Kinetics, Equilibrium, and Thermodynamic Studies on Adsorption of Methylene Blue by Carbonized Plant Leaf Powder

V Ponnusami,V Gunasekar

doi:10.1155/2013/415280

Abstract

Carbon synthesized from plant leaf powder was employed for the adsorption of methylene blue from aqueous effluent. Effects of pH (2, 4, 6, 8, and 9), dye concentration (50, 100, 150, and 200 mg/dm3), adsorbent dosage (0.5, 1.0, 1.5, and 2.0 g/dm3), and temperature (303, 313, and 323 K) were studied. The process followed pseudo-second-order kinetics. Equilibrium data was examined with Langmuir and Freundlich isotherm models and Langmuir model was found to be the best fitting model with highR2and low chi2values. Langmuir monolayer adsorption capacity of the adsorbent was found to be 61.22 mg/g. From the thermodynamic analysis, ΔH, ΔG, and ΔSvalues for the adsorption of MB onto the plant leaf carbon were found out. From the values of free energy change, the process was found out to be feasible process. From the magnitude of ΔH, the process was found to be endothermic physisorption.

Highlights

Synthetic dyes in large variety and quantity are used by several industries for coloring their products [1,2,3]
Equilibrium uptakes of PLC at various initial solution pH are shown in Figure 1 along with corresponding nal pH
High RR2 value con rms the suitability of pseudosecond-order model to explain the kinetics of methylene blue (MB) adsorption onto PLC

Summary

Introduction

Synthetic dyes in large variety and quantity are used by several industries for coloring their products [1,2,3]. Considerable amount of the dyes added in the process remain unconsumed and nd their way to water bodies. Presence of dyes in water bodies poses serious threat to the environment as the color affects the nature of the water and makes it unsuitable for human consumption. Some dyes and/or their metabolites have carcinogenic, mutagenic and teratogenic effects on aquatic life and human beings [2, 4]. As adsorption is one of the most efficient techniques available for dye removal [5] and the commercial adsorbents like activated carbon are expensive [6], search is carried by several researchers for identifying low-cost adsorbents

Methods

Results

Conclusion