| 周艺艺,刘存,王玉军.不同主导晶面赤铁矿对Cr（Ⅵ）吸附与迁移行为的影响[J].农业环境科学学报,2021,40(8):1667-1674. |
| 不同主导晶面赤铁矿对Cr（Ⅵ）吸附与迁移行为的影响 |
| Facet-dependent Cr(Ⅵ) adsorption and transport on hematite nano-particles |
| 投稿时间：2021-03-31 |
| DOI：10.11654/jaes.2021-0386 |
| 中文关键词: 赤铁矿 晶面效应 Cr（Ⅵ） 穿透曲线 |
| 英文关键词: hematite facet-dependent adsorption Cr(Ⅵ) breakthrough curve |
| 基金项目:国家重点研发计划项目（2018YFC1800503） |
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| 中文摘要: |
| 为探究赤铁矿的晶面效应对Cr（Ⅵ）迁移的影响，采用批实验研究了{001}主导晶面的片状纳米赤铁矿（HNPs）与{110}主导晶面的棒状纳米赤铁矿（HNRs）对Cr（Ⅵ）的吸附机制，并通过柱实验考察了不同环境因素（pH、入流浓度、流速和离子强度）对Cr（Ⅵ）在两种赤铁矿修饰石英砂表面的迁移规律。批实验结果表明：HNPs与HNRs对Cr（Ⅵ）的吸附过程符合准二级动力学模型和Langmuir等温吸附模型。HNPs与HNRs对Cr（Ⅵ）的最大吸附量分别为2.97 mg·g-1和4.95 mg·g-1。pH和离子强度增加，HNPs与HNRs对Cr（Ⅵ）的吸附量降低，表明吸附过程同时存在化学吸附和静电吸附机制。柱实验结果表明：pH增大，填充柱表面负电荷增多，减少了对Cr（Ⅵ）的滞留；增加初始浓度能够加快位点占据速度，增大流速导致Cr（Ⅵ）在柱内停留时间减少。离子强度增大，增强了阴离子竞争吸附，促进了HNPs与HNRs上Cr（Ⅵ）的解吸和迁移。相同条件下，由于{001}晶面对Cr（Ⅵ）的吸附点位密度低，导致Cr（Ⅵ）在HNPs中的滞留量小于HNRs。研究表明，赤铁矿不同主导晶面吸附构型的差异显著影响Cr（Ⅵ）吸附与迁移行为。 |
| 英文摘要: |
| This study investigated the facet-dependent Cr(Ⅵ) adsorption and transport on hematite nanoparticles using batch and column experiments, respectively. Two hematite nanoparticles were characterized as nano-plates(HNPs) with dominant-exposed {001} facets and nano-rods(HNRs) with dominant-exposed {110} facets. We determined how the flow conditions, including pH, inflow concentration, flow velocity, and ionic strength, could impact Cr(Ⅵ) transport. The batch experiments showed that the HNR- and HNP-related isothermal and kinetic adsorption of Cr(Ⅵ) could be described well by the Langmuir and the pseudo-second-order kinetic models, respectively. The maximum Cr(Ⅵ) adsorption capacities of the HNPs and HNRs were 2.97 mg·g-1 and 4.95 mg·g-1, respectively. The increase in the pH and ionic strength reduced both the HNP- and HNR-related Cr(Ⅵ) adsorption, indicating both chemical and electrostatic adsorption mechanisms. The column experiments showed that the pH increase augmented the electronegativity in the packed columns and reduced the Cr(Ⅵ) retention. The initial concentration increase accelerated the site occupation, while the increase in the flow rate reduced the Cr(Ⅵ) residence time in the columns. The increasing ionic strength increased the competition for the surface sites from the competing anions and promoted the Cr(Ⅵ) transport. The retention of the HNPs is less than that of the HNRs due to the lower adsorption site density of the {001} facets. Results indicated that the different binding modes on hematite facets significantly influence the adsorption and transport behaviors of Cr (Ⅵ). |
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