College of Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
J Hazard Mater. 2012 Oct 30;237-238:194-8. doi: 10.1016/j.jhazmat.2012.08.024. Epub 2012 Aug 19.
The efficient conversion of Cr(VI) to Cr(III) has attracted an increasing concern in recent years owing to its threat to the environment. In the present paper, the catalytic role of biogenetic schwertmannite in the reduction of Cr(VI) by sulfide and its mechanism were investigated under different conditions through batch experiments. The results demonstrated that schwertmannite markedly accelerated the removal of Cr(VI) by sulfide, and the rates of the reaction were enhanced by 11, 8 and 6 times, respectively at pH 7.5, 8.0 and 8.8 as compared with control (no schwertmannite). In addition, the conversion of Cr(VI) into Cr(III) increased with schwertmannite loading and temperature. However, the facilitating role of schwertmannite in the reduction of Cr(VI) by sulfide was markedly suppressed by an introduction of F(-), a complex agent for Fe(III). It is concluded that the catalysis of schwertmannite results from the activated Fe(III) on the surface of schwertmannite, serving as a "bridge" in the transportation of electrons between sulfide and Cr(VI), and leading to the improving reduction of Cr(VI) by sulfide.
近年来，由于六价铬（Cr(VI)）对环境的威胁，将其高效转化为三价铬（Cr(III)）引起了越来越多的关注。本文通过批实验，研究了生物成因的纤铁矿在不同条件下对硫化物还原 Cr(VI)的催化作用及其机制。结果表明，纤铁矿显著加速了硫化物对 Cr(VI)的去除，与对照（无纤铁矿）相比，在 pH 值为 7.5、8.0 和 8.8 时，反应速率分别提高了 11、8 和 6 倍。此外，Cr(VI)向 Cr(III)的转化率随纤铁矿负载量和温度的增加而增加。然而，引入氟（F(-)），一种三价铁的络合剂，显著抑制了纤铁矿在硫化物还原 Cr(VI)中的促进作用。因此，纤铁矿的催化作用源自表面的活化三价铁（Fe(III)），它在硫化物和 Cr(VI)之间的电子传递中充当“桥梁”，从而促进了硫化物对 Cr(VI)的还原。
