Hydrothermally synthesized mesoporous CS-g-PA@TSM functional nanocomposite for efficient photocatalytic degradation of Ciprofloxacin and treatment of metal ions

Article abstract of DOI:10.1016/j.molliq.2021.116144

Tin-based ternary inorganic semiconductors enable new opportunities for the development of functional hydrogel nanocomposites to cope with environmental pollution. In this regard, we have synthesized highly functionalize CS-g-PA@TSM nanocomposites by the impregnation of Tin- Si/Mo (TSM) semiconductor in the matrix of chitosan/polyacrylamide (CS-g-PA) using the hydrothermal route. Multifunction platform showed ammonia vapor sensing, fluorescent detection as well as removal and exchange recovery of lead ions from wastewater and its photocatalytic behavior towards antibiotic degradation. The CS-g-PA@TSM nanocomposite achieved almost 96% photodegradation towards Ciprofloxacin (CIP) after 130 min of irradiation which was further monitored and confirmed by 3-D excitation-emission matrix fluorescence and GC–MS techniques, respectively. The photocatalytic mechanism of the CS-g-PA@TSM under visible light irradiation was clarified, which established the generation of [rad]O₂^? / [rad]OH species in the form of dominant radicals. The experimental results indicated that the improved photocatalytic performance of CS-g-PA@TSM could be attributed to enhance the optical absorption and efficient separation along with the migration of photoinduced charge carriers. The nanomaterial also exhibits significant Pb²⁺ recovery (95.6%) from wastewater with a limit of detection (LOD) and limit of quantification (LOQ) as 3.38 μg L^?1 and 9.34 μg L^?1, respectively. The CS-g-PA@TSM nanocomposite was successfully employed up to five regeneration cycles with 98% regeneration capacity. Thus, the finding of the present study establishes that the multifunctional CS-g-PA@TSM nanocomposite platform could be used for the treatment of antibiotics (CIP), ammonia, and Pb²⁺ from wastewater.

Full text of DOI:10.1016/j.molliq.2021.116144

Journal of Molecular Liquids 335 (2021) 116144
Contents lists available at ScienceDirect
Journal of Molecular Liquids
journal homepage: www.elsevier.com/locate/molliq
Hydrothermally synthesized mesoporous CS-g-PA@TSM functional
nanocomposite for efficient photocatalytic degradation of Ciprofloxacin
and treatment of metal ions
a
a
Yahiya Kadaf Manea a,c, Amjad Mumtaz Khan a, , Ajaz Ahmad Wani , Mohsen T.A. Qashqoosh ,
⇑
Mohammad Shahadat b, Mansour A.S. Salem a
a Department of Chemistry, Aligarh Muslim University, Aligarh 202002, India
b School of Chemical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia
c Department of Chemistry, University of Aden, Aden, Yemen
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 11 November 2020
Revised 4 April 2021
Accepted 9 April 2021
Available online 17 April 2021
Tin-based ternary inorganic semiconductors enable new opportunities for the development of functional
hydrogel nanocomposites to cope with environmental pollution. In this regard, we have synthesized
highly functionalize CS-g-PA@TSM nanocomposites by the impregnation of Tin- Si/Mo (TSM) semicon-
ductor in the matrix of chitosan/polyacrylamide (CS-g-PA) using the hydrothermal route.
Multifunction platform showed ammonia vapor sensing, fluorescent detection as well as removal and
exchange recovery of lead ions from wastewater and its photocatalytic behavior towards antibiotic
degradation. The CS-g-PA@TSM nanocomposite achieved almost 96% photodegradation towards
Ciprofloxacin (CIP) after 130 min of irradiation which was further monitored and confirmed by 3-D
excitation-emission matrix fluorescence and GC–MS techniques, respectively. The photocatalytic mech-
anism of the CS-g-PA@TSM under visible light irradiation was clarified, which established the generation
of ÅOꢀ2 / ÅOH species in the form of dominant radicals. The experimental results indicated that the
improved photocatalytic performance of CS-g-PA@TSM could be attributed to enhance the optical
absorption and efficient separation along with the migration of photoinduced charge carriers. The nano-
material also exhibits significant Pb2+ recovery (95.6%) from wastewater with a limit of detection (LOD)
Keywords:
Nano-photocatalyst
Optical property
Lead removal
Ammonia sensing
Antibiotics degradation
and limit of quantification (LOQ) as 3.38
l l
g Lꢀ1 and 9.34 g Lꢀ1, respectively. The CS-g-PA@TSM
nanocomposite was successfully employed up to five regeneration cycles with 98% regeneration capacity.
Thus, the finding of the present study establishes that the multifunctional CS-g-PA@TSM nanocomposite
platform could be used for the treatment of antibiotics (CIP), ammonia, and Pb2+ from wastewater.
Ó 2021 Elsevier B.V. All rights reserved.
1. Introduction
hormones, and antibiotics (e.g., ciprofloxacin, tetracycline, amoxi-
cillin, salbutamol, estrone, etc.)] have been detected in the wastew-
The emission of environmental pollutants consisting of metal
ions, emerging contaminants (ECs), and organic pollutants to the
water bodies has disturbed the aquatic ecosystem, which severely
affects the environment and human health [1,2]. Ingestion of these
pollutants through water, food, and the air is injurious to health as
they interrupt normal body function by damaging soft body parts
(e.g., liver, kidney, brain, and reproductive systems, etc.) [3,4]. On
the other hand, hospital sewage having ECs such as pharmaceutical
compounds [anti-inflammatory drugs (NSAIDs), steroidal
ater around the world [5-8]. Therefore, it is necessary to apply an
effective technology to treat wastewater consisting of these pollu-
tants from wastewater before being used for any useful purpose.
Among various used techniques, removal and recovery of environ-
mental contaminants using functional nanocomposites has
attracted more attention owing to its low cost, energy-savings,
and higher efficiency [9]. Degradation of environmental pollutants
using photocatalytic oxidation under visible light irradiation is
gaining considerable interest to utilize maximum energy sources
[10-12]. Alternatively, cation exchange-based photocatalysis has
proved to be a promising green technology to counter global issues
related to detoxification and degradation of organic pollutants.
Recently, transition metal salt (TMS) doped with semiconductors
⇑
Corresponding author.
E-mail address: amjad.mt.khan@gmail.com (A.M. Khan).
https://doi.org/10.1016/j.molliq.2021.116144
0167-7322/Ó 2021 Elsevier B.V. All rights reserved.

