Hybridization of Al2O3 microspheres and acrylic ester resins as a synergistic absorbent for selective oil and organic solvent absorption

Article abstract of DOI:10.1002/aoc.4244

In this study, we have focused on the synthesis, characterization, and oil absorption properties of Al₂O₃ microspheres/acrylic ester resin (AER) hybrids. The Al₂O₃ microspheres are prepared by a combined hydrothermal and sintering processes, followed by surface modification with silane coupling agent (KH 570). The Al₂O₃ microspheres/AER hybrids with a rough surface are synthesized by a microwave polymerization route by using modified Al₂O₃ microspheres as modifiers. In this hybrid materials system, the Al₂O₃ microspheres with porous structures may provide fast oil absorption due to the low oils absorption energy and short diffusion lengths. The resin hybrids exhibited reversible oils and organic solvents adsorption with maximum absorption capacities up to 29.85?g/g. This study suggests potential environmental advantage in using metal oxide microspheres in improving the oil absorption properties of oil-absorbing resins as absorbents for recovering oil and organic solvent from water.

Full text of DOI:10.1002/aoc.4244

Received: 22 October 2017
DOI: 10.1002/aoc.4244
Revised: 4 December 2017
Accepted: 4 December 2017
F U L L P A P E R
Hybridization of Al O microspheres and acrylic ester resins
2
3
as a synergistic absorbent for selective oil and organic
solvent absorption
1
,2
1
1
3
1
1
Tao Zhang
| Xuejie Yue | Dongya Yang | Qing Guo | Fengxian Qiu
| Zhangdi Li
1
School of Chemistry and Chemical
Engineering, Jiangsu University,
Zhenjiang 212013, Jiangsu Province,
China
In this study, we have focused on the synthesis, characterization, and oil
absorption properties of Al O microspheres/acrylic ester resin (AER) hybrids.
2
3
The Al O microspheres are prepared by a combined hydrothermal and
2
3
2
Institute of Green Chemistry and
sintering processes, followed by surface modification with silane coupling agent
(KH 570). The Al O microspheres/AER hybrids with a rough surface are
Chemical Technology, School of
Chemistry and Chemical Engineering,
Jiangsu University, Zhenjiang 212013,
Jiangsu Province, China
2
3
synthesized by a microwave polymerization route by using modified Al O
2
3
microspheres as modifiers. In this hybrid materials system, the Al O micro-
2 3
3
School of the Environment and Safety
spheres with porous structures may provide fast oil absorption due to the low
oils absorption energy and short diffusion lengths. The resin hybrids exhibited
reversible oils and organic solvents adsorption with maximum absorption
capacities up to 29.85 g/g. This study suggests potential environmental
advantage in using metal oxide microspheres in improving the oil absorption
properties of oil‐absorbing resins as absorbents for recovering oil and organic
solvent from water.
Engineering, Jiangsu University,
Zhenjiang 212013, China
Correspondence
Dongya Yang and Fengxian Qiu, School of
Chemistry and Chemical Engineering,
Jiangsu University, Zhenjiang 212013,
Jiangsu Province, China.
Email: yangdyxxb@ujs.edu.cn;
fxqiu@126.com
KEYWORDS
Funding information
absorption, acrylic ester resin, hollow microspheres, resin hybrids, reusability
National Nature Science Foundation of
China, Grant/Award Numbers: 21706100
and U1507115; Natural Science Founda-
tion of Jiangsu Province, Grant/Award
Numbers: BK20160500, BK20161264 and
BK20161362; Scientific Research Founda-
tion for Advanced Talents, Jiangsu Uni-
versity, Grant/Award Number: 15JDG142;
China Postdoctoral Science Foundation of
Jiangsu Province, Grant/Award Numbers:
1701067C, 1701073C and 1601016A; Key
Research and Development Program of
Jiangxi Province, Grant/Award Number:
20071BBH80008; High‐Level Personnel
Training Project of Jiangsu Province,
Grant/Award Number: BRA2016142;
China Postdoctoral Science Foundation,
Grant/Award Numbers: 2016 M601747,
2017 M621694 and 2016 M600373
Appl Organometal Chem. 2018;e4244.
wileyonlinelibrary.com/journal/aoc
Copyright © 2018 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4244

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ZHANG ET AL.
