論文
DOI
：
10.1016/j.watres.2022.118377
圖文摘要
高鐵酸鹽
(Fe(VI))
如
K
2
FeO
4
是修復水處理中有機污染物的有效綠色氧化劑。礦物是有效的污染物吸附劑，也是優(yōu)良的固體多相催化劑，可能會影響
Fe(VI)
的修復過程。
最近，
中國科學院南京土壤研究所
王芳
老師團隊在Water Research期刊上發(fā)表題為“
Degradation of mineral-immobilized pyrene by ferrate oxidation: role of mineral type and intermediate oxidative iron species
”的綜述文章。
在這項研究中，
以典型的多環(huán)芳烴化合物芘為對象，首次研究了Fe(VI)在蒙脫石、高嶺石和針鐵礦三種礦物上固定化芘的氧化作用。
在Fe(VI)濃度為50倍摩爾的條件下，pH9.0條件下，芘(10 μM)的降解率為87% ~ 99%。
不同礦物降解芘的最適pH值不同，最適pH值由中性到堿性依次為蒙脫石(pH 7.0)、高嶺石(pH 8.0)和針鐵礦(pH 9.0)。
雖然針鐵礦對Fe(VI)降解芘的催化活性最高，但由于針鐵礦體系中氧
化物質(zhì)的自衰變導致其降解效率低于蒙脫石。
質(zhì)子化和劉易斯酸在蒙脫土和針鐵礦上輔助Fe(VI)氧化芘。
中間高鐵酸鹽(Fe(V)/Fe(IV))是芘氧化的主要氧化種，而Fe(VI)的貢獻很小。
羥基自由基猝滅實驗表明，羥基自由基參與了礦物固定化芘的降解，在蒙脫土體系中，羥基自由基對芘降解的貢獻為11.5% ~ 27.4%，其次為高嶺石(10.8% ~ 21.4%)和針鐵礦(5.1% ~ 12.2%)。
基質(zhì)中大量的陽離子和溶解的腐殖酸阻礙了芘的降解。
最后，確定了兩種產(chǎn)生鄰苯二甲酸的降解途徑。
本研究證實了固定在礦物上的芘的Fe(VI)的高效氧化，有助于開發(fā)基于Fe(VI)的高效環(huán)保修復技術(shù)。
圖文導讀
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.
礦物固定芘的降解動力學
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)對礦物固定化芘降解的影響
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、礦物催化Fe(VI)氧化芘的可能機理
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，F(xiàn)e(VI)在pH 7.0-9.0的條件下對固定在礦物上的芘進行了有效的氧化。不同礦物降解芘的最適pH值從中性到堿性依次為蒙脫石、高嶺石和針鐵礦。質(zhì)子化作用和礦物表面官能團在Fe(VI)氧化芘中起重要作用。針鐵礦催化高鐵酸鹽的快速分解不利于芘的降解。芘的Fe(VI)氧化主要歸因于其氧化中間體Fe(V)/ Fe(IV)。高濃度的陽離子和可溶性腐植酸由于可能出現(xiàn)在環(huán)境中，對芘的降解有不利影響。
本
研究為揭示高鐵酸鹽降解礦物表面吸附多環(huán)芳烴的潛在機理提供了有價值的信息。
文獻信息：
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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