Highly efficient oil–water separation using superhydrophobic cellulose aerogels derived from corn straw

Li Chen; Gengyuan Zhang; Baofeng Xu; Jianwei Guo

doi:10.1515/gps-2024-0063

Article Open Access

Highly efficient oil–water separation using superhydrophobic cellulose aerogels derived from corn straw

Li Chen , Gengyuan Zhang , Baofeng Xu and Jianwei Guo

Published/Copyright: August 23, 2024

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From the journal Green Processing and Synthesis Volume 13 Issue 1

Abstract

Cellulose-based aerogels have become promising adsorbents for organic pollutants and spilled oil due to their high selectivity and excellent sorption capacity. However, the high costs of preparation limit their practicality. In this study, cellulose fibers were fabricated from corn straw via simple alkaline pulping and bleaching. A cellulose aerogel (CA) was then prepared by the freeze-drying method with polyvinyl alcohol as the binder. After treatment with methyltrimethoxysilane by facile chemical vapor deposition, a modified cellulose aerogel (MCA) with water contact angles up to 154.8° was obtained, which exhibited superhydrophobicity. Importantly, the MCA has both high porosity (98.35–98.94%) and low density (16.33–23.95 mg·cm⁻³). In addition, the MCA can separate oil–water mixtures by gravity filtration with separation efficiency up to 97.3% and flux as high as 9827 L·m⁻²·h⁻¹. This conversion of agricultural wastes into an efficient and high value-added adsorbing material is a promising development in the field of oil–water separation that offers a green and efficient strategy to combat the leakage of organic solvents and oil into the environment.

Keywords: corn straw; cellulose aerogel; superhydrophobic; oil/water separation; chemical vapor deposition

1 Introduction

With the continuous expansion of industrialization in recent years, the problem of oily wastewater discharge has become increasingly serious. The frequent occurrence of marine oil spills has brought about serious environmental and ecological problems that have seriously threatened human health and economic development. In addition, oily wastewater is widely derived from manufacturing, petroleum, food, pharmaceutical and other industries [1]. To date, oily wastewater treatment methods fall into three categories: physical methods (such as gravitational sedimentation and adsorption) [2,3], chemical methods (such as flocculants) [4], and biological methods (such as microbial degradation and bioremediation) [3,5]. The use of flocculants can lead to secondary contamination, and biological treatment takes a long time to work [6,7]. Among the currently available methods, physical adsorption is therefore the most desirable for the oily wastewater treatment because of its high efficiency and low cost [8].

As a type of lightweight material with high porosity, aerogels are generally obtained by freeze-drying or critical point drying cryogels [9] and have attracted widespread attention as adsorbent materials. In the freeze-drying process, the solvent in the frozen aquagel is replaced with air to form a three-dimensional porous material [10]. Carbon-based aerogels, such as graphene oxide/carbon nanotube-based foam [11], chemically modified graphene [12,13], carbon nanotube sponges [14], and carbon nanofiber aerogels [15] that have shown low density, high compressibility, high porosity, and superhydrophobicity/superoleophilicity, have already been widely studied and used in the field of oil–water separation. However, the preparation of these aerogels involves the use of harmful or costly precursors, which hinder their large-scale usage as adsorbents [16]. Furthermore, although commercial organic aerogels such as polyimide aerogels [17], polyurethane [18], and melamine aerogels [19] have good reusability, their scope of application is limited due to secondary contamination and poor environmental compatibility. Recently, bio-based aerogels have attracted much attention due to the availability of the key source materials, as well as their renewability, degradability, and biocompatibility [20]. As the most abundant resource in nature, cellulose has the advantages of being renewable, offering environmental protection and of low cost, and is considered to be an ideal alternative material for the preparation of aerogel [21]. Cellulose can be applied in the field of oil/water separation through simple deployment methods and even reused, thus offering both environmental protection and economic benefits [22].

As a large agricultural country, the planting area of corn in China reached 4.33 × 10⁷ hectare in 2021 [23]. However, a large amount of corn straw is hitherto crushed, buried, or burned after corn harvesting, resulting in both a waste of resources and serious environmental problem [24]. Corn straw has three main components similar to trees, but corn straw has an advantage over trees because of its shorter growth cycle [25]. Corn stover is an ideal biomass resource with high cellulose content. Therefore, it has already been demonstrated that corn straw can be used as a green and low-cost carbonaceous precursor to synthesize porous cellulose aerogels (CAs) for applications of adsorption and separation [26]. Moreover, hydrophobic groups with a low surface energy can be introduced into the CA by physical or chemical methods to improve its hydrophobicity and oil adsorption capacity [27]. In the present study, chemical vapor deposition (CVD) modification was used to reduce the dosage of the modifier needed compared to the impregnation process.