1
| INTRODUCTION
can effectively reduce the mass transfer resistance,
resulting in fast sorption kinetics. In addition, the porous
architectures of the microspheres can provide more space
and absorption sites for oils and organic solvents absorp-
tion. Therefore, the development of porous oxide micro-
spheres is of great significance in oils and organic
solvents separation.
As a nonrenewable resource, crude oil is an essential raw
material for chemical industry and materials engineering.
The worldwide consumption of crude oil for 2016 is pre-
dicted to be ∼94 million barrels per day. Crude oil
exploration, storage, transportation, processing and usage
[1]
[
2]
activities are all accompanied by the risk of oil spillage.
The oil absorption properties are limited by the pore
structure and density of absorbents. As a novel class of
functional polymer, oil‐absorbing resins with 3D network
structure, hydrophobic and oleophilic nature are consid-
ered as promising materials for oils separation due to
the high oil retention ability, high selectivity and good
Water pollution from oil spills has become one of the
major threats to the environment and has become a global
concern due to its toxicity and non‐biodegradable proper-
ties. A typical example is the 2010 Gulf of Mexico oil spill,
the largest accidental ocean spill in history, which
released an estimated 4.9 million barrels of crude oil into
the ocean, resulting in severe damage to marine life,
fishing industry, coastal wetlands and so on. Therefore,
it is essential to separate and clean the oil promptly after
a spillage.
Organic solvents, which are widely used in laboratory
and industrial production, can release toxic organic pol-
lutants into environment and thereby cause environmen-
tal contamination as well as resource and economic
losses. The trace water organic solvents need to be
removed before use. The long‐term effects of environ-
mental pollution by oil spills or organic solvents/water
separation call for an urgent need to develop separation
technologies and relevant oil/water separation materials
[
22–24]
reusability.
Nevertheless, low oil absorption proper-
[3]
ties, complicated fabrication procedures and poor thermal
stability of oil‐absorbing resins seriously hinder the prac-
tical applications in oil separation. To overcome these
restrictions, introducing the porous functional materials
[25]
into oil‐absorbing resins was suggested. Wu et al.
pre-
pared the magnetic, durable, superhydrophobic and
superoleophilic polyurethane (PU) sponges by chemical
vapor deposition of tetraethoxysilane to bind the Fe O
3
4
particles tightly on PU sponge surfaces. The Fe O /
3
4
[4]
sponges also show very high efficiency in oil/water sepa-
ration, which could absorb a large amount of floating oils
on a water surface and heavy oils under water. Our group
recently reported a facile and inexpensive to fabricate
[
5]
[26]
for the cleanup of oils and organic solvents from water.
MnO2 nanowires/PU foam composites,
using the
Selective removal and separation of oils and organic sol-
vents from water surfaces or under water by oil/water sep-
arating materials is of great interest from economic and
ecological standpoints. Therefore, various oil‐separating
materials have been applied for separation of oils and
organic solvents.
MnO nanowires as modifiers and PU sponge as a porous
substrate. The obtained PU foam composites are demon-
strated to have excellent oils absorption properties by
2
introducing the MnO nanowires and may have some
2
promising applications in oils and organic solvents sepa-
ration. However, the MnO nanowires cannot provide
2
The preferable oil‐separating materials should possess
enough oil storage space, and thus largely restricts the oils
absorbency of the oil‐absorbing resins.
[
6]
these properties such as high oil separation properties,
[
7]
[8,9]
fast oil separation rate,
good reusability,
good
Herein, to explore the advantage of porous oils
absorption materials and oil‐absorbing resins in terms of
synergistic absorption, we report the synthesis and char-
acterization of porous Al O microspheres/AER hybrids.
[10]
mechanical and chemical stability.
In recent years,
porous functional materials are interesting because of
their wide range of applications, such as chemical separa-
2
3
[
11,12]
[13,14]
[15]
tion and purification,
filtration
adsorption,
catalysis,
Furthermore, the prepared resin hybrids are employed
for oils and organic solvents adsorption. Firstly, the
Al O microspheres were prepared by a simple hydrother-
[16]
[17]
and drug delivery.
structures of foam material, Chen et al.
Utilizing the porous
[
18]
prepared
2
3
porous carbon foam for selectively oils absorption via car-
bonization of polymer foam and reported the oils and
organic solvents absorption capacity of 148.4‐411.2 g/g.
mal method followed by calcination. Then, the porous
Al O microspheres/AER hybrids were synthesized by
suspension polymerization. The introduction of porous
2
3
[19]
Dutta et al. synthesized cone‐shaped superhydrophobic
CaAl‐LDH intercalated with dodecyl sulphate anions that
can separate and regenerate oil from oil–water mixtures.