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
such as silicon have been attracted more research interest world-
wide owing to their environmental benignity and significant elec-
tronic conductivity [13]. In particular, metal silico/molybdates (M
(Si/Mo)xOy = Zn, Ti, Mg, Sr, Ba, Ni, Co, Pb, Ca, Cd, Cu, Sn, and so
forth) are one of the most significant families of inorganic materi-
als that have been widely used in various fields. Among them, Si
intercalated tin molybdate (Tin(Si/Mo)xOy) is found an interesting
inorganic material due to its excellent peculiar properties such as
optical and electronic structure [14]. The treatment of these semi-
conductors with proton indicates a reversible bandgap with
improved activity for H2 production [15] which confirms that the
polymeric semiconductor has potential to cover a wide range of
potential applications [16].
Recently, hydrogel-based nanocomposites represent an innova-
tive class of materials that has attracted attention because of their
thermal and chemical stability and synergic effect of nanoparticles
(inorganic fillers) in the polymer matrix. Hydrogel nanocomposites
exhibit multi-functional and stimuli-responsive properties due to
the interconnectivity of the hydrogel network with inorganic
NPs. In the current study, a facile approach was used to synthesize
Chitosan-g-Polyacrylamide@Tin (Si/M o)xOy (CS-g-PA@TSM)
nanocomposite via radical-polymerization. Further, the CS-g-
PA@TSM nanocomposite was developed, followed by using a
‘‘bottom-up” approach involving in-situ hydrothermal deposition
of TSM in the matrix of the porous hydrogel. These composite
materials could be used in different fields because of multi-
functionality. This study also provides a deep understanding and
feasible methods to prepare efficient, recyclable material in terms
of ecological restoration. The CS-g-PA@TSM nanocomposite is
expected to enhance thermal stability, biocompatibility, porosity
and maintain high capacity along with high surface area while
simultaneously persisting/maintaining the inbuilt properties of
the inorganic Sn(IV) complex.
(CS-g-PA) as prepared in Section 2.1.1 was used as a host, whereas
the inorganic precipitate of Tin(IV)Si/Mo)xOy (TSM) was employed
as the guest (filler). The inorganic precipitate of tin silicomolybdate
(TSM) was mixed dropwise (using different mixing ratios) in the
matrix of CS-g-PA under vigorous stirring at 70 °C for 3 h. The N,
N methylene bisacrylamide crosslinking agent was employed to
couple organic–inorganic species [19]. Hence, the redox initiator
(KPS) generates hydroxyl radicals (ꢁOH), which then produce
active free-radical sites on PA. These sites then undergo graft
copolymerization with CS biopolymer to create CS-g-PA hydrogel
three-dimensional (3D) network of cross-linked polymer matrices.
The resultant precipitate of CS-g-PA@TSM was inserted into a
Teflon-lined autoclave and heated at 120 °C for 24 h. Afterward,
it was allowed to cool down at room temperature. The precipitate
(gel) was washed with deionized water trice and finally dried at
40 2 °C in an electrically controlled oven. The nanocomposite
was stored in a desiccator for further use as shown in Scheme 1a.
3. Results and discussion
3.1. FTIR, XRD and TGA-DTA analyses
The mixing of inorganic precipitate (TSM) into the matrix of chi-
tosan/ polyacrylamide (CS/PA) hydrogel using a sol–gel route fol-
lowed by hydrothermal method results in the formation of CS-g-
PA@TSM nanocomposite. Thus, by varying the mixing ratio of acry-
lamide and chitosan, different samples of CS-g-PA@TSM were syn-
thesized (as listed in Table S-1). Among different prepared samples,
the CS-g-PA@TSM showed the highest capacity along with better
optical property (the lowest band gap = 2.45 eV). It might be due
to the existence of a functional group; therefore, sample S-3*
(CS-g-PA@TSM) was chosen for detailed studies. The FTIR spectra
were examined to identify changes in the functional group of pre-
pared nanomaterials. Comparative FTIR spectra of CS-g-PA, TSM,
PTSM, and CS-g-PA@TSM nanocomposite are presented in Fig. 1a.
The broadband in the region of 3401 cmꢀ1 is attributed to the
hydroxyl group of water [20]. Another sharp band at 1622 cmꢀ1
is ascribed due to HAOAH bonding [21]. Other medium intensity
bands at 1633 cmꢀ1 and 1504 cmꢀ1 are accredited to amine and
amide groups of chitosan of CS-g-PA@TSM. The peak at
1404 cmꢀ1 is indicated the presence of a considerable amide in
CS-g-PA@TSM and PTSM composites. Other sharp frequency bands
at 1109 cmꢀ1 and 943 cmꢀ1 are related to the silicate and molyb-
date groups, respectively. The peak at 561 cmꢀ1 represents the Sn-
O-Sn vibrations of CS-g-PA@TSM and PTSM. Shifting of H2N-CO-
band to 1630 cmꢀ1 is possibly due to the interfacial electrostatic
interaction between nitrogen group of co-polymer matrix of CS-
g-PA (amine and imine groups) and inorganic complex of Tin(IV)
silicomolybdate (TSM) as shown in Scheme S-1b.
The result of DTA-TGA analysis of CS-g-PA@TSM nanocomposite
is shown in Fig. 1b. The TGA curve of CS-g-PA@TSM showed ~8.52%
weight loss up to 180 °C due to the elimination of water molecules
[22]. Another moderate loss in weight (~26%) from 180 to 250 °C
was attributed to the conversion of the silicate group to pyrosili-
cate as a result of the hydroxyl group due to condensation.
Onwards, the decomposition of CS-g-PA@TSM was found at
350 °C, which may be owing to the formation of metal oxide.
DTA measurements of CS-g-PA@TMS nanocomposite exhibited
one endothermic peak at 80.3 °C (transition temperature) and
two sharp exothermic peaks at 319.8 and 500 °C due to the loss
of adsorbed water molecules and dehydration and decomposition
of CS-g-PA@TMS, respectively [23]. Additionally, the TGA-DTA
curves of CS-g-PA hydrogel revealed significant weight loss (30%)
in the temperature range of 300–550 °C because of CS-g-PA hydro-
gel decomposition (Fig. 1c).
2. Experimental
Chemicals and reagents (S-2.1), Instrumentation (S-2.2), Pho-
todegradation of Ciprofloxacin (S-2.3), Gas chromatography-mass
spectrometry (S-2.4), fluorescence method for Pb2+ sensing (S-
2.5), Removal of Pb2+ from wastewater (S-2.6), Swelling study (S-
2.7), Gas vapor sensing behavior (S-2.8), Optical properties (S-
2.9), Ion-exchange capacity (S-3.0) along with Sorption studies
(S-3.1), and quantitative separation of metal ions from synthetic
and real water samples (S-3.2) were carried out are described in
the supplementary file.
2.1. Nanocomposites preparation
2.1.1. Synthesis of chitosan grafted polyacrylamide hydrogel (CS-g-PA)
The polymeric-matrix hydrogel was synthesized by using the
precursors of AA wM, and CS via the free-radical graft copolymer-
ization method. In a typical procedure, a mixture of acrylamide
(5%) and N, N methylene bisacrylamide (0.1 M) was added drop-
wise to the micellar media containing transparent chitosan solu-
tion. Potassium persulfate (KPS) prepared in 1 M HCl was added
dropwise to the above solution as an initiator. The mixture was
heated in a thermostat shaker at 70 °C for 2 h to obtain the viscous
gel. Finally, the product was filtered off and washed with deionized
water, dried in a vacuum, and stored in a desiccator for further use
[17,18].
2.1.2. Synthesis of CS-g-PA@TSM nanocomposite
Chitosan/polyacrylamide @Tin(IV) silicomolybdate (CS-g-
PA@TSM) nanocomposites were synthesized using the hydrother-
mal method. In this method, chitosan-grafted polyacrylamide gel
2