In this study, based on the utilization of agricultural waste and the advantages of CAs, we chose corn straw as the raw material to fabricate a modified cellulose aerogel (MCA). Crucially, the low-cost methyltrimethoxysilane (MTMS) was selected to modify the corn straw fiber aerogel to achieve hydrophobic performance compared with other studies. The influence of different mass ratios of corn straw cellulose (CSC)/PVA on its structure, morphology, hydrophobicity, and oil adsorption capacity was compared and analyzed. A comparative study was conducted on the performance and recyclability of MCA in adsorbing various organic solvents and oils. MCA was used to efficiently and continuously remove organic solvents and oils from water. This study can provide an environment-protecting and economical method to fabricate the biomass aerogels that could be easily used to deal with oil spill and environmental pollution.

2 Experimental methods

2.1 Materials and reagents

The corn straw was collected from a farm in Jiangsu province, China. Sodium hydroxide, sodium chlorite, glacial acetic acid, Sudan red III, methylene blue, poly(vinyl alcohol) (molecular weight: 75,000; hydrolysis rate: over 99%), and MTMS (98% were all of analytical grade and obtained from Shanghai Macklin Biochemical Co., Ltd. n-Hexane, petroleum ether, cyclohexane, dichloromethane, chloroform, carbon tetrachloride, and other chemicals were all purchased from Aladdin (Shanghai). Engine oil (5w40), dimethyl silicone oil (PMX-200), and castor oil were purchased commercially (Guangdong, China). All reagents were used as obtained without additional processing.

2.2 Pre-treatment of the corn straw

First, the dried corn straw was cut into 3 cm segments, then cleaned with deionized water, and dried. Next, the straw was ground with a high-speed grinder, passed through a 60-mesh screen, and stored for subsequent experiments. The ground material (20 g) was placed into a beaker containing sodium hydroxide solution (1.0 L, 4 wt%) and heated to 80°C for 2 h under mechanical agitation. The resulting crude straw cellulose was filtered and washed with deionized water (DI) until the pH value was constant. Subsequently, the crude straw cellulose was mixed with a 5% (w/v) bleaching solution that consisted of an equal amount of sodium chlorite solution (2%, w/v), an acetic acid buffer solution (2N), and deionized water and stirred at 80°C for 2 h. Finally, the residue was filtered and washed with DI until neutral pH, and CSC was obtained after drying the residue at 60°C for 36 h.

2.3 Preparation of hydrophobic CA

Dried cellulose fibers (1 g) obtained from the previous pre-treatments were mixed with water (50 mL). After that, the mixture was homogenized using a blender for 10 min. Approximately 50 mL of PVA solution (0.4, 0.8, 1.2, 1.6, and 2.0 wt%) was added to the above cellulose fiber suspension, and the mixture was heated at 80°C for 2 h. Then, the mixture was sonicated for 5 min, and the uniformly dispersed system was frozen below 0°C for 24 h before being lyophilized at −50°C for 48 h to obtain the CA.

The preparation process of MCA and the corresponding reaction mechanism are illustrated in Figure 1. In order to enhance the hydrophobicity of the aerogel, the CVD method was used to silanize the CA. A vial containing MTMS (5 mL) and CA was fixed in a sealed glass chamber and heated at 80°C for 6 h to get the MCA [28]. The above-obtained materials were labeled CA-X and MCA-X, as indicated in Table 1.

Figure 1

Schematic diagram of the preparation of MCA from corn straw.

Table 1

Ratio of cellulose to PVA

Samples	Cellulose/PVA (g:g)
Samples	5:1	5:2	5:3	5:4	5:5
CA	CA-1	CA-2	CA-3	CA-4	CA-5
MTMS modified	MCA-1	MCA-2	MCA-3	MCA-4	MCA-5

2.4 Characterization

The SEM images of the samples were obtained using a field-emission scanning electron microscope (SEM, SU8010) to investigate the microscopic morphologies. The water contact angle (WCA) values were measured using a DataPhysics OCA 100 optical system with a water droplet of 4 μL. The surface area and pore structure of MCA were determined by an Autosorb iQ-MP-MP device (Quantachrome Instruments). A Fourier transform infrared (FT-IR) spectrometer (Nicolet 5700) was used to determine the change in the groups in the modified samples. X-ray diffraction (XRD) patterns of the aerogels were obtained on a Rigaku SmartLab X-ray powder diffractometer (Cu-Kα radiation). X-ray photoelectron spectroscopy (XPS) measurements of the aerogels were carried out with a Thermo Scientific K-Alpha spectrometer.

