Y. ZHONG et al.: APPLICATION OF A CS/ATP COMPOSITE FLOCCULANT FOR RECYCLING THE MAIN COMPONENTS ...
547–553
APPLICATION OF A CS/ATP COMPOSITE FLOCCULANT FOR
RECYCLING THE MAIN COMPONENTS FROM A BEZAFIBRATE
SYNTHESIS WASTE SOLUTION
UPORABA CS/ATP KOMPOZITNEGA FLOKULANTA ZA
RECIKLIRANJE GLAVNIH KOMPONENT V BEZAFIBRATNI
SINTEZI ODPADNE RAZTOPINE
Yuan Zhong
1
, Jie Wu
1*
, Su-Zhen Wang
2
, Seng Tang
3
1
Jiangsu Health Vocational College, Nanjing, China
2
Key Laboratory for Palygorskite Science and Applied Technology of Jiangsu Province, Huaian, China
3
Key Laboratory for Specialized Resources and Medical Research of Jiangsu Province, Huaian, China
Prejem rokopisa – received: 2022-03-23; sprejem za objavo – accepted for publication: 2022-08-08
doi:10.17222/mit.2022.456
A chitosan/attapulgite (CS/ATP) composite flocculant with excellent adsorption was prepared from chitosan (CS) and attapul-
gite clay (ATP). The micro morphology and structure of the composite flocculant were characterized with SEM and IR. The ef-
fect of the CS/ATP composite flocculant on the recovery of the main components from the bezafibrate (BZ) wastewater of a
pharmaceutical plant was investigated. The influences of the flocculation temperature, mixing time and standing time on the
flocculation effect were investigated by determining the BZ content of the recovered crude products as the evaluation index so
as to obtain the best recovery process. The experimental results show that the best flocculation condition is created when we add
20 mg/mL of CS/ATP to the waste liquid, stir it at 30 °C for 10 min and allow it to stand for 30 min. Compared with the tradi-
tional recovery process, the BZ content of the recovered crude products can be increased from 47 % to 74 % when using the
CS/ATP composite flocculant. This flocculant can effectively overcome the defects of single material residues and difficult sep-
aration, accelerate the settlement of impurities in a waste liquid effectively, and can be used in the field of solution clearing and
waste liquid separation.
Keywords: chitosan, attapulgite, flocculant, bezafibrate waste solution, recycling
Avtorji so iz me{anice hitosana (CS) in atapulgitne gline (ATP) pripravili novo vrsto hitozan/atapulgitnega (CS/ATP)
kompozitnega flokulanta z odli~no adsorpcijsko flokulacijo oz. sposobnostjo kosmi~enja. Mikromorfologijo in strukturo
kompozitnega flokulanta so dolo~ili z vrsti~nim elektronskim mikroskopom (SEM) in infrarde~im spektrometrom (IR). Nato so
ugotavljali vpliv CS/ATP kompozitnega flokulanta na popravek glavnih komponent bezafibratnih (BZ) odplak iz farmacevtske
tovarne. Ugotavljali so vpliv flokulacijske temperature, ~asa me{anja in stojnega ~asa na vpliv flokulacije. Indeks ovrednotenja,
s katerim so dobili najbolj{i proces o~i{~enja odplak, je predstavljal vsebnost oz. koli~ino odstranjenih snovi v BZ odplakah.
Eksperimentalni rezultati raziskave so pokazali, da so najbolj{e pogoje flokulacije dosegli pri dodatku 20 mg/mL CS/ATP,
me{anju raztopine 10 min pri temperaturi 30 °C in njeni odstavitvi za 30 min. Primerjava s standardnim procesom poprave oz.
~i{~enja je pri uporabi CS/ATP kompozitnega flokulanta vsebnost BZ v ostanku narasla s 47 % na 74 %. Kompozitni flokulant
dejansko u~inkovito premaga napake ostankov posameznega materiala in izbolj{a te`avno lo~evanje ter pospe{i posedanje
ne~isto~ v odpadni teko~ini oz. odplakah. Zato se lahko uporablja na podro~ju razbistrenja raztopin in lo~evanja ne~isto~ v
odplakah.
