Maithreepala R A, Doong Ruey-an
Department of Limnology, Faculty of Fisheries, Marine Science and Technologies (FMST), University of Ruhuna, Matara, Sri Lanka.
J Hazard Mater. 2009 May 15;164(1):337-44. doi: 10.1016/j.jhazmat.2008.08.007. Epub 2008 Aug 13.
The transformation of carbon tetrachloride (CT) by biogenic iron species produced from the bioreduction of various Fe(III) oxides in the presence of Geobacter sulfurreducens and electron shuttles were investigated. Cysteine and anthraquinone-2,6-disulfonate (AQDS) at concentrations of 0.5mM and 10microM, respectively, were added as the electron shuttles. Addition of electron shuttles enhanced the extent of reduction and rate of ferric oxide reduction. The bioreduction extents of ferric oxides by G. sulfurreducens in the presence of electron shuttles were 22.8-48.3% for ferrihydrite, 6.5-17.2% for hematite, and 3.0-11.3% for goethite. After normalization to the surface areas, a higher rate of CT reduction was observed per unit of adsorbed Fe(II) on crystalline oxides. The produced biogenic Fe(II) from crystalline iron oxides was 2.8-7.6 times lower than that obtained from ferrihydrite, while the surface area-normalized rate constant for iron-mediated CT transformation in the presence of goethite and hematite were, by factors of 2-21, higher than that obtained using ferrihydrite. These results clearly depict that G. sulfurreducens drove the reduction of CT primarily through the formation of biogenic iron species in the presence of electron shuttle under iron-reducing conditions and that it is a surface area dependent process.
研究了在硫还原地杆菌和电子穿梭体存在的情况下，各种Fe(III)氧化物生物还原产生的生物源铁物种对四氯化碳（CT）的转化作用。分别添加浓度为0.5mM的半胱氨酸和浓度为10μM的蒽醌-2,6-二磺酸盐（AQDS）作为电子穿梭体。电子穿梭体的添加提高了还原程度和氧化铁还原速率。在电子穿梭体存在的情况下，硫还原地杆菌对氧化铁的生物还原程度，对于水铁矿为22.8-48.3%，对于赤铁矿为6.5-17.2%，对于针铁矿为3.0-11.3%。经表面积归一化后，在结晶氧化物上每单位吸附的Fe(II)观察到更高的CT还原速率。从结晶铁氧化物产生的生物源Fe(II)比从水铁矿获得的低2.8-7.6倍，而在针铁矿和赤铁矿存在的情况下，铁介导的CT转化的表面积归一化速率常数比使用水铁矿时高2-21倍。这些结果清楚地表明，在铁还原条件下，硫还原地杆菌主要通过在电子穿梭体存在下形成生物源铁物种来驱动CT的还原，并且这是一个依赖于表面积的过程。
