Preparation and characterization of cellulose grafted with epoxidized

Subscriber access provided by Iowa State University | Library

Biofuels and Biobased Materials

Preparation and characterization of cellulose grafted with epoxidized soybean oil aerogels for oil absorbing materials Xu Xu, Fuhao Dong, Xinxin Yang, He Liu, Lizhen Guo, Yuehan Qian, Aiting Wang, Shifa Wang, and Jinyue Luo J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b05161 • Publication Date (Web): 02 Jan 2019 Downloaded from http://pubs.acs.org on January 3, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 25

Journal of Agricultural and Food Chemistry

1

Preparation and characterization of cellulose grafted with

2

epoxidized soybean oil aerogels for oil absorbing materials

3

Xu Xu*a,b, Fuhao Donga, Xinxin Yang c, He Liu*c, Lizhen Guoa, Yuehan Qiana,

4

Aiting Wangc, Shifa Wanga,b, Jinyue Luoa,b

5

a. College of Chemical Engineering, Nanjing Forestry University Nanjing, Jiangsu

6

Provincial Key Lab for the Chemistry and Utilization of Agro-forest Biomass, Nanjing

7

210037, Jiangsu Province, China.

8

b. Jiangsu Co-Innovation Centre of Efficient Processing and Utilization of Forest

9

Resources, Nanjing 210037, Jiangsu Province, China.

10

c. Institute of Chemical Industry of Forestry Products, Chinese Academy of Forestry,

11

Nanjing 210042, Jiangsu Province, China

12

Contact information: College of Chemical Engineering, Nanjing Forestry University

13

Jiangsu Nanjing 210037, Jiangsu Province, China;

14

*Corresponding author: [email protected] and [email protected]

15 16

Abstract: The absorbent materials synthesized from bio-sources with low cost and high

17

selectivity for oils and organic solvents have attracted increasing attention in the field

18

of oil spillage and discharge of organic chemicals. We developed a convenient surface-

19

grafting method to prepare efficient and recyclable bio-based aerogels from epoxidized

20

soybean oil (ESO)-modified cellulose at room temperature. The porous network-like

21

structure of the cellulose aerogel was still fully retained after undergoing hydrophobic 1

ACS Paragon Plus Environment


22

modification with ESO. Moreover, the modified aerogels possessed excellent

23

hydrophobicity with a water-contact angle of 132.6°. Moreover, the absorbent ability

24

of the hydrophobic cellulose aerogels was systematically assessed. The results showed

25

that modified aerogels could retain more than 90% absorption capacity even after 30

26

absorption−desorption cycles, indicating that the ESO-grafted cellulose aerogels have

27

practical applications in the oil-water separation from industrial wastewater and oil-

28

leakage removal.

29

Keywords: Cellulose aerogels, Epoxidized soybean oil, Oil-absorbing materials, Oil-

30

water separation, Oil/water selectivity

31 32

1. Introduction

33

The ocean is one of Earth's most valuable natural resources, but the ocean pollution

34

due to oil spillage accidents and discharge of organic chemicals has become more and

35

more severe to global environment.1-3 Therefore, scientists focus on developing

36

efficient methods for collection and removal of oil spills and organic chemicals from

37

the ocean. Generally, oil-absorbing materials are commonly used to handle oil leakages

38

due to its fast and efficient absorption in water.4-10

39

The oil-absorbing materials usually include inorganic products, synthetic resins,

40

and natural polymers.11, 12 The inorganic oil-absorbing materials, such as clay, activated

41

carbon, and silica, etc. appear as powders or small particles, making the transportation

42

and recycling costs high.2, 3, 8, 13 Synthetic oil-absorbing resins, including acrylic and 2


Page 2 of 25

Page 3 of 25


43

olefinic resins, are one of the most efficient oil-absorbing materials widely used in the

44

treatment of oil spills. However, the resin may not be degradable or easy to be

45

biodegraded, which results in some environmental problems. Furthermore, some

46

natural polymers, like cellulose, straw, wood chips, and other natural plant fiber-based

47

products, play an essential role in this field because of its recyclability, low cost, and

48

biodegradability.4, 6, 7, 14-18

49

Among bio-based absorbents, hydrophobic aerogels have been used as oil

50

absorbents due to their low density, high porosity, and large specific surface area.7, 19-

51

21

52

renewability, biodegradability, and porosity.17, 18, 22-24 However, the hydroxyl groups in

53

the cellulose aerogels lead to several issues, including poor oil/water selectivity and

54

loss of mechanical properties after prolonged exposure to water. On the other hand, the

55

hydroxyl groups have good reactivity, which can lead to surface modification of

56

cellulose aerogels. Indeed, cellulose aerogels can overcome the inherent hydrophilicity

