Degradation of p-nitrophenol (PNP)in aqueous solution by mFe/Cu-air-PS system

Article abstract of DOI:10.1016/j.cclet.2019.01.025

In this study, batch experiments were conducted to investigate the performance of microscale Fe/Cu bimetallic particles-air-persulfate system (mFe/Cu-air-PS)for p-nitrophenol (PNP)treatment in aqueous solution. First, the optimal operating parameters (i.e., aeration rate of 1.0 L/min, theoretical Cu mass loading (TMLCu)of 0.110 g Cu/g Fe, mFe/Cu dosage of 15 g/L, PS total dosage of 15 mmol/L, feeding times of PS of 5, initial pH 5.4)were obtained successively by single-factor experiments. Under the optimal conditions, high COD and TOC removal efficiencies (71.0%, 65.8%)were obtained after 60 min treatment. Afterword, compared with control experiments (i.e., mFe/Cu, air, PS, mFe/Cu-air, mFe/Cu–PS, air-PS and mFe-air-PS), mFe/Cu-air-PS system exerted superior performance for pollutants removal due to the synergistic effect between mFe/Cu, air and PS. In addition, the results of control experiments and radical quenching experiments indicate this reinforcement by feeding of PS was greater than by aeration in mFe/Cu-air-PS system. Furthermore, the degradation intermediates of PNP in mFe/Cu-air-PS process were identified and measured by HPLC. Based on the detected intermediates, the degradation pathways of PNP were proposed comprehensively, which revealed that toxic and refractory PNP in aqueous solution could be decomposed effectively and transformed into lower toxicity intermediates. As a result, mFe/Cu-air-PS system with the performance of oxidation combined reduction can be also a potential technology for the treatment of toxic and refractory PNP contained wastewater.

Full text of DOI:10.1016/j.cclet.2019.01.025

G Model
CCLET 4793 No. of Pages 4
Chinese Chemical Letters xxx (2018) xxx–xxx
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Communication
Degradation of p-nitrophenol (PNP) in aqueous solution by mFe/Cu-air-
PS system
Heng Zhanga,b, Qingqing Jia,b, Leiduo Laia,b, Gang Yaob,c, Bo Laia,b,
*
a
State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China
b
c
Institute of Environmental Engineering, RWTH Aachen University, Aachen, Germany
A R T I C L E I N F O
A B S T R A C T
Article history:
In this study, batch experiments were conducted to investigate the performance of microscale Fe/Cu
bimetallic particles-air-persulfate system (mFe/Cu-air-PS) for p-nitrophenol (PNP) treatment in aqueous
solution. First, the optimal operating parameters (i.e., aeration rate of 1.0 L/min, theoretical Cu mass
loading (TMLCu) of 0.110 g Cu/g Fe, mFe/Cu dosage of 15 g/L, PS total dosage of 15 mmol/L, feeding times of
PS of 5, initial pH 5.4) were obtained successively by single-factor experiments. Under the optimal
conditions, high COD and TOC removal efficiencies (71.0%, 65.8%) were obtained after 60 min treatment.
Afterword, compared with control experiments (i.e., mFe/Cu, air, PS, mFe/Cu-air, mFe/Cu–PS, air-PS and
mFe-air-PS), mFe/Cu-air-PS system exerted superior performance for pollutants removal due to the
synergistic effect between mFe/Cu, air and PS. In addition, the results of control experiments and radical
quenching experiments indicate this reinforcement by feeding of PS was greater than by aeration in mFe/
Cu-air-PS system. Furthermore, the degradation intermediates of PNP in mFe/Cu-air-PS process were
identified and measured by HPLC. Based on the detected intermediates, the degradation pathways of PNP
were proposed comprehensively, which revealed that toxic and refractory PNP in aqueous solution could
be decomposed effectively and transformed into lower toxicity intermediates. As a result, mFe/Cu-air-PS
system with the performance of oxidation combined reduction can be also a potential technology for the
treatment of toxic and refractory PNP contained wastewater.
