Synthesis And Characterization Of Activated Carbon Zeolite Composite From Cool FLy Ash Fo Pb(II) Removal From Aqueous Solution

Abstract

The present work deals with the preparation of activated carbon zeolite composite by activating Coal Fly ash (CFA) with NaOH at 650 ºC in N2 atmosphere followed by heating at 80 ºC for 24 hrs. The heavy metal removal performance of the obtained fly ash based zeolite was investigated in Pb 2 removal experiments. Lead (Pb 2+) is a positively charged toxic pollutant that can be present in surface water and industrial waste water and may cause harmful physiological effects to human beings. Since zeolites have an inherent negative charge in their framework, they are capable of removing heavy metal from water. The activated carbon zeolite composite were characterized by XRD analysis, FTIR and methylene blue adsorption method. The XRD peaks at 2θ values of 33 and 35º were due to NaAlO2 and 26-29 and 45º were due to NaAlSiO4 which shows the strong evidence for the formation of zeolitic product. The AAS was employed for Pb analysis. For Lead (II) ion adsorption, the effect of pH, initial concentration and reaction time were studied. The optimum pH for Lead(II) ion adsorption was found to be 6. The value of ∆G was -24.00 kJ/mole which confirmed the adsorption process was spontaneous and favored by physio-chemical adsorption. The value of 2 for the Langmuir model was smaller than that of the Freundlich model and the correlation coefficient value for Langmuir plot was more approaching to 1 than that of Freundlich plot which concludes that adsorption of Lead (II) on activated carbon-zeolite follows the Langmuir adsorption isotherm. The equilibrium monolayer adsorption capacity calculated from Langmuir model was 270.270 mg/g. The adsorption reached equilibrium in 120 minutes and the kinetics data fit well to pseudo second order model with the rate constant value of 0.0056 g/(mg.min).