This study investigates the use of eucalyptus peels as a permeable reactive barrier (PRB) for treating groundwater contaminated with copper ions. Activated carbon was produced from eucalyptus peels, and its adsorption capacity for copper removal was evaluated through laboratory experiments. COMSOL software was used to simulate the performance of the eucalyptus peel-based PRB in order to optimize the design and predict the efficiency and longevity of the barrier. Batch studies were conducted to evaluate how factors such as the initial concentration of the contaminant, pH level, contact time, amount of sorbent used, and agitation speed affected the results. The results show that the optimal values of these factors were a 50 ppm concentration, a pH of 6, an 80-minute contact time, a dosage of 2 mg per 100 ml, and a stirring speed of 250 rpm. These findings demonstrate that eucalyptus peels, being an agricultural waste product, can be effectively converted into activated carbon with a high adsorption capacity (equal to 91.5%) for copper ions. To analyze the data, researchers utilized COMSOL Multiphysics 3.5a software, which employs the finite element method to solve the equations that describe the one-dimensional (1D) movement of copper under equilibrium conditions. Compared to other organic and inorganic adsorbents commonly used in PRBs, eucalyptus peels showed promising results in terms of adsorption capacity and cost-effectiveness. This study contributes to the development of innovative and sustainable remediation strategies for groundwater contaminated with heavy metals like copper. The findings demonstrate the potential of eucalyptus peels as a viable alternative to traditional adsorbents used in PRBs, promoting the use of renewable materials in environmental management and indicating that the PRB significantly impedes the movement of the copper plume. Ultimately, the predictions from the COMSOL simulations were very close to the actual experimental results, with a root mean square error (RMSE) of less than 1%.