Received 28 December 2018
Received in revised form 16 January 2019
Accepted 23 January 2019
Available online xxx
Keywords:
p-Nitrophenol (PNP)
Microscale Fe/Cu bimetallic particles (mFe/
Cu)
Persulfate (PS)
Air aeration
mFe/Cu-air-PS system
©
2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
Published by Elsevier B.V. All rights reserved.
4ꢀꢁ
p-Nitrophenol (PNP) is a common and prominent pollutant that
exhibits high toxicity, carcinogenicity, bioaccumulation, and
normally let out in the aquatic system from the industries such
as synthetic dyes, petrochemical, plasticizers, pesticides and
pharmaceutical [1]. If PNP wastewater is directly discharged into
the environment, it will cause serious environmental problems
that endanger public health and welfare due to its wide presence,
toxicity, and slow rate of degradation. Therefore, it is necessary to
develop a potential technology for the treatment of toxic and
refractory PNP contained wastewater.
sulfate radical (SO )-advanced oxidation processes (AOPs) to be
effective in oxidizing toxic and refractory organic contaminants,
ꢀ
ꢁ
and the generated of SO
2.6 V. Persulfate (PS) is a common source of SO
4
is a strong oxidant with the potential of
ꢀ
ꢁ
4
through
activation strategies including heat [5], light [6–8], electrochemi-
0
cal [9], transition metal ions [10] and so on. Fe as an alternative
2
+
activator has been employed to activate PS by releasing Fe stably
and continuously [11]. Fe0 can not only release Fe in aerobic/
2+
2
+
anaerobic condition, but also release Fe by the reaction with PS
0
3+
2+
(Eq. (1)). Moreover, Fe can also recycle Fe to Fe (Eq. (2)) during
0
0
Over the past decades, zero-valent iron (ZVI or Fe ) applied to
the reaction process. However, the reactivity of Fe is susceptible to
treat toxic and refractory pollutants in wastewater or groundwater
has drawn great attention and its inspiring removal efficiencies
have been documented [2–4]. Moreover, studies have also proven
surface passivation and narrow working pH [12]. In order to
0
enhance the performance of Fe , microscale Fe/Cu (mFe/Cu)
0
prepared by plating Cu on mFe particles has been attempted to
0
overcome shortcomings of Fe , since planted Cu can facilitate iron
corrosion due to the high potential between Fe and Cu (0.78 V) and
0
hence enhance remarkably Fe reactivity [13]. The performance of
*
Corresponding author at: State Key Laboratory of Hydraulics and Mountain
mFe/Cu-air system and mFe/Cu-PS system has been investigated in
our previous studies [14,15]. However, its oxidative reactivity
coupled with the aerobic condition and PS for treatment pollutants
River Engineering, College of Architecture and Environment, Sichuan University,
Chengdu 610065, China.
E-mail address: laibo@scu.edu.cn (B. Lai).
https://doi.org/10.1016/j.cclet.2019.01.025
1001-8417/© 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: H. Zhang, et al., Degradation of p-nitrophenol (PNP) in aqueous solution by mFe/Cu-air-PS system, Chin.
Chem. Lett. (2019), https://doi.org/10.1016/j.cclet.2019.01.025

G Model
CCLET 4793 No. of Pages 4
2
H. Zhang et al. / Chinese Chemical Letters xxx (2018) xxx–xxx
in water has not been studied in detail.
10 min. In addition, the uptrends of mFe/Cu-air-PS system was
higher the mFe/Cu-air and mFe/Cu-PS system. The phenomena
demonstrate that oxidization ability for PNP by mFe/Cu-based
system was elevated obviously by PS or aeration.