Among the porous materials, porous oxides are crucial
because of their large surface area, lightweight and tun-
Al O microspheres into oil‐absorbing resins can effec-
2
3
tively improve the pore structure and stability of the resin
hybrids, and thus improved the oils absorption properties.
In order to explore the feasibility of resin hybrids as an
absorbent, the oils absorption performances were evalu-
ated using various oils and organic solvents. It is expected
that the resin hybrids would have excellent oils
[20,21]
able surface properties.
In oils and organic solvents
absorption, the large surface area of porous microspheres

ZHANG ET AL.
3 of 11
absorption properties due to synergistic advantages of the
high porosity of Al O microspheres and swelling proper-
in air at 80 °C. Finally, the samples were calcined at
600 °C in air for 4 h to obtain porous Al O microspheres
2
3
2 3
ties of resin, as well as the strong oils and organic solvents
affinity attributable to the hydrophobic surface. It makes
them very promising materials as an oil/water separator
and oil absorbent.
(as shown in Scheme 1).
The hydrophobic modification of Al O microspheres
was performed by grafting the hydrophobic group on the
surfaces of microspheres (as shown in Scheme 1). 50 mL
2
3
of water suspension of porous Al O3 microspheres
2
(
2
0.01 g/ml) was subjected to ultrasonic vibration for
0 min. The pH of the suspension was adjusted to 3‐4 by
2
2
| MATERIALS AND METHODS
.1 | Chemicals and materials
careful addition of HCl (10 wt %). Then, 50 ml of anhy-
drous ethanol and 0.5 g of KH 570 were added into the
mixture. The obtained mixture was sealed in a 250 ml
three‐necked round bottom flask and heated in a micro-
wave reactor to 85 °C for 60 min, and the obtained pow-
ders were filtered, washed with distilled water, and then
dried at 60 °C in air for 12 h before characterization.
N,N‐methylene‐bis‐acrylamide (MBA), methyl methacry-
late (MMA), polyvinyl alcohol (PVA), butyl acrylate
(BA), γ‐methacryloxypropyl trimethoxysilane (KH‐570),
benzoyl peroxide (BPO), ethyl acetate, polydimethylsilox-
ane (PDMS), toluene and carbon tetrachloride (CCl ) and
4
chloroform (CHCl ) were obtained from Sinopharm
3
Chemical Reagent Co., Ltd. Aluminum nitrate
2
.3 | Synthesis of porous Al O3
2
nonahydrate (Al(NO ) •9H O) and glucose (C H O )
3
3
2
6
12 6
microspheres/AER hybrids
were provided by Shanghai Chemical Company. Diesel
oil and engine oil were collected from the local service sta-
tion. Some edible oils, including soybean oil, sesame oil
and sunflower oil, were purchased from the local super-
market. And the initiator BPO was recrystallized before
using and stored in an amber bottle. Double‐distilled
water was employed in all experiments.
The porous Al O spheres/AER hybrids were synthesized
2
3
by utilizing the microwave polymerization between the
grafted functional groups and monomer of AER on the
porous spheres surfaces. Firstly, 0.27 g of PVA was dis-
solved in 27 ml of distilled water at 90 °C with a mechan-
ical stirrer. After natural cooling, the PVA solution was
transferred into a XH‐100A microwave reactor. Then,
the mixture, which contained hydrophobic porous Al O
2
3
2
.2 | Preparation and surface hydrophobic
spheres (0.27 g), BA (6.0 g), MMA (3.0 g), of ethyl acetate
4.5 g), BPO (0.09 g) and MBA (0.135 g), was added into
modification of porous Al O spheres
2
3
(
the microwave reactor under N atmosphere. The temper-
ature was ramped from room temperature to preset reac-
tion temperatures, and the reaction was continued at
The preparation of porous Al O spheres was carried out
2
2
3
[
27]
by classical template method with a modification.