2.5 Density and porosity measurements

The density of the MCA was calculated from Eq. 1 [29].

(1) ρ a = m V

where a stands for the aerogel and m (mg) and V (cm³) represent the mass and volume of the aerogels, respectively.

The porosity of the aerogel was calculated using Eq. 2 [30].

(2) P orosity ( % ) = 1 − ρ a × ω c ρ c + ω PVA ρ PVA × 100 %

where ω _c and ω _PVA are the weight percentages of cellulose and PVA, respectively. ρ _c and ρ _PVA are the bulk densities of cellulose and PVA, which have the values of 1.6 and 1.3 g·cm⁻³, respectively [31].

2.6 Oil adsorption property and reusability measurements

To test the adsorption capacity of the material, the mass of MCA was weighed on an electronic balance, then removed and immersed in various oils or organic solvents until saturation. The saturated MCA was removed and placed in air for 20 s until the weight did not change. The saturated aerogel was then weighed to obtain M₁. For some organic solvents, the saturated MCA was placed in a closed container and weighed quickly to avoid volatilization. The adsorption capacity of various oils and the organic solvent was calculated as follows:

(3) Q = ( M 1 − M 0 ) M 0

where Q is the adsorption capacity of the MCA, and M ₀ and M ₁ are the MCA’s weight before and after adsorption, respectively. Each adsorption datum is the average value obtained from three repeated experiments.

By squeezing and centrifugation, oils or organic solvents adsorbed by MCA could be directly removed. Then, the compressed sample was immersed in oil again, and its adsorption capacity was measured. In the centrifugation test, the same method was used as before. Carbon tetrachloride was used in the test. The contaminant removal process was cycled ten times to test its reusability.

2.7 Continuous oil–water separation experiment

Continuous oil–water separation was conducted by a peristaltic pump assisted MCA. The oil–water mixture was obtained by directly mixing oil (Sudan red III, dyed red) and water (dyed blue). Specifically, the peristaltic pump suction pipe was connected to a cylindrical MCA (R = 2 cm; H = 2 cm), and the other end of the pipe was fixed to the collection beaker. n-Hexane was sucked into the container using the peristaltic pump to achieve continuous separation. The MCA was placed in an 8 mm inner diameter funnel as a filter element, and the CH₂Cl₂/water mixture was injected into the funnel. CH₂Cl₂ was then collected in the beaker below, and its volume measured with a measuring cylinder. The flux (F) could be evaluated according to the following equation:

(4) F = V S·t

where V (L) is the volume of the collected liquid, S (m²) is the filter area of the separation layer, and t (h) is the filtration time.

2.8 Water-in-oil emulsion separation

To prepare the water-in-n-hexane emulsions, Span 80 was first dissolved in 49 mL of water (0.1 mg·mL⁻¹), and then 1 mL of n-hexane was added under stirring at 800 rpm for 2 h. The MCA was fixed as a filter layer in the device to separate the emulsions. The entire separation process was only carried out under the action of gravity.