57

of aerogel skeleton to obtain hydrophobicity and oleophilicity; in other words, it means

58

they can exhibit excellent oil/water selectivity. Therefore, natural cellulose aerogels are

59

promising candidates as oil sorbents after undergoing surface hydrophobization to

60

improve their oil selectivity.25-28 Among the methods to improve the cellulose-aerogel

61

surface hydrophobicity, the absorption of surfactants or polymers and covalent

62

modification of the surfaces are widely used. However, most of the modified cellulose

63

aerogels by surfactants have excess surfactant that has to be removed and are unstable

Cellulose aerogels exhibit good advantages, such as abundant sources, natural

3



64

in different media.11,

65

urethanization, amidation, and silylation.16,

66

modifications are carried out at high temperature, in toxic organic solvents and by non-

67

renewable resources, which might cause significant environmental and ecological

68

impacts. Consequently, increasing effort has been dedicated to attaching natural

69

polymer chains via grafting to prepare hydrophobic and oleophilic porous cellulose

70

based on aerogels with excellent oil-water selective absorption ability.32-36

29

Covalent modifications mostly consist of esterification, 23, 30, 31

However, most of these

71

We report on an efficient method for the formation of modified cellulose based on

72

materials with enhanced hydrophobic properties, which were grafted with polymeric

73

epoxidized soybean oil (ESO) as a renewable environmentally friendly and low-cost

74

raw material.37 Based on this previous work, cellulose grafted with ESO aerogels were

75

prepared and used as oil-absorbing materials. The effects of ESO on the structure,

76

thermal stability, and surface morphology of the ESO modified cellulose aerogels were

77

studied as well. The oil selectivity, oil absorption capacity, and repeated absorption

78

performance of the oil-absorbing material were evaluated in the water-oil mixture

79

system as well.

80

2. Experimental section

81

2.1. Materials.

82

Cellulose pulp from hardwood was provided by the Hubei Chemical Fiber Group

83

Ltd. ESO, sodium hydroxide (NaOH), 1,4-butanediol diglycidyl ether (BDE), and urea

84

were purchased from Aladdin Reagent Corporation. Crude oil was obtained from China 4


Page 4 of 25

Page 5 of 25


85

Petroleum & Chemical Corporation, Jinan Petroleum Branch. Engine oil, silicone oil,

86

paraffin liquid, cyclohexane (≥98%), and n-hexane (≥99%) were purchased from

87

Macklin Chemical Reagents Co., Ltd. (Shanghai, China). Dimethyl sulfoxide (DMSO,

88

≥99%), toluene (≥99.5%), isopropyl alcohol (≥99%), and dichloromethane (CH2Cl2,

89

≥99.5%) were bought from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China).

90

All chemicals and solvents were used as received without further purification.

91

Deionized water was used in all experiments.

92

2.2. Preparation of cellulose aerogels.

93

Cellulose pulp was dried to remove moisture by vacuum and precooled to -10 °C

94

before use. The aqueous solution containing NaOH/urea/H2O at 7:12:81 by weight was

95

used as the solvent. 4.0 g of cellulose pulp was added to 96.0 g NaOH/urea/H2O

96

solution and mixed at -12 °C under stirring for 30 min; thus, a transparent and viscous

97

cellulose solution was obtained. BDE was added to the solution, and the mixture was

98

kept at room temperature for 1 h to form the cellulose hydrogels. Here, the molar ratio

99

between anhydroglucose unit (AGU, M = 162) of cellulose and BDE was 1:3. The

100

hydrogels were separated via centrifugation and purified with water until the pH was 7.

101

Next, the purified hydrogels were diluted to 1.5% by adding deionized water. Finally,

102

the diluted hydrogels were freeze-dried in a lyophilizer for 48 h to obtain the porous

103

cellulose aerogels.

104

2.3. Preparation of cellulose grafted with ESO aerogels.

5



Page 6 of 25

105

0.1 g of cellulose aerogels and 15 g of n-hexane solvent were charged into a three-

106

necked flask with magnetically stirrer and reflux. 10 μL SnCl4 was added as a catalyst.

107

1, 2, 4, 6, and 8 g of ESO (5, 10, 20, 30, and 40 wt% of n-hexane, respectively) were

108

dissolved in 20 g n-hexane, respectively. The ESO solution was dropped into a three-

109

necked flask with a constant-pressure dropping funnel. The hydrophobically modified

110

cellulose material was prepared at room temperature for 30 min reaction and, then, was

111

washed three times with n-hexane to remove the unreacted ESO and ESO self-

112

aggregated products. The cellulose grafted with ESO aerogels was obtained after

113

drying. Cellulose aerogel without ESO modification is defined as Cell/BDE and ESO

114

in 5, 10, 20, 30, and 40 wt% of n-hexane are defined as 5Cell/BDE,

115

20Cell/BDE, 30Cell/BDE,

116

2.4. Characterization.

117

2.4.1. Fourier-transform infrared (FT-IR) spectroscopy. The chemical composition

118

of cellulose samples was analyzed via FT-IR spectroscopy (Nicolet iS 10 spectrometer).