2
ꢁ
þFe ! Fe2þþ2SO þ 2SO4
0
2ꢁ
ꢀꢁ
2S
2
O
ð1Þ
8
4
Fig. 1b shows the effluent pH of different systems during the
60 min treatment. It is clear that the effluent pH of mFe/Cu-air-PS,
mFe-air-PS, mFe/Cu-PS, mFe/Cu-air, mFe/Cu systems dramatically
rose up to 9.5 at 10 min. However, the pH values of those systems
withPSsharplydroppedafter10 minandthenmildlydeclinedtoless
than 7.0 in the following process, while that of those two systems
without PS continued to creepup and eventuallyexceeded 10.5 after
2
Fe3 þFe ! 3Fe
þ
0
2þ
ð2Þ
ꢀ
ꢀꢁ
Therefore, to combine the benefits of OH and SO
4
generated
during Fenton-like and PS activated processes by mFe/Cu particles,
the mFe/Cu-air-PS system was proposed for treatment of PNP in
this work. Firstly, it is important to obtain the best performance for
mFe/Cu-air-PS system through optimizing its operational param-
eters. Meanwhile, the superiority of mFe/Cu-air-PS system would
be evaluated through control systems (i.e., mFe/Cu, air, PS, mFe/Cu-
air, mFe/Cu-PS, air-PS and mFe-air-PS). Furthermore, the degrada-
tion pathway of PNP in mFe/Cu-air-PS system was proposed by
analysis of COD, TOC, UV–vis spectra and HPLC chromatography.
Through analysis COD removal efficiency and pH variation of
effluent in mFe/Cu-air-PS system, the key operating parameters
10 min.Inaddition,Fig.1balsoshowsthattheeffluentpHofPS-air,PS
system decreased mildly from 5.4 to about 3.4 during the 60 min
treatment. The phenomenon could be explained from two aspects:
(
i) the processes of iron corrosion and Fenton-like reactions could
+
consume H ions and cause the increase of solution pH, (ii) the
decomposition ofPScouldreleaseH ions and causea decrease ofpH
+
values when PS was added reaction solution.
Meanwhile, when PS was added, there was evident different
between mFe/Cu-air-PS and mFe/Cu-PS system that the effluent pH
of the former was lower than that of the latter in the whole process,
and finallyitreached5.2and6.2after60 min, respectively. Theresult
supports the previous section of effect of aeration rate that the
effluent pH declined with an increase of air aeration rate in mFe/Cu-
air-PS system. However, inthe systems withoutPS, the effluent pHof
mFe/Cu system was higher than that of mFe/Cu-air system at first
(
i.e., aeration rate, TMLCu, mFe/Cu dosage, PS total dosage, the
feeding times of PS (N) and initial pH) were optimized. The optimal
conditions (i.e., TMLCu of 0.110 g Cu/g Fe, mFe/Cu dosage of 15 g/L,
PS total dosage of 15 mmol/L, N of 5, initial pH 5.4) were obtained
by the single-factor experiments (in the Supporting information).
To comparative study the superiority of mFe/Cu-air-PS system,
seven control systems including mFe/Cu, air, PS, mFe/Cu-air, mFe/
Cu-PS, air-PS and mFe-air-PS were set up under same conditions
within 60 min process. The performance of mFe/Cu-air-PS system
and control systems were investigated comparatively through
analyzing the COD removal efficiency, effluent pH, total iron ions
2
5 min and no longer increased andstayed around 10.5, whilethatof
mFe/Cu-air system rose continuously and exceeded mFe/Cu system
after 25 min and eventually maintained about 11.1 after 60 min
treatment. The results could be explained from two aspects: (i)
oxidizing capacity of PNP by mFe/Cu-air system was stronger than
mFe/Cu system, which benefited to generation of small molecule
organicacidsthatleadtothedecreaseofpH,andhenceitseffluentpH
was lower than thatof mFe/Cu system at first 25 min, (ii) airaeration
in mFe/Cu-air system would accelerate iron corrosion and Fenton-
like reactions which would consume acid in solution and generate
iron hydroxides, and hence cause higher effluent pH after 25min. In
conclusion, adding PS in reaction solution has an obvious impact on
effluent pH.
2
+
3+
concentration (i.e., Fe , Fe and flocculent precipitate) and UV–vis
spectra in different reaction systems.