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
Scheme 1a. Schematic for synthesis of CS-g-PA@TSM nanocomposite.
Fig. 1. (a, b, c, d, e, f). FTIR spectra of CS-g-PA, PTSM, CS@PTSM (a); TGA-DTA curves of CS-g-PA and CS-g-PA@TSM (b,c); and XRD pattren of TSM, PTSM and CS-g-PA@TSM (d).
3.2. Morphological categorization
with PTSM, which suggested a higher degree of crystallinity in
CS-g-PA@TSM. A typical XRD pattern of the Tin(IV) molybdosilicate
was showed crystalline nature. The Bragg reflections at 2h = 28.6°,
35.5°, and 53.5° can be indexed to the (110), (200), and (211)
orientation, respectively [24]. These peaks confirm the complex
formation of the Tin(IV) on the silicate/molybdate surfaces. For
The amorphous or crystalline nature of synthesized TSM, PTSM,
and CS-g-PA@TSM nanohybrid materials was analyzed using XRD
analysis as shown in Fig. 1 d. The X-ray diffraction spectra of CS-
g-PA@TSM showed a high-intensity peak at 2h = 26.2° compared
3

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
range of 15–20 nm. Further, the particles size of TSM and PTSM
was 30 and 40 nm, respectively.
composite material polyacrylamide Tin(IV)silicomolybdate
(PTSM), well-defined peaks with 2h values at 11.8°, 28.8°, 35◦,
and 53.3°, respectively, ascribed to the association of polyacry-
lamide with Tin(IV) silicomolybdate (TSM). Additionally, high-
intensity peaks at 2h = 28.4°, 31.0°, 33.2°, 51.5°, and 65.3° were
responsible for intercalated TSM with CS/PA composites which
confirmed its crystalline nature. The XRD result revealed the crys-
talline nature of CS-g-PA@TSM nanocomposite enhanced by
impregnation of TSM in the matrix of CS@PA hydrogel.
From XRD analysis, considering the peak position at degrees,
average particle size has been calculated by using Debye–Scherrer
formula
SEM images of CS-g-PA@TSM, CS-g-PA, and PTSM are shown in
Fig. 2 a-d. The particle size of CS-g-PA@TSM was almost uniform
with 10–19 nm. However, the morphology of PTSM (Fig. 2b) was
found different than that of CS-g-PA@TSM (Fig. 2 c, d). The SEM
images of CS-g-PA@TSM nanocomposite have well-defined spheri-
cal microspheres. In addition, SEM images demonstrated interac-
tion and nucleate of CS-g-PA co-polymer around TSM particles
due to the coordination of tin (Sn4+) with silicate and molybdate
(Mo6+) at the surface of TSM [25]. This established the excellent
intercalation between the inorganic TSM particles and CS@PA co-
polymer matrix. Association of CS-g-PA with TSM was further pro-
ven by the EDX analysis (as shown in Fig. 2 j and k).
A higher percentage of carbon was found in CS-g-PA@TSM as
compared to C PTSM sample, and the elemental mapping showed
uniform distribution of CS-g-PA on the surface of TSM particles
(Fig. 2i). The strong association of CS-g-PA co-polymer hydrogel
with TSM was further confirmed by TEM analysis (Fig. 2 e, f, g,
h). TEM studies revealed the spherical surface morphology of the
Kk
D ¼
bCOSh
where ’K’ is a dimensionless shape factor, with a value close to
unity, the shape factor has a typical value of about 0.9, ’k’ is the
wavelength of X-ray (0.154 nm), ’b’ is the FWHM (full width at half
maximum), ’h’ is the diffraction angle and ’D’ is particle diameter
size. The crystallite size of CS-PA@TSM particles was found in the
Fig. 2. (a, b, c, d). SEM images for (a) Chitosan -g-polyacrylamide hydrogel; (b) PTSM; (c, d) CS-g-PA@TSM; TEM micrographs of PTSM (e), TEM micrographs of CS-g-PA @TSM
at different magnifications (f, g, and h). Mapping analysis of Cs-g-PA@TSM (i), EDS spectrum of PTSM (j), and CS-g-PA@TSM (k).
4

