Abstract

The dried papyrus plant (DP) treated with 0.025 M ethylenediaminetetraacetic acid (EDTA) at pH=10 was used as effective adsorbent for the removal of Methylene Blue (MB) (cationic azo dye) from aqueous solution. The dried papyrus plant sample characterized by Fourier Transform Infrared (FTIR), and Scanning Electron Microscopy (SEM). The effects of initial dye concentration (5-250 mg/L), pH (2-10), temperature (298-318 K), adsorbent dose (0.005-0.035 g), and contact time were investigated and discussed. The batch adsorption experiments, showed that the maximum adsorption of MB (qemax) at pH=8 was 101.60 mg/g and increased with the increase in temperature from 298 to 318 K. The adsorption of MB onto (DP) reached equilibrium within about 150 min. The adsorption equilibrium is described using Langmuir and Freundlich isotherm models. It can be found that the regression coefficient R2 obtained from Langmuir model is much higher than that from Freundlich model and the practical adsorption capacity is very close to that calculated from Langmuir isotherm, suggesting that the Langmuir isotherm fits better with the experimental data. The adsorption kinetics followed a pseudo-second order kinetic model and intra particle diffusion was involved in the adsorption process. Thermodynamic results indicated that the adsorption process was spontaneous and endothermic in nature. The proposed adsorbent was successfully applied for the removal of MB from aqueous solution with a percent recovery 81.65 % by using 0.1 N HCl.

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