Effects Of Gamma-Irradiation On The Cu2+ Sorption Behaviour Of Naoh-Modified Philippine Natural Zeolites

Adsorption kinetic and thermodynamic tests were conducted using non-irradiated and gamma-irradiated (400 kGy) NaOH-modified Philippine natural zeolites for the removal of Cu2+ ions in aqueous solution. The effects of gamma-radiation on zeolites were investigated. Samples were equilibrated with binary systems of Cu2+ <-> 2Na(+) at room temperature. There were no significant changes in the elemental composition of the irradiated zeolite. Irradiation primarily results in the shrinking of the zeolite framework and improvements in the crystallinity. The gamma-irradiation increases the sorption uptake according to the kinetic study in which the adsorption kinetics followed a pseudo-second-order model. Thermodynamic tests show that the adsorption isotherms of the two samples are best described by the Langmuir model. The maximum adsorption capacities of the non-irradiated and gamma-irradiated NaOH-modified zeolites are 33.00 and 43.22 mg Cu2+ g(-1), respectively, suggesting that gamma-irradiation might enhance the maximum adsorption capacity by up to 30.8%.