Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China.
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
Sci Total Environ. 2023 Jul 15;882:163541. doi: 10.1016/j.scitotenv.2023.163541. Epub 2023 Apr 17.
Vivianite as a significant secondary mineral of dissimilatory iron reduction (DIR) exhibits marvelous potential to solve eutrophication as well as phosphorus shortage. Geobattery represents by natural organic matters (NOM) with rich functional groups influences bioreduction of natural iron mineral. Activated carbon (AC) which contains abundant functional groups is expected to serve as geobattery, but there remains insufficient understanding on its geobattery mechanism and how it benefits the vivianite formation. In this study, the charging and discharging cycle of "geobattery" AC enhanced extracellular electron transfer (EET) and vivianite recovery was demonstrated. Feeding with ferric citrate, AC addition increased vivianite formation efficiency by 141 %. The enhancement was attributed to the electron shuttle capacity of storage battery AC, which was contributed by the redox cycle between CO and O-H. Feeding with iron oxides, huge gap of redox potential between AC and Fe(III) minerals broke through the reduction energy barrier. Therefore the iron reduction efficiency of four Fe(III) minerals was accelerated to the same high level around 80 %, and the vivianite formation efficiency were increased by 104 %-256 % in pure culture batches. Except acting as storage battery, AC as a dry cell contributed 80 % to the whole enhancement towards iron reduction, in which O-H groups were the dominant driver. Due to the rechargeable nature and considerable electron exchange capacity, AC served as geobattery playing the role of both storage battery and dry cell on electron storaging and transferring to influence biogeochemical Fe cycle and vivianite recovery.
磷铁锂矿作为异化铁还原（DIR）的重要次生矿物，具有解决富营养化和磷短缺的巨大潜力。以天然有机物（NOM）为代表的地球电池具有丰富的官能团，影响天然铁矿物的生物还原。富含官能团的活性炭（AC）有望作为地球电池，但对其地球电池机制及其如何有利于磷铁锂矿形成的认识仍不充分。本研究证明了“地球电池”AC 的充放电循环增强了细胞外电子转移（EET）和磷铁锂矿的回收。用柠檬酸铁喂养时，AC 的添加将磷铁锂矿的形成效率提高了 141%。这种增强归因于存储电池 AC 的电子穿梭能力，这是由 CO 和 O-H 之间的氧化还原循环贡献的。用氧化铁喂养时，AC 和 Fe(III)矿物之间巨大的氧化还原电位差突破了还原能垒。因此，四种 Fe(III)矿物的铁还原效率被加速到相同的高水平，约 80%，纯培养批次中磷铁锂矿的形成效率提高了 104%-256%。除了作为存储电池外，AC 作为干电池对铁还原的整体增强贡献了 80%，其中 O-H 基团是主要驱动力。由于其可充电性质和相当大的电子交换容量，AC 作为地球电池，作为存储电池和干电池在电子存储和转移方面发挥作用，影响生物地球化学 Fe 循环和磷铁锂矿的回收。