Klju~ne besede: hitosan, atapulgit, flokulant, bezafibratna odpadna raztopina, recikliranje
1 INTRODUCTION
Bezafibrate (BZ), belonging to fibrates, is a first-line
drug in the treatment of various types of lipid metabolic
disorders.
1,2
The synthesis of BZ includes two steps of
acylation and condensation, in which the condensation
reaction leads to an increase in the coproducts as the re-
action temperature rises rapidly in a short time due to
spontaneous exothermic heat. However, there is still
a b o u t7%o fB Zi nt h er e m a ining waste liquid (the
high-performance liquid method)
3
after the crystalliza-
tion and solvent recovery of the mother liquor in this re-
action. The crude BZ obtained with the traditional recov-
ery is directly discarded by enterprises due to a large
amount of impurities, high viscosity and high purifica-
tion cost. Therefore, developing a green method with a
simple operation and low cost to recover BZ from waste
liquids is an effective way to improve the product yield
and reduce the production cost. Previous studies have
found that the major impurities in a waste liquid can be
removed by using the carbon dioxide precipitation
method,
4
but simple filtration and general centrifugation
methods cannot separate BZ because the precipitation is
often difficult to settle due to small impurity particles,
large viscosity of the waste liquid, and is even suspended
in the form of colloid in the waste liquid.
Attapulgite (ATP), a non-metallic clay mineral,
formed from the layered chain structures of hydrated
magnesium aluminum silicates, has a large specific sur-
face area and an internal porous characterization due to
Materiali in tehnologije / Materials and technology 56 (2022) 5, 547–553 547
UDK 544.77.052.22:504.5:615 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 56(5)547(2022)
*Corresponding author's e-mail:
wujie1760@126.com (Jie Wu)

large channels resembling zeolite. In recent years, ATP
has been developed considerably in the wastewater treat-
ment industry. Due to its excellent adsorption and
decolorization performance, non-toxic, pollution-free
and in-depth research on the treatment of pharmaceutical
and chemical waste liquids has been carried out.
5–7
Espe-
cially after organic modification, ATP improves its
hydrophobicity and enhances its adsorption capacity for
organic matter as some of the crystal water and adsorbed
water inside and outside the lattice is replaced by organic
matter.
8,9
However, it is difficult to form only ATP as a
powder adsorbent, and perform a solid-liquid separation
of liquid with high viscosity. Chitosan (CS), a biodegrad-
able natural amino polysaccharide polymer compound, is
an excellent natural cation clarifier, and it is commonly
used for the flocculation and clearing of Chinese drug
extracts and fruit juices as it is non-toxic and taste-
less.
10,11
This study intends to realize the recovery of BZ
from a waste solution, using CS to modify ATP and pre-
pare a chitosan/attapulgite (CS/ATP) composite floccu-
lant to enhance the adsorption performance of ATP on
organic impurities, improving the separation effect of the
impurities in the waste solution of BZ synthesis.
2 EXPERIMENTAL PART
2.1 Materials
BZ control products were purchased from the Na-
tional Institutes for Food and Drug Control (batch
No.100732-200501), BZ waste liquid was from Jiangsu
Tasly Diyi Pharmaceutical Co., Ltd. (lot No.20170509),
CS from Zhejiang Golden-Shell Pharmaceutical Co.,
Ltd. (95 % deacetyl), ATP was from Jiangsu Jiuchuan
Nano Material Technology Co., Ltd. (100 screen),
chromatographically pure methanol was from Tianjin
Oubokai Chemical Co., Ltd., water was deionized water
and other, analytically pure reagents were purchased
from Sinopharm Group Chemical Reagent Co., Ltd.
2.2 Instruments
We used a 1100LC HPLC, G1315B UV detector
(Agilent), Nicolet 5700 infrared spectrometer (Thermo
Electron), S-3000N scanning electron microscope
(Hitachi, Japan), IKA-Werke thermostatic magnetic stir-
rer (Guangzhou Yike Laboratory Technology Co., Ltd.)
and Allegra X-30 centrifuge (Beckman, USA).