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
CS-g-PA@TSM in comparison with PTSM nanocomposite. It is con-
firmed by analyzing TEM images that confirmed that the average
size of spherical CS-g-PA@TSM nanocatalyst (Fig. 2 f, g, h) was
found to be in the range of 10–20 nm, smaller than the average
diameter of PTSM composite (Fig. 2e). The crystalline transforma-
tion might be due to the impregnation of CS@PA co-polymer to
the inorganic counterpart TSM. TEM images of the CS-g-PA@TSM
composites also illustrated the association of TSM with CS-g-PA
matrix, which is uniformly dispersed onto its surface (Fig. 2f).
The interlayer spaces of the lattice fringe of CS-g-PA@TSM were
0.366 and 0.263 nm, which were similar to the XRD spaces of the
(003) and (015) planes of TSM (2h = 11.3°, d = 0.3 nm and 2h =
25.9°, d = 0.264 nm), respectively. The oxidation state and elemen-
tal composition of CS-g-PA@TSM were investigated by XPS analysis
as shown in Fig. 3 (a-f). The full scan spectrum of CS-g-PA@TSM
(Fig. 3a) approves the presence of C, Mo, Sn, N, Si, and O elements
in CS@PTSM which agreed with the EDS data. Fig. 3b shows high
resolution of N 1 s spectrum, which was fitted with four peaks.
The four observed peaks correspond to -N < at 394.9 eV, -N-H at
397.8 eV, C-N-H at 399.8 eV, and -N = at 405.3 eV, respectively.
The XPS spectrum of Sn showed two sharp peaks at 487.1 and
495.4 eV corresponding to the Sn 3d5/2 and Sn 3d3/2 spin–orbit
levels of Sn4+. For molybdenum, the XPS spectrum of Mo can be
well fitted by two peaks at 230.1 eV and 234.2 eV corresponding
to the 3d5/2 and 3d3/2 states of Mo6+, respectively (Fig. 3 c, d)
[26]. The XPS spectrum of oxygen (different oxidation states) was
found on the range of 529, 531, and 533 eV, which provide infor-
mation about the lattice oxygen as chemisorbed oxygen and
Fig. 3. (a, b, c, d, e): X-ray photoelectron scanning spectra (a) and N. 1s (b) Sn 3d (c), Mo2p core level regions (d), O 1 s (e), and Si 2P (f).
5

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
adsorbed water molecules via C-O, O–M, and M-O-H, respectively
(Fig. 3e) [27]. Fig. 3f corresponds to the high resolution of Si 2p
spectrum was fitted with two peaks appear at 101.3 and
103.1 eV. The first peak is believed to arise from Si-O bonding
and the second peak at 101.3 eV is representative of Si-C bonding
[28]. The surface area and pore size of CS-g-PA @TSM were anal-
ysed by BET. According to N2 adsorption/desorption measurement,
the BET surface area was found to be (165 m2 gꢀ1), indicating a
high porosity of the CS-g-PA @TSM nanocomposite. The total pore
volume of CS-g-PA @TSM was found to be (5.6 ꢂ 10ꢀ3 cm3 gꢀ1),
and the average pore size 4.4 to 7.5 nm. These results prove the
mesoporous nature of CS-g-PA@TSM.
The optical property, EPR, CV, and PL studies
The UV–Vis diffuse reflectance spectra of nanocomposites were
measured to study the electronic structure and optical absorption
properties. The UV–vis. ranges of TSM, PTSM and, CS-g-PA @TSM
nanocomposite are presented in Fig. 4a0. The TSM nanoparticles
showed a strong bandgap at about 400 nm (2.85 eV). The UV
absorption capacities might be produced due to band transition
from O2 (2p) to Sn4+ (5p), while the visible-light absorption is
Fig. 4. (a0, b0, a, c, d): UV–Vis diffuses reflectance spectra (DRS) (a 0); and band gap of CS-g-PA@TSM (b0); EPR spectra of CS-g-PA@TSM fresh catalyst (a); recycled catalyst
after forth run corresponding spin densities and g ~ values (b), CV of CS-g-PA@TSM (red) and Pb2+ /CS-g-PA@TSM (black) (c); Photoluminescence spectra of CS-g-PA@TSM and
CS-g-PA (d).
6