As shown in Fig. 1a, the COD removal efficiency of 71.0%, 60.8%,
0.8%, 42.5%, 11.2%, 0%, 0%, 0% were obtained by mFe/Cu-air-PS,
5
mFe-air-PS, mFe/Cu-PS, mFe/Cu-air, mFe/Cu, PS-air, PS, air systems,
respectively. It can be concluded that PNP was rarely oxidized by PS
due to the limited oxidation capability of PS (E = 2.0 V). In addition,
it also could be found that PNP cannot be removed by air blowing.
Moreover, the COD removal obtained by mFe/Cu-air-PS system was
remarkably higher than those of seven control experiments during
u
Fig. 1c shows the variation of total iron ions (i.e., Fe2+, Fe3+ and
flocculent precipitate) concentration in reaction solution during
6
0 min treatment. It further confirms the capacity of oxidative
degradation of PNP by mFe/Cu-air-PS system was superior to other
seven control systems. Meanwhile, the COD removal efficiencies of
mFe/Cu-air-PS, mFe-air-PS, mFe/Cu-PS, mFe/Cu-air and mFe/Cu
system were about 8.0% at 10 min treatment, indicating that
oxidization ability for PNP by these systems was poor before
adding PS. However, it was obvious different when added PS after
6
0 min treatment process by the different systems. It presented
that the all total iron ions concentrations of mFe/Cu-air-PS system
were much higher than mFe/Cu-air, mFe/Cu, mFe-air-PS and mFe/
Cu-PS system during 60 min treatment. In addition, it is clear that
total iron ion concentration was lower than 335.0
0 min in each system, and it increased remarkably faster after
0 min for mFe/Cu-air-PS, mFe-air-PS and mFe/Cu-PS system, and
eventually rose up to 2051.0, 1800.9 and 1622.6 g/mL, respec-
tively. It also could be found that the total iron ion concentration in
mg/mL at first
1
1
1
0 min reaction. For instance, the uptrend of mFe/Cu system was
slowest in these systems, and the uptrend of mFe/Cu-air system
had clearly increased after 20 min, but the uptrends of mFe/Cu-PS,
mFe-air-PS and mFe/Cu-air-PS systems rose significantly after
m
Fig. 1. COD removal efficiency (a), effluent pH (b), total iron ion concentration (c) obtained by the different system during 60 min treatment ([PNP] = 500 mg/L, mFe/Cu
dosage = 15 g/L, mFe dosage = 15 g/L, PS dosage = 15 mmol/L, aeration rate = 1.0 L/min, initial solution pH 5.4).
Please cite this article in press as: H. Zhang, et al., Degradation of p-nitrophenol (PNP) in aqueous solution by mFe/Cu-air-PS system, Chin.
Chem. Lett. (2019), https://doi.org/10.1016/j.cclet.2019.01.025

G Model
CCLET 4793 No. of Pages 4
H. Zhang et al. / Chinese Chemical Letters xxx (2018) xxx–xxx
3
mFe/Cu and mFe/Cu-PS system was lower than its air aeration
condition within the whole reaction process. The above results
suggest that both of adding PS and air aeration could significantly
promote iron corrosion and releasing of iron ions [16], however the
contribution by PS was greater than by air aeration because the
descended, but HQ gradually rose and BQ fluctuated with further
adding PS after 20 min. Finally, the molar balance, PAP and HQ of
the effluent achieved 1.236, 0.580 and 0.655 mmol/L, respectively
after 60 min treatment, indicating oxidative degradation PNP was
further promoted by feeding PS in mFe/Cu-air-PS system. In a
word, reduction action and oxidation action both facilitate the PNP
degradation in mFe/Cu-air-PS system.
