School of Chemistry & Environment, South China Normal University, Guangzhou, 510631, China.
School of Chemistry & Environment, South China Normal University, Guangzhou, 510631, China; MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou, 510006, China.
Water Res. 2019 Jun 15;157:621-629. doi: 10.1016/j.watres.2019.03.066. Epub 2019 Mar 27.
A novel iron-cycling process based on core-shell iron granules, which contained zero-valent iron (Fe) in the core and maghemite (γ-FeO) on the shell (Fe@Fe granules), was proposed to in-situ control hydrogen sulfide in the sediments of the polluted urban rivers. The Fe@Fe granules added in the top sediment layer removed 97% of sulfide generated by sulfate-reducing bacteria in the sediments, and the sulfide removal capacity of virgin granules was 163 mg S/g Fe (114 mg S/g granule). The Fe@Fe granules removed the formed sulfide through the abiotic sulfide oxidation and precipitation, and they also stimulated the microbial iron reduction, which competitively consumed wastewater-derived organics and partially inhibited the sulfate reduction in the sediments. The used Fe@Fe granules were easily regenerated through magnetic separation from sediments and air exposure for 12 h, which enhanced the sulfide removal capacities of the regenerated granules by 12%-22%, compared to the virgin granules. During the air exposure, ferrous products (i.e., iron sulfide and surface-associated Fe) on the granule shell were completely oxidized to poorly ordered Fe hydroxides (γ-FeOOH and amorphous FeOOH) having larger specific surface areas and higher reactivity to sulfide than γ-FeO on the virgin granules. Meanwhile, the Fe in the core was also partially oxidized through the indirect electron transfer, which was facilitated by the electrically conductive iron oxide minerals (FeO and FeO) and the microbial electron carriers (e.g., Geobacter). The oxidation of Fe core contributed additional Fe hydroxides to the sulfide control. The Fe@Fe granules were reused for four times in a 293-day trial, and their overall sulfide removal capacity was at least 920 mg S/g Fe. The proposed iron-cycling process can be a chemical-saving, energy-saving and cost-effective approach for the hydrogen sulfide control in the sediments of polluted urban rivers, as well as lakes, aquaculture ponds and marine.
提出了一种基于核壳型铁颗粒的新型铁循环工艺，该颗粒的核含有零价铁（Fe），壳层含有磁赤铁矿（γ-FeO）（Fe@Fe 颗粒），用于原位控制受污染城市河流沉积物中的硫化氢。添加到顶层沉积物中的 Fe@Fe 颗粒去除了沉积物中硫酸盐还原菌产生的 97%的硫化物，原始颗粒的硫化物去除能力为 163mgS/gFe（114mgS/g 颗粒）。Fe@Fe 颗粒通过非生物硫化物氧化和沉淀去除生成的硫化物，同时还刺激微生物铁还原，这竞争性地消耗废水中的有机物，并部分抑制沉积物中的硫酸盐还原。用过的 Fe@Fe 颗粒可以通过从沉积物中磁性分离并在空气中暴露 12 小时来轻松再生，与原始颗粒相比，再生颗粒的硫化物去除能力提高了 12%-22%。在空气暴露过程中，颗粒壳上的亚铁产物（即硫化亚铁和表面结合的 Fe）完全氧化为具有较大比表面积和比原始颗粒上的 γ-FeO 更高的硫化物反应性的无序 Fe 氢氧化物（γ-FeOOH 和无定形 FeOOH）。同时，通过微生物电子载体（例如，地杆菌）促进的电传导氧化铁矿物（FeO 和 FeO）的间接电子传递，核心中的 Fe 也部分被氧化。Fe 核的氧化为硫化物控制贡献了额外的 Fe 氢氧化物。在 293 天的试验中，Fe@Fe 颗粒重复使用了四次，其总硫化物去除能力至少为 920mgS/gFe。该提出的铁循环工艺可作为一种节省化学药品、节能且经济有效的方法，用于控制受污染城市河流以及湖泊、水产养殖池塘和海洋中的沉积物中的硫化氢。