In
a typical preparation, 15 mmol of glucose and 3 mmol of
40 °C for 15 min, 60 °C for 15 min, 80 °C for 150 min with
Al(NO ) •9H O were dissolved in 60 ml of distilled water
3
3
2
stirring. After the reaction was complete, the product was
collected and sequentially washed with deionized water
to form a mixed solution under vigorous stirring for
0 min. The mixed solution was placed in a 80 ml Tef-
lon‐lined stainless steel autoclave and maintained at
80 °C for 24 h. The black products were collected and
3
(
60~70 °C) and anhydrous ethanol, dried at 80 °C for
1
2 h to obtain porous Al O spheres/AER hybrids.
1
2 3
washed with distilled water and anhydrous alcohol sev-
eral times. Then, the products were dispersed in 100 ml
of distilled water and treated under ultrasound for
2.4 | Sample characterization
3
0 min. After that, the obtained products were filtered
The SEM images of the porous Al O spheres, raw AER,
2 3
and washed several times with distilled water, and dried
and porous Al O spheres/AER hybrids were acquired
2
3
2 3
SCHEME 1 Schematic illustration for preparation and surface hydrophobic modification of Al O spheres

4
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ZHANG ET AL.
using a JEOL JSM‐ PLUS/LA scanning electron micro-
scope. The surface properties and pore structures of as‐
prepared porous Al O spheres were analyzed by nitrogen
2
3
adsorption measurements, operated at 77 K on a
Micromeritics ASAP 2020 adsorption analyzer. The con-
tact angle of hydrophobic Al O spheres was tested by
2
3
using a commercial CAM200 optical system by the sessile
drop method. X‐ray diffraction (XRD) data were recorded
using a Shimadzu XRD‐6100 instrument with Cu Kα radi-
ation at 40 kV and 30 mA, a scanning rate of 4°/min, and
a 2 theta angle ranging from 10° to 80°.
2.5 | Oils adsorption
The oil absorption properties were evaluated by a weighing
method via dipping resin hybrids into oils (or organic sol-
vents)/water mixtures. In a typical absorption process,
0
.2 g of resin hybrids was immersed in oils (including edi-
ble oils, organic solvents and fuels) at 25 °C for 24 h. After
that, the samples were taken out from the oil, drained for
3
~5 min to remove residual oil, and then weighed immedi-
ately. The oil absorption properties of resin hybrids were
calculated by the following formula:
Qðg=gÞ ¼ ðmt−m0Þ=m0
(1)
where m and m are the weight of the oil absorbents
t
0
dispersed in oil for time t and the dry weight of the oil
absorbent, respectively.
To test the regeneration capacity of the porous Al O
2
3
spheres/AER hybrids, the saturated organic solvents and
oils were firstly squeezed from the oil‐absorbing materials
by a simple mechanical compression method. Then, the
samples were immersed in anhydrous ethanol to release
the absorbed oil, followed by drying at 120 °C for 12 h.
The oils absorption and desorption process were repeated
5
times to confirm the reusability of resin hybrids. For
each cycle, the resin hybrids were weighed before and
after oils absorption.
3
| RESULTS AND DISCUSSION
FIGURE 1 SEM micrographs of alumina/carbon spheres and
As a carbon precursor, the glucose was hydrolyzed during
the hydrothermal process, forming the carbon micro-
spheres via the condensation, polymerization and aromati-
zation of glucose. During this process, the alumina
precursors are easily adsorbed to the surface of carbon
spheres due to the oxygencontaining groups in the carbon
spheres, forming the alumina/carbon spheres with a
2 3
hollow Al O microspheres
microspheres. As shown in Figure 1(a) and (b), the alu-
mina/carbon particles are spherical in shape and relatively
homogeneous. The microspheres shown in Figure 1B have
a narrow particle size distribution with the mean size of
2.0 μm. Figure 1(c) and (d) give the SEM images of the
porous Al O microspheres. Observed from the images, it
polycrystalline Al O3 shell structure. Therefore, the
2
2 3
porous Al O microspheres are obtained by the calcination
of the carbon spheres. Figure 1 shows the typical SEM
is obvious that the spherical morphologies are retained in
Al O microspheres. It is also noted that a rough surface
2
3
2
3
images of alumina/carbon spheres and porous Al O3
is obtained after the thermal decomposition of the carbon
2

ZHANG ET AL.
5 of 11
spheres as revealed in Figure 1(d). They appeared to have
rough surfaces, which is attributed to the fact that the
amorphous Al O is formed by the calcination.
