/view/19