A Polymerization-Cutting Strategy: Self-Protection Synthesis of Thiol-Based Nanoporous Adsorbents for Efficient Mercury Removal

Article abstract of DOI:10.1002/chem.201802378

Highly toxic heavy metal ions such as mercury ions (Hg²⁺) are a great threat to human life and the environment. Developing new strategies and materials to remove the toxic heavy metal ions has attracted more and more attentions. Herein a facile

Full text of DOI:10.1002/chem.201802378

A Journal of
Accepted Article
Title: A Polymerization-Cutting Strategy: Self-Protection Synthesis
of Thiol-Based Nanoporous Adsorbents for Efficient Mercury
Removal
Authors: yang xu, Tianqi Wang, zidong he, Minghong Zhou, Wei Yu,
Buyin Shi, and Kun Huang
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To be cited as: Chem. Eur. J. 10.1002/chem.201802378
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A Polymerization-Cutting Strategy: Self-Protection Synthesis of
Thiol-Based Nanoporous Adsorbents for Efficient Mercury
Removal
Yang Xu, Tianqi Wang, Zidong He, Minghong Zhou, Wei Yu, Buyin Shi and Kun Huang*[a]
Abstract: Highly toxic heavy metal ions such as mercury ions (Hg2+)
are a great threat to human life and the environment. Developing
new strategies and materials to remove the toxic heavy metal ions
has attracted more and more attentions. Herein we report a facile
self-protection synthesis of thiol-based nanoporous adsorbents for
efficient mercury removal via a polymerization-cutting strategy. The
direct free radical polymerization of divinyl disulfide derivative and
subsequently cutting off the disulfide linkage, without post-synthesis
or modification, can give rise to an exceptionally high density of thiol
chelating sites. Moreover, the resultant thiol-based nanoporous
adsorbents (NAs-SH) exhibit a high saturation uptake capacity (1240
mg/g) and reused ability for mercury removal from water solution.
The proposed polymerization-cutting strategy may provide an
alternative and cost-effective method for the design and synthesis of
various effcient nanoporous adsorbents at large scale in the future.
materials (clays, activated carbons, and zeolites) with limited
uptake capacity, current research efforts have focused on the
development of functional porous adsorbents with various sulfur-
based ligands, such as thiol, thiourea, and thioether groups,
which can enhance the removal efficiency of Hg2+ from
contaminated wastewater through soft Lewis acid-based
interaction.[5, 8-9, 12-18] Generally, there are two main strategies to
incorporate sulfur-based functional groups into porous
adsorbents: that are direct synthesis and post-synthesis. For the
former, the sulfur-based functional monomers are directly used
to construct the final adsorbents with great adsorption
performance, such as thioether-based covalent organic
frameworks (COFs),[8] thiol-based metal-organic frameworks
(MOFs)[15]
and
various
sulfur-containing
nanoporous
adsorbents.[19] Despite the great success in the development of
various functional adsorbents via direct synthesis, the pre-
synthesis of special sulfur-based functional monomers are
usually complex, and the scope of functional ligands for
constructing the porous adsorbents remained relatively limited,
which will impede the further applications. Compared to the
direct synthesis strategy, the post-synthesis is regarded as a
more general approach to prepare various sulfur-based
functional porous adsorbents. For example, a series of thiol-
based porous adsorbents can be prepared by thiol-ene
Introduction
Water is a vitally important resource for human life. However,
with the rapid generation of an enormous amount of detrimental
chemical waste from various industries, the water pollution has
been a serious worldwide problem for several decades.[1-4] As
one of the hazardous metal ions, mercury has drawn increasing
attention due to its poisonous and harmful effects on human
health. Especially, the soluble divalent mercury ions (Hg2+) can
9, 14, 20]
transformations or chloromethylation modification.[5,
However, this strategy highly relies on the reactive nature of the
post-synthesis anchor, and the multistep post-synthetic
modifications are usually required, which complicates the
synthesis process. Therefore, developing an efficient, cost-
effective and large-scale synthesis strategy to prepare sulfur-
based functional porous adsorbents remains a challenge in
chemistry.
be easily transferred into higher toxic organometallic forms via
5-6]
biological methylation.[2-3,
Therefore, the removal of the
mercury ions pollutant from aqueous solution has become one
of the most critical aspects of environment research.
