Iron oxide nanoparticles: applicability for heavy metal removal from contaminated water

Due to the infinite size of nanoparticles, the surface area is relatively large and, as a result, they usually have high reactivity and sorption to various heavy metals. In this work, we investigated the sorption behavior of the iron oxide (alpha-Fe2O3) nanoparticles and its applicability to purify water from the aluminum (Al III), arsenic (As III), cadmium (Cd II), cobalt (Cd II), copper (Cu II), and nickel (Ni II). A batch experiment was performed, in which aqueous solutions of the metallic ions were prepared. The adsorption behaviors of the alpha-Fe2O3 nanoparticles towards the metallic ions were studied under different conditions of contact time, pH, temperature, alpha-Fe2O3 dosage and metal concentration. 10 mL of aqueous solutions contaminated with each metal were artificially prepared and treated with the nanoparticles. The adsorption behaviors study was performed by changing one of the conditions while keeping the others fixed. The fixed conditions were: metal concentration = 1 ppm; alpha-Fe2O3 dosage = 0.35 g; contact time = 30 minutes; temperature = 21+1 degrees C; and pH -7. According to the results, maximum percent removals (%) for all metals tested were reached within a short period of time (5 minutes). The maximum percent removal (%) of both Cu (II) and As (II) reached more than 95%, while the other metal had percent removal between 35% and 65%. Increasing the pH of solution led to increase of the percent removal for all metals except Al which had plateau shape with pH, reaching a maximum percent removal at pH 5 and decreasing back at higher pH.