119

The spectra were recorded ranging from 4000-600 cm−1 at a resolution of 4 cm−1 and

120

averaged over 16 scans per sample.

121

2.4.2. X-ray diffraction (XRD). The X-ray diffraction patterns were measured via an

122

X-ray diffractometer (D8 FOCUS, Bruker, Germany) with a Cu-Kα anode. The analysis

123

was recorded at a scanning speed of 0.01° s-1 in the range of 2θ = 10-50°.

124

2.4.3. Thermodynamic analysis. The thermal stability was assessed with a TGA-

125

60AH thermogravimetric analyzer (Shimadzu, Japan) in the range from 25 to 800 °C at

10Cell/BDE,

and 40Cell/BDE, respectively.

6


Page 7 of 25


126

a constant heating rate of 10 °C/min under a nitrogen atmosphere. Differential scanning

127

calorimetry (DSC) was conducted via DSC-60A (Shimadzu, Japan) under a nitrogen

128

atmosphere.

129

2.4.4. Scanning electron microscopy (SEM). The surface morphology of the samples

130

was analyzed via scanning electron microscopy (FE-SEM, JSM-7600F, JEOL, Japan).

131

The samples were attached to the sample holders with conductive double-sided carbon

132

tape and sputter-coated with a platinum layer to avoid charging during the tests.

133

2.4.5. Contact angle measurements. The contact angles of the water droplets were

134

measured at room temperature via a goniometer (Attension® Theta Lite,

135

BolinScientific, Sweden). A double-sided piece of adhesive tape was placed on a glass

136

coverslip, on top of which the cellulose specimen was placed. Then, 5 μL of deionized

137

water were placed on the surface for measurement of the contact angle. Three

138

measurements were taken at different points for each sample from which the average

139

contact angle values were determined.

140

2.4.6. Absorbent ability. The absorption capacity of cellulose grafted with ESO

141

aerogels was measured by immersing samples in 200 mL solvent. The saturated

142

aerogels were weighed after absorbing the surface solvent with filter paper. The

143

absorbent ability (g/g) of cellulose aerogels was measured and calculated as:

144

Absorbent ability = (m1 - m0)/m0 × 100%

145

here, m1 is the weight of the solvent-saturated cellulose aerogel, whereas m0 is the

146

weight of the dried-cellulose aerogel, respectively.

(1)

7



147

3. Results and discussion

148

3.1. Structural characterization of cellulose grafted with ESO aerogels.

149

Figure 1 shows the FT-IR spectrum of cellulose grafted with ESO aerogels before

150

and after undergoing the hydrophobic modification. The band ranging from 3350 to

151

3500 cm-1 in the spectra of cellulose aerogel can be associated to the stretching vibration

152

of O–H. The peaks at 2860 cm-1 and 2935 cm-1 correspond to the symmetric and

153

asymmetric stretching vibrations of methylene, respectively. It can be seen from Figure

154

1a that there is no absorption peak of ester carbonyl group before hydrophobicity

155

modification. With the increase of ESO content during the modification process, the

156

absorption peak of ester carbonyl group at 1742 cm-1 in cellulose grafted with ESO

157

aerogels is enhanced. The results indicate that the cellulose aerogel has been modified

158

by ESO successfully. However, the increase of the absorption intensity of ester

159

carbonyl in

160

increased to 40 wt%, which is consistent with fact that the hydrophobicity of the

161

40Cellu/BDE-modified aerogel was similar to that of the 30Cellu/BDE-modified aerogel.

40Cellu/BDE

was no longer obvious when the mass fraction of ESO

162 8


Page 8 of 25

Page 9 of 25

163


Figure 1. FT-IR spectra of cellulose grafted with ESO aerogels.

164

XRD was used to investigate the effect of the surface modification on the cellulose-

165

aerogel crystal structure. Figure 2 shows the XRD pattern of cellulose grafted with ESO

166

aerogels with different ESO content. There is a significant diffraction absorption peak

167

near 20.9° before and after hydrophobic modification by ESO that can be associated to

168

the amorphous cellulose.7 It indicates that cellulose grafted with ESO aerogels exhibits

169

an amorphous structure, which is not affected by the amount of ESO used in the

170

modification process.