To date, several methods have been developed to remove the
mercury ions pollutant in contaminated industrial effluents.[3, 7-11]
Among them, adsorption using porous adsorbents is always
regarded as a superior technology for wastewater purification
due to its simplicity and low cost. Compared to traditional porous
[a]
Y, Xu; T, Wang; Z, He; M, Zhong; W, Yu; B, Shi and Prof. K, Huang
Department: School of Chemistry and Molecular Engineering
East China Normal University
500N, Dongchuan Road, Shanghai, 200241, P. R. China.
E-mail: khuang@chem.ecnu.edu.cn
Scheme 1. Synthetic scheme of thiol-based nanoporous adsorbents (NAs-SH)
via a facile polymerization-cutting strategy. Reaction conditions: (1) Free
radical polymerization: AIBN, THF, 100 oC and 24 hr. (2) Cutting off process:
TBP, THF/H2O (5:1, v/v), room temperature and 24 hr.
Supporting information for this article is given via a link at the end of
the document.
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Free radical polymerization (FRP), as a powerful method, has
been recently used to synthesize various functional materials.[21-
named as NAs-SHx:y (x:y represents the molar ratio of DVB to
bis-(4-vinylbenzyl)-disulfide monomer).
25]
Considering that FRP is a metal-free process, it can be an
environmentally friendly synthetic strategy to prepare useful
adsorbents for heavy metal ions removal. Moreover, to the best
of our knowledge, the direct synthesis of sulfur-containing
nanoporous adsorbents via FRP is still a great challenge.[26]
Keeping this idea in perspective, in this work, we report a facile
polymerization-cutting strategy to synthesize thiol-based cross-
linked nanoporous adsorbents for efficient mercury removal from
water. The proposed methodology allows a direct free radical
polymerization of divinyl disulfide derivative (bis-(4-vinylbenzyl)-
disulfide) with divinylbenzene (DVB) as a co-crosslinker to form
the disulfide and DVB co-crosslinked nanoporous adsorbents
(NAs-SS). Then, the disulfide linkage in the backbone can be
easily cut off and reduced to thiol groups within the networks
(Scheme 1). The advantages of this polymerization-cutting
strategy include: (1) without post-synthesis or modification of
sulfur-containing groups, simplifying the synthesis procedure; (2)
suppressing the quenching effect of thiol group for free radical
polymerization, offering a flexible strategy to position thiol
groups into the adsorbents with a large scale; (3) giving rise to
an exceptionally high density of thiol chelating sites for
adsorption, which one disulfide linkage can be converted to two
thiol groups. The resultant thiol-based nanoporous adsorbents
(NAs-SH) showed a high saturation uptake capacity of 1240
mg/g for Hg2+ in the water and can be recycled four times. In
short, this polymerization-cutting strategy may offer an
alternative and cost-effective method for the design and
synthesis of efficient nanoporous adsorbents at large scale.
Figure 1. The advantage of self-protection synthesis compared with the direct
synthesis for the preparation of NAs-SH. .
Results and Discussion
Designed Synthesis and Structural Characterization.
