Khairullah MFA, Wahyuni IR, Amalia V, Fathar IR. NaOH-Activated Fly Ash Adsorbent in Copper(II) Metal Ion Removal from Laboratory Wastewater. envirotek [Internet]. 2026Oct.30 [cited 2026Oct.31];18(2):54-9. Available from: https://envirotek.upnjatim.ac.id/index.php/envirotek/article/view/2356