Chromium (VI) and nickel removal by resin supported nanomagnetite: column experiments

Magnetite is a mixed-valent iron oxide with magnetic properties, which is considered as an efficient adsorbent for the removal of Cr(VI) from the aquatic environment. However nanomagnetite possesses difficulties for in situ remediation applications due to clogging effects and high separation cost. For this reason a nanocomposite material consisting of nanomagnetite supported on a cation exchange resin, denoted as R-nFe3O4 was synthesized and was evaluated for chromates and nickel removal from contaminated waters under flow conditions. A column test was carried out using a glass column, with 1.80 cm internal diameter and ~7 cm length. The column was filled with 12.1 g of resin supported nanomagnetite. The efficiency of R-nFe3O4 was examined for mixed polluted streams with 1.25 mg L−1 concentration for both hexavalent chromium and nickel. The experiment was carried out using NaCl as background electrolyte and the pH of feed solution was around 3. The total amount of reduced Cr(VI) was equal to 10 mg, while the total amount of removed Ni was 20.2 mg. The adsorption of Cr(VI) was described by the Bohart–Adams kinetic model and the adsorption capacity per unit volume of sorbent bed was found equal to 690 mg/dm3.