The effect of heavy doses (up to 200 Mrad) of γ-radiation on the short-range structural organization in montmorillonite was studied using infrared (IR) spectroscopy and solid-state high-resolution 27Al and 29Si nuclear magnetic resonance (NMR). No change attributable to irradiation was observed. A small variation in the water content was noted but it is not systematic. The results show that the montmorillonite structure can accumulate high doses of radiation without damage and therefore this clay is a suitable material for use in the safe disposal of radioactive waste.

Adsorption kinetic and thermodynamic tests were conducted using non-irradiated and γ-irradiated (400 kGy) NaOH-modified Philippine natural zeolites for the removal of Cu2+ ions in aqueous solution. The effects of γ-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 γ-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 γ-irradiated NaOH-modified zeolites are 33.00 and 43.22 mg Cu2+ g–1, respectively, suggesting that γ-irradiation might enhance the maximum adsorption capacity by up to 30.8%.