Utilization of NaOH modified Desmostachya bipinnata (Kush grass) leaves and Bambusa arundinacea (bamboo) leaves for Cd(II) removal from aqueous solution

Abstract

A fundamental investigation for the Cd(II) ions removal from aqueous solutions by NaOH modified Desmostachya bipinnata (Kush grass) leaves (MDBL) and Bambusa arundinacea (bamboo) leaves (MBAL) was conducted in batch experiments. The influence of different experimental parameters such as pH, contact time, initial Cd(II) ion concentration, adsorbent dosage, on the Cd(II) adsorption was studied. The Cd(II) uptake by MDBL and MBAL was quantitatively evaluated using sorption isotherms. Freundlich and Langmuir isotherm models were used to fit the equilibria data, of which Langmuir model is considered better in correlation and the maximum adsorption capacity was found to be 15.22mgg−1 for MDBL and 19.70mgg−1 for MBAL at room temperature. The kinetic data were found to follow closely the pseudo second order kinetic model by both adsorbents. FTIR and SEM were recorded, before and after adsorption, to explore number and position of the functional groups available for Cd(II) binding on to studied adsorbents and changes in surface morphology of adsorbent. Desorption studies show 94.18% and 92.08% recovery for adsorbed Cd(II) ions from MDBL and MBAL, respectively using 0.1 N HNO3. Thermodynamic studies indicated that the adsorption reaction was a spontaneous and exothermic process. It can be concluded that MDBL and MBAL are low-cost biosorbent alternatives for wastewater treatment, since both have a considerable high adsorption capacity.