2.3 Preparation of CS/ATP
1 g of CS was added to 100 mL of 1 % (w/w) acetic
acid solution, which was stirred slowly and heated to
40 °C so that CS dissolved completely and a CS solution
was obtained. ATP was added to the CS solution
(w
CS
: w
ATP
= 6 : 100) slowly and stirred in (400 min
–1
)
continuously at room temperature for 24 h. After being
allowed to stand for 8 h, the upper acetic acid solution
was dumped, the solid product was washed with water to
become neutral and dried at 60 °C for 12 h. The CS/ATP
complex obtained was ground, screened through a 100
mesh sieve and sealed in a dryer for storage.
2.4 BZ recovery from the waste liquid
2.4.1 Traditional post-processing method (method A)
The BZ waste solution was diluted with water at a ra-
tio of 1 : 25 (v/v), acidified and the pH was adjusted to
3–4 with 15 % of HCl. The solution was allowed to stand
until the precipitation was complete, then it was filtered
and dried to obtain the BZ crude product.
2.4.2 CO2
precipitation method (method B)
The BZ waste solution was diluted with water at a ra-
tioof1:25( v/v) and CO
2
was passed into the solution
under airtight conditions. Then the solution was centri-
fuged (5000 min
–1
) after 40 min to get the supernatant,
which was acidified and allowed to stand until the pre-
cipitation was complete, then filtered and dried to get the
BZ crude product, as with method A.
2.4.3 CS flocculation method (method C)
After passing CO
2
into the solution according to
method B, a 1.2 % (w/w) CS solution was added to the
solution, which was filtered after 30 min of flocculation.
The filtrate was acidified, allowed to stand until the pre-
cipitation was complete, then filtered and dried to get the
BZ crude product as with method A.
2.4.4 ATP adsorption method (method D)
After passing CO
2
into the solution according to
method B, a certain amount of ATP was added to the so-
lution, which was stirred for 10 min and filtered after be-
ing allowed to stand for 30 min. The filtrate was acidi-
fied, allowed to stand until the precipitation was
complete, filtered and dried to get the BZ crude product
as with method A.
2.4.5 CS/ATP flocculation adsorption method (method E)
After passing CO
2
into the solution according to
method B, a 1.2 % (w/w) CS solution was added to the
solution, which was filtered after 30 min of flocculation.
A certain amount of CS/ATP was added to the filtrate,
which was stirred for 10 min and filtered after standing
for 30 min. The secondary filtrate was acidified, allowed
to stand until the precipitation was complete, filtered and
dried to get the BZ crude product as with method A.
2.5 Measurement of the BZ content
HPLC analyses were performed in a Hypersil ODS2
column (4.6 mm × 250 mm and 5 μm), at a column tem-
perature of 30 °C with a mobile phase of 0.01 mol/L po-
tassium dihydrogen phosphate solution (the pH was ad-
justed to 3.8 with phosphoric acid) – methanol (40 : 60,
v/v), at a flow rate of 1 mL/min, an injection volume of
10 μL and a detection wavelength of 228 nm. The sam-
ples were the BZ crude products recovered with different
Y. ZHONG et al.: APPLICATION OF A CS/ATP COMPOSITE FLOCCULANT FOR RECYCLING THE MAIN COMPONENTS ...
548 Materiali in tehnologije / Materials and technology 56 (2022) 5, 547–553

methods. 100 mg of a sample was dissolved with the mo-
bile phase to prepare the solution with a certain concen-
tration. The solution was filtered with a 0.25 μm
microporous membrane and injected into a liquid chro-
matographic analysis system. The chromatogram was re-
corded and the content was determined with the area nor-
malization method.
3 RESULTS AND DISCUSSION
3.1 Characterization of the CS/ATP composite floccu-
lant
3.1.1 FTIR of the materials
ATP, chitosan and their complex of CS/ATP were
characterized by the FTIR spectra, and the results are
shown in Figure 1. When a degree of CS deacetylation
of 95 % was used, the peak of CS at 1600 cm
–1
belonged
to the bent vibration peak of the amino group, which was
blue shifted to 1560 cm
–1
in the CS/ATP complex. More-
over, the stretching vibration peak at 3550 cm
–1
which
was attributed to Si-OH in ATP became weak in the
complex, indicating that the amino group in CS formed
hydrogen bonds with the hydroxyl group in ATP.
