Comparative analysis among coating methods of flexible polyurethane foams with graphene oxide

Accepted Manuscript Comparative analysis among coating methods of flexible polyurethane foams with graphene oxide

Bruna R. Fenner, Matheus V.G. Zimmermann, Michelle P. da Silva, Ademir J. Zattera PII: DOI: Reference:

S0167-7322(18)31342-4 doi:10.1016/j.molliq.2018.08.113 MOLLIQ 9558

To appear in:

Journal of Molecular Liquids

Received date: Revised date: Accepted date:

14 March 2018 31 July 2018 21 August 2018

Please cite this article as: Bruna R. Fenner, Matheus V.G. Zimmermann, Michelle P. da Silva, Ademir J. Zattera , Comparative analysis among coating methods of flexible polyurethane foams with graphene oxide. Molliq (2018), doi:10.1016/ j.molliq.2018.08.113

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ACCEPTED MANUSCRIPT

COMPARATIVE ANALYSIS AMONG COATING METHODS OF FLEXIBLE POLYURETHANE FOAMS WITH GRAPHENE OXIDE

Bruna R. Fennera*, Matheus V. G. Zimmermannb, Michelle P. da Silvac, Ademir J. Zatterac

Federal University of Rio Grande do Sul (UFRGS), 9500 Bento Gonçalves Avenue, 91501-970

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a

Farroupilha, Porto Alegre - RS, Brazil.

SENAI Institute of Polymer Engineering and Innovation, 682 Presidente João Goulart Avenue,

93030-090 Morro do Espelho, São Leopoldo - RS, Brazil.

University of Caxias do Sul (UCS), 1130 Francisco Getúlio Vargas Street, 95070-560 Petrópolis,

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Caxias do Sul - RS, Brazil.

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* Corresponding author.

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E-mail address: [email protected] (B. R. Fenner)

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Abstract: The growth in the exploration of petroleum and the transportation of this and its derivatives in marine environments increased the concern with potential environmental disasters caused by accidents of oil spillage. With this, several materials are being studied to minimize these environmental impacts. In this study, facile and inexpesiv methods of coating polyurethane foams with graphene oxide to produce reusable sorbents with hydrophobic and oleophilic characteristics were evaluated. To compare the coating methods of the sorbent foams produced in suspensions of graphene oxide in ethanol and in petroleum ether, density, morphology, sorption capacity, selectivity, contact angle and reusability tests were performed. The main results indicate higher homogeneity in the coating produced in petroleum ether suspension than in ethanol, but the sorption capacity in both sorbents was similar, about 60 g.g-1. In addition, developed sorbents also presented selectivity to apolar solvents and also fluctuating capacity.

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Keywords: Coating method, graphene oxide, polyurethane foam, sorbent.

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ACCEPTED MANUSCRIPT 1. Introduction

The increasing exploration and transportation of petroleum and by-products in marine environments, together with the discovery of the pre-salt, brings with it potential environmental disasters caused by oil spills in marine environments [1-4]. Currently, several methods are being used to minimize the environmental impacts caused by these disasters, some of them being: dispersants; skimmers; containment barriers; in situ burning; manual removal; bioremediation and

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sorbents [5-8]. Generally, the use of sorbents is considered a promising remediation measure, since it can

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efficiently remove and recover the oil from the water surface. The sorbents recover the oil into the porous material or on its surface, and when reach saturation these are replaced. The advantage of

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this method is by adding it in an area with spilled oil, the oil is transferred to the same changing from the liquid phase to the semi-liquid without changing the chemical composition of the sorbent.

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This facilitates the removal of the oil from the area as it is only necessary to remove the sorbent material from the site [7,8]. Sorbents are divided into two categories: natural (organic and

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inorganic) and synthetic. The natural ones are low cost and easily found, being that the organic can absorb oil from 3 to 15 times its weight and the inorganic 4 to 20 times its weight. On the other hand, synthetic sorbents can absorb oil up to 70 times their weight [9].