3 Results and discussion

3.1 Structural and chemical properties of aerogels

As shown in Figure 2a, the prepared MCA had a spongy appearance. It possessed operability as to be fashioned into a variety of shapes and sizes by molding. From the SEM images of MCA (Figure 2b–d), it can be seen that the MCA consisted of a 3D network structure. During the preparation process, the cellulose fibers were stirred and cut at a high speed by the blender. After stirring and ultrasonic treatment, cellulose dispersion was formed. During the lyophilization process, highly porous structures were gradually formed as the ice sublimates, and the aerogel structure did not shrink and collapse [32]. These porous structures provide storage space for oil adsorption, which was beneficial for the filtration of oil or emulsions. Moreover, nitrogen adsorption–desorption isotherms of MCA-3 (Figure S1a) exhibited a type-IV isotherm with a hysteresis loop, indicating the average pore diameter exceeds 10 nm. It can be concluded from the Barrett–Joyner–Halenda pore size distributions (Figure S1b) that the corresponding pore diameters were mainly distributed in the range of 1.8–25 nm, which indicated the presence of mesoporous structures [33]. Notably, the contribution of micropores and mesopores to the total pore volume was low, as seen from the SEM images. Macroscopic and microscopic pores of MCA were interconnected to form numerous liquid transport and storage channels. In Figure 2e, the energy-dispersive X-ray spectrum of MCA shows the presence Si element and a uniform distribution of silicon on the aerogel, proving that the CA was successfully modified by MTMS. The CA was successfully modified by MTMS. Considering the effect of the porosity of aerogel on its adsorption capacity, the effects of different ratios of CSC/PVA on the density and porosity of MCA were subsequently investigated. The average density of aerogel increased and the porosity decreased with the increase of PVA content, which in turn may affect the adsorption properties of MCA. The porosity of the aerogel decreased from 98.94% to 98.35%, and the density increased from 16.33 to 23.95 mg·cm⁻³ (Figure 2f). Therefore, MCA-3 with moderate porosity and density was selected for subsequent experiments.

Figure 2

(a) Photograph of the MCA, (b)–(d) SEM images of the MCA in different magnification times, (e) EDX mapping of Si on MCA, and (f) density and porosity of MCA.

The effect of functional groups on the modification process was investigated by comparing and analyzing the changes in chemical groups of aerogels before and after modification. FT-IR spectra (Figure 3a) show that both CA-3 and MCA-3 have a wide band at 3,380 cm⁻¹, caused by the stretching vibration of hydroxyl (–OH) groups. The reason is that the reaction between the hydroxyl groups of cellulose and MTMS led to the reduction of the hydroxyl groups in the CA. The characteristic peaks of CH₃, CH₂, and C–O groups appear at 2,920, 1,450, and 1,090 cm⁻¹, respectively, and correspond to the functional groups of the cellulose composites [34]. Among them, the in-plane bending vibration of CH₂ at 1,450 cm⁻¹ indicates the presence of long carbon chains. In addition, MCA-3 shows new vibration bands at 1,270 cm⁻¹ (Si–CH₃) and 771 cm⁻¹ (Si–O–Si) which confirm that Si–CH₃ groups were successfully grafted onto CA [35]. These Si–CH₃ groups on the surface of the CA have a lower surface energy, which is conducive to improving the hydrophobicity of the aerogel. To investigate the structural changes of aerogels, CA-3 and MCA-3 were characterized by XRD (Figure 3b). CA-3 shows two apparent diffraction peaks at 2θ = 16° and 22.4°, which are the characteristic peaks of natural cellulose [36]. Compared with CA-3, the XRD peaks of MCA-3 disappear at 16° and weaken at 22.4°, which was caused by the decrease in cellulose mass fraction after aerogel modification.

Figure 3

(a) FTIR spectra, (b) XRD patterns, and (c) XPS survey spectra of the original aerogel CA-3 and the modified aerogel MCA-3. (d) C 1s spectrum, (e) O 1s spectrum, and (f) Si 2p spectrum of MCA-3.

XPS was employed to investigate the changes in the surface chemical structure of MCA-3 compared to CA-3 and to confirm the effective silylation (Figure 3c–f). The CA-3 contains elements C and O, and the MCA-3 is composed of elements C, O, and Si (Figure 4c). In the case of MCA-3, the O 1s spectrum shows two peaks at 531.6 and 533.0 eV (Figure 3d) that correspond to C–O and Si–O components, respectively. Furthermore, the Si–C bond at 101.7 eV and the Si–O bond at 103.4 eV are observed in the Si 2p spectrum of the MCA-3 (Figure 3f). These results further confirm the silanization reaction between the hydroxyl groups of cellulose and MTMS.

Figure 4

The photographs of water contact angle (WCA) of (a) MCA-0, (b) MCA-1, (c) MCA-2, (d) MCA-3, (e) MCA-4, and (f) MCA-5.