+
decomposition of PS could release H ions in solution and the
2
ꢁ
2ꢁ
standard redox potential for S
2
O
8
/SO
4
(2.01 V) is higher than
that of O /H O (1.23 V). Meanwhile, throughout the whole process,
2
2
In literature, methanol (MeOH) has a similar reaction rate with
ꢀ
ꢀ
ꢁ
7
ꢁ1 ꢁ1
9
ꢁ1
the total iron concentration in mFe/Cu-air-PS system was more
than in mFe/Cu-PS system. It indicates that the intensity of iron
SO
s
4
(1.6–7.7 ꢂ10 L mol
s
) and OH (1.2–2.8 ꢂ 10 L mol
ꢀ
ꢁ
1
ꢁ
5
), but tert-butyl alcohol (TBA) react with SO
4
(4.9–9.1 ꢂ10 L
ꢀ
2
+
ꢁ1 ꢁ1
corrosion was stronger and the availability of dissolved Fe was
mol
s
) much slower about 1000 times than with OH (3.8–
8
ꢁ1 ꢁ1
more efficient in mFe/Cu-air-PS system since Fenton-like reactions
7.6 ꢂ10 L mol
s
) [19]. Therefore, these two radical scavengers
2+
happened under aeration. The dissolved Fe could facilitate the
with concentration of 100 mmol/L were applied to quenching tests
in order to explore contribution for PNP oxidative degradation
ꢀ
ꢀ
ꢁ
generation of amount of OH and SO
4
by Fenton-like reaction and
ꢀ
ꢀ
ꢁ
activation PS reaction, which result in higher reaction reactivity of
mFe/Cu-air-PS system. It further demonstrates aeration condition
could enhance the capacity of oxidative degradation pollutants by
mFe/Cu-PS system.
The UV–vis spectra from 190 nm to 500 nm of the influent and
effluent of mFe/Cu-air-PS, mFe/Cu-air, mFe/Cu-PS and mFe/Cu
system are provided in the Supporting information. The results
further suggested that toxic and refractory PNP in aqueous solution
could be decomposed effectively and transformed into lower
toxicity intermediates by mFe/Cu-air-PS system.
The previous studies show that main intermediates during PNP
degradation processes include reductive product of p-amino-
phenol (PAP), oxidative products of hydroquinone (HQ), p-
benzoquinone (BQ) and some small molecular organics (e.g.,
fumanic acid, arylic acid) [17,18]. In order to investigate degrada-
tion pathway of PNP in mFe/Cu-air-PS system, including target
pollutant of PNP, three intermediates (PAP, HQ and BQ) were
detected by HPLC analysis during reaction process. The concentra-
tion of PNP, PAP, HQ and BQ were also quantified by HPLC. And
molar balance profile over the duration of process was obtained by
summing these four species (PNP, PAP, HQ, BQ). Fig. 2a shows that
there were 1.570 mmol/L of residual PNP, 1.891 mmol/L,
through SO
4
of PS activation reaction and OH of Fenton-like
reaction in mFe/Cu-air-PS system. It could be observed from
Figs. 2(b) and (c) that the evolution profiles of these species in mFe/
Cu-air-PS systems with MeOH and TBA were similar to that
without scavengers, but their concentrations and molar balance
were lower than that without scavengers. In addition, it also could
be found from Fig. 2d that the UV–vis spectral curves with the
added scavengers were higher than that without the scavengers.
The results indicate that these scavengers could restrained PNP
degradation during reaction process. Compared the system added
MeOH and TBA in mFe/Cu-air-PS system, the concentration of
residual PNP, PAP, HQ and BQ in the existence of MeOH was similar
to that in the existence of TBA, as well as the intensities of UV–vis
spectra peaked at 317 nm and 227 nm. However, the concen-
trations of PAP and molar balance of the former (1.311 and
1.747 mmol/L) were higher than the latter (0.679 and 1.607 mmol/
L) after 60 min treatment, while those of HQ and BQ (0.436 and
<0.001 mmol/L) were lower that the latter (0.926 and 0.003 mmol/
L). Furthermore, the UV–vis spectrum peaked at 227 nm of the
former was higher the latter after 60 min treatment. The results
ꢀ
ꢀ
4
ꢁ
suggest that OH and SO
both facilitate the degradation of
ꢀ
ꢁ
pollutants, and SO
4
act as the main oxidant.