It is seen from the pore sizes of porous Al O micro-
2
3
spheres are distributed mostly between 2.76 and
10.77 nm, a narrow pore size distribution centered at
3.55 nm, implying that the sample possesses uniform pore
channels in the mesoporous region. The mesopores
resulted in a higher surface area, which will facilitate
the mass transfer from the liquid phase into solid phase.
For oils and organics selective separation, the surfaces
modified Al O microspheres, which are treated by sur-
2
3
In oils absorption, the large surface area of micro-
spheres can effectively reduce the mass transfer resistance
and rapid absorb organics from water. While, the porous
structures of the microspheres can absorb oils, and store
in the internal space of Al O . To obtain further insight
2
3
into the surface properties of the as‐prepared Al O3
2
2 3
microspheres. The N adsorption‐desorption method was
also employed to confirm the specific surface area and
face grafting of hydrophobic groups, is suitable for the
demand of interfacial hydrophobicity and lipophilicity.
In addition, the grafted functional group can be related
with the monomers of AER to form the organic‐inorganic
hybrids. Figure 3 presents the XRD patterns of porous
Al O microspheres and surface modified Al O micro-
2
the pore sizes distribution of the obtained Al O micro-
2
3
spheres. Figure 2(a) shows their adsorption and desorp-
tion isotherm curve. The isotherm curve of Al O3
2
microspheres exhibits the typical adsorption hysteresis
that belongs to type IV isotherm curves, indicating that
these the samples have mesoporous structures. The spe-
cific surface area and pore volume of samples are calcu-
2
3
2 3
spheres. In XRD patterns, the porous Al O microspheres
2
3
show showed only very broad and diffuse patterns, indi-
cating the amorphous nature of the Al O microspheres
2
3
2
3
lated to be 111.73 m /g and 0.1634 cm /g, respectively.
The high BET surface area and mesoporous structures of
the porous Al O microspheres are beneficial to oils and
obtained by sacrificial template method. To further con-
firm the structural changes, the as‐prepared Al O micro-
2
3
spheres were modified by hydrophobic functional groups
and the corresponding XRD patterns are presented in
Figure 3b. As can be seen in XRD pattern, no observable
change in the Al O microspheres was observed after sur-
2
3
organic solvents transport and absorption. A plot of the
pore size distribution, calculated using the BJH method
from the adsorption branch, is shown in the Figure 2(b).
2
3
face hydrophobic modification, which meant that the
silane coupling agent did not affect the structure of Al O .
2
3
In this case, the surfaces of porous Al O microspheres
2
3
were chemically modified using KH 570 in order to termi-
nate the hydrophilic groups such as hydroxyl groups,
forming the hydrophobic interface. In order to verify the
changes on the surface properties of the Al O micro-
2
3
spheres, the surface functional groups of raw Al O
2
3
microspheres and surface modified Al O microspheres
2
3
were investigated by FT‐IR spectroscopy. The broad
FIGURE 2
distribution of hollow Al
N
2
adsorption–desorption isotherm and BJH pore size
microspheres
FIGURE 3 XRD patterns of raw and surface modified hollow
Al microspheres
2
O
3
2 3
O

6
of 11
ZHANG ET AL.
adsorption band at 3400 cm‐1 could be ascribed to
stretching vibrations of hydroxyl group. It can be seen
from Figure 4a, the strong peaks at low frequency
groups on the surface of Al O3 microspheres. These
2
results indicated that the hydrophobic groups are success-
fully grafted on the surfaces of Al O microspheres. The
2
3
‐
1
(
880~530 cm ) in both spectra of raw Al O microspheres
surfaces of Al O microspheres are treated by KH 570,
2 3
2
3
and surface modified Al O microspheres are attributed to
resulting in the formation of hydrophobic interface.
For comparison, the FT‐IR spectrum of silane coupling
agent is also given, as shown in Figure 4c. It should be
noted that the peak intensities of surface modified Al O
2
3
the M‐O vibration of chemical bonds in Al O . After
2
3
surface modification of Al O microspheres, a variety of
2
3
surface functional groups were introduced onto the sur-
face, as can be seen in Figure 4b. These functional groups
centered at 2955.95 1704.45, 1635.75, and 1300.41 cm‐
could be ascribed to C‐H, C=O, C=C, and C‐O, respec-
tively, indicating the existence of hydrophobic functional
2
3
microspheres are lower than that of pure silane coupling
agent. The reason for this phenomenon may be due to
the low content of hydrophobic groups in the Al O
1
2
3
microspheres.
