LAUSR

Three marine algal biomasses, namely Gelidium latifolium (Grev.) Bornet et Thuret, Ulva lactuca Linnaeus and Colpomenia sinuosa (Mertens et Roth) Derbes et Solier, were used in their raw dried forms to biosorb Al3+, Fe3+, and Zn2+ from aqueous solutions. The optimum biosorption conditions were initial element concentration, 1000 mg L−1; temperature, 40 °C; contact time, 1 h; pH, 4, 3, and 6 for Al3+, Fe3+, and Zn2+, respectively. The highest biosorption efficiency reached 63.78, 65.95, and 111.57 mg g−1 for Al3+, Fe3+, and Zn2+, respectively, using the brown algal biomass C. sinuosa. Examination of algal biomass surface using SEM showed several morphological changes in the cell wall surface due to biosorption such as rupturing, wrinkling, some cavity appearance, protuberance, and roughness as well as each algal type had a unique surface structure in its raw form. FTIR was used to characterize algal biomasses, and the contributing groups were variable according to heave metals and algal type as well. The thermodynamic studies revealed that the biosorption was nonspontaneous, endothermic, and chemical in nature. Freundlich isotherm model fitted slightly better than the Langmuir model in case of Zn2+ biosorption; meanwhile, Langmuir model fitted better in case of trivalent Al3+ and Fe3+. The algal biomasses were efficiently regenerated and reused for four cycles via 0.01 M Na2EDTA. Algal biomasses were applied under the optimum concluded conditions to treat 21 actual polluted industrial effluents from Borg El-Arab region, Egypt. The removal efficiency reached 80.81, 38.25, 91.79, 59.96, 95.33, 98.54, 27.39, 88.42, 36.59, and 96.98% for Al, Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn, respectively.