12
The
OH bending vibration peaks of 1650 cm
–1
attributed to
the ATP coordination water and the adsorbed water be-
come weak in the complex. The characteristic absorption
double peaks of ATP at 1030 cm
–1
and 990 cm
–1
caused
by the stretching vibration of the Si-O-Si bond also ap-
peared in the complex, indicating that ATP had success-
fully recombined with CS.
13
3.1.2 Microstructure of the material
Electron micrographs of ATP and its complex
CS/ATP are shown in Figure 2. This figure shows that
ATP is a kind of fibrous rod-like crystal, easy to agglom-
erate in bundles due to a large specific surface area. In
the composite with chitosan, the rod crystals of ATP are
covered with a layer of polymer, forming a composite
material with organic-phase chitosan as the matrix and
inorganic-phase ATP as the core, having a denser struc-
ture compared with ATP. However, when compared with
the single polymerization system, the presence of the in-
organic phase provides the dispersion medium for
chitosan and gives it a rough microstructure, providing a
structural basis for its adsorption and flocculation prop-
erties. At the same time, the presence of chitosan also
provides the material basis for the processing and mould-
ing of ATP.
3.1.3 Flocculation morphology
According to the experimental optimum process con-
ditions for the flocculation of the BZ waste solution by
ATP/CS, ATP and CS, the flocculated waste solution was
diluted with deionized water at a certain concentration,
and the structures of the flocs were photographed and
observed, as shown in Figure 3.
Figure 3 shows the flocs produced after the addition
of ATP, CS and ATP/CS to the waste solution, respec-
tively. It can be seen that after adding ATP to the waste
solution, ATP flocculates with the adsorption of impuri-
ties through the van der Waals force, and the floc parti-
cles are small and loose, with a slow settling speed and
difficult filtration. After adding CS to the waste solution,
although CS can form larger flocs by bridging through
the electrostatic gravitational force, there are still a large
number of fine flocs, affecting the settling speed. On the
Y. ZHONG et al.: APPLICATION OF A CS/ATP COMPOSITE FLOCCULANT FOR RECYCLING THE MAIN COMPONENTS ...
Materiali in tehnologije / Materials and technology 56 (2022) 5, 547–553 549
Figure 2: SEM micrographs of: a) ATP, b) CS/ATP
Figure 1: FTIR spectra of ATP, CS and CS/ATP

contrary, after adding ATP/CS, large and dense flocs are
generated, easy to separate. It can be seen that ATP with
good adsorption performance quickly adsorbs impurities,
while the CS polymer compound with the bridging effect
makes the flocs larger, accelerating the settling of the
flocs, and has a netting effect, which can clarify the
waste solution and separate impurities in a short time.
Here, the effect is obviously better than in the case of the
adsorption and flocculation effect of only CS or ATP.
3.2 Recovery of BZ from the waste solution
3.2.1 Comparison of different recovery processes
The effects of different recovery processes on the
content of BZ in the waste solution are shown in Fig-
ure 4. Compared with the conventional recovery method
(A), the CO
2
precipitation method (B) makes it difficult
to filter the fine precipitation formed as larger particles
in the viscous liquid because the treatment target is a vis-
cous waste solution with lots impurities, thus causing the
content of BZ in the resulting crude product to be lower
than that of the conventional recovery method. However,
using the C method that adds CS to the flocculate in the
waste solution after the CO
2
precipitation, the content of
BZ in the resulting crude product is significantly higher
than that of the B method, increasing from 44 % to
57 %; the solution is clear after the flocculation and the
flocs at the bottom can be removed by filtration, showing
that chitosan has an obvious charge neutralization and
adsorption bridging effect on the precipitation formed by
CO
2
and other tiny impurities in the waste solution.
14
The
effect of the ATP treatment (the D method) is similar to
that of the C method, indicating that the large specific
surface area of ATP allows it to have a significant ad-
sorption effect on impurities and also enables fine pre-
cipitates to form larger precipitates by depositing them
on the surface of ATP for easy filtration.
The CS/ATP complex (the E method) formed by
compounding chitosan and ATP has the best effect on the
impurity removal in the waste solution, and the recov-
ered crude product contains up to 62 % of BZ, which is
due to the fact that on the one hand, the floc formed by
chitosan only was lighter and less likely to settle, while
the presence of ATP effectively increased the floc
weight, making the aggregated floc more compact. In ad-
dition, the rough microstructure of the complex is condu-
cive to the adhesion of fine precipitation and flocs,
speeding up the settling speed and making it easier to re-
move them.