Wettability of porous Al O microspheres to water is
2
3
one of the most important considerations when selecting
an absorbent suitable for oils and organic solvents absorp-
tion. The surfaces of porous Al O microspheres were
2
3
chemically modified using KH 570 to form the hydropho-
bic interfaces. To further verify the surface properties,
contact angle measurements were conducted to examine
the surface wettability at different places of the samples.
Figure 5 shows the water contact angle profiles of the sub-
strates coated with the porous Al O microspheres before
2
3
and after surface modification. As shown in Figure 5(a),
the contact angle of unmodified Al O3 microspheres
2
could not be measured because it was extremely low, indi-
cating the existence of lipophilic. When KH 570 coated on
Al O microspheres contacted with the oil‐water mixture,
2
3
oils molecules can be trapped in the macroporous struc-
ture of materials. It can be seen from Figure 5(b) and (c)
that the droplets are nearly spherical in shape for surfaces
modified Al O microspheres. The water contact angle,
FIGURE 4 FT‐IR spectra of raw hollow Al
2 3
O microspheres (a),
surface modified hollow Al microspheres (b) and KH 570 (c)
2 3
O
2
3
FIGURE 5 Oil (a) and water (b and c) wettability of the substrates coated with the KH 570 modified hollow Al
droplet rolling on the femtosecond laser ablated surface (e‐f)
2 3
O microspheres; Water

ZHANG ET AL.
7 of 11
SCHEME 2 Schematic illustration for
oils absorption of hollow Al
microspheres/AER hybrids
2 3
O
measured at room temperature, was varied between
64.53° and 165.77°, implying that superhydrophobic
without apparent porosity. It made oil molecules and
organic solvents not easy to diffuse into the interiors of
AER. However, the surface structures of resin hybrids
are changed greatly by adding the porous Al O micro-
1
properties of microspheres closer to the grafted hydropho-
bic functional groups. Besides, while immersing surfaces
modified Al O microspheres in aqueous solution for 6 h
2
3
spheres which can be observed from Figure 6(c) and (d).
2
3
,
under the condition of ultrasonic vibrations or exposing
samples in air environment for 5 days at room tempera-
ture, samples in both cases remained hydrophobicity with
water contact angle higher than 160°. It is clearly indi-
cated the high stability of the hydrophilic or lipophilic
The resin hybrids exhibited a convex surface, which are
beneficial for organic molecules absorption and diffusion
into the interiors of materials. In this hybrid materials sys-
tem, the porous Al O microspheres with hierarchical
2
3
porous structures may provide fast oil absorption owing
to the lowering of absorption energy and diffusion length.
In addition, the porous structures of Al O microspheres
properties of surface hydrophobic modification of Al O3
2
microspheres. Figure 5(d)‐(f) displays the rolling process
2
3
of a water droplet on the alumina coating surface. When
may provide more oil storage space that can enhance
the oil absorption efficiency. Compared with the raw
AR, thermal stability of resin hybrids is improved slightly
enhanced by introducing inorganic materials (see
Supporting Information).
the droplet was falling on the surfaces modified Al O3
2
microspheres surface, it bounced immediately without
any delay. In the case of an inclined surface, the water
droplet rolled off the surface quite quickly within a very
short time. The ultimate tilt angle of substrate when the
droplet started to roll was below 2°. The results indicate
that the hydrophobic groups are successfully grafted on
the surfaces of Al O microspheres, which are in agree-
With low density, high porosity, superhydrophobicity,
and excellent flexibility, the as‐prepared resin hybrids can
be considered as ideal oil absorbents to separate oils and
organic solvents from water. In order to investigate the
absorption properties, the resin hybrids were immersed
in oils or solvents without water and the maximum
absorption capacities were determined by mass change.
Several kinds of frequently encountered oils, namely
PDMS, soybean oil, sesame oil, sunflower oil, engine oil,
and castor oil, were used to evaluate the absorption prop-
erties of the resin hybrids, and the results are shown in
Figure 7(a). The oils absorption capacities of the resin
hybrids towards different organic solvents range from
1.88 g/g to 2.95 g/g, partly depending on the density, vis-
cosity and surface tension of the solvents. The absorbed
organics are stored in the 3D network structure of oil
absorbing resins.
