School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China; School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, 525000, PR China.
School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China; School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, 525000, PR China; Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China.
J Environ Manage. 2022 Oct 1;319:115771. doi: 10.1016/j.jenvman.2022.115771. Epub 2022 Jul 31.
While nanoscale zero-valent iron modified biochar (nZVI-BC) have been widely investigated for the removal of heavy metals, the corrosion products of nZVI and their interaction with heavy metals have not been revealed yet. In this paper, nZVI-BC was synthesized and applied for the removal of Cr(VI). Batch experiments indicated that the adsorption of Cr(VI) fit Langmuir isotherm, with the maximum removal capacity at 172.4 mg/g at pH 2.0. SEM-EDS, BET, XRD, FT-IR, Raman and XPS investigation suggested that reduction of Cr(VI) to Cr(III) was the major removal mechanism. pH played an important role on the corrosion of nZVI-BC, at pH 4.5 and 2.0, FeOOH and FeO were detected as the major iron oxide, respectively. Therefore, FeOOH-BC and FeO-BC were further prepared and their interaction with Cr were studied. Combining with DFT calculations, it revealed that FeO has higher adsorption capacity and was responsible for the effective removal of Cr(VI) through electrostatic attraction and reduction under acidic conditions. However, FeO will continue to convert to the more stable FeOOH, which is the key to for the subsequent stabilization of the reduced Cr(III). The results showed that the oxide corrosion products of nZVI-BC were subjected to the environment, which will eventually affect the fate and transport of the adsorbed heavy metal.
虽然纳米零价铁修饰生物炭（nZVI-BC）已被广泛研究用于去除重金属，但 nZVI 的腐蚀产物及其与重金属的相互作用尚未揭示。本文合成了 nZVI-BC 并将其用于去除 Cr(VI)。批实验表明，Cr(VI)的吸附符合 Langmuir 等温线，在 pH 2.0 时最大去除容量为 172.4mg/g。SEM-EDS、BET、XRD、FT-IR、Raman 和 XPS 研究表明，Cr(VI)还原为 Cr(III)是主要的去除机制。pH 值对 nZVI-BC 的腐蚀起着重要作用，在 pH 4.5 和 2.0 时，分别检测到 FeOOH 和 FeO 作为主要的氧化铁。因此，进一步制备了 FeOOH-BC 和 FeO-BC 并研究了它们与 Cr 的相互作用。结合 DFT 计算，结果表明，FeO 具有更高的吸附容量，通过静电吸引和还原作用在酸性条件下对 Cr(VI)的有效去除起作用。然而，FeO 会继续转化为更稳定的 FeOOH，这是随后稳定还原态 Cr(III)的关键。结果表明，nZVI-BC 的氧化物腐蚀产物受环境影响，这将最终影响吸附重金属的命运和迁移。
