Synthesis and Characterization of Electro-Crystallized Alumina Nanoparticles and Investigation of Their Application in Removal of Cobalt and Cadmium from Seimareh and Karoon Rivers in Iran

Al₂O₃ nanoparticles were successfully synthesized in an electrolytic cell containing two Al sheets as electrodes and an aqueous solution in the presence of an amine. To measure the effect of growth parameters on the properties of alumina nanoparticles, different samples were synthesized under different voltages (5–25 V), electrolyte concentration (0.02–0.1 M) and growth temperatures (10–60°C). X-ray diffraction patterns clearly approved the formation of the Al₂O₃ phase with cubic structure after annealing at 600°C for 2 h, and no sign of impurities was observed. SEM images showed that the particles are quasi-spherical and their mean size ranged from 7 to 270 nm depending on the growth conditions. The ultraviolet–visible results showed that the alumina nanoparticles mainly disperse rather than absorb light. The photoluminescence emission spectrum of nanoparticles showed an original peak at 395 nm, which is related to the electron transition between the levels and the photon emission. The removal of cobalt and cadmium from experimentally polluted water and the Seimareh and Karoon Rivers in Iran has been investigated. The water treatments were studied in an electrochemical cell with polluted water as the electrolyte, and by mixing the alumina nanoparticles with polluted water in a shaker. The results of atomic absorption spectroscopy showed that it is possible to remove about 100% of cadmium from the Seimareh and Karoon rivers. Also, by mixing the alumina nanoparticles with polluted water in a shaker, about 37.77% and 91.06% of cobalt were removed from the Seimareh and Karoon rivers, respectively.