171 172 173

Figure 2. X-ray diffraction patterns of cellulose grafted with ESO aerogels. 3.2. Thermal stability of cellulose grafted with ESO aerogels.

174

Thermogravimetric analysis (TG) and Differential thermal analysis (DTG) curves

175

of cellulose aerogel and cellulose grafted with ESO aerogels are shown in Figure 3. As

176

shown in the Figure 3A, the weight loss of the cellulose aerogel Cellu/BDE within 100

177

°C is more than that of cellulose grafted with ESO aerogels because of the volatilization

178

of water, which indicates that the pure cellulose aerogel without modification has a

179

hydrophilic property and high water-absorption ability, while samples from 9



180

5Cellu/BDE

181

The temperature of the maximum thermal-decomposition rate of Cellu/BDE is 345 °C;

182

however, that of cellulose grafted with ESO is slightly lower but still higher than 271

183

°C, which still shows excellent thermal stability. When the mass fraction of ESO

184

reaches 40 wt%, the final residual rate is the highest in all samples due to the carbon

185

residue produced by the decomposition of the grafted ESO on the surface of aerogels.

186

In addition, two maximum thermal decomposition peaks of 40Cellu/BDE appear in the

187

DTG curve (Figure 3B), which are ascribed to the maximum thermal decomposition of

188

the ESO grafted on the aerogel surface and that of the cellulose skeleton, respectively.

to 40Cellu/BDE after modification by ESO exhibits high hydrophobicity.

189 190

Figure 3. TG and DTG curves of cellulose grafted with ESO aerogels.

191

The thermal behavior of the cellulose aerogels before and after hydrophobic

192

modification can be evaluated via DSC as well. Figure 4 shows the thermal behavior of

193

the unmodified-cellulose aerogel Cellu/BDE (Figure 4a) and the cellulose grafted with

194

ESO aerogels with ESO content of 10 wt% and 20 wt%, respectively (Figure 4b and

195

4c). As a result of the low concentration of ESO grafted on the aerogel surface, no glass-

196

transition temperature Tg appears in the test temperature range from -50 to 50 °C, when 10


Page 10 of 25

Page 11 of 25


197

the mass fraction of ESO is less than 10 wt%. In Figure 4c, it can be found that Tg of

198

20Cellu/BDE

199

glass-transition temperature of 20Cellu/BDE is that ESO has reacted with the hydroxyl

200

groups on the cellulose aerogel surface and then form polymeric ESO. This reaction

201

has affected the chemical composition and surface free energy of the cellulose grafted

202

with ESO aerogels, which increases the mobility of the molecular chains and enhances

203

the plasticity of the material.

is -9.43 °C when EOS content is 20 wt%. The reason for the significant

204 205 206

Figure 4. DSC curves of the cellulose samples. 3.3. Morphological analysis of the cellulose grafted with ESO aerogels.

207

The SEM images of the three-dimensional network structure of cellulose aerogels

208

consisting of continuous and homogeneous porous are shown in Figure 5 at the micro

209

level. After the hydrophobic modification with ESO, the porous web-like structure is

210

still fully retained. However, with the increase of ESO content, more protrusions and

211

uneven wrinkles appear on the aerogel surface. This phenomenon is attributed to

212

polymerized particles formed by ESO grafted with cellulose by the ring-opening

213

reaction on the aerogel surface. When the mass fraction of ESO is increased to 40 wt%, 11



214

the porosity of 40Cellu/BDE is reduced as more pores are covered by film-like polymers

215

due to ESO-grafted cellulose inside the pores.

216 217 218

Figure 5. SEM images of the cellulose samples. 3.4. Wettability of the cellulose grafted with ESO aerogels.

219

Oil/water selectivity plays a vital role in oil-absorbing materials. The cellulose

220

aerogels without hydrophobic modification have a large number of hydroxyl groups

221

lacking good oil/water selectivity; therefore, they cannot be used as oil absorbents for

222

the oil-water mixture. As presented in Figure 6, both the macromorphologies of

223

cellulose before and after hydrophobic modification are white and regular cuboid,

224

indicating that the process with ESO has not affected the shape of the cellulose, which

225

is consistent with the SEM results. But the density of the cellulose aerogel was 26.7

226

mg·cm-3 and that of the 30Cellu/BDE aerogel was 72.8 mg·cm-3. The increase of density

227

also indicates that cellulose was successfully grafted with ESO. As shown in Figure 6a1 12


Page 12 of 25

Page 13 of 25


228

and a2, 5 μL of water (stained with CuSO4 in blue colour) were dropped on the

229

Cellu/BDE aerogel surface; then, its surface becomes rapidly wet and with a contact

