论文
DOI
：
10.1016/j.watres.2022.118377
图文摘要
高铁酸盐
(Fe(VI))
如
K
2
FeO
4
是修复水处理中有机污染物的有效绿色氧化剂。矿物是有效的污染物吸附剂，也是优良的固体多相催化剂，可能会影响
Fe(VI)
的修复过程。
最近，
中国科学院南京土壤研究所
王芳
老师团队在Water Research期刊上发表题为“
Degradation of mineral-immobilized pyrene by ferrate oxidation: role of mineral type and intermediate oxidative iron species
”的综述文章。
在这项研究中，
以典型的多环芳烃化合物芘为对象，首次研究了Fe(VI)在蒙脱石、高岭石和针铁矿三种矿物上固定化芘的氧化作用。
在Fe(VI)浓度为50倍摩尔的条件下，pH9.0条件下，芘(10 μM)的降解率为87% ~ 99%。
不同矿物降解芘的最适pH值不同，最适pH值由中性到碱性依次为蒙脱石(pH 7.0)、高岭石(pH 8.0)和针铁矿(pH 9.0)。
虽然针铁矿对Fe(VI)降解芘的催化活性最高，但由于针铁矿体系中氧
化物质的自衰变导致其降解效率低于蒙脱石。
质子化和刘易斯酸在蒙脱土和针铁矿上辅助Fe(VI)氧化芘。
中间高铁酸盐(Fe(V)/Fe(IV))是芘氧化的主要氧化种，而Fe(VI)的贡献很小。
羟基自由基猝灭实验表明，羟基自由基参与了矿物固定化芘的降解，在蒙脱土体系中，羟基自由基对芘降解的贡献为11.5% ~ 27.4%，其次为高岭石(10.8% ~ 21.4%)和针铁矿(5.1% ~ 12.2%)。
基质中大量的阳离子和溶解的腐殖酸阻碍了芘的降解。
最后，确定了两种产生邻苯二甲酸的降解途径。
本研究证实了固定在矿物上的芘的Fe(VI)的高效氧化，有助于开发基于Fe(VI)的高效环保修复技术。
图文导读
Fig. 1. Effects of oxidant dosage and solution pH on mineral-immobilized pyrene degradation by Fe(VI). Different letters on the bars in each graph indicate significant differences at p < 0.05 level. Experiment condition: [Pyrene]
0
: 10 μM; t: 2 h.
2.
矿物固定芘的降解动力学
Fig. 2. Degradation of mineral-immobilized pyrene with varied initial Fe(VI) concentration at pH 8.0 (a-c), and with varied pH at initial Fe(VI) concentration of 0.50 mM (d-f).
Fig. 3. Plot of second- and third-order reaction kinetics for mineral-immobilized pyrene oxidation by Fe(VI) with different Fe(VI) dosages and pH according to
equation 2
and
7
, respectively. Symbols and solid lines stand for the experimental data and the model fitting results, respectively. Experimental conditions: a-c, g-i: pH 8.0, [Fe(VI)]
0
: 0.06−0.50 mM; d-f, i-l: [Fe(VI)]
0
: 0.50 mM, pH 7.0−9.0.
Fig. 4. Degradation kinetics of pyrene without pre-immobilization on minerals by Fe(VI) at pH 9.0. (a) and (b) are residual pyrene and Fe(VI) with reaction time, respectively; (c) and (d) are fitting of first-order and second-order degradation kinetics, respectively. Experimental condition: [Fe(VI)]
0
: 0.22 mM; [Pyrene]
0
: 21 μM.
Fig. 5. Formation of hydrogen peroxide (a) and Fe(II) (b) in mineral-pyrene-Fe(VI) degradation system at pH 8.0. Reaction time: 8 min for H
2
O
2
determination, 2 h for Fe(II) determination. [Fe(VI)]
0
: 0.06-0.25 mM and 0.12 mM for H
2
O
2
and Fe(II) analysis, respectively; [Pyrene]
0
: 10 μM. (c) pyrene removal with bipyridine (BPY) at pH 8.0. [Fe(VI)
0
]: 0.25 mM; [Pyrene]: 21 μM; t: 2 h. (d) EPR spectrum of the mineral-Fe(VI) reaction systems at pH 8.0. [Fe(VI)]
0
: 1.0 mM; t: 20 min. (e) Effect of tert-butyl alcohol (TBA, 10 mM) and phenyl sulfoxide (PMSO, 0.05 and 0.08 mM) on pyrene removal by Fe(VI) oxidation. [Fe(VI)]
0
: 0.25 mM; [Pyrene]
0
: 21 μM; t: 2 h. Asterisk on the bars represents significant difference at p< 0.05 (*) or 0.01 (**) level compared to the control treatment.
4、H2O2和Fe(III)对矿物固定化芘降解的影响
Fig. 6. Effect of initial added different concentration of H
2
O
2
(a) and Fe
3+
(b) on mineral-immobilized pyrene degradation by Fe(VI) oxidation. Asterisk on the bars with same color represents significant difference at p< 0.05 (*) or 0.01 (**) level compared to the treatment without H
2
O
2
or Fe
3+
addition for each mineral, respectively. Experiment condition: pH 8.0; [Fe(VI)]
0
: 0.12 mM for H
2
O
2
treatment, 0.25 mM for Fe(III) treatment; t: 1 h.
Fig. 7. Effect of cations (a), anions (b) and humic acid (HA) (c) on mineral-immobilized pyrene degradation by Fe(VI) oxidation. Asterisk on the bars represents significant difference at p< 0.05 (*) or 0.01 (**) level compared to the control treatment of each mineral. Experiment condition: pH 8.0; [Fe(VI)]
0:
0.06 mM; [ions]: 2 mM; t: 1 h.
Fig. 8. Proposed reaction pathways of pyrene degradation by Fe(VI) oxidation. Structure in brackets are unidentified intermediates.
7、矿物催化Fe(VI)氧化芘的可能机理
Fig. 9. Possible mechanisms of minerals (a, montmorillonite; b, kaolinite; c, goethite) as catalysts on efficient pyrene oxidation by Fe(VI)
研究表明，Fe(VI)在pH 7.0-9.0的条件下对固定在矿物上的芘进行了有效的氧化。不同矿物降解芘的最适pH值从中性到碱性依次为蒙脱石、高岭石和针铁矿。质子化作用和矿物表面官能团在Fe(VI)氧化芘中起重要作用。针铁矿催化高铁酸盐的快速分解不利于芘的降解。芘的Fe(VI)氧化主要归因于其氧化中间体Fe(V)/ Fe(IV)。高浓度的阳离子和可溶性腐植酸由于可能出现在环境中，对芘的降解有不利影响。
本
研究为揭示高铁酸盐降解矿物表面吸附多环芳烃的潜在机理提供了有价值的信息。
文献信息：
Ziquan Wang,
et al.
Degradation of mineral-immobilized pyrene by ferrate oxidation: role of mineral type and intermediate oxidative iron species
,
Water Research
, 2022
https://doi.org/10.1016/j.watres.2022.118377
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