Herein, the aforementioned NAs-SS were firstly synthesized via
direct free radical polymerization of bis-(4-vinylbenzyl)-disulfide
(Figure S1 and S2) with divinylbenzene (DVB) as a co-
crosslinker in the presence of azobisisobutyronitrile (AIBN) as a
free radical initiator. Typically, monomers and AIBN are
dissolved in tetrahydrofuran (THF) and heated to 100 °C in a
solvothermal autoclave for 24 hr. As we all know, the thiol group
cannot be direct introduced into the materials through free
radical polymerization because it is a free radical quencher.[5]
However, the divinyl disulfide derivative can be direct
incorporated into the framework without quenching effect
(Figure 1). This can be named as a self-protection synthesis,
which can conquer the deficiency of direct free radical
polymerization of thiol monomers. Subsequently, the internal
disulfide linkage was cut off by using tributylphosphine (TBP) as
a reducing reagent in the THF/H2O solution at room temperature,
producing the final thiol-based nanoporous adsorbents NAs-SH
(Scheme 1). It is should be note that the content of DVB can
influence the content of thiol chelating sites in NAs-SH.Therefore,
we have prepared a series of NAs-SH for comparison, which are
Figure 2. (A) FT-IR spectra and (B) 13C MAS NMR spectra of (a) NAs-SS0.8:1
before reduction and (b) NAs-SH0.8:1 after reduction, respectively. (C) N2
adsorption-desorption isotherm of NAs-SH0.8:1 and BJH pore size distribution
was provided in the inset. (D) SEM image for NAs-SH0.8:1 and (E, F) elemental
mapping images of carbon and sulfur distributions. Scale bar: 100 nm.
To confirm the disulfide bond has been converted to thiol
group, the Fourier transform infrared (FT-IR) characterization,
solid-state 13C NMR and Raman spectroscopy studies were
performed. Here, the NAs-SH0.8:1 was selected as a typical
adsorbent for study in detail. Notably, compared with that of
pristine disulfide precursor NAs-SS0.8:1, a new characteristic
peak of S-H at 2556 cm-1 can be observed for the NAs-SH0.8:1 in
the FT-IR spectra, which demonstrates the successful formation
of free thiol groups (Figure 2A).[15] In addition, the solid-state 13
C
NMR studies also revealed that a new peak at 25 ppm ascribed
to the methylene C near thiol groups appeared and the peak at
39 ppm ascribed to the methylene C near disulfide groups
disappeared (Figure 2B), indicating the successful conversion
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of disulfide to thiol groups, which is in compliance with 13C NMR
characterization of their relative monomers (Figure S2 and
S3).[9] Moreover, the absence of the S-S stretching band at
around 500 cm-1 in the Raman spectrum of NAs-SH0.8:1 further
confirmed that the disulfide bond has been converted to thiol
group completely (Figure 6A).[5] These results also demonstrate
that TBP as a reducing reagent can cut the disulfide bond
thoroughly. To further support this claim, the comparison photos
of NAs-SS0:1 and NAs-SS0.8:1 before and after cutting process
are provided (Figure 3). The containing NAs-SS0:1 solution,
without DVB as co-crosslinker, was clear completely after
reduction process, while the containing NAs-SS0.8:1 solution kept
its turbid under the same condition, which proved that the TBP
can cut the disulfide bond completely and the co-crosslinker
DVB is important for construction of porous structure.
ratio of DVB to disulfide monomer, the NAs-SH0.8:1 with 80%
molar content of DVB showed the highest saturated Hg2+
removal capacity (1240 mg/g) (Figure 5A and 5B). This
phenomenon might be related to the sulfur content and surface
area of NAs-SH0.8:1. As shown in Figure 4, the BET surface area
increased from 0 to 45 m2/g when the molar ratio of DVB to
disulfide monomer changed from 0.2:1 to 1:1. The high surface
area will facilitate the mass transfer. Meanwhile, the
corresponding sulfur contents decreased from 15.5% to 11.7%
with the increase of DVB contents, which will result in decrease
of the density of thiol chelating sites. Therefore, the sulfur
content and surface area of NAs-SH are two key factors for Hg
removal. The equilibrium adsorption isotherm of NAs-SH0.8:1 was
well-fitted with Langmuir model that yielded a correlation
coefficient as high as 0.994 (Figure 5B). Remarkly, this Hg2+
removal capacity is much higher than those of most benchmark
porous materials, including MOF Zr-DMBD (197 mg/g),[15]
porous carbon (518 mg/g),[27] TAPB-BMTTPA-COF (734
mg/g),[8] chalcogel-1 (645 mg/g)[28] and some previously reported
thiol-based functional adsorbents (Table. S1). Such the
outstanding capacity of NAs-SH0.8:1 can be attributed to the
combination of high thiol content and relative high surface area,
which could facilitate to trap Hg2+ ions throughout the pore
surface of NAs-SH0.8:1. The disulfide crosslinked nanoporous
adsorbents (NAs-SS0.8:1) were also employed as control sample
to verify the contribution of the thiol groups in the uptake of Hg2+
(SI). Under the same conditions, the saturated Hg2+ removal
capacity of NAs-SS0.8:1 is only 350 mg/g, which indicates that the
disulfide linkages in the NAs-SS0.8:1 contribute little to the
capture of Hg2+ and the thiol groups in the NAs-SH0.8:1 play
critical role for Hg2+ removal.
