Preparation of Amidoxime Adsorbent by Radiation Induced Grafting of Acrylonitrile on Polyethylene Film and Its Application in Cr(VI) Removal

ABSTRACT

Pre-irradiation technique was applied to graft acrylonitrile (AN) onto polyethylene film. The graft yield was optimised with respect to radiation dose, monomer concentration and reaction time. H2SO4 was added to the monomer solution to improve the graft yield. The highest graft yield obtained was 120% at 70 kGy radiation dose, 60% monomer concentration and 4 h reaction time using H2SO4 as additive. The AN grafted films were modified with hydroxyl amine hydrochloride to prepare amidoxime adsorbent. The prepared adsorbent was characterised by using Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The prepared amidoxime adsorbent showed high affinity towards Cr(VI) adsorption. Adsorption capacity was studied under different conditions: contact time, pH and initial metal ion concentration. The highest adsorption capacity obtained was 200 mg g–1 of adsorbent after 72 h contact time at pH 1.5 and initial metal ion concentration 200 ppm. Pseudo-first-order and pseudo-second-order equations were used for interpretation of kinetic adsorption data. The equilibrium experimental data of Cr(VI) adsorption were also fitted with Langmuir isotherm model. Desorption and reuse of the adsorbent film was studied. The adsorbent showed no significant loss of adsorption capacity upon repeated use.

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