230

angle of 0°. Moreover, the Cellu/BDE aerogel still displays good absorption ability of

231

pump oil (stained with Sudan red in red colour) as well, which means that the

232

unmodified cellulose aerogels do not have the advantage of oil/water selectivity. In

233

contrast, the same water droplet exhibits a nearly spherical shape on the surface of

234

30Cellu/BDE

235

hydrophobicity of the cellulose grafted with ESO aerogel. In addition, the pump-oil

236

droplet was absorbed by the

237

cellulose aerosol grafted with ESO has both lipophilic and hydrophobic properties.

with a contact angle of 132.6° (Figure 6b1 and b2), indicating good

30Cellu/BDE

aerogel immediately, suggesting that the

238 239

Figure 6. Contact angle of Cellu/BDE and 30Cellu/BDE. (a1) Image of the contact angle

240

with water in Cellu/BDE; (a2) Photo of the water and oil droplets on the surface of 13



241

Cellu/BDE; (b1) Image of the contact angle with water in 30Cellu/BDE; (b2) Photo of

242

the water and oil droplets on the surface of 30Cellu/BDE. The water and pump oil were

243

pained with CuSO4 and Sudan red, respectively.

244

3.5. Deformation recovery of the cellulose grafted with ESO aerogels.

245

The deformation recovery of

30Cellu/BDE

aerogels was further tested by

246

performing several cycles of squeezing and re-absorption (Figure 7). The 30Cellu/BDE

247

aerogel was immersed in red-colored pump oil (stained with Sudan red) (Figure 7a-d);

248

it reached its maximum absorption capacity after 16 s. Then, it was squeezed out with

249

an external force until no more water was removed, as shown in Figure 7e-f. The

250

30Cellu/BDE

251

reached its maximum absorption capacity after 11 s (Figure 7g-h), indicating that the

252

aerogel can be reused when the squeezed cylinder could swell to its original shape.

253

Figure 7i shows the height recovery of 30Cellu/BDE as a function of the recycle number.

254

The height of 30Cellu/BDE sample can still reach 90% of the original height after 30

255

cycles of repeated compression-recovery, which confirms its good elasticity and

256

deformation recovery. Compared with some other brittle carbon-absorbent materials,

257

the

258

undergoing the hydrophobic modification.

aerogel was re-immersed in red-colored pump oil; in this second cycle it

30Cellu/BDE

aerogels display improved flexibility and re-use performance after

14


Page 14 of 25

Page 15 of 25


259 260

Figure 7. High efficiency in pump oil recovery and absorbent reusability of

261

30Cellu/BDE.

262

30Cellu/BDE

263

a function of squeezing–re-absorption cycles.

264

3.6. Absorbent ability evaluation of the cellulose grafted with ESO aerogels.

(a-d) Absorption of

30Cellu/BDE

in pump oil; (e-h) Re- absorption of

in pump oil after squeezing; (i) The absorbent abilities of 30Cellu/BDE as

265

As shown in Figure 8, pump oil and dichloromethane were dropped on the surface

266

and bottom of the water, respectively. The cellulose grafted with ESO aerogels can

267

selectively absorb the pump oil and dichloromethane from water as well as the oil-filled

268

cellulose grafted with ESO aerogels can be separated from water expediently (Figure

269

8). Figure 8 shows different states of the unmodified cellulose aerogel Cellu/BDE and

270

the cellulose oil-absorbing material

271

Cellu/BDE is placed in pump oil-water system (top row in Figure 8), it absorbs both

272

part of pump oil (red color) and part of water (blue color) due to hydroxyl groups in the

273

molecular chain of the cellulose aerogels, which exhibit hydrophilic and lipophilic

274

properties. Cellu/BDE moves down to the aqueous layer after 15 min and then sinks

275

into the bottom of the water layer after 30 min, which confirms that the unmodified

30Cellu/BDE

in the oil-water system. When

15



276

cellulose aerogel can absorb oil, but its selectivity to water is higher than that of oil.

277

When the modified-cellulose aerogel 30Cellu/BDE is placed in pump oil/water system

278

(middle row in Figure 8), it keeps floating on the blue-colored water layer surface after

279

selectively absorbing red-colored pump oil, which shows its lipophilic and hydrophobic

280

performance because of the hydrophobization with ESO. This modified aerogel absorbs

281

not only the oil with lower density than water but also the oil with higher density than

282

water, such as dichloromethane (as shown in the bottom row in Figure 8). When

283

30Cellu/BDE

284

colored dichloromethane, while the volume of the water remains unchanged. This

285

observation demonstrates that cellulose aerogel modified by ESO exhibits good

286

oil/water selectivity.

has been placed into the bottom of the beaker, it absorbs all of the red-

287

16


Page 16 of 25

Page 17 of 25


288

Figure 8. Removal of a red-colored pump oil spill from water with the slices of (top

289

row) Cellu/BDE and (middle row) 30Cellu/BDE; (bottom row) removal of

290

dichloromethane from the bottom of water with the slice of 30Cellu/BDE.

