Green composite beads of Dunaliella sp. AL-1 and sodium alginate: an innovative biosorbent for efficient copper removal from aqueous systems
摘要
Calcium alginate beads immobilizing Dunaliella sp. AL-1 biomass (Ds–SA) were developed and evaluated for Cu(II) removal using batch and fixed-bed column systems. The structural and chemical properties of the biosorbent were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analyses before and after adsorption. In batch mode, optimal Cu(II) removal was achieved at an initial concentration of 300 mg L−1, adsorbent dosage of 25 mg, pH 10, contact time of 135 min, and 40 °C, resulting in an equilibrium adsorption capacity of 11.93 mg g−1. Fixed-bed column experiments showed a significant improvement in removal efficiency from 26 to 60%, corresponding to adsorption capacities of 15.9 and 74.17 mg g−1, respectively, when the bed height increased from 15 to 30 cm at an influent concentration of 150 mg L−1 and 25 °C. Adsorption kinetics followed a pseudo-first-order model, while thermodynamic analysis confirmed an endothermic adsorption process. Equilibrium data were best fitted by the Freundlich and Temkin isotherm models, indicating heterogeneous and multilayer adsorption. The dynamic behavior of the column system was well described by the Adams–Bohart and Yoon–Nelson models. Overall, Ds–SA beads demonstrate high efficiency, reusability, and strong potential for continuous Cu(II) removal from contaminated water.