Preparation and evaluation of Fe-loaded activated carbon for enrichment of selenium for analytical and environmental purposes

The adsorbent, based on the thermal modification of activated carbon impregnated by iron(III) nitrate(V), has been prepared and applied for selenium enrichment from aqueous solution. Various ratios of the impregnating agent to carbon mass were carefully examined with respect to selenium adsorption capacity and selectivity. The basic Se(VI) ions adsorption parameters affecting the adsorption ability onto the prepared activated carbons were studied. The carbon impregnated by 10% Fe(NO3)2 and thermally treated at 200 °C possessed the highest adsorption capacity and selectivity towards selenium ions. The physico-chemical characterization of the prepared adsorbents before and after selenium uptake were carried out using scanning electron microscopy (SEM) equipped with an energy dispersive X-ray detector (EDX) and X-ray photoelectron spectroscopy (XPS). The studies confirmed the surface complexation reactions of iron species and selenium on the Fe-loaded activated carbon. Due to its high adsorption capacity enrichment of selenium on the studied adsorbent has been successfully applied for its determination in the complementary feeds, using the carbon slurry sampling graphite furnace atomic absorption spectrometry technique (GFAAS) and standard calibration method.

Highlights► The 10% Fe-AC possesses great adsorption capacity and selectivity for Se(VI). ► XPS data proved the presence of Fe2O3 and FeO(OH) on the Fe-loaded AC surface. ► The main Se adsorption mechanism on Fe-AC is the surface complexation. ► SEM-EDX study confirmed non-uniform Se distribution on the 10% Fe-AC surface. ► Carbon slurry sampling GFAAS for Se determination in food samples is proposed.