291

The absorption performance of

30Cellu/BDE

towards different oils and organic

292

solvents was further investigated (Figure 9A). We found that the samples reach

293

absorption equilibrium within 16 s in oils or organic solvents. As shown in Figure 9A,

294

30Cellu/BDE

295

absorbent abilities of

296

liquid, silicone oil, DMSO, cyclohexane, toluene, isopropyl alcohol, and

297

dichloromethane are 37, 30, 28, 32, 34, 43, 9, 27, 13, and 48 g/g, respectively.

has different absorption capacity for oils or organic solvents. The 30Cellu/BDE

towards crude oil, engine oil, pump oil, paraffin

298

To test the reusability, the cellulose grafted with ESO aerogels absorbed crude oil,

299

DMSO, and CH2Cl2, respectively until reaching absorption equilibrium, as described

300

in the Experimental Section. Then, the oil and the solvents were removed thoroughly

301

as one cycle. The cellulose grafted with ESO aerogels were used to absorb oil again, as

302

shown in Figure 9B. After 30 cycles, the absorption capacity of 30Cellu/BDE towards

303

crude oil, DMSO, and CH2Cl2 decreased from 37, 43, and 48 g/g to 33, 39, and 43 g/g,

304

respectively, whereas the absorption capacity remains higher than 90%.

17



305 306

Figure 9. The absorbent ability of

307

30Cellu/BDE

308

absorbent ability of 30Cellu/BDE of crude oil, DMSO, and CH2Cl2.

30Cellu/BDE.

(A) The absorbent ability of

towards a series of oils and organic solvents; (B) The recycle of the

309

Cellulose-based oil-absorbing material grafted with ESO was successfully

310

fabricated via freeze-drying without undergoing any shape and microstructure change.

311

The grafting reaction occurs on the hydroxyl groups attached to the surface of cellulose

312

with ESO. It results in the modification of the cellulose-aerogel surface characteristics

313

from being hydrophilic to hydrophobic. The so-prepared aerogels have multiple

314

advantages in terms of straightforward fabrication process with mild reaction

315

conditions, shape recoverability, and excellent selective absorption of oils and organic

316

solvents. When the mass fraction of ESO is 30 wt%, the water contact angle of modified

317

cellulose aerogels is 132.6°, whereas the absorption ability towards crude oil, DMSO,

318

and CH2Cl2 reaches 37, 43, and 48 g/g, respectively. The absorbed aerogels can retain

319

more than 90 % of the initial absorption capacity and high hydrophobicity even after

320

30 separation cycles. These newly developed cellulose-based oil-absorbing materials 18


Page 18 of 25

Page 19 of 25


321

are promising candidates for absorption applications in industrial wastewater,

322

environmental remediation, and oil spill containment.

323

Acknowledgments

324

This work was supported by the Fundamental Research Funds of CAF

325

(CAFYBB2017QB007),

326

(2017YFD0601004), Jiangsu Provincial Department of Education (JPDE), Top-notch

327

Academic Programs Project of Jiangsu Higher Education Institutions (ATPP) and the

328

priority Academic Program Development of Jiangsu Higher Education Institutions

329

(PAPD).

330

References

331 332 333 334

the

National

Key

R&D

Program

of

China

(1) Chen, D.; Zhu, H.; Yang, S.; Li, N.; Xu, Q.; Li, H.; He, J.; Lu, J. Micronanocomposites in environmental management. Adv. Mater. 2016, 28, 10443-10458. (2) Liu, H.; Geng, B.; Chen, Y.; Wang, H. Review on the aerogel-type oil sorbents derived from nanocellulose. ACS Sustainable Chem. Eng. 2016, 5, 49-66.

335

(3)Xiong, Y.; Wang, C.; Wang, H.; Yao, Q.; Fan, B.; Chen, Y.; Sun, Q.; Jin, C.; Xu,

336

X. A 3D titanate aerogel with cellulose as the adsorption-aggregator for highly efficient

337

water quality purification. J. Mater. Chem. A 2017, 5, 5813-5819.

338

(4) Chen, X.; Weibel, J. A.; Garimella, S. V. Continuous oil-water separation using

339

polydimethylsiloxane-functionalized melamine sponge. Ind. Eng. Chem. Res. 2016, 55,

340

3596-3602.