The CA prepared from pure cellulose aqueous dispersion exhibit an obvious collapse phenomenon, and its structure is easy to destroy. The addition of PVA prevented the significant contraction of CA and added structural support. The hydrophobic properties of MCA modified by MTMS of aerogels prepared with different proportions of CSC/PVA were also different. In the contact angle measurement, it was found that the MCA containing PVA modified by MTMS showed better hydrophobic properties (Figure 4), meaning that the functional groups on the surface of MCA also affected the hydrophobic property [37]. When the PVA solution concentration increased from 0 to 1.2 wt%, the contact angle increased from 102.4° to 154.8°, as presented in Figure 4a–d. However, as the PVA solution continued to increase, the MCA contact angle decreased, as shown in Figure 4e–f. The excellent hydrophobic properties of the MCA were the basis of its separation of oil and water by the aerogel adsorbent [38]. In summary, from the combined results of SEM, FTIR spectroscopy, XPS, and WCA, the low surface energy functional groups, and porous structure of the MCA sample determine its superhydrophobicity [39].

3.2 Oil sorption capacity and reusability

The aerogel showed different wettability behaviors before and after modification. With a large number of hydroxyl groups, water and oil droplets were rapidly adsorbed when placed on the surface of CA, indicating that CA has high affinity for oil and water (Figure S2a). When water and oil droplets dripped onto the MCA, it was observed that the droplets remained spherical on the MCA, and the oil was rapidly adsorbed (Figure S2b). To further investigate its hydrophobicity, MCA was immersed in water (Figure S2c), which formed an air gap on the surface due to its hydrophobicity and lipophilicity. When MCA was placed in a petroleum ether/water mixture, saturated MCA can float stably on water for a long time because of its low density and hydrophobicity (Figure S2d).

Due to its porous structure and superhydrophobicity, the MCA could be an excellent candidate for oil/water separation [40]. As shown in Figure 5a, the MCA quickly adsorbed n-hexane floating on water when it came into contact with it (dyed with Sudan red III). Similarly, when MCA was pressed into a beaker containing tetrachloromethane at the bottom, the organic solvent was also completely captured by the hydrophobic MCA (Figure 5b). By virtue of its excellent water resistance and adsorption capacity for surface and underwater solvents, MCA has the potential to adsorb both floating and underwater pollutants.

Figure 5

Removal performance for (a) cyclohexane and (b) tetrachloromethane by MCA. (c) Adsorption performance of MCA-3 for various oils and organic solvents. (d) Adsorption capacity as a function of solvent density. (e) Adsorption performance of MCA-3 at multiple centrifugation and squeezing cycles.

Due to its porous structure and superoleophilicity, MCA-3 displayed a large adsorption capacity for various oils and organic solvents (29.5–78.2 g·g⁻¹) (Figure 5c). Furthermore, the adsorption capacities for high-density tetrachloromethane and chloroform were higher than those for low-density hexane, alcohol, and engine oil, which is positively related to their density (Figure 5d). Generally, as the volume and porosity of the aerogel are constant, we can say that the adsorption capacity is dependent on the density of solvent [41].

In the next part of the investigation, two methods, compression and centrifugation, were used to recover the adsorbed tetrachloromethane to evaluate the recoverability and reusability of the MCA [42]. From Figure 5e, it is evident that as the number of cycles increased, the oil adsorption capacity of MCA decreased. However, the adsorption performance tended to stabilize after the MCA was recycled ten times. Compared to other typical adsorption materials (Table S1), the synthesized MCA has the advantage that the raw material came from agricultural wastes generated from farming production. In particular, the MCA-3 had a contact angle of up to 154.8°, which was significantly better than most aerogel materials currently used to separate oil from water.

3.3 Continuous oil/water separation capability

As illustrated in Figure 6a, MCA-3 could be used as a filter element to separate the CH₂Cl₂/H₂O mixed solution. CH₂Cl₂ (stained with Sudan red III) quickly passed through the porous structure of MCA-3 into the conical flask placed below it under the effect of gravity, while the water (stained with methylene blue) was retained in the funnel due to the excellent hydrophobicity of MCA-3. During the process, the MCA achieved both high filtration efficiency (97.3%) and high flux (9,827.1 L·m⁻²·h⁻¹). In conclusion, the MCA effectively separated wastewater containing heavy oil from water without requiring additional driving pressure. During practical applications, the MCA can also be combined with a peristaltic pump to achieve high-efficiency continuous oil/water separation (Figure 6b and c) (Supporting information video S1). The catheter of the peristaltic pump was inserted into the MCA and then the MCA was placed in the n-hexane/water mixture solution. When the peristaltic pump power was turned on, n-hexane was continuously adsorbed by the MCA and collected into a container through the pipeline. Afterward, the MCA adsorbed the remaining organic solvent while repelling water simultaneously to maintain a continuous solvent flow. Ultimately, the light solvent can be successfully and efficiently separated from water, leaving only water in the container.

