Effective adsorption of aqueous Pb2+ by dried biomass of Landoltia punctata and Spirodela polyrhiza

Lead contamination has become a serious issue and approaches are continuously searched for lead removal. Here, dried biomasses of Landoltia punctata and Spirodela polyrhiza were utilized as adsorbent for Pb2+ removal. Batch experiments were conducted to investigate effects of contact time, initial pH, temperature, stirring speed, adsorbent dosage, and initial Pb2+ concentrations on Pb2+ adsorption. Results showed that all these parameters had significant effect on Pb2+ removal efficiency of the adsorbents. Both the adsorption processes followed the pseudo-second-order kinetic model, and were well described by Langmuir isotherm. Spectroscopy analysis indicated the involvement of functional groups (-OH, C-N, C=O, N-H and C-O) in Pb2+ adsorption. Remarkably, the maximum Pb2+ adsorption capacity of L. punctata and S. polyrhiza were 250 and 200 mg g−1 (dry weight), respectively. Thus, it could be concluded that the dried biomass of L. punctata and S. polyrhiza are promising adsorbents for effective lead removal.