Figure 3. The comparison photos of (A, B) NAs-SS0:1 and (C, D) NAs-SS0.8:1
before and after TBP cutting process.
To analyze the structure and composition of the obtained
material, N2 sorption analysis, elemental analysis and scanning
electron microscopy (SEM) characterizations were conducted.
The porosity and specific surface area of NAs-SH0.8:1 were
determined to be 25 m2 g-1 from N2 sorption isotherms at 77K.
BJH model of the adsorption branches showed pore size
distributions mainly at 2.44, 7.77, 23.4 and 37.7 nm, which
demonstrated that NAs-SH0.8:1 has a nanoporous property with
wider pore sizes distribution (Figure 2C). In addition, SEM
image of NAs-SH0.8:1 exhibited a nanoporous structure in
agreement with that of N2 sorption isotherms (Figure 2D). The
corresponding elemental mapping also showed homogeneous
distribution of carbon and sulfur in the entire range (Figure 2E
and 2F), indicating that exceptionally high density of thiol
chelating sites within the framework, which is consistent with the
result of elemental analysis (S 12.5%).
Figure 4. The relationship of surface area and sulfur contents for different
molar ratio of DVB to disulfide. Black line: surface area. Blue dot: sulfur
content.
Removal of Hg2+.
In addition to the high removal capacity, NAs-SH0.8:1 also
showed a good removal effectiveness. A time-course adsorption
measurement of NAs-SH0.8:1 for Hg2+ removal was conducted. It
can attain 95% of the adsorption capacity at equilibrium within
10 min and the Hg2+ concentration decreased from 10 ppm to
0.01 ppm within 20 min (Figure 5C). In addition, distribution
coefficient (Kd) is generally used to evaluate the affinity of
In order to investigate the Hg2+ removal capacity of the resultant
NAs-SH, adsorption isotherms for Hg2+ capture from water were
collected by using inductively coupled plasma (ICP) analysis.
Herein, a series of NAs-SHx:y with different DVB contents were
prepared for comparasion. Surprisingly, from 0.2:1 to 1:1 molar
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adsorbents for metal ions. Impressively, the Kd value of NAs-
SH0.8:1 at 25 °C was calculated to be 2.50 × 107 mL/g, which
ranks as one of the top values compared with those of typical
benchmark materials, including FJI-H12 (1.86 × 106 mL/g),[12]
TAPB-BMTTPA-COF (7.82 × 105 mL/g),[8] POP-SH (5.5 × 108
mL/g),[5] COF-S-SH (1.5 × 109 mL/g),[9] Zr-DMBD (9.99 × 105
mL/g),[15] S-FMCs (5.13 × 105 mL/g),[27] chalagel-1 (9.9 × 106
mL/g),[28] LHMS-1 (6.4 × 106 mL/g),[29] PAF-1-SH (5.76 × 107
mL/g)[14] and some best mercury adsorbent materials reported
(Figure 5D).[30] Although, removal capacity and removal
effectiveness of NAs-SH0.8:1 for Hg2+ is not the best, the simple
synthesis with a large scale and high density of thiol chelating
sites can make them to be a candidate nanoporous adsorbent
for practical applictioans in the future.