Figure 6

(a) Oil (dyed red)–water (dyed blue) mixture filtration test. (b) Continuous oil/water separation by a peristaltic pump. (c) Schematic diagram of the oil/water separation mechanism of the MCA.

The above results demonstrated that MCA has potential for practical application in large-scale oil spill collection. The process of continuous oil/water separation could be divided into three steps. First, the solvent diffused into the abundant pores inside the MCA. Second, the adsorbed liquid filled the entire adsorbent. Finally, the solvent was sucked out of the MCA under additional driving pressure.

Moreover, the MCA could separate n-hexane from stabilized water-in-oil emulsion due to its superhydrophobic/superoleophilic character [43]. The MCA was made into a suitable shape and placed in the filtering device. After pouring the stable n-hexane aqueous emulsion into the device, it can be seen that n-hexane flowed through the MCA, while water was kept in the device (Figure 7a). After filtration, obvious droplets were not observed in the collected filtrate when viewed under a microscope (Figure 7b), which proved that n-hexane was effectively removed from the emulsion. The separation mechanism of water-in-oil emulsions is shown in Figure S3. Due to the good lipophilicity of MCA, it was captured from the emulsion when the outer oil droplets came into contact with the surface of MCA and then diffused and permeated through the MCA. At the same time, the water droplets were intercepted by the hydrophobic layer owing to the hydrophobicity of MCA, while the oil passed through the aerogel under the action of gravity and capillary force. Subsequently, the water droplets gradually left and floated off the surface of the MCA.

Figure 7

(a) Process of water-in-oil emulsion separation. (b) Light micrographs of emulsion before and after filtration.

4 Conclusions

In summary, a handy and low-cost method was successfully applied to synthesize CAs from corn straw. The obtained CA was modified with MTMS to obtain more hydrophobic MCA with a WCA of up to 154.8°, which is higher than most cellulose-based superhydrophobic aerogels reported to date. The stable three-dimensional network structure coupled with high porosity (98.35–98.94%) and low density (16.33–23.95 mg·cm⁻³) promoted the adsorption of oils and organic solvents via the internal channels of the MCA, leading to a high adsorption capacity (29.5–78.2 g·g⁻¹). In addition, the MCA recovered oils from the oil/water systems within seconds, demonstrating high separation efficiency. After ten cycles of oil adsorption, it continued to exhibit good adsorption performance and reusability. With the above advantages of high adsorption capacity, excellent oil/water sorption selectivity, and renewable source material, the MCA is an ideal adsorbent to combat water pollution caused by oil spills and chemical leakage.

Acknowledgements

This work was supported by the Innovation Team Project in the Universities of Guangdong province, China [grant number 2017GKCXTD006]. The authors thank AiMi Academic Services for English language editing.

Funding information: This work was supported by the Innovation Team Project in the Universities of Guangdong province, China [grant number 2017GKCXTD006].
Author contributions: All authors have accepted responsibility for the entire content of this manuscript and consented to its submission to the journal, reviewed all the results, and approved the final version of the manuscript. Li Chen: investigation, data curation, and writing – original draft. Gengyuan Zhang: software and methodology. Baofeng Xu: methodology and supervision. Juanwei Guo: writing – review & editing, supervision, and funding acquisition.
Conflict of interest: The authors state no conflict of interest.
Data availability statement: All data generated or analyzed during this study are included in this published article (and its supplementary information files).

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Received: 2024-03-26

Accepted: 2024-07-23

Published Online: 2024-08-23

This work is licensed under the Creative Commons Attribution 4.0 International License.

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https://doi.org/10.1515/gps-2024-0063

Keywords for this article

corn straw; cellulose aerogel; superhydrophobic; oil/water separation; chemical vapor deposition

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Highly efficient oil–water separation using superhydrophobic cellulose aerogels derived from corn straw

Article

Abstract

1 Introduction

2 Experimental methods

2.1 Materials and reagents

2.2 Pre-treatment of the corn straw

2.3 Preparation of hydrophobic CA

2.4 Characterization

2.5 Density and porosity measurements

2.6 Oil adsorption property and reusability measurements

2.7 Continuous oil–water separation experiment

2.8 Water-in-oil emulsion separation

3 Results and discussion

3.1 Structural and chemical properties of aerogels

3.2 Oil sorption capacity and reusability

3.3 Continuous oil/water separation capability

4 Conclusions

Acknowledgements

References

Supplementary Material

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