15,16
On the other hand, based on the FTIR
spectra from Figure 1, it can be suggested that the
three-dimensional network structure formed by the
hydroxyl group on ATP and the amino group on CS
through hydrogen bonding in the complex also has a net-
ting effect on the precipitated particles.
3.2.2 Effect of the flocculation temperature
The variation in the BZ content in the waste solution
with the flocculation temperature is shown in Figure 5.
With the increase in the temperature, the content of BZ
gradually increases and reaches the highest value at
30 °C. Due to the fact that with the temperature increase,
the Brownian motion of particles in the waste solution is
strengthened, the collision frequency between the parti-
cles increases and the electrical neutralization and ad-
Y. ZHONG et al.: APPLICATION OF A CS/ATP COMPOSITE FLOCCULANT FOR RECYCLING THE MAIN COMPONENTS ...
550 Materiali in tehnologije / Materials and technology 56 (2022) 5, 547–553
Figure 3: Observation of flocculation morphology: a) ATP, b) CS, c) ATP/CS
Figure 4: Effects of different recovery processes on the BZ content in
the waste solution

sorption bridging effects are gradually enhanced, while
the temperature continues to increase and the effective
number of collisions per unit time increases, leading to
the self-polymerization reaction of the flocculant itself,
which affects the flocculation effect.
17
At the same time,
the acceleration of the reaction rate also makes the fine
particles unfavourable for settling.
3.2.3 Effect of the flocculant dosage
The effect of the flocculant dosage on the BZ content
in the waste solution is shown in Figure 6. The BZ con-
tent tends to increase and then decrease with the
flocculant dosage, reaching the maximum value at 20
mg/mL. This is due to the fact that when the amount of
flocculant is low, the electrical neutralization and adsorp-
tion bridging effects between the flocculant and impurity
molecules are extremely weak, resulting in insufficient
flocculation.
14
On the other hand, when the amount of
flocculant is too high, an excessive amount of positively
charged particles is adsorbed on the surface of colloidal
particles, and bridging cannot be formed between the
particles under the effect of their electrostatic repulsion
because the premise for flocculation is that the surfaces
of the particles in a solution should be left blank to pro-
duce bridging adsorption. So a continued increase in the
amount of flocculant produces a colloid protecting ef-
fect, which enhances the stability of the particle system
and makes it less likely to settle. On the other hand, CS
is positively charged and an excessive amount of
flocculant can also reduce the BZ content with the ad-
sorption on the dissociated negative ions of BZ.
3.2.4 Stirring and standing time
After adding the flocculant, the effect of the solution
stirring and standing time on the BZ content in the waste
solution is shown in Figure 7. The stirring time is one of
the important factors affecting the flocculation effect.
The whole flocculation process consists of two stages:
mixing and reaction. In the mixing stage, stirring can
promote the full contact of the objects, while in the reac-
tion stage, a stirring time that is too long leads to the
fragmentation of the formed flocs. In addition, the stand-
ing stage of flocculation is the process of floc gathering
and settling. If the time is too short, the flocs do not set-
tle completely, causing difficulties during separation; if
the time is too long, the flocs may adsorb the main com-
ponents in the solution, resulting in a reduction in the
main-component content. As shown in Figure 7, the best
flocculation effect was achieved after 10 min of stirring
and standing.
3.2.5 Orthogonal test
An L
9
(3
4
) orthogonal test was designed based on the
above experimental results to further optimize the floc-
culation process, and the lever factors are shown in Ta-
Y. ZHONG et al.: APPLICATION OF A CS/ATP COMPOSITE FLOCCULANT FOR RECYCLING THE MAIN COMPONENTS ...
Materiali in tehnologije / Materials and technology 56 (2022) 5, 547–553 551
Figure 5: Effect of the flocculation temperature on the BZ content in
the waste solution
Figure 7: Effect of the stirring and standing time on the BZ content in
the waste solution
Figure 6: Effect of the flocculant dosage on the BZ content in the
waste solution

ble 1. The optimum flocculation process was determined
with an extreme difference analysis based on the experi-
mental results, with a flocculation temperature of 30 °C,
CS/ATP dosage of 20 mg/mL, stirring time of 10 min,
and standing time of 30 min. The order of the influenc-
ing factors was standing time > flocculant dosage > floc-
culation temperature > stirring time. A validation experi-
ment for this optimal flocculation condition was
performed, and its result showed that the BZ content of
the crude product recovered from the waste solution was
74 %.