hardness (η). The η values of Hg2+ and Pb2+ are 7.7 and 8.46 eV,
respectively. Therefore, Hg2+ and Pb2+ should have the similar
interaction towards thiol groups, which is also agreement with
their capturing behavior.[31] Recycle performance of adsorbents
is also critical for practicle use. Significantly, NAs-SH0.8:1 can
easily be regenerated by treating them with an aqueous HCl
solution (6.0 M) and then subjected to the next round Hg2+
removal. Notably, it was demonstrated that NAs-SH0.8:1 could
retain their high uptake capacity for at least four cycles, affording
a value of 1000 mg/g (Figure 5F).
Interaction between Thiol and Hg2+.
The outstanding performance of NAs-SH0.8:1 for Hg2+ capture
can be traced to the remarkable coordination interactions
between the Hg2+ ions and thiol groups in NAs-SH0.8:1, which
have been elucidated by Raman and X-ray photoelectron
spectroscopy (XPS) spectroscopy studies. The Raman spectrum
of Hg@NAs-SH0.8:1 displayed a wide peak from 275 to 290 cm-1,
attributed to the Hg-S stretching vibrations, confirmed the
coordination between sulfur and Hg (Figure 6A).[5, 15] Moreover,
Hg loaded on NAs-SH0.8:1 was confirmed by the appearance of
Hg2+ XPS signals at 100.6 and 104.7 eV assigned to the Hg 4f5/2
and Hg 4f7/2 spectrum, respectively (Figure S5).[9] Additionally,
the strong coordination interactions between the Hg2+ and S
species in Hg@NAs-SH0.8:1 were proved from the S 2p XPS
spectra, which showed a 0.9 eV shift for the S binding energy in
Hg@NAs-SH0.8:1 compared to that of pristine NAs-SH0.8:1
(Figure 6B).[9] Therefore, the effective capture of Hg2+ by NAs-
SH0.8:1 stems essentially from the coordination interactions
between Hg2+ and the thiol groups.
Figure 5. (A) Hg2+ adsorption capacity based on various molar ratio of DVB to
disulfide of NAs-SHx:y (x:y = 0.2:1, 0.4:1, 0.6:1, 0.8:1 and 1:1) (B) Hg2+
adsorption isotherm of NAs-SH0.8:1. Inset shows the linear regression by fitting
the equilibrium data with the Langmuir adsorption model. (C) Hg2+ sorption
kinetics under the initial Hg2+ concentration of 10 ppm. (D) Comparison of Hg2+
saturation uptake capacity and Kd value for NAs-SH0.8:1 with various reported
porous materials. (E) Capture efficiency in selective removing metal ions. (F)
Recycle performance of NAs-SH0.8:1 for Hg2+ removal in water.
Figure 6. (A) Raman spectra of (a) NAs-SS0.8:1, (b) NAs-SH0.8:1 and (c)
Hg@NAs-SH0.8:1. (B) S 2p XPS spectra of (a) NAs-SH0.8:1 and (b) Hg@NAs-
SH0.8:1
.
Conclusions
For practical applications, selectivity and recycle performance
of adsorbents are two important factors for Hg2+ removal from
water. As shown in Figure 5E, NAs-SH0.8:1 can effectively
capture toxic heavy metal ions Hg2+ and Pb2+, but they showed
negligible capturing capability for other metal ions, such as Cu2+,
Fe3+, Na+, Mg2+, Cd2+ and Ca2+. Therefore, NAs-SH0.8:1 have a
outstanding selectivity for heavy metal ions removal, which can
be attributed to the soft-soft interactions between thiol-based
chelating groups and the soft metal ions.[5] In addition, the soft
acids degree of metal ions can be quantified through absolute
In conclusion, we developed a facile polymerization-cutting
strategy to synthesize thiol-based crosslinked nanoporous
adsorbents for efficient mercury removal from water. The direct
incorporation of disulfide monomer within the framework without
post-synthesis and post-modification can obviously simplify the
preparation process. Based on the high thiol content and
nanoporous structure, one of the resultant thiol-based
nanoporous adsorbents (NAs-SH0.8:1) exhibits exceedingly high
Hg2+ uptake capacity of 1240 mg/g, high affinity for Hg2+ with
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J = 8 Hz, 2H). 13C NMR (500 MHz, CDCl3): δ 28.95, 114.00, 126.68,
128.65, 129.58, 136.64, 140.99.
