Harahap, Fadhil Maulana2023-12-142023-12-142023-09PerpustakaanElfitrahttps://repository.unri.ac.id/handle/123456789/11264Maredan clay is a type of clay composed of tetrahedral silica and octahedral alumina compounds which can act as adsorbents. This research aims to determine the optimum conditions of solution pH (variations 2, 4, 6, 8, 10, and 11) on the adsorption efficiency of Maredan clay in adsorbing lead(II) ions. Maredan clay was characterized by determining functional groups using testsFourrier Transform Infra-Red (FTIR). The results of Maredan clay analysis using FTIR show that before and after adsorption there are Si-OH, Si-O-Si, Si-O-Mg, Si-O-Al and –OH functional groups, while after adsorption there are additional Pb-O-Pb functional groups. Optimum adsorption parameters were obtained at pH 10 with an adsorption efficiency of 98.57% and an adsorption capacity of 7.8048 mg/g.enadsorptionpHstirring speedArticle