Clay is a cheap and abundant adsorbent that can remediate acid mine drainage. This research aims to observe the potential of modified clay, which is believed to have better adsorption performance than natural clay. Simulation using data analysis software is conducted to understand the performance (i.e., contact time to reach the equilibrium of adsorption capacity and maximum adsorption capacity) and determine the phenomena that occur during adsorption. Performance simulation is done by simulating the kinetics adsorption, with pseudo-first and pseudo-second order, and isotherms adsorption, with Langmuir, Freundlich, and Temkin models. A nonlinear model is utilized to prevent change in statistical interpretation (such as error variance). The simulation result shows that the equilibrium and maximum adsorption capacity performance parameter modeled with the nonlinear model is close to the reported result using linear modeling. Comparisons of several modified and unmodified clay types are also conducted to determine which modified clay exhibits the best performance to adsorb Fe3+ and Mn2+ ions. Fe3+ adsorption can achieve a maximum capacity of 19.25 mg/g by utilizing acid-modified smectite. Nano lignocellulose montmorillonite can reach a maximum adsorption capacity of 628 mg/g for Mn2+. Similarly, trimethyl-decyl ammonium bromide bentonite can achieve a maximum adsorption capacity of 26.86 mg/g for SO42-. Various factors, including CEC, pore volume, and surface area, significantly influence the adsorption capacity of clay and its modified forms. Increasing the CEC, pore volume, and surface area enhances the adsorption capacity of clay. Generally, modifying clay tends to increase its adsorption capacity in most cases—furthermore, polymer nanoparticle-modified clay offers a promising result for heavy metal ions adsorption. [ABSTRACT FROM AUTHOR]