Modeling of copper fixed-bed biosorption from wastewater by Posidonia oceanica

Biosorption of copper from aqueous solutions by Posidonia oceanica was investigated in batch and fixed-bed experiments. Batch experiments were conducted to evaluate the removal equilibrium at pH 5.0 and 6.0; experimental data were fitted to Langmuir model with maximum uptake capacities of 56.92 and 85.78 mg g−1, respectively. Five column experiments were carried out at different feed concentrations. Breakthrough times and continuous sorption isotherm were obtained from breakthrough curves. Differences among batch and continuous isotherms were observed; the maximum uptake capacity in dynamic conditions was found in 56.70 mg g−1 for final pH between 5.0 and 5.5. The biosorbent was regenerated with HCl. Hydrodynamic axial dispersion was estimated by tracing experiments at different velocities using LiCl as tracer. A mass transport model including convection–dispersion and sorption processes was successfully applied to breakthrough curve modeling. Results indicate that P. oceanica can be used as an effective biosorbent for copper removal.