Table 1: Orthogonal-factor table for the recovery technology using
CS/ATP
Level
Factor
Tempera-
ture (°C)
Dosage
(mg/mL)
Stirring
time (min)
Standing
time (min)
12 01 51 01 0
23 02 02 02 0
34 02 53 03 0
3.3 Comparison of recovery processes
A comparison of the best process obtained with the
orthogonal test and the conventional recovery process is
shown in Figure 8; the results show that the crude prod-
uct obtained with the ATP/CS flocculation treatment had
a BZ content of 74 %. The crude product was then
recrystallized once with ethanol (95 %), and the BZ con-
tent reached 98 % with a yield of 20 %. The crude prod-
uct obtained with the conventional recovery was very
sticky due to the BZ content of only 47 %, and the con-
tent reached 81 % after one recrystallization. The syner-
gistic adsorption and flocculation of ATP and CS in the
compound flocculant promoted the sedimentation of fine
impurities suspended in the waste solution, which was
conducive to the separation of impurities and the in-
crease in the BZ content in the waste solution, thus more
favourable to the recovery of BZ from the waste solution.
4 CONCLUSIONS
The preparation of the CS/ATP composite flocculant
with the synergistic effect of adsorption and flocculation
using CS and ATP as raw materials is simple and easy,
suitable for industrial mass production, and can effec-
tively recover a high-purity BZ crude product from a BZ
synthesis waste solution, thus reducing the production
cost.
Through a single-factor experiment and orthogonal
test, the best flocculation conditions for using CS/ATP in
a BZ waste solution were created when 20 mg/mL of
CS/ATP were added to the solution at 30 °C, stirred for
10 min and allowed to rest for 30 min. Under these con-
ditions, the flocculant not only facilitated the recovery of
BZ from the waste solution, but also increased the BZ
content in the crude product from 47 % to 74 %, and the
content of crude product from 81 % to 98 % after one
recrystallization.
The CS/ATP composite flocculant is a natural green
composite material, which avoids the disadvantages of
the residuals of a single CS flocculant and difficult sepa-
ration after a single ATP adsorption. It effectively accel-
erates the settling of impurities in a waste solution, and
can be used in the fields of solution clearing and waste
solution separation and purification.
Acknowledgment
This research was funded by the Natural Science
Foundation of the Jiangsu Higher Education Institutions
of China (19KJD430005), Qinglan project of excellent
teaching team in Jiangsu, and teaching and research pro-
ject of the Jiangsu Health Vocational College
(JKA202004, JKB202002, JKB202008).