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
associated with the transition from the valence band to (Sn4+ 5p)
conduction band [29]. Therefore, better optical properties of CS-
g-PA@TSM were achieved as compared to both PTSM and TSM.
The direct bandgap of the samples was evaluated by plotting the
modified Kubeka-Munk function [F(R) ꢂ hv] versus photon energy
(hv) (Fig. 4 b0) [30–32]. The coupling of TSM with polyacrylamide
demonstrates that no change was found in the bandgap absorption
of (TSM). However, in the case of TSM impregnated with CS-g-PA
to form (CS-g-PA @TSM) nanocomposite, the bandgap absorption
was extended into the visible light region (about 440 nm). Interest-
ingly, a moderate redshift towards the visible region was observed
in the CS-g-PA@TSM nanocomposite. It might be due to the quan-
tum size effect of TSM nanoparticles deposited on the CS-g-PA
hydrogel support. Moreover, the potent interfacial interaction
between CS-g-PA and TSM plays an important role in tailoring their
band structure. This characteristic of CS-g-PA @TSM nanocompos-
ite assists in improving its photo-activity under visible light irradi-
ation. The bandgap of the TSM, PTSM, and CS-g-PA @TSM
nanocomposite was found as 2.85, 3.25, and 2.45 eV, respectively,
which confirms that TSM particles were successfully immobilized
onto the CS-g-PA co-polymer hydrogel network.
From the UV (DRS) data, the bandgap values were found suit-
able and lie within the range of semiconductors; this feature makes
CS-g-PA@TSM a promising material that can be used as an efficient
photocatalyst. The EPR spectroscopy provided clear evidence about
the existence of unpaired electrons in any system. The EPR spectra
of CS-g-PA@TSM before and after CIP degradation, along with other
related parameters (spin population, g-value) are shown in Fig. 4a,
b [33,34]. The EPR analysis results revealed that oxygen vacancies
create reactive sites on Tin (IV) surface, which are responsible for
the degradation of CIP [35]. The EPR spectra of CS-g-PA@TSM
showed a sharp and distinct EPR line centered at g ~2.00254,
attributed to the unpaired electrons trapped in surface oxygen
vacancies by adsorbed oxygen (O2), which proves that tin assists
in the formation of oxygen vacancies during the degradation of
CIP (Fig. 4a) [36]. The electrochemical measurements of the CS-g-
PA@TSM were performed with a potential of ꢀ1.0 to 0.1 V at the
scan rate of 100 mVsꢀ1 using a three-electrode system (modified
GCE, Ag/AgCl, and KCl act as working, reference, and counter elec-
trode). Cyclic voltammograms of CS-g-PA@TSM exhibited well-
separated redox peaks located near ꢀ0.46 V and ꢀ0.60 V, respec-
tively (Fig. 4c). Shifting of these peaks at higher potential
ꢀ0.40 V and ꢀ0.50 V, respectively, was found due to the presence
of metal ions (Pb2+). The PL spectrum of CS-g-PA@TSM nanocom-
posite was analyzed to determine the generation of electrons and
holes together with their recombination efficiency. The PL emis-
sion peaks of CS-g-PA and CS-g-PA @TSM (excitation wavelength
of 325 nm) are shown in Fig. 4 d.
aration, and faster transfer of photogenerated electron-hole pairs,
responsible for the promoted photocatalytic activity of CS-g-
PA@TSM nanocomposites.
4. Applications
4.1. As a photocatalyst
The photocatalytic degradation of CIP was carried out under vis-
ible light to examine the efficiency of nanocomposites (TSM, PTSM,
and CS-g-PA@TSM). The results of CIP photodegradation are shown
in Fig. 5 (a, b, c, d). Interestingly, no photolysis of CIP was found in
the absence of a catalyst (CS-g-PA@TSM) (Fig. 5 b). However, the
CS-g-PA@TSM achieved significant photocatalytic activity (96.1%)
as compared to PTSM (63.4%), TSM (52.1%), and CS-g-PA (44.3%)
130 min.
The improvement in CIP degradation using nanocatalysts is
attributed to the superior visible light absorption ability and effec-
tive separation of photo-generated electron-hole pairs. Further-
more, the large surface area provided by CS/PA on which Sn(Si/
Mo)xOy complex was immobilized showed enhancement in photo-
catalytic degradation efficiency. Generation of free radicals (during
photocatalysis) from Sn(Si/Mo)xOy was possibly transferred owing
to the amino groups of CS-g-PA. The electrons trapped in this pro-
cess (transferred to O2 molecules) were further adsorbed on the
surface and produce reactive species (ÅOH, eꢀ, O2ꢁꢀ and h+). Because
of the above observations, a reasonable photocatalytic degradation
mechanism of CS-g-PA@TSM core/shell nanocomposite is illus-
trated by the schematic in Fig. 5e.
The suggested mechanism of the degradation of CIP can be dis-
played as [37]:
ꢀ
CS-g-PA@TSM + h
m
! CS-g-PA@TSM * + e + hþ
hþ + H2O ! ÅOH + Hþ
ꢀ
ꢀ
e
+ O2 ! ÅO2
ꢀ
ÅO2 + ÅOH + Hþ ! H2O2 + O2
ꢀ
ꢀ
ÅO2 + ÅOH + hþ + CIP ! intermediate ! CO2 + H2O + F
From Fig. 5 c, it is observed that the photocatalytic degradation
of CIP followed pseudo first order kinetics. The k values were deter-
mined from the slopes of the straight lines for PTSM, CS-g-PA, TSM,
and CS-g-PA@TSM (as listed in Table S-1), and the plots of ln C/C0
vs. time are shown in Fig. 5 c. The degradation efficiency of CIP was
studied over a wide pH range (3–10), as shown in Fig. 5 d. It is
inferred from the pH study that the degradation efficiency of CIP
increases with increasing the solution pH up to 7 [38]. On the other
hand, in basic medium, CIP molecules and the photocatalyst attain
a negative charge, which leads to repulsion, thereby reducing the
degradation efficiency.
At neutral pH (7), the surface of photocatalyst remains slightly
positive with the CIP, which enhanced degradation efficiency of CIP
owing to the degradation of CIP on the surface of the nanocompos-
ite. Accordingly, the synergistic effect of the CS-g-PA@TSM photo-
catalyst for CIP degradation was observed at neutral pH. As
displayed in Fig. S-1a, a positive zeta potential of CS-g-PA@TSM
was found at low pH, which gradually became negative with
increasing pH. The pHPZC value of CS-g-PA@TSM is noticed as ~8,
and pH < 8, suggests that the surface of composite bears a positive
charge. Meanwhile, CIP as an amphoteric substance has two pKa
values that confirm three species (i.e., CIP+, CIP+ꢀ, and CIPꢀ) at dif-
ferent pH levels.
The PL spectrum of CS-g-PA@TSM showed the emission peak at
~410 nm, which might be due to the electronic behavior of Tin. In
the spectra, the CS@PA showed the highest at 420 nm, while for
CS@PA-TSM it is comparatively lower. Hence, the PL peak intensity
is preferably reduced which results in efficient charge transfer over
the catalyst surface. Besides, the emission data of the CS-g-
PA@TSM catalyst slightly shifted to the blue wavelength side
(~410 nm) is attributed to the defect trap state due to the quantum
confinement effect. The PL is found well-matched with the UV–vis-
DRS absorption analysis. It assures electron transfer from the con-
duction band of the photoexcited TSM (core) to the CS-g-PA (shell).
This efficient charge transfer by TSM prevented electron-hole
recombination, resulted in enhancing the photo-activity of CS-g-
PA@TSM nanocomposite. The present study confirmed the sup-
pression of the recombination of electrons and holes on the surface
of the CS-g-PA@TSM compared to the bare CS-g-PA. Finally, we can
conclude that all UV–vis DRS, PL, CV, and EPR test/ studies provided
powerful evidence that widens visible light absorption, higher sep-
7

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
Fig. 5. (a, b, c, d, e) UV–vis absorbance spectra of Ciprofloxacin photocatalytic degradation (15 mg/L; pH 7) with CS-g-PA @TSM catalyst (a). photocatalytic activity of CS-g-PA
@TSM with bare TSM, and PTSM (b); Kinetic of CS-g-PA @TSM towards photocatalytic degradation of CIP (c); The effect of pH for photocatalytic degradation of CIP with CS-g-
PA @TSM (d); Reactive species rules on the photocatalytic degradation of CIP using the CS-g-PA@TSM (e).
The degradation of CIP onto CS-g-PA@TSM initially increased
with pH; however, (as shown in Fig. 5d), it decreased at high pH
(pH = 10), which indicates that the maximum degradation of CIP
occurred at pH 6–8 (when CIP was zwitterion). The hydrophobic
interaction and p–p bonding dominated under this condition as a
result of the high surface area of CS-g-PA@TSM. For detecting the
main reactive species in the CIP decomposition, the scavenging
experiment was carried out under identical experimental
8

