School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
Sci Total Environ. 2020 Jul 15;726:138650. doi: 10.1016/j.scitotenv.2020.138650. Epub 2020 Apr 13.
Soluble iron from atmospheric aerosol particles has toxicological effects on ambient environment due to their oxidative potential. However, the dissolution process and factors affecting this process are poorly understood. In this study, by solid phase characterization and aqueous dissolution experiments, we investigated the influence of acids, including HCl, HSO and HNO, and H concentration on iron dissolution rate, solubility and speciation of iron in chlorite, illite, kaolinite and pyrite. The dissolution of iron-bearing clay minerals, i.e. chlorite, illite and kaolinite, was a multi-stage process with a rapid rate in the initial stage and then decreasing rate in the following stages. In contrast, the regularly crystallized pyrite proceeded with an extremely rapid dissolution rate at very beginning and then remained almost constant. In all acid solutions, the dissolution rate was in the order of pyrite > illite > chlorite > kaolinite. HSO was stronger than HCl and HNO in the destruction of mineral structures to release iron, while HNO dissolved more iron in pyrite (FeS). High H concentration easily destroyed the mineral structures to release the structural or interlayer iron, whereas low H concentration increased the proportion of Fe (II) in clay minerals. Non-linear fitting of continuous dissolution models showed that the iron dissolution rates and iron redox speciation as functions of time were well predicted, with r > 0.99 for chlorite and illite, and r > 0.96 for kaolinite. Oxidative potential analysis proved that the dissolved iron possessed a considerable potential to generate reactive oxygen species.
大气气溶胶颗粒中的溶解态铁因其氧化能力而对环境具有毒理学效应。然而，目前人们对这一溶解过程及其影响因素的了解还很有限。在这项研究中，我们通过固相特征描述和水相溶解实验，研究了包括 HCl、HSO 和 HNO 在内的酸以及 H 浓度对绿泥石、伊利石、高岭石和黄铁矿中铁溶解速率、溶解度和形态的影响。含铁黏土矿物（即绿泥石、伊利石和高岭石）的溶解是一个多阶段过程，初始阶段溶解速率较快，随后逐渐降低。相比之下，结晶规则的黄铁矿在开始时具有极高的溶解速率，随后几乎保持不变。在所有酸溶液中，溶解速率的顺序为黄铁矿＞伊利石＞绿泥石＞高岭石。HSO 在破坏矿物结构以释放铁方面比 HCl 和 HNO 更强，而 HNO 在黄铁矿（FeS）中溶解了更多的铁。高 H 浓度容易破坏矿物结构，释放结构或层间铁，而低 H 浓度则增加了黏土矿物中 Fe（II）的比例。连续溶解模型的非线性拟合表明，铁溶解速率和铁的氧化还原形态随时间的变化得到了很好的预测，绿泥石和伊利石的 r 值均大于 0.99，高岭石的 r 值大于 0.96。氧化潜力分析证明，溶解态铁具有产生活性氧物质的可观潜力。