2
3
ment with the FT‐IR results as shown in Figure 4.
For the oils and organic solvents absorption of
organic‐inorganic hybrid materials, the absorption prop-
erties of hybrid materials are largely determined by the
pore structures (inorganic absorbing materials) or swell-
ing properties (polymer absorbing material). The porous
structures of oil‐absorbing materials are beneficial for
reducing the mass transfer resistance and accelerating
the oil absorption rate. The swelling properties of oil‐
absorbing resins not only determine the oils absorption
properties of obtaining materials (as shown in Scheme 2),
but also affect the retention ability of materials. The mor-
phologies of the raw AER and Al O resin hybrids were
2
3
observed by the SEM images displayed in Figure 6. It
appears from the observation of the surfaces of raw AER
that they have a smooth and dense surface appeared
To further verify the feasibility for oil/water separation
applications, the dyed edible oils were chosen as a model
absorbate to investigate the separation performance of

8
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ZHANG ET AL.
FIGURE 7 (a) Comparison of oils absorption capacities of resin
hybrids, (b) photos of edible oils absorption from oily water by
resin hybrids
it was able to be easily fetched out without assimilating
any moisture.
The versatility of resin hybrid for the adsorption of
organic compounds was also studied by employing a series
of commonly used organic solvents, such as acetone, DFM,
CHCl , ether, CCl and THF. It can be seen in Figure 8(a)
3
4
FIGURE 6 SEM images of raw AER (a and b) and hollow
Al microspheres/AER hybrids (c and d)
that the resin hybrid exhibited a very high absorption
capacity (6.54 ‐ 29.85 g/g). It was obvious that the resin
hybrids reported here exhibited much higher adsorption
capacity than oil‐absorbing resins. To demonstrate the fea-
sibility of heavy organic solvents absorption, chloroform
dyed with Sudan III was selected as the representative
absorbates on behalf of organic solvents for absorption.
Compared with several reported oil‐absorbing materials
for oils and organic solvents absorption (Table 1), the
hybrid resins show a high oil absorption capacity, and the
maximum oil absorption capacity can reach up to
29.85 g/g. As can be seen in Figure 8(b), the resin hybrids
2 3
O
the resin hybrids. As can be seen in Figure 7(b), when the
resin hybrids were dropped on the oil/water surface, it
absorbed the surrounding oil film at once. Thereupon,
the white resin hybrids become succulent full with red oil
within 3 min, resulting in transparent and clear water.
Such rapid absorption process is due to the combined
effect of its high porosity of porous Al O microspheres
2
3
and excellent swelling properties of oil‐absorbing resins
as shown in Scheme 2). Owing to the oleophilic nature,
(

ZHANG ET AL.
9 of 11
surface and water. The chloroform in contact with the
resin hybrids is rapidly absorbed, and no obvious organic
solvents remain in the water after taking the resin hybrids
out. This commendable property indicated the possibility
for environmental applications in absorbing floating
pollutants and those underwater. Therefore, the resin
hybrids were effective with low cost and high performance,
environment‐friendly and had a high scalability for the
practical separation of oil/water mixture.
Effect of contact time on oils and organic solvents
absorption is presented in Figure 9(a) and (b). It can be
seen that the increase in the contact time led to an
increase in oils and organic solvents absorption capacity.
The oils adsorption was very fast in the first 60 min and
after 80 min, complete oils and organic solvents absorp-
tion was obtained. In order to get further information on
the oils and organic solvents absorption process, the oils
adsorption obtained from different oils and organic
solvents were further analyzed by different kinetic
FIGURE 8 (a) Comparison of organic solvents absorption
capacities of resin hybrids, (b) photos of chloroform absorption
from oily water by resin hybrids
TABLE 1 Comparison of several reported absorbents for oils and
organic solvents absorption
‐
1
Adsorbents
Q (g g )
References
[
[
[
[
[
[
28]
29]
30]
31]
32]
1]
Cellulose/chitosan composite aerogel
10
SPION/b‐cyclodextrin
Polymethacrylate‐based Fiber
superhydrophobic sponge
Populus fiber
7.2
1.0‐19.6
25.0
3.9‐18.4
7.0
Ferric oxide nanoparticles doped
carbon nanotubes
[
33]
Pure oil absorption resins
Hybrid resins
23.5
6.54 ‐ 29.85* This work
could be also used for the absorption of heavy organic sol-
vents under water. When the resin hybrids were immersed
in the water, a silver mirror‐like surface is observed owing
to a continuous air layer trapped between the hybrids
FIGURE 9 Effect of contact time on oils and organic solvents
absorption

10 of 11
ZHANG ET AL.
models (pseudo‐first order equation, pseudo‐second order
equation and intraparticle diffusion). The kinetic models
and correlation coefficients for oil and organic solvent
absorption are compiled in Table S1. The sesame oil,
CHCl3 and THF adsorptions were fitted well by the
pseudo‐first order equation over the entire absorption
water‐polluted oil from both industrial drainage and
daily emission.