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
conditions. Isopropanol (IPA), disodium ethylenediaamine
tetraaceticacid (Na2-EDTA), p-benzoquinone (BQ) and formic acid
(FA) were chosen as ÅOH, h+, ÅOꢀ2 [39] and eꢀ [40] scavengers,
respectively. The experimental results for the scavenging test
showed that the reaction rate was relatively retained upon using
formic acid (10.50 mM) reflecting the negligible effects of eꢀ spe-
cies. However, in the case of IPA (1.60 mM), Na2-EDTA
(12.60 mM), and (60 mM)BQ scavengers were indicated a signifi-
cant decrement proposing the influential effect of ÅOH, h+, and
ÅOꢀ2 [41].
33.1%, 19.7%, and 74.3% respectively, which established the forma-
tion of h+, ÅOH and ÅOꢀ2 during CIP photodegradation process
(Fig. S-1b).
4.1.1. Mechanism of CIP degradation
To identify various photocatalytic decomposition pathways, the
formation of intermediates produced during the degradation of CIP
was analyzed by the GC–MS technique. A proposed scheme in
Fig. 6e illustrates fragmentations of seven major during the degra-
dation. The cleavage of the C–N and C–C bonds resulted in by-
products formation which may be converted into CO2 and H2O
through mineralization of the CIP [42]. For more details, the path-
The CIP degradation efficiency decreases in the presence of dif-
ferent scavengers (IPA, Na2-EDTA, BQ, and FA) to be ca. 27.3%,
Fig. 6. (a, b, c, d, e): Three-dimensional excitation–emission matrix fluorescence spectra (3D) of the CIP solution after visible light irradiation durations at different time
intervals 0 (a), 20 (b), 60 (c), and 100 min. (d), Proposed degradation pathway of CIP (e).
9

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
ways of the cleavage piperazine ring and decarboxylation of quino-
lone ring in CIP were evaluated (FigS-5 a,b). Specifically, ÅOꢀ2 radi-
cal prefers to attack the piperazine side chain to produce oxidative
intermediates A (m/z 362). Then, intermediates B1 (m/z 333) were
derived from the loss of formyl group (–CO) during the piperazinyl
rings broken as described in pathway I. The intermediates B2 (m/z
316) arose from the decarboxylation of quinolone as reported by
Deng et al., [43]. The secondary degradation pathway corre-
sponded to continue cleavage of the -C-N bond on the piperazine
ring (related to further radical attacks) leading to the formation
of the intermediates C with (m/z = 277), while the loss of ‘‘-
CH2NH2 fragment was attributed to the photo h+ oxidation to pro-
duce intermediate D (m/z 262) [42]. The intermediates E (m/z 234)
was derived from the loss of the -CO group during the cleavage of
piperazinyl rings. Finally, intermediates F (m/z = 207) and E might
be transformed into small molecules such as CO2, H2O, and Fꢀ [44].
All suggested pathways were compatible with previously reported
work [44,45]. In order to confirm the photodegradation of Cipro-
floxacin, a three-dimensional (3D) (excitation-emission matrix flu-
orescence spectra) technique was performed (Fig. 6a-d). Pure CIP
solution exhibited multiple fluorescence peaks (Ex/Em = 250–300
/425–475 and Ex/Em = 300–350/425–475 nm) as shown in
Fig. 6a [46]. Under visible light irradiation, the emission peak
intensity decreased with time thereby suggesting the decrease in
the concentration of CIP (Fig. 6b, c). After 100 min, a negligible
peak in the emission spectra of CIP was found indicating the com-
plete degradation of CIP (Fig. 6d). Therefore, 3D FL study results
further confirmed that the CIP molecules could be degraded by
photocatalytic processes.
4.1.2. Re-usability of nanocomposite catalyst
The surface morphology of catalyst greatly affects the perfor-
mance of photocatalysts. The recycling behavior of CS-g-PA@TSM
catalyst was examined towards the degradation of CIP (as shown
in Fig. 7 a, b). The photocatalytic performance in term of recycabil-
ity revealed that after 4 times repeatedly used, the CS-g-PA@TSM
nanocatalyst retained almost 92% of its initial activity. Slight aggre-
gation of the CS-g-PA@TSM even after 4 cycles indicated excellent
stability and durability of the CS-g-PA@TSM catalyst. The high cat-
alytic efficiency and stability of CS-g-PA @TSM could be explained
due to the highly dispersed state of chitosan biopolymer, abundant
oxygen vacancies on the TSM support, and the strong metal-
Fig. 7. (a, b, c, d) Degradation (%)of CIP using CS-g-PA @TSM with bare TSM, CS/PA and PTSM under visible light irradiation (a), Cyclic stability for photodegradation of CIP
using the recycled CS-g-PA @TSM nanocomposite (b), FL spectra of the CS-g-PA @TSM in the absence and presence of Pb2+ (pH 7.0), kmax = 320 nm (c), Stern Volmer (1-F/F0) vs
concentration of CS@PTSM and CS-g-PA samples (d).
10

