Egyptian seaweed resources from the South Sinai coast to develop alginate-based biohybrid composites for enhanced lead(II) removal from industrial wastewater

Herein, crosslinked-alginate (CAL) was extracted from Egyptian marine biowaste (brown seaweed discarded near seashore of Ras Sedr, Sinai). Novel biohybrid composites were fabricated by hybridizing CAL chains with either carbohydrate polymer (starch, St) or proteinaceous content (albumin, Alb). Physicochemical properties of such biocomposites were characterized using XRD, FTIR, Raman, DLS, SEM and AFM analyses. Compared to CAL, starch as hybridizing agent enthuses existence of stacking-oriented alginate chains of higher amorphicity and lower zeta-potential (-17 mV). Hybridization of alginate matrix with albumin chains yielded high negatively charged (-37.8 mV) crystalline biocomposite with smooth surfaces. Performance of St-CAL and Alb-CAL biocomposites toward Pb 2+ removal from wastewater was scrutinized. The impact of pH, adsorbate concentration, contact time, and thermodynamic studies on Pb 2+ removal using these biocomposites were estimated. Removal efficiency of St-CAL was superior to that of Alb-CAL yielding ~ 70% for 5 succussive runs. Pb 2+ adsorption process over St-CAL was spontaneous with exothermic nature at room temperature and followed Freundlich model with pronounced adsorption energy and capacity. Fitness of kinetic models for St-CAL was ranked as pseudo-first-order with escalated intra-particle diffusion rates. Construction of oxygen-rich hybrid carbohydrate systems is willingly applied in future as green cleaner to wastewater from heavy metal ions.