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In order to be efficient, besides having a high sorption capacity, these materials must repel water,

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that is, have a characteristic of hydrophobicity, so that they do not allow water to enter its pores. Besides that, the sorbent has to present oleophilic characteristics, attracting oil. The production of these hydrophobic and oleophilic sorbents is carried out in two stages, which are the preparation of

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a material with porous morphology and the coating of this material with molecules that form a covalent bond with the hydrophilic groups of its surface [10]. Studies have been carried out to obtain sorbents with higher sorption capacity compared to, for

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example, a commercial polypropylene sorbent (PP), which has a sorption capacity of 15-25 g.g-1, approximately [11]. Johnson, Manjrekar e Halligan (1973), and Singh et al. (2013) studies show cotton sorption capacity of 30.5 to 40 g.g-1 in static environment using oil for. Toyoda and Inagaki (2003) presented the expanded graphite sorption capacity of four types of petroleum, which was from 60 to 80 g.g-1. Qi et al. (2011) obtained a result of 32 g.g-1 in crude oil for expanded graphite. Li, Liu and Yang (2012) developed PU sponges modified by grafting, which showed a sorption capacity in diesel, kerosene and oil of 50, 69 and 59.9 g.g-1, respectively. Niu et al. (2012) developed a reduced graphene oxide foam with sorption capacity in chlorobenzene, toluene, motor oils and others of 5 to 40 g.g-1.

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ACCEPTED MANUSCRIPT For this reason, the development of polyurethane (PU) sorbent materials is increasing, mainly in the form of foams because they have a three-dimensional porous structure, contain high volume of voids, have physical and chemical resistance, flexibility, low density and low production. However, PU foams have low oil selectivity, being able to draw both water and oil when submitted to a heterogeneous water/oil system [4]. Thus, it is necessary to apply a coating that renders the surface of the non-polar PU foam increasing its efficiency in the sorption process of non-polar liquids in a heterogeneous system and, consequently, reducing the sorption capacity of polar liquids such as

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water. In this study, facile and inexpensive coating methodologies of PU foams with graphene oxide (GO) for production of sorbents with hydrophobic and oleophilic characteristics using diisocyanate

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to maintain sorbents sorption capacity after sorption cycles were evaluated. Also, the dispersion of GO in two different solvents, ethanol and petroleum ether was compared, as well as its effects on

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PU coating.

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2. Materials and Methods

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2.1 Materials

The following reagents were used for the development of polyurethane foam (PU): Voranol WL

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4010 and VoraneteTM T-80 TDI (TDI) supplied by Dow Brasil Sudoeste Industrial; deionized

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water; methylene chloride provided by Didática; Amina Dabco 2033 Catalyst produced by Air Products; tin octoate manufactured by Evonik Industries; Niax Silicone L-595 produced by Momentive Performance Materials Inc. The following materials were used to chemically coat the

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foams: petroleum ether and ethanol provided by Didática, and graphene oxide (GO) with thickness from 0.55 to 1.20 nm supplied by Timesnano.

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2.2 Obtaining method of PU foams

PU foams were developed by free expansion method with mechanical stirring. The developed foam formulation was based on a foaming formulation with theoretical density of 8 kg.m-3 (experimental density: 10 kg.m-3), which is presented in Tab. 1 in parts per polyol parts (pphp) [14]. Specimens of 25 x 30 x 30 mm were produced in the direction of foam growth and were washed in acetone using a Maxiclean 800A ultrasound (Unique) for 30 minutes to remove excess polyol from the surface of the foams as in Li et al. (2015) study, but without washing with water for another 30 minutes.