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
Table 1
Comparison of various photocatalyst systems for CIP degradation.
S. No
Catalysts
Drug (CIP) (int.con)/dosage
Time (min)
Degradation Efficiency (%)
Ref.
1
2
3
4
5
6
7
Fe2+/H2O2
C-TO2
Fe3O4-TiO2/C-Dot
g-C3N4/BiOBr
TP-TO2
TiO2/g-C3N4
CS-g-PA@TSM
15 mg Lꢀ1
270
180
150
360
60
74.4
88.7
90.0
85.0
90.0
93.4
96.1
[48]
[38]
[49]
[50]
[41]
[42]
This study
15 mg ꢀL1ꢀ1/1g Lꢀ1
20mgL /0.75gLꢀ1
10mgLꢀ1/0.2gLꢀ1
32 mM/0.1gLꢀ1
15
l
mol Lꢀ1/0.2gLꢀ1
60
130
15mgLꢀ1/1g Lꢀ1
support interaction between chitosan/PA and TSM [47]. Compara-
tive catalytic performance of some reported nanocomposites in
comparison to our prepared nanocomposite is listed in Table 1.
of 140 mM of Pb2+. To explain the mechanism of Pb2+-CS-g-
PA@TSM interaction, the fluorophore units of CS-g-PA @TSM
dispersed in the solution and the increasing the concentration of
Pb2+ ions trigger the aggregation of CS-g-PA@TSM probe to form
a complex structure which led to destroying the stability of the col-
loidal solution and the fluorescence signal decreased markedly
[51,52].
As illustrated in Fig. 7 c, d, the FL intensity of CS-g-PA @TSM
was linearly decreased with increasing Pb2+ concentration
(1–10 ppm). Moreover, the linear response was observed in the
range from 1.1 to 2 mM (by plotting (1 ꢀ F/F0) against the logarith-
mic values of Pb2+ concentration, as shown in Fig. 8a. The value of
4.2. As a sensor for the detection of Pb2+
Luminescence studies were carried out to analyze the selective
behavior of CS-g-PA@TSM for the detection of Pb2+ in real water at
ultra-low trace levels. Different concentrations of Pb2+ were mixed
with CS-g-PA@TSM (individually) and fluorescence spectra were
recorded at kmax = 389 nm. The fluorescence intensity of the CS-
g-PA@TSM nanocomposite was decreased by 58% in the presence
Fig. 8. (a, b, c, d); Plot of (1-F/F0) for the FL intensities of CS-g-PA@TSM at 389 nm against the log value of Pb2+ ions (a); Temperature dependence of the electrical conductivity
of CS-g-PA@TSM nanocomposite; (b) Resistivity response of CS-g-PA@TSM nanocomposite towards different concentrations of ammonia vapours with respect to time (c);
Reversible resistivity response of CS-g-PA@TSM nanocomposite on intermittent exposure to 0.2 N ammonia (d).
11

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
Table 2
Compilation of Pb2+ adsorption using different types of adsorbents.
S. No.
Composite Material
Pb2+ (mg/g)
Time (min)
Removal efficiency (%)
Reference
1
2
4
5
7
8
CS-PAA/GO
EDTA/MCS-GO
PEI–PD/GO
Zr(WO4)(IO3)(PO4)
PEI-RCSA
CS-g-PA@TSM
138.89
206.70
113.89
82.30
234
270
240
180
540
480
180
74.4
84.0
90.0
96.0
81.76
95.6
[61]
[62]
[63]
[64]
[65]
238.30
The present study
limit of detection (LOD) was found to be 1.98 ꢂ 10ꢀ8 M and corre-
lation coefficient (R2) of 0.97, which was lower than that of the
other reported Pb2+ sensors [53,54]. The selectivity of CS-g-
PA@TSM for Pb2+ detection was examined by investigating its
capability with other environmentally relevant metal cations
(Na+, K+, Sr2+, Cd2+, Mg2+, Zn2+, and Ba2+). No fluorescent signal vari-
ations were observed in the presence of these interfering species,
indicating that the CS-g-PA@TSM fluorescence probe exhibits
promising results for Pb2+ sensing with high selectivity. The results
indicated that the proposed method (fluorescence sensing) is com-
parable with that of the AAS method (LOD = 3.38mgLꢀ1). It estab-
lished that the prepared composite with multifunctional behavior
could be employed for various practical applications.
4.4. As an ion-exchanger for removal and recovery of metal ions
4.4.1. Removal of Pb2+ in wastewater
In this study, we applied the recommended column procedure
to test this method’s applicability for the analysis of lead ions in
Jheel Lake and groundwater (U.P, Aligarh, India). The optimum
conditions (pH and temperature) were adjusted prior to the exper-
iment. The concentration of lead in wastewater and groundwater
samples was analyzed using the FAAS method as reported earlier
[59], by spiking (3.0 mg) of lead was water samples as listed in
Table S-5. The limit of detection for lead ions was found to be
3.38
l
g Lꢀ1 with its corresponding better limit of quantification
g Lꢀ1) than previously reported study for detec-
value (LOQ = 9.34
l
tion Pb2+ [60]. A compilation of relevant literature for the Pb2+
adsorption using different adsorbents is summarized in Table 2.
The adsorption capacity of CS-g-PA@TSM was higher than most
other adsorbents with an excellent removal percentage of 95.6%
having a high sorption capacity of 238.3 mg gꢀ1 which is closer
to the maximum sorption capacity as described by the Langmuir
equation and plotted in (Fig. S-3 and Fig. S-4). These findings indi-
cated that the practical applicability of CS-g-PA@TSM nanocom-
posite exhibited excellent removal performance of Pb2+ from the
real wastewater samples also showed the feasibility of CS-g-
PA@TSM for use in industrial purposes.
4.3. As a gas sensor
The relation between electrical resistivity and temperature was
studied with the help of the Arrhenius equation by plotting a graph
of lnr versus 1000/T (Fig. S-1c). The electrical conductivity of CS-
g-PA @TSM core–shell nanocomposite was found to be increased
with increasing the temperature which revealed the ’thermal acti-
vated behavior‘‘ of nanocomposite due to improvement in charge
transfer between TSM and co-polymer chains as presented in
Fig. 8b [55]. Furthermore, temperature-dependent electrical con-
ductivity results indicated that the thermal treatment affects the
polymer’s chain alignment, which results in the increment of con-
jugation length that brings about the increment electrical conduc-
tivity of the composite. Moreover, molecular reorder on heating
enhances the molecular conformation for electron delocalization
[56].
The degree of the conductivity depends on both the number of
charge carriers and their mobility. It has been observed that mobil-
ity of charge carriers increases with increasing temperature lead-
ing to the improvement in conductivity similar to the reported
POA-TP nanocomposite [57]. The electrical resistivity response of
CS-g-PA @TSM nanocomposite as a function of time demonstrated
remarkable changes in exposure to various concentrations of
ammonia gas (0.05, 0.10, 0.15, and 0.20 N) as illustrated in
Fig. 8c. The results indicated that the CS-g-PA @TSM nanocompos-
ite exhibits a relatively fast response towards NH3 vapors at 0.2 N
and the resistivity can be recovered on flushing in air. Fig. 8d illus-
trates response characteristic curves of CS-g-PA @TSM sensor on
exposure ammonia vapors (0.2 N) by a 4-in-line- electrical conduc-
tivity probe (using laboratory-made apparatus set up).
4.4.2. Regeneration efficiency
The reusability of CS-g-PA@TSM was studied by performing
multiple cycles for the removal of Pb2+. Nitric acid and deionized
water were used to rinse Pb2+ loaded CS-g-PA@TSM. The CS-g-
PA@TSM showed 98% recycle efficiency even after five cycles hav-
ing significant precision (2.65% RSD). After each set of adsorption/
desorption experiments, distilled water was used to remove excess
acid from the surface of the composite. These results established
that CS-g-PA@TSM has excellent regeneration capacity.
4.5. Swelling behavior and valuable economic
Swelling ratios of the CS-g-PA@TSM with different TSM con-
tents at pH 7.4 are listed in Table S-6. The swelling capacity of
CS-g-PA@TSM decreased with increasing TSM contents. Under
swelling conditions (pH 7.4 and 37 °C), the CS-g-PA@TSM had a
lower swelling ratio than CS-g-PA (Fig. S-2b). As reported by Fan
et al., [66], the suppression of swelling for nanocomposites hydro-
gel and degree of swelling help in maintaining their initial shape
and retain their mechanical property. Hydrogel-based nanomateri-
als are regarded as economic, eco-friendly, and prime candidates to
create a green and sustainable environment. However, due to high
cost, their applications are limited. Presently the cost of hydrogel-
based nanocomposites prepared by supercritical drying is about
$2870 per kg, while hydrogel-nanocomposites are made from
chitosan-g-polyacrylamide NCs is found only $176 per kg, thereby
making the latter commercially important. Moreover, hydrogel-
based nanocomposites are economical, and their efficiency in envi-
ronmental clean-up is also high.
Mesoporous CS-g-PA@TSM nanocomposite covered a significant
sensitivity (Rair/Rgas ~ 1.3) on the exposure of ammonia vapors in
the concentration range from 0.05 to 0.20 N. The resistivity
response of the CS-g-PA@TSM nanocomposites reflected its poten-
tial in gas sensing [58]. The gas sensing of CS-g-PA@TSM is related
to the change in electrical resistance between the material surface
and target gas molecules due to interaction (gas adsorption, des-
orption, and charge transfer). Depletion of ammonia vapors on
the surface and interfacial region causes changes in the resistivity
of CS-g-PA @TSM nanocomposite as illustrated in Fig S-2c.
12

