Abstract
The adsorption parameters of Pb(II) on the Amberlyst 36 were investigated and solid phase extraction was applied for the preconcentration of lead ions. Flame atomic absorption spectrometry was used for detection. The recovery of lead at optimum parameters such as pH (2), elution solution type and volume (5 mL of 3 mol/L HCl solution), flow rate (3 mL/min) etc. was obtained as (98.4±1.6) % at confidence level of 95% for eight measurements. The relative standard deviation of the recovery was about 1.9%. The analytical detection limit calculated by dividing the instrumental detection limit by the enrichment factor (150) was 0.68 μg/L. The matrix effect on the adsorption was also investigated and the application of proposed method to the real samples was done. The accuracy of the method was controlled with applying the standard reference material (CWW-TM-D Waste Water) containing lead. Kinetic studies were performed to determine the kinetic parameters and the thermodynamic parameters. The process of lead adsorption was found to be follow pseudo second- order rate expression and obey the Langmuir's isotherm model with the maximum adsorption capacity of 232.6 mg/g at 328 K. Thermodynamic parameters such as the changes of standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were also evaluated. According to results, the adsorption of Pb(II) on to Amberlyst 36 is a spontaneous, endothermic and ion-exchange process.
Keywords: Lead, preconcentration, solid phase extraction, amberlyst 36, FAAS, thermodynamic parameters
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