exceptional distribution coefficient value and good recycle
performance. In short, this polymerization-cutting strategy may
offer an alternative and cost-effective method for the design and
synthesis of efficient nanoporous adsorbents at large scale for
heavy metal ions capture in practical applications.
Synthetic procedure for disulfide cross-linked nanoporous
adsorbents (NAs-SS).
Experimental Section
General Procedures. All reagents were used as received unless stated
otherwise. Divinylbenzene (DVB) was purified by passing over basic
alumina. 2, 2-Azoisobutyronitrile (AIBN) was purified by recrystallization
from methanol. All 1H NMR spectra were recorded on a Bruker AVANCE
III™ 500 spectrometer (500 MHz) by using CDCl3 as solvent. The solid-
state NMR spectra were recorded on a Bruker AVANCE III 400 WB
spectrometer. The contents of the metal ions were determined by using a
PerkinElmer Optima™ 5300 DV ICP optical emission spectrometer. A
Quantachrome Autosorb IQ surface area and porosity analyzer was
utilized to study the pore structure of the samples. Before measurements,
the polymer samples were degassed for more than 10 h at 120 °C. The
Brunauer-Emmett-Teller (BET) surface area was determined by the BET
equation. The pore size distribution was analyzed by original Barrett-
Joyner-Halenda (BJH) method. Scanning electron microscope (SEM)
image was obtained using JEOL JSM-7800F Prime SEM instrument. The
infrared (IR) spectra were recorded using Thermo NICOLET is 50.
Raman spectra were collected on a ThermoDXR instrument with a λ =
532 nm excitation laser. X-ray photoelectron spectroscopy (XPS) spectra
were obtained on an ESCALAB 250Xi spectrometer. Elemental analysis
was carried out on an Elementar Analysensysteme GmbH Vario EL III
elemental analyzer.
NAs-SS0.8:1 was selected as a typical sample for description in detail.
The bis-(4-vinylbenzyl)-disulfide (400 mg) was mixed with AIBN (4 mg,
2 % molar ratio to disulfide monomer), DVB (0.15 mL, 80 % molar ratio to
disulfide monomer) and THF (5 mL) in a reaction vessel and degassed
by 3 freeze-pump-thaw cycles. The reaction was then conducted at
100 °C for 24 h. After that, the reaction was stopped by cooling to room
temperature and opening the flask to air. The resulting white solid was
washed by THF and dried under vacuum at 25 °C for 24 h. Yield > 95 %.
Synthetic procedure for thiol-based cross-linked nanoporous
adsorbents (NAs-SH0.8:1).
Synthetic procedure for divinyl disulfide derivative (bis-(4-
vinylbenzyl)-disulfide).
The typical procedure to prepare bis-(4-vinylbenzyl)-disulfide is as follow.