Yahiya Kadaf Manea, Amjad Mumtaz Khan, Ajaz Ahmad Wani et al.
Journal of Molecular Liquids 335 (2021) 116144
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5. Conclusions
A novel CS-g-PA@TSM nanocomposite was successfully synthe-
sized by the hydrothermal method with excellent photodegrada-
tion of CIP compared with pristine TSM and PTSM. The improved
photocatalytic activity and stability of 3D CS-g-PA@TSM hydrogel
nanocomposite established three aspects: (i) The introduction of
Chitosan (CS) biopolymer matrix reinforced the strength of the
polyacrylamide to produce the hydrogel, thereby enhanced the
catalytic performance of the system; (ii). The 3D network structure
provided more reactive sites and medium transport channels; (iii).
The interactions between CS-g-PA gel and semiconductor TSM,
enhances the efficiency of the migration and separation of photo-
generated charge carriers owing to trapping of excited electrons
on the surface of CS-g-PA@TSM. Besides, experimental results indi-
cated that ÅOꢀ2 , h+ and ÅOH species played a major role in the pho-
todegradation of CIP. Hence, the CS-g-PA@TSM nanocomposite has
potential in the oxidation of organic pollutants in aqueous phases
due to its high photocatalytic activity. The porous structure of CS-
g-PA@TSM facilitated the sorption and exchange capacity of vari-
ous metal ions within the surface. The CS-g-PA@TSM was found
to be highly efficient for the removal of Pb2+ from wastewater.
The presence of various functional groups (such as hydroxyl, car-
boxyl, and amide) in the matrix of hydrogel-based nanocomposite
(CS-g-PA) resulted in high adsorption capacity (95.6%) of Pb2+ from
wastewater.
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blue and adsorption of metal ions by SDS-TiP nanocomposite, SN Appl. Sci. 1
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V. Muthuraj, Investigation on the electrocatalytic determination and
photocatalytic degradation of neurotoxicity drug clioquinol by Sn(MoO 4) 2
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Yahiya Kadaf Manea: Conceptualization, Methodology, Investi-
gation, Writing - original draft, Writing. Amjad Mumtaz Khan:
Supervision. Ajaz Ahmad Wani: Data curation. Mohsen T.A. Qash-
qoosh: Validation. Mohammad Shahadat: Visualization, - review
& editing. Mansour A.S. Salem: Software.
Declaration of Competing Interest
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared
to influence the work reported in this paper.
[19] Amjad Mumtaz Khan, Y.K. Manea, S.A. Nabi, Synthesis and characterization of
nanocomposite acrylamide TIN(IV) silicomolybdate: photocatalytic activity
and chromatographic column separations, J. Anal. Chem. 74 (4) (2019) 330–
338.
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characterization of polyanilineZr(IV)sulphosalicylate composite and its
applications (1) electrical conductivity, and (2) antimicrobial activity studies,
Chem. Eng. J. 173 (3) (2011) 706–714.
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characterization, photolytic degradation, electrical conductivity and
applications of a nanocomposite adsorbent for the treatment of pollutants,
RSC Adv. 2 (18) (2012) 7207, https://doi.org/10.1039/c2ra20589k.
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composite ion-exchange adsorbent for pollutants removal from
environmental wastes, Chem. Eng. J. 165 (2) (2010) 405–412.
[23] S. Feih, E. Boiocchi, G. Mathys, Z. Mathys, A.G. Gibson, A.P. Mouritz, Mechanical
properties of thermally-treated and recycled glass fibres, Compos. B Eng. 42
(3) (2011) 350–358.
Acknowledgment
The authors would like thank Chairman of the Department of
Chemistry, Aligarh Muslim University for providing research facil-
ities. The authors would like to acknowledge DST and UGC, for
research support (DRS II, PURSE & FIST) to the Department of
Chemistry, AMU, Aligarh.
Appendix A. Supplementary material
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.molliq.2021.116144.
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