5 REFERENCES
1
L. M. Luo, Q. W. Zhu, B Zhu, Y. H. Li, J. Gu, X. Y. Li, Q. Ma, Q.
Zeng, X. Yang, H. M. Wu, L. Mao, P. Ye, The effects of homemade
bezafibrate on abnormal metabolism of glucose and lipid in patients
with high serum triglycerides level, Chin. J. Pract. Intern. Med., 29
(2009) 4, 350–353
2
A. Tenenbaum, E. Z. Fisman, Balanced pan-PPAR activator
bezafibrate in combination with statin: comprehensive lipids control
and diabetes prevention, Cardiovasc. Diabetol., 14 (2012) 11, 140,
doi:10.1186/1475-2840-11-140
3
Chinese Pharmacopoeia Commission, Chinese Pharmacopoeia. Part
2, Chinese Medicine Science and Technology Press, Beijing 2020,
740
4
J. Wu, H. J. Zhang, G. J. Yang, X. C. Wu, Removal of the Main Im-
purity from Benzafibrate by a Precipitation Method with Carbon Di-
oxide, Chin. J. Appl. Chem., 32 (2015) 9, 1088–1092
5
Y. Teng, Z. Y. Liu, K. Yao, W. B. Song, Y. J. Sun, H. L. Wang, Y. H.
Xu, Preparation of Attapulgite/CoFe2O4Magnetic Composites for Ef-
ficient Adsorption of Tannic Acid from Aqueous Solution, Int. J. En-
viron. Res. Public Health, 16 (2019) 2, 2187, doi:10.3390/
ijerph16122187
6
J. Wu, S. J. Ding, J. Chen, J. L. Jiang, J. J. Wang, Preparation and
sustained release properties of acidified-attapulgite/alginate compos-
ite material, CIESC Journal, 65 (2014), 4627–4632
7
Y. Deng, Y. Li, W. Nie, X. Gao, L. Zhang, P. Yang, X. Tan, Fast Re-
moval of Propranolol from Water by Attapulgite/Graphene Oxide
Y. ZHONG et al.: APPLICATION OF A CS/ATP COMPOSITE FLOCCULANT FOR RECYCLING THE MAIN COMPONENTS ...
552 Materiali in tehnologije / Materials and technology 56 (2022) 5, 547–553
Figure 8: HPLC of the conventional recovery process (1) and ATP/CS
recovery process (2)

Magnetic Ternary Composites, Materials, 12 (2019) 6, 924,
doi:10.3390/ma12060924
8
H. Guo, K. Xia, M. Cao, X. Zhang, Surface Modification of Attapul-
gite by Grafting Cationic Polymers for Treating Dye Wastewaters,
Materials, 14 (2021) 4, 792, doi:10.3390/ma14040792
9
J. H. Huang, Y. F. Liu, X. G. Wang, Selective adsorption of tannin
from flavonoids by organically modified attapulgite clay, J. Hazard.
Mater., 160 (2008) 2–3, 382–387, doi:10.1016/j.jhazmat.2008.03.008
10
J. W. Zhang, X. W. Wang, Y. Feng, C. C. Su, Floccultion effect and
flocs’ fractal characteristics of peony’s water-extraction with
chitosan, J. Zhejiang Univ. (Sci. Ed.), 44 (2017), 561–567
11
F. Cosme, A Vilela, Chitin and Chitosan in the Alcoholic and
Non-Alcoholic Beverage Industry: An Overview, Appl. Sci., 23
(2021) 11, 11427, doi:10.3390/app112311427
12
X. Y. Wang, Y. M. Du, J. W. Luo, J. H. Yang, W. P. Wang, J. F. Ken-
nedy, A novel biopolymer/rectorite nanocomposite with anti-
microbial activity, Carbohydr. Polym., 77 (2009) 3, 449–456,
doi:10.1016/j.carbpol.2009.01.015
13
W. W. Dai, Y. X. Liu, Mineralogical characteristics and pore struc-
ture of palygorskite pre- and post-hydrochloric acid modification
from Mingguang Anhui, Acta Mineral. Sin., 25 (2005), 393–398
14
S. Bhalkaran, L. D. Wilson, Investigation of Self-Assembly Pro-
cesses for Chitosan-Based Coagulant-Flocculant Systems: A
Mini-Review, Int. J. Mol. Sci., 17 (2016) 10, 1662, doi:10.3390/
ijms17101662
15
R. Dong, N. N. Wang, J. Zhou, P. Fu, Flocculation of chlorella by
composite of modified chitosan and attapulgite, Chin. J. Environ.
Eng., 10 (2016) 2, 709–716, doi:10.12030/j.cjee.20160231
16
A. S. Eltaweil, E. M. A. El-Monaem, M. S. Mohy-Eldin, A. M.
Omer, Fabrication of attapulgite/magnetic aminated chitosan com-
posite as efficient and reusable adsorbent for Cr (VI) ions, Sci. Rep.,
11 (2021), 16598, doi:10.1038/s41598-021-96145-6
17
P. Ma}czak, H. Kaczmarek, M. Ziegler-Borowska, Recent Achieve-
ments in Polymer Bio-Based Flocculants for Water Treatment, Mate-
rials, 13 (2020) 18, 3951, doi:10.3390/ma13183951
Y. ZHONG et al.: APPLICATION OF A CS/ATP COMPOSITE FLOCCULANT FOR RECYCLING THE MAIN COMPONENTS ...
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