0
.046 mmol/L and 0.015 mmol/L of generation of PAP, BQ and
Furthermore, as shown in Fig. S3(Supporting information), the
removal efficiencies of COD and TOC both increased as the reaction
progress, and reached 71.0%, 65.8% after 60 min treatment,
respectively. The results suggest that aeration and feeding of PS
in batches could obviously improve the performance of mFe/Cu to
degradation of PNP, and the intermediates also could be further
mineralized. As above described, thus the main degradation
pathway of PNP in mFe/Cu-air-PS is proposed and presented in
Scheme 1. Specifically, at the early stage of the reaction (10 min),
PNP was mainly reduced to PAP through directly accepting electron
from Fe0 or by indirectly [H] formed on the active sites of Cu,
HQ at 10 min treatment by mFe/Cu-air-PS system. The results
demonstrate that in the first 10 min reaction period, reduction
reaction is the main reaction pathway in this system due to no PS
addition. Furthermore, it also could be found from Fig. 2a that
nearly 95.17% PNP vanished, but PAP increased and peaked at
2
.19 mmol/L at 20 min when adding PS for the first time, which
indicates PS could improve the performance of mFe/Cu-air-PS
system for PNP degradation through facilitating iron corrosion. In
addition, HQ increased slightly up to 0.07 mmol/L, but BQ nearly
decomposed and the molar balance obviously dropped at 20 min
treatment process. Based on previous analysis of UV–vis spectra,
once the PS was added into the solution, PS could be decomposed
to generate amount of SO
degradation efficiency of PNP via oxidation reaction. And then,
PNP was entirely decomposed, PAP and the molar balance
combined slight oxidative degradation of PNP into BQ and further
ꢀ
ring opening compounds (e.g., small molecular organics) by OH
ꢀ
ꢁ
4
. Thus, PS could enhance the
formed through Fenton-like reactions. Furthermore, the oxidative
products of BQ and HQ largely formed because the added PS could
ꢀ
ꢁ
be activated to generate SO
4
, making the oxidation reaction
Fig. 2. Comparison of (a–c) molar concentration profiles of PNP and the intermediates (PAP, HQ, BQ) with treatment time and (d) UV–vis spectra of the effluent participated
with MeOH or TBA in mFe/Cu-air-PS system.
Please cite this article in press as: H. Zhang, et al., Degradation of p-nitrophenol (PNP) in aqueous solution by mFe/Cu-air-PS system, Chin.
Chem. Lett. (2019), https://doi.org/10.1016/j.cclet.2019.01.025

G Model
CCLET 4793 No. of Pages 4
4
H. Zhang et al. / Chinese Chemical Letters xxx (2018) xxx–xxx
Scheme 1. Proposed possible reaction pathway for the degradation of PNP by mFe/Cu-air-PS system.
predominant. Meanwhile, a part of PNP was further reduced to PAP
due to little PS in the reaction solution at 10 min. Oxidation
reaction proceed with the PS further added into solution. In other
words, when PS was further added in reaction solution, the
Acknowledgments
The authors would like to acknowledge the financial support
from the National Natural Science Foundation of China (No.
51878423) and China Postdoctoral Science Foundation (No.
2018M631077).
ꢀ
ꢀ
ꢁ
oxidation by SO
4
and OH instead of reduction of PNP plays a
predominant role, thus PAP was further oxidized to HQ and BQ.
Finally, their benzene rings were broken to small molecular
organics, and further mineralized to CO
2
and H
2
O.
Appendix A. Supplementary data
In this study, a system of mFe/Cu-air-PS was conducted to treat
PNP in aqueous solution. Firstly, the optimal operating parameters
Supplementary material related to this article can be
found, in the online version, at doi:https://doi.org/10.1016/j.
cclet.2019.01.025.
