Adsorption behavior of Fe (III) in aqueous solution on melamine.

This paper focused on the adsorption behavior of Fe (III) in aqueous solution on melamine. The effects of experimental conditions including dosage of melamine, reaction time and reaction temperature were investigated. The results showed that nearly 99% Fe (III) was adsorbed under the optimal conditions: melamine dosage (mole ratio) at n(CHN)/n(Fe) = 3.5:1, reaction time of 60 min and reaction temperature of 90 °C. The optimal processing factors were obtained from response surface methodology and the effects of processing parameters on the removal efficiency of Fe (III) followed the order: mole ratio (n(CNH):n(Fe)) > reaction temperature > reaction time. The adsorption kinetics behavior was fitted well with the pseudo-second-order model. The thermodynamic study showed that the adsorption process was unspontaneous and endothermic. The value of free energy change and standard enthalpy change disclosed that the mechanism of adsorption onto melamine was physisorption. The results will be useful for further applications of system design in the treatment of practical waste effluents.