Comprehensive study on copper adsorption using an innovative graphene carbonate sand composite adsorbent: Batch, fixed-bed columns, and CFD modeling insights

This study focused on an innovative graphene carbonate sand composite adsorbent, synthesized from carbonated porous sand and sucrose as raw materials, for the removal of copper ions via the adsorption process. The characteristics of this adsorbent are determined through comprehensive experiments and numerical simulations in batch and fixed-bed column conditions, which has not been extensively explored. Extensive experimentation demonstrated a remarkable 100 % removal efficiency under optimal conditions, which included a copper ion concentration of 3 g/L, a contact time of 10 h, and an adsorbent dosage of 35 g/L. The adsorption kinetics and isotherm results exhibited that the Elovich model (R² = 0.998) and the Langmuir model (R² = 0.996 for linear with q_m=123.91 mg g^-1, and R² = 0.993 for nonlinear fitting) more effectively described the adsorption of copper onto the adsorbent. In the fixed-bed column studies, among the well-known analytical models, the Log-Gompertz model showed better compatibility (R² = 0.97∼0.99) between breakthrough curves with experimental results for various copper inlet concentrations. Also, numerical results obtained using computational fluid dynamics and mass transfer simulations with the linear driving force model were successfully validated by experimental results, particularly in the initial and transition zones of the breakthrough curve.