Pengaruh Variasi pH pada Penjerapan Kation Fe3+, Pb2+ Menggunakan Senyawa 5,11,17,23-tetra-(t-butil)-25,26,27,28-tetra-Hidroksi-Kaliks[4]arena sebagai Adsorben: Kajian Kapasitas Adsorpsi: Effect of pH Variations on Adsorption of Fe3+, Pb2+ Cations Using 5,11,17,23-tetra-(t-butyl)-25,26,27,28-tetra-Hydroxy-Calix[4]arene Compounds as Adsorbents: Adsorption Capacity Study - BUSRONI, BUSRONI (Center for Environmental Technology - Agency for Assessment and Application of Technology, 2022)