19



341

(5) Feng, J.; Nguyen, S. T.; Fan, Z.; Duong, H. M. Advanced fabrication and oil

342

absorption properties of super-hydrophobic recycled cellulose aerogels. Chem. Eng. J.

343

2015, 270, 168-175.

344

(6) Nguyen, S. T.; Feng, J.; Le, N. T.; Le, A. T. T.; Hoang, N.; Tan, V. B. C.; Duong,

345

H. M. Cellulose aerogel from paper waste for crude oil spill cleaning. Ind. Eng. Chem.

346

Res. 2013, 52, 18386-18391.

347

(7) Meng, G.; Peng, H.; Wu, J.; Wang, Y.; Wang, H.; Liu, Z.; Guo, X. Fabrication of

348

superhydrophobic cellulose/chitosan composite aerogel for oil/water separation. Fibers

349

Polym. 2017, 18, 706-712.

350

(8) Yu, L.; Zhou, X.; Jiang, W. Low-cost and superhydrophobic magnetic foam as an

351

absorbent for oil and organic solvent removal. Ind. Eng. Chem. Res. 2016, 55, 9498-

352

9506.

353 354

(9) Yang, Y.; Yi, H.; Wang, C. Oil absorbents based on melamine/lignin by a dip adsorbing method. ACS Sustainable Chem. Eng. 2015, 3, 3012-3018.

355

(10) Pham, V. H.; Dickerson, J. H. Superhydrophobic silanized melamine sponges as

356

high efficiency oil absorbent materials. ACS Appl. Mater. Interfaces 2014, 6, 14181-

357

14188.

358

(11) Shimizu, M.; Saito, T.; Isogai, A. Bulky quaternary alkylammonium counterions

359

enhance the nanodispersibility of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized

360

cellulose in diverse solvents. Biomacromolecules 2014, 15, 1904-1909.

20


Page 20 of 25

Page 21 of 25


361

(12) Lei, Z.; Zhang, G.; Deng, Y.; Wang, C. Thermoresponsive melamine sponges

362

with switchable wettability by interface-initiated atom transfer radical polymerization

363

for oil/water separation. ACS Appl. Mater. Interfaces 2017, 9, 8967-8974.

364

(13) Cheng, W.; Liu, G.; Wang, X.; Han, L. Adsorption removal of glycidyl esters

365

from palm oil and oil model solution by using acid-washed oil palm wood-based

366

activated carbon: kinetic and mechanism study. J. Agric. Food Chem. 2017, 65, 9753-

367

9762.

368

(14) Li, D.; Zhu, F. Z.; Li, J. Y.; Na, P.; Wang, N. Preparation and characterization of

369

cellulose fibers from corn straw as natural oil sorbents. Ind. Eng. Chem. Res. 2013, 52,

370

516-524.

371

(15) Wang, B.; Karthikeyan, R.; Lu, X. Y.; Xuan, J.; Leung, M. K. H. Hollow carbon

372

fibers derived from natural cotton as effective sorbents for oil spill cleanup. Ind. Eng.

373

Chem. Res. 2013, 52, 18251-18261.

374

(16) Fumagalli, M.; Sanchez, F.; Boisseau, S. M.; Heux, L. Gas-phase esterification

375

of cellulose nanocrystal aerogels for colloidal dispersion in apolar solvents. Soft Matter

376

2013, 9, 11309-11317.

377

(17) Liao, H.; Zhang, H.; Hong, H.; Li, Z.; Qin, G.; Zhu, H.; Lin, Y. Novel cellulose

378

aerogel coated on polypropylene separators as gel polymer electrolyte with high ionic

379

conductivity for lithium-ion batteries. J. Membr. Sci. 2016, 514, 332-339.

380 381

(18) Zhuo, X.; Liu, C.; Pan, R.; Dong, X.; Li, Y. Nanocellulose mechanically isolated from amorpha fruticosa linn. ACS Sustainable Chem. Eng. 2017, 5, 4414-4420. 21



382

(19) Yu, M.; Li, J.; Wang, L. Preparation and characterization of magnetic carbon

383

aerogel from pyrolysis of sodium carboxymethyl cellulose aerogel crosslinked by iron

384

trichloride. J. Porous Mater. 2016, 23, 997-1003.

385

(20) Rege, A.; Schestakow, M.; Karadagli, I.; Ratke, L.; Itskov, M. Micro-mechanical

386

modelling of cellulose aerogels from molten salt hydrates. Soft Matter 2016, 12, 7079-

387

7088.

388

(21) Jiang, J.; Zhang, Q.; Zhan, X.; Chen, F. Renewable, biomass-derived,

389

honeycomblike aerogel as a robust oil absorbent with two-way reusability. ACS

390

Sustainable Chem. Eng. 2017, 5, 10307-10316.

