Adsorption characteristics of methylene blue onto low cost biomass material lotus leaf

摘要

The potential of lotus leaf for the removal of methylene blue (MB) from aqueous solution was investigated. The experiments were performed under various conditions including contact time, adsorbent dose, initial MB concentration, solution pH, salt ionic strength and temperature. The Langmuir, Freundlich and Koble-Corrigan isotherm models were employed to discuss the adsorption behavior. The results of analysis indicated that the equilibrium data were perfectly represented by Koble-Corrigan isotherm. The maximum monolayer adsorption capacity of lotus leaf was found to be 221.7 mg g~(-1) at 293 K. Thermodynamic parameters such as ΔG, ΔH and ΔS were calculated. The kinetic studies indicated that adsorption process followed the pseudo second-order mode, suggesting that the adsorption might be a chemisorp-tion process. FTIR analysis indicated that a large number of carbonyl and hydroxyl groups were included on the surface of the material. The present study implied that lotus leaf was a promising candidate as low cost biosorbent for the removal of MB from aqueous solution.