SYNTHESIZE AND CHARACTERIZATION OF 5-Br-PADAP FUNCTIONALIZED SBA-15 FOR REMOVAL OF Cd IONS : KINETIC AND THERMODYNAMIC STUDY

In this study, removal of Cd ions from aqueous solution by mesoporous silicate SBA-15 modified by 2-(5-Bromo-2-pyridylazo) -5- (diethyl amino) phenol (5-Br-ADAP) composite was studied. Properties of synthesized nanocomposite were analyzed and confirmed by TEM and EDX. Results show that Langmuir adsorption isotherm has the best compatibility with the results of experiments. Kinetic analysis using pseudo-first-order model, pseudosecond-order and the intra-particle diffusion model was carried out. Results also confirmed that adsorption process is compatible with the pseudo-secondorder kinetic model. Thermodynamic parameters such as Gibbs free energy changes (ΔGo), Enthalpy changes (ΔHo) and Entropy changes (ΔSo) were calculated. Negative value of ΔGo and positive value of ΔHo show that adsorption of Cd ions on nanocomposite is a spontaneous process also endothermic.