KHAIRULLAH, M. F. A.; WAHYUNI, I. R.; AMALIA, V.; FATHAR, I. R. NaOH-Activated Fly Ash Adsorbent in Copper(II) Metal Ion Removal from Laboratory Wastewater. Envirotek : Jurnal Ilmiah Teknik Lingkungan, [S. l.], v. 18, n. 2, p. 54–59, 2026. DOI: 10.33005/envirotek.v18i2.2356. Disponível em: https://envirotek.upnjatim.ac.id/index.php/envirotek/article/view/2356. Acesso em: 31 oct. 2026.