391

(22) Liao, Q.; Su, X.; Zhu, W.; Hua, W.; Qian, Z.; Liu, L.; Yao, J. Flexible and durable

392

cellulose aerogels for highly effective oil/water separation. RSC Adv. 2016, 6, 63773-

393

63781.

394 395

(23) Jiang, F.; Hsieh, Y. L. Cellulose nanocrystal isolation from tomato peels and assembled nanofibers. Carbohydr. Polym. 2015, 122, 60-68.

396

(24) Zhang, H.; Li, Y.; Xu, Y.; Lu, Z.; Chen, L.; Huang, L.; Fan, M. Versatile

397

fabrication of a superhydrophobic and ultralight cellulose-based aerogel for oil spillage

398

clean-up. Phys. Chem. Chem. Phys. 2016, 18, 28297-28306.

399

(25) Sai, H.; Fu, R.; Xing, L.; Xiang, J.; Li, Z.; Li, F.; Zhang, T. Surface modification

400

of bacterial cellulose aerogels' web-like skeleton for oil/water separation. ACS Appl.

401

Mater. Interfaces 2015, 7, 7373-7281.

22


Page 22 of 25

Page 23 of 25


402

(26) Nemoto, J.; Saito, T.; Isogai, A. Simple freeze-drying procedure for producing

403

nanocellulose aerogel-containing, high-performance air filters. ACS Appl. Mater.

404

Interfaces 2015, 7, 19809-19815.

405 406

(27) Mulyadi, A.; Zhang, Z.; Deng, Y. Fluorine-free oil absorbents made from cellulose nanofibril aerogels. ACS Appl. Mater. Interfaces 2016, 8, 2732-2740.

407

(28) Jiang, F.; Hsieh, Y. L. Dual wet and dry resilient cellulose II fibrous aerogel for

408

hydrocarbon–water separation and energy storage applications. ACS Omega 2018, 3,

409

3530-3539.

410

(29) Hu, Z.; Berry, R. M.; Pelton, R.; Cranston, E. D. One-pot water-based

411

hydrophobic surface modification of cellulose nanocrystals using plant polyphenols.

412

ACS Sustainable Chem. Eng. 2017, 5, 5018-5026.

413

(30) Dash, R.; Elder, T.; Ragauskas, A. J. Grafting of model primary amine

414

compounds to cellulose nanowhiskers through periodate oxidation. Cellulose 2012, 19,

415

2069-2079.

416

(31) Taipina; Oliveira, M. D.; Ferrarezi, F.; Maria, M.; Yoshida, P.; Valeria, I.;

417

Goncalves; Carmo, M. D. Surface modification of cotton nanocrystals with a silane

418

agent. Cellulose 2013, 20, 217-226.

419

(32) Alatalo, S. M.; Pileidis, F.; Makila, E.; Sevilla, M.; Repo, E.; Salonen, J.;

420

Sillanpaa, M.; Titirici, M. M. Versatile cellulose-based carbon aerogel for the removal

421

of both cationic and anionic metal contaminants from water. ACS Appl. Mater.

422

Interfaces 2015, 7, 25875-25883. 23



423

(33) Feng, J.; Le, D.; Nguyen, S. T.; Tan Chin Nien, V.; Jewell, D.; Duong, H. M.

424

Silica cellulose hybrid aerogels for thermal and acoustic insulation applications.

425

Colloids Surf., A 2016, 506, 298-305.

426

(34) Yang, H.; Sheikhi, A.; Tg, V. D. V. Reusable green aerogels from crosslinked

427

hairy nanocrystalline cellulose and modified chitosan for dye removal. Langmuir 2016,

428

32, 11771-11779.

429

(35) Jiang, F.; Hsieh, Y. L. Cellulose nanofibril aerogels: synergistic improvement of

430

hydrophobicity, strength, and thermal stability via cross-linking with diisocyanate.

431

ACS Appl. Mater. Interfaces 2017, 9, 2825-2834.

432 433

(36) Jiang, F.; Hsieh, Y. L. Amphiphilic superabsorbent cellulose nanofibril aerogels. J. Mater. Chem. A, 2014, 2, 6337-6342.

434

(37) Huang, X.; Wang, A.; Xu, X.; Liu, H.; Shang, S. Enhancement of hydrophobic

435

properties of cellulose fibers via grafting with polymeric epoxidized soybean oil. ACS

436

Sustainable Chem. Eng. 2016, 5, 1619-1627.

437 438 439 440 441 442

24


Page 24 of 25

Page 25 of 25

443


TOC Graphic

444

25


Preparation and characterization of cellulose grafted with epoxidized

Recommend Documents