| 朱晓东,杨敏,吴松,施维林,周东美.铁还原条件下铁负载生物质炭固定三价砷的能力及其稳定性[J].农业环境科学学报,2020,39(12):2735-2742. |
| 铁还原条件下铁负载生物质炭固定三价砷的能力及其稳定性 |
| Arsenite immobilization capacity and stability of iron-loaded biochar under an iron-reducing environment |
| 投稿时间：2020-05-15 |
| DOI：10.11654/jaes.2020-0548 |
| 中文关键词: 铁负载生物质炭 氧化还原特性 三价砷 铁还原 微生物胞外电子传递 |
| 英文关键词: iron-loaded biochar redox property arsenite iron reduction microbial extracellular electron transfer |
| 基金项目:国家自然科学基金青年项目（41907310）；苏州市环保科技项目（B201702） |
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| 中文摘要: |
| 为研究还原条件下铁负载生物质炭固定三价砷[As（Ⅲ）]的能力及其自身稳定性，首先探究了铁负载生物质炭介导铁还原菌（Shewanella oneidensis MR-1）还原含As（Ⅲ）的水铁矿[As（Ⅲ）-FH]时对As（Ⅲ）的释放和固定能力；其次评估了铁还原菌的还原作用对铁负载生物质炭固定As（Ⅲ）稳定性的影响。研究表明，400~700℃制备的铁负载生物质炭在好氧条件下可以吸附0.94~1.63 mg·g-1的As（Ⅲ）。在As（Ⅲ）-FH还原体系中，随着铁负载生物质炭制备温度的提升：0~400 h时，铁负载生物质炭加速S.oneidensis MR-1还原As（Ⅲ）-FH释放二价铁和As（Ⅲ）的能力也逐渐提升；在400~646 h，分别加速溶液中的Fe2+沉淀生成蓝铁矿和菱铁矿，以及As（Ⅲ）的部分固定，在646 h时As（Ⅲ）的固定量为0.211~0.676 mg·g-1。在铁负载生物质炭固定As（Ⅲ）稳定性评估体系中：铁还原菌的还原作用虽然会导致铁负载生物质炭中磁铁矿还原转化生成蓝铁矿和菱铁矿，但却可以在342 h内提升固定As（Ⅲ）的能力，达到2.16~2.29 mg·g-1。因而在铁还原菌构建的还原生境中，铁负载生物质炭的As（Ⅲ）固定能力在342 h的短期内呈现增加的趋势，而在646 h的长时间培养条件下As（Ⅲ）的固定能力逐渐降低。通过构建简单的铁还原生境，评估了铁负载生物质炭在还原环境中固定As（Ⅲ）的潜能，为稻田土壤砷污染阻控材料的筛选提供了一种评估方法。 |
| 英文摘要: |
| In an aerobic environment, iron-loaded biochar has the capacity to adsorb arsenic, which makes it a promising material for tackling arsenic pollution in water and soil environments. In an anaerobic environment, redox-active biochar accelerated the microbial extracellular electron transfer for iron-oxide reduction, which led to the dissolution and release of arsenite[As(Ⅲ)]. However, the capacity and stability of iron-loaded biochar for immobilization of As(Ⅲ)under a reducing environment were not evaluated. Herein, the effect of iron-loaded biochar on Fe(Ⅲ)reduction and As(Ⅲ)release or immobilization during the microbial reduction of arsenite-bearing ferrihydrite[As(Ⅲ) -FH] was studied. Additionally, the stability of immobilized As(Ⅲ)and the loaded iron-oxides were evaluated under an iron-reducing environment created by Shewanella oneidensis MR-1. Magnetite-loaded biochar was synthesized by pyrolysis of iron pre-sorbed sawdust char at 400~700℃, and these iron-loaded biochars had As(Ⅲ)adsorption capacities of 0.94~1.63 mg·g-1. The iron-loaded biochar facilitated the reduction of Fe(Ⅲ)and release of As(Ⅲ)from 0 to 400 h, and the higher preparation temperature of iron-loaded biochar facilitated the faster rates of Fe(Ⅲ)reduction and As(Ⅲ)release. By prolonging the bio-reduction time to 646 h, the Fe2+ ions were precipitated to form vivianite and siderite and the presence of iron-loaded biochar promoted the immobilization of As(Ⅲ) (0.211~0.676 mg·g-1)compared to the control. On the other hand, the reduction of iron-loaded biochar by S. oneidensis MR-1 led to the transformation of magnetite to vivianite and siderite, but the As(Ⅲ)immobilization capacity was enhanced to 2.16~2.29 mg·g-1. In contrast to the aerobic environment, an iron-reducing environment led to an improvement of As(Ⅲ)immobilization capacity within 342 h, but it decreased when the incubation time was further increased to 646 h. The evaluation method will help in screening of materials suitable for the control of arsenic contamination in paddy soils. |
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