Exploring the efficacy of Cystoseira sedoide alga for cadmium and copper biosorption: an integrated experimental and...

Pollution by heavy metals is a major global issue. The biosorptive removal of Cd²⁺ and Cu²⁺ by Cystoseira sedoide (C. sedoide) was evaluated in this work. FTIR and XRD analysis were performed to determine the characteristics of the biosorbent. In batch biosorption studies, several operating parameters such as solution pH and concentration, contact time, biosorbent dose and temperature were tested and optimized for the effective elimination of cadmium and copper ions. Results were further compared to industrial activated carbon (Ac.C). The biosorption capacities for Cd²⁺ and Cu²⁺ were 23.78 and 14.66 mg g^-1, respectively. Excellent removal rates were achieved for both Cd²⁺ and Cu²⁺ by C. sedoide. In experiments with varying temperature, biosorbent dose, and heavy metal ions concentration, almost steady states were observed whatever the operating conditions and no notable differences were observed within the studied range of conditions. However, Ac.C performance was dependent on the operating conditions. Moreover, cadmium ion removal by C. sedoide was efficient even in the presence of copper ions. Based on the density functional theory (DFT) computations, it can be stated that the attraction forces between the heavy metal ion and the biosorbent depend on the considered structure and arrangement of the proposed complex models. Besides the revealed benefits of using C. sedoide for the removal of heavy metals, the biomass can be reused as a feedstock for the production of biochar or bioethanol, leading to economic and environmental sustainability when implemented on a large scale.