(
aeration rate of 1.0 L/min, TMLCu of 0.110 g Cu/g Fe, mFe/Cu dosage
of 15 g/L, PS total dosage of 15 mmol/L, feeding times of PS of 5,
initial pH of 5.4 (unadjusted)) were obtained by the batch
experiments. Moreover, compared with the control experiments
References
(
i.e., mFe/Cu, air, PS, mFe/Cu-air, mFe/Cu –PS, air-PS and mFe-air-
[
[
1] Z. Xiong, B. Lai, Y. Yuan, et al., Chem. Eng. J. 302 (2016) 137–145.
2] W.J. Epolito, H. Yang, L.A. Bottomley, S.G. Pavlostathis, J. Hazard. Mater. 160
PS), mFe/Cu-air-PS system exerted superior performance for
degradation of PNP, and higher COD and TOC removal efficiencies
(
2008) 594–600.
(
71.0%, 65.8%) after 60 min treatment due to the strong synergistic
[3] T. Suzuki, M. Moribe, Y. Oyama, M. Niinae, Chem. Eng. J. 183 (2012) 271–277.
[
[
[
4] H. Liu, Q. Wang, C. Wang, X.Z. Li, Chem. Eng. J. 215 (2013) 90–95.
5] Y.Q.Gao,N.Y.Gao,Y.Deng,Y.Q.Yang,Y.Ma,Chem.Eng.J.195–196(2012)248–253.
6] Y.J. Shih, W.N. Putra, Y.H. Huang, J.C. Tsai, Chemosphere 89 (2012) 1262–1266.
effect between mFe/Cu, air and PS. In addition, this reinforcement
by feeding of PS in batches was greater than by aeration based on
control systems and radical quenching tests results. Furthermore,
the degradation pathway of PNP in mFe/Cu-air-PS process was
proposed through formed intermediates measured by HPLC, which
reveals that both oxidation and reduction effects facilitate the PNP
degradation. As a result, toxic and refractory PNP in aqueous
solution could be degraded into intermediates with lower toxicity
[7] J.P. Zou, D.D. Wu, J. Luo, et al., ACS Catal. 6 (2016) 6861–6867.
[8] F. Li, D. Wang, Q.J. Xing, et al., Appl. Catal. B: Environ. 243 (2019) 621–628.
[
9] J.P. Zou, Y. Chen, S.S. Liu, et al., Water Res. 150 (2019) 330–339.
10] C.S. Liu, K. Shih, C.X. Sun, F. Wang, Sci. Total Environ. 416 (2012) 507–512.
11] M. Nie, C. Yan, M. Li, et al., Chem. Eng. J. 279 (2015) 507–515.
[12] X. Guan, Y. Sun, H. Qin, et al., Water Res. 75 (2015) 224–248.
[
[
[
[
[
13] B. Lai, Y.H. Zhang, Z.Y. Chen, et al., Appl. Catal. B: Environ. 144 (2014) 816–830.
14] Z. Xiong, B. Lai, P. Yang, Y. Zhou, J. Wang, S. Fang, J. Hazard. Mater. 297 (2015) 261–268.
15] Q. Ji, J. Li, Z. Xiong, B. Lai, Chemosphere 172 (2016) 10.
2 2
products and could be further mineralized into CO and H O.
Therefore, the mFe/Cu-air-PS system can be considered as an
effective, robust and feasible treatment method for PNP in aqueous
solution.
[16] X. Guo, Z. Yang, H. Dong, et al., Water Res. 88 (2016) 671–680.
[17] L. Tang, J. Tang, G. Zeng, et al., Appl. Surf. Sci. 333 (2015) 220–228.
[18] Y. Nakatsuji, Z. Salehi, Y. Kawase, J. Environ. Manage. 152 (2015) 183–191.
[19] H.Y. Liang, Y.Q. Zhang, S.B. Huang, I. Hussain, Chem. Eng. J. 218 (2013) 384–391.
Please cite this article in press as: H. Zhang, et al., Degradation of p-nitrophenol (PNP) in aqueous solution by mFe/Cu-air-PS system, Chin.
Chem. Lett. (2019), https://doi.org/10.1016/j.cclet.2019.01.025