Preparation: |
synthesized according to the method of Schwertmann and Cornell (27). Five hundred milliliters of 0.2 M ferric nitrate solution was prepared at pH 8 and heated at 98 °C for 7 days. The precipitate was washed several times with deionized water by centrifugation and decantation until the nitrate concentration was reduced to < 0.003 mM. The hematite paste was freeze-dried. |