Fe2O3-palygorskite nanoparticles, efficient adsorbates for pesticide removal

Recently, magnetic adsorbents have aroused a significant attention because of their excellent adsorption capacity. An Algerian palygorskite/magnetic iron oxide was prepared by chemical co-precipitation and characterized using infrared spectroscopy, X-ray diffraction and X-ray fluorescence. The results prove the formation of a red brick powder, with magnetic character, showing a high percentage of iron oxide on palygorskite. To verify the ability of the magnetic palygorskite for retaining organic pollutants, three different samples were evaluated for the adsorption of the fungicide fenarimol from aqueous samples: sifted palygorskite, purified palygorskite and Fe2O3/palygorskite. The effects of different variables were assessed: adsorbent mass, reaction time, initial pesticide concentration and desorption stability. Fenarimol adsorption kinetics followed a pseudo-second order model. The adsorption rates were 11%, 50% and 70%, for sifted, purified and Fe2O3/palygorskite, respectively. Both Langmuir and Freundlich models could be used to describe fenarimol adsorption on sifted and purified palygorskites. However only the Freundlich model could fit the adsorption data on Fe2O3/palygorskite, probably due to the adsorbent heterogeneity. Stability of fenarimol desorption from the three samples, where the fungicide had been previously preadsorbed, showed that the extent of desorbed fenarimol from Fe2O3/palygorskite remained constant along the studied period (15 days).