|
| Effects of reduction degree of structure Fe（Ⅲ） in chlorite on hydroxyl radical formation and mineralization of organic matter during oxidation |
| Received:November 20, 2023 |
| View Full Text View/Add Comment Download reader |
| KeyWord:nontronite;structural Fe（Ⅱ）;reduction extent;hydroxyl radicals（·OH）;natural DOM transformation |
| Author Name | Affiliation | E-mail | | XIAO Yanqi | College of Resources, Hunan Agricultural University, Changsha 410128, China | | | FU Junhong | College of Resources, Hunan Agricultural University, Changsha 410128, China | | | LIU Xixiang | Guangxi Colleges and Universities Key Laboratory of Environmental-friendly Materials and New Technology for Carbon Neutralization, Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization, School of Materials and Environment, Guangxi Minzu University, Nanning 530006, China | liuxx200208@163.com | | LIAO Wenjuan | College of Resources, Hunan Agricultural University, Changsha 410128, China
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China | | | ZHANG Na | State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China
Hebei Key Laboratory of Wetland Ecology and Conservation, Hengshui University, Hengshui 053000, China | | | CUI Haojie | College of Resources, Hunan Agricultural University, Changsha 410128, China | hjcui@hunau.edu.cn |
|
| Hits: 1454 |
| Download times: 1831 |
| Abstract: |
| Hydroxyl radicals（·OH） produced by the oxidation of structure Fe（Ⅱ）in clay mineral at the aerobic-anaerobic interface of soil and sediment play an important role in the transformation of organic matter. The reduction degree of structure Fe（Ⅲ） in the clay mineral of soil and sediment varies with environmental conditions. However, the effect of the reduction degree of iron-containing clay minerals [Fe（Ⅱ）/ Fe total] on the formation of · OH and the mineralization of organic matter during the oxidation process is still unclear. Taking iron-rich nontronite（NAu-2） as the representative clay ore, the oxidation mechanism of NAu-2 with different reduction degrees（Fe（Ⅱ）/ Fe total：15%, 22%, 39%, and 56%）to produce ·OH and the difference of this process to natural DOM transformation were studied. The results demonstrated that when the concentration of structural Fe（Ⅱ）in NAu-2 suspension was 2.2 mmol·L-1, the reduction degree increased from 15% to 56%, cumulative concentration of ·OH increased from 13.6 to 27.1 μmol·L-1 after 120 min of oxidation, and the conversion efficiency of unit O2 to ·OH increased from 3.3% to 5.9%. The results of Fourier transform infrared spectroscopy（FTIR）, Nitrotetrazolium blue chloride（NBT）deactivation experiments, and 2, 2'-dipyridyl（BPY）edge reaction site passivation proved that the chlorite with 15% reduction degree mainly existed in dioctahedral Fe（Ⅱ）[Al-Fe（Ⅱ）], and it activated O2 at the edge site to produce ·OH. In addition to octahedral Fe（Ⅱ）, highly active trioctahedral Fe（Ⅱ）[Fe（Ⅱ）-Fe（Ⅱ）-Fe（Ⅱ）] were present in chlorite with a reduction degree of 56%. Both the basal and marginal sites could activate O2 to produce ·OH, and the reduction efficiency of O2 to form ·OH at the basal site was higher. The CO2content formed by·OH mineralized dissolved organic matter（DOM）increased with the increase of NAu-2 reduction degree. Therefore, compared with the low reduction degree of NAu-2（15%）, the high reduction degree of NAu-2（56%）has a highly active trioctahedral and can form ·OH from the bottom site, which improves the efficiency of ·OH formation and further promotes the mineralization of DOM. |
|
|
|