Na2S·9H2O (5.52 g, 23 mmol) was mixed with sulfur powder (0.75 g, 23
mmol) in water (45 mL) and stirred at 100 oC for 1 hr. After the mixture
was cooled to room temperature, toluene (84 mL) and
tetrabutylammonium (TBAB, 0.74 g, 2.3 mmol) was added into above
solution. Next, 4-vinly benzyl chloride (6.24 mL, 44 mmol) was added
dropwise into the mixture. After stirring at 60 oC for 24 hr, the mixture was
cooled to room temperature. The organic layer was washed with cold
water (100 mL x 3 times) and then the solvent was evaporated. The
residue was dissolved in ether / hexane and cooled to -78 oC. The
precipitates were filtered and crystallized twice in the similar way. The
obtained crude products were then dissolved in ether and filtered off by
Celite. Finally, the filtrate was concentrated. The brilliant white solid was
dried under vacuum at 25 °C for 24 h. Yield > 60 %. 1H NMR (500 MHz,
CDCl3): δ 3.62 (s, 2H); 5.24 (d, J = 11 Hz, 2H); 5.74 (d, J = 18 Hz, 2H);
6.71 (dd, 2H); 7.20 (d, J = 8 Hz, 4H); 7.37 (d, J = 8 Hz, 4H). 13C NMR
(500 MHz, CDCl3): δ 43.05, 113.99, 126.35, 129.63, 136.42, 136.84,
136.93. For comparison, 4-vinyl-phenyl methane thiol (Figure S3 and S4)
is prepared according to the literature procedure.[32] 1H NMR (500 MHz,
CDCl3): δ 1.77 (t, J = 8 Hz, 1H); 3.75 (d, J = 8 Hz, 2H); 5.26 (d, J = 11 Hz,
1H); 5.76 (d, J = 18 Hz, 1H); 6.73 (dd, 2H); 7.30 (d, J = 8 Hz, 2H); 7.39 (d,
The NAs-SS0.8:1 (400 mg) was mixed with TBP (1 mL) in THF / H2O (10
mL / 2 mL) solution under N2 atmosphere. The mixture was stirred at
room temperature 24 hr. Then, the resulting white solid was washed by
THF (5 mL x 3 times) and dried under vacuum at 25 °C for 24 h. Yield >
95 %. Elemental analysis: C 72.6%, H 7.83%, S 12.5%.
Sorption Experiments.
Hg2+ sorption isotherm. To obtain the adsorption isotherm of NAs-SH, 5
mg of adsorbents were placed in 10 mL aqueous solutions of varying
Hg2+ concentrations (25-800 ppm). The solutions were sonicated to
create full dispersion and then stirred 12 hr. The solutions were filtered
and the filtrate was analyzed via ICP to determine the residual Hg2+
concentrations. The adsorption capacity (qe) was calculated according to
the equation
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where C0 and Ce are the initial and equilibrium concentrations,
respectively. V is the volume of used, and m represents the weight of the
adsorbents.
Hg2+ sorption kinetics. 10 mg of NAs-SH0.8:1 was added to an
Erlenmeyer flask containing 200 mL of a 10 ppm Hg2+ solution. The
mixture was sonicated for full dispersion. At increasing time intervals 3
mL aliquots were removed from the mixture and the filtrate was analyzed
by ICP-OES for the remaining Hg2+ concentration.
Selectivity test. 20 mg of NAs-SH0.8:1 was added to 200 mL of the mixed
metal solution, which was made with various salts of Hg2+, Cu2+, Mg2+
,
Cd2+, Fe3+, Pb2+, Na+, and Ca2+, with equal concentrations of ~5 ppm.
After stirring overnight, the solutions were filtered and the filtrate was
analyzed by ICP for the remaining metal ions concentrations. The
removal efficiency was calculated according to the equation
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This article is protected by copyright. All rights reserved.

10.1002/chem.201802378
Chemistry - A European Journal
FULL PAPER
Entry for the Table of Contents
FULL PAPER
Yang Xu, Tianqi Wang, Zidong He,
Minghong Zhou, Wei Yu, Buyin Shi and
Kun Huang*
Page No. – Page No.
A
Polymerization-Cutting Strategy:
Text for Table of Contents
Self-Protection Synthesis of Thiol-
Based Nanoporous Adsorbents for
Efficient Mercury Removal
A facial self-protection synthesis of thiol-based nanoporous adsorbents
via a polymerization-cutting strategy was reported for the first time.
The resultant thiol-based nanoporous adsorbents (NAs-SH) showed a
high saturation uptake capacity of 1240 mg/g for Hg2+ in the water and
can be recycled four times.
This article is protected by copyright. All rights reserved.