Jing Chuanyong, Liu Suqin, Meng Xiaoguang
Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
Sci Total Environ. 2008 Jan 15;389(1):188-94. doi: 10.1016/j.scitotenv.2007.08.030. Epub 2007 Sep 25.
The redox transformation and mobility of arsenic in spent adsorbents under reducing conditions were studied using an incubation test with mixed reducing bacteria, high-performance liquid chromatography-atomic fluorescence spectrometry for speciation of soluble arsenic (As), and thermodynamic calculations. The spent adsorptive media, including granular ferric hydroxide, granular ferric oxide, titanium dioxide, activated alumina and modified activated alumina, were collected from pilot-scale filters that were tested for removal of arsenate [As(V)] from groundwater in New Jersey, USA. During 65 days of incubation of the spent adsorbents with nutrient media in closed containers, the electron activity, pe, was reduced from about 1.7 to -7. Meanwhile, reduction of Fe(III) to Fe(II), As(V) to arsenite [As(III)], and sulfate to sulfide occurred. Less than 4% total As was released from iron-based media in the pe range between -3 and -7 due to reduction of As(V) to As(III) and reductive dissolution of ferric (hydr)oxides. Up to 38% As was released from the TiO2 adsorbent, which occurred at extremely low redox potential (i.e., pe<-6). The findings of this study will improve our ability to predict arsenic mobility when As-containing spent media are disposed of in landfills and the environment.
利用混合还原菌培养试验、高效液相色谱 - 原子荧光光谱法测定可溶性砷（As）的形态以及热力学计算，研究了还原条件下废吸附剂中砷的氧化还原转化和迁移性。废吸附介质，包括氢氧化铁颗粒、氧化铁颗粒、二氧化钛、活性氧化铝和改性活性氧化铝，取自美国新泽西州用于去除地下水中砷酸盐[As(V)]的中试规模过滤器。在封闭容器中，将废吸附剂与营养培养基一起培养65天的过程中，电子活度pe从约1.7降至 -7。同时，发生了Fe(III)还原为Fe(II)、As(V)还原为亚砷酸盐[As(III)]以及硫酸盐还原为硫化物的反应。在pe为 -3至 -7的范围内，由于As(V)还原为As(III)以及铁（氢）氧化物的还原溶解，铁基介质中总砷的释放量不到4%。高达38%的As从TiO2吸附剂中释放出来，这发生在极低的氧化还原电位下（即pe < -6）。本研究结果将提高我们预测含砷废介质在填埋场和环境中处置时砷迁移性的能力。