4
| CONCLUSIONS
In summary, we have synthesized the porous Al O
2
3
process according to the high correlation coefficient
microspheres/AER hybrids by a microwave polymeriza-
2
(
R >0.97). However, the intraparticle diffusion model
tion route by using Al O3 spheres as modifiers. The
2
fitted the castor oil adsorption very well according to the
porous Al O3 spheres were prepared by a combined
2
2
high correlation coefficients (R ).
hydrothermal and sintering method. In order to enhance
the hydrophobicity and reactivity, the surfaces of Al O
Reusability of oil‐absorbents is a significant property
for oil separation in practical application. As far as oil
absorbency is concerned, the resin hybrids are also reus-
able, besides having excellent performance in oils and
organic solvents absorption. During the cycled experi-
ments, the as‐synthesized resin hybrids were firstly
immersed in oils and organic solvents for saturated
absorption. After each absorption experiment, it was easy
to clean resin hybrids by ethanol. 5 times cycled absorp-
tion experiments were performed and results were shown
in Figure 10. It is worthy to note that no obviously mea-
surable weight loss of the samples was detected after
being reused, indicating that resin hybrids still displayed
high oils absorption efficiency. The slightly reduced
absorption properties can be ascribed to the fact that a
handful of soluble fraction remained in the composites
is dissolved in repeated swelling, and a fraction of net-
work might collapse by extraction and drying.
2
3
spheres were chemically modified using silane coupling
agent. The results demonstrated that all surface modified
Al O microspheres showed high water contact angles
2
3
(
>160°), implying that the hydrophobic groups are suc-
cessfully grafted on the surfaces of Al O microspheres.
2
3
The large surface area of Al O microspheres can effec-
2
3
tively reduce the mass transfer resistance and rapid
absorb organics from water. And the absorbed oil can be
stored in the porous architectures of the microspheres.
The as‐prepared resin hybrids can separate the oil/water
mixtures effectively with the maximum oil absorbency of
high up to 29.85 g/g. Owing to their unique pore struc-
tures and superhydrophobic and swelling properties, the
resin hybrids can absorb not only floating oil but also
heavy organic solvents underwater with high selectivity
and absorption capacity. Furthermore, the reusability
studies confirm the repeatable usage of the resin hybrid
and its efficacy in oil spill remediation. We believe that
introduction of porous microspheres into oil‐absorbing
resins will widen the range of their applications in oily
wastewater treatment, oils absorption and separation.
As suggested by the results above, the as‐prepared
resin hybrids can be suitable for the separation of various
types of oils and organic solvents with high oil separation
properties, fast oil separation rate and good reusability.
These could imply the resin hybrids as a good
candidate for the cleaning up of oil‐polluted water or
ACKNOWLEDGMENTS
We thank the National Nature Science Foundation of
China (21706100 and U1507115) and Natural Science
Foundation of Jiangsu Province (BK20160500,
BK20161362 and BK20161264) for financial support. This
study was also financially supported by the China Post-
doctoral
Science
Foundation
(2016
M600373,
2017 M621694 and 2016 M601747), High‐Level Personnel
Training Project of Jiangsu Province (BRA2016142), Key
Research and Development Program of Jiangxi Province
(
20071BBH80008), China Postdoctoral Science Founda-
tion of Jiangsu Province (1601016A, 1701073C and
701067C) and Scientific Research Foundation for
1
Advanced Talents, Jiangsu University (15JDG142).
ORCID
FIGURE 10 Absorption capacity of several oils for five
absorption‐regeneration cycles
Tao Zhang http://orcid.org/0000-0001-9255-9802
Fengxian Qiu http://orcid.org/0000-0001-7475-7565

ZHANG ET AL.
11 of 11
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