The removal of metals (Cd, Cu and Zn) from the Tensift river using the diatom Navicula subminuscula Manguin: A laboratory study

Abstract

Various biomaterials have shown promise as sorbents to remove heavy metals from polluted waters at lower cost than conventional wastewater treatment technologies. The aim of this study is to characterize the ability of the freshwater diatom Navicula subminuscula Manguin to biosorb cadmium, copper and zinc from aqueous solutions. Our results indicate that the biosorption of metals by N. subminuscula increased as the initial concentration of metal ions increased in the medium until a concentration of 100-130 mg L -1 . Biosorption equilibrium was established in 30 minutes. The maximum metal ions biosorbed was found to be 42, 90 and 127 for 16 10 8 diatoms per liter for Cd, Cu and Zn, respectively. The maximum uptake of metals was obtained at pH 6.0 for Cu and at pH 8.0 for Cd and Zn. An increase in the biosorp tion of P. lanceolatum was observed with an increase in temperature from 15 to 25°C. The biosorption of all three metal ions followed the Langmuir isotherm. Competitive biosorption of cadmium, copper and zinc ions was also achieved. The FTIR (Fourier Transformed Infra Red spectroscopy) results of algal biomass revealed the different functional groups at the diatom surface that are able to react with metals in the med ium. The results all together suggest that N. subminusculacan be used as a biosorbent for an efficient removal of heavy metals from aqueous solutions which temperature and pH values could be close to the mean ones of the Tensiftriver.