Competitive removal of cadmium and lead ions from synthetic wastewater using Kappaphycus striatum

•Comparative sorption of heavy metals on Kappaphycus sp. was carried out which was not studied earlier.•The total removal efficiencies of Kappaphycus sp. for total 350 mg/L Pb2+ and Cd2+ ions mixture was found to be 45.77 %.•Kappaphycus is environment friendly for removal of heavy metals.•Adsorption isotherms equation, adsorption thermodynamics and kinetics were demonstrated.