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ACCEPTED MANUSCRIPT Table 1. PU foam formulation expressed in phpp. Component

pphp

Polyol

TDI

Water

Amina

Silicone

Tin octoate

Methylene chloride

100

91.25

7.00

0.24

2.62

0.59

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2.3 GO coating method of PU foams

The methodology adopted for coating the foams was immersing the foam in a GO suspension

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(5% w/w relative to foam mass) with 300 ml of petroleum ether or ethanol. The solution was sonicated with a VC505 sonicator (SONICS) for 5 minutes with amplitude of 50% measured in

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relation to the maximum capacity of the equipment (500 W). After 15 minutes, the addition of three

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PU specimens were added into the suspension solution with the system under magnetic stirring. When the solution became clear and the GO was on foams surface, 0.5 mL of TDI was added to

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keep the GO on the foam surface after the reuse cycles. The system was kept under stirring for 40 minutes, after which the foams were removed from the solution and dried in an oven at 100°C during 3 hours [4, 13]. The PU foam samples coated on the GO suspension in ethanol and

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petroleum ether were named PUGO.et and PUGO.pe, respectively.

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2.4 Morphology

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The morphological analysis of the coated PU foams was made by field emission scanning electron microscopy (FEG-SEM) using a Tescan FEG Mira 3 with a voltage of 15 kV. The PU

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samples were precoated with gold. In addition, a visual evaluation was made.

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2.5 Density

The foams density were calculated by the mass and volume ratio of the samples, as described in ASTM D3574-11 (A), with the dimensions of the test pieces being 25 x 30 x 30 mm. For each coated foam sample, the density calculation was done on same previously uncoated sample.

2.6 Contact angle

The contact angle test was used to evaluate the hydrophobic characteristics of coated foams. A drop of deionized water was applied in surface specimens (2 x 20 x 60 mm) over five different

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ACCEPTED MANUSCRIPT points and images were made with a Lumix FZ40 digital camera right after the drop reaches surface sample. The angle was analyzed with Surftens 3.0 program.

2.7 Selectivity

To determine selectivity of coated foams, samples were added to a heterogeneous system, consisting of polar (water) and an apolar (heptane) phase, with continuous stirring. Samples of

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10 x 13 x 13 mm were added in triplicate in a 50 mL beaker with 20 mL of water and 20 mL of heptane with stirring for 5 minutes and, after stopping the stirring, the system was maintained rest

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for 5 minutes. Subsequently, images were take for qualitative analysis of the result, evaluating in

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with phase the foam was deposited.

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2.8 Fluctuating capacity

The fluctuating capacity test follow the methodology described in item 2.7. After 15 minutes of

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free flotation, images were made of samples in the end of sorption test. The fluid used was SAE 20W50 due to its color and transparency, thus allowing visualization of samples during sorption

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test.

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2.9 Sorption capacity

The sorption capacity of the samples was obtained by a static sorption test using petroleum as

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sorbate. The methodology adopted for this test was based on ASTM F726-12, where the preweighed specimen was added to the fluid for a period of 15 minutes for free flotation. After, the sample was removed, suspended for 30 seconds to drain the petroleum excess and re-weighed.

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Samples were tested in triplicate with specimens measuring 10 x 13 x 13 mm, and the sorption capacity is determined through Eq. 1.

(1)

Where m0 is dry sorbent mass (g) and m1 is sorbent mass plus sorbate mass (g), that is, sorbent mass after sorption test.

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ACCEPTED MANUSCRIPT 2.10 Reusability

The reusability test was based on the methodology proposed by ASTM F726-12, in which the sorbent measuring 12 x 25 x 25 mm was exposed to 50 sorption cycles (described in item 2.7). After measurement of sorbents sorption capacity, a compression process was used to remove the oil in each cycle. This process was performed with the aid of two smooth rollers rotating in

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complementary direction with 1.5 mm distance between them, thus suffering a compression effort.

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3. Results and discussion

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Fig. 1 presents the production scheme of GO coated flexible PU foams. In Fig. 1(a,b) the foam obtained by free batch expansion method is shown and optical micrography allow better

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visualization of its structure as shown in Fig. 1(b). The foam developed has a structure composed of open and closed pores, and in the open pores there is connectivity between the cells of its structure.

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This type of structure contributes to the oil sorption by facilitating the oil diffusion into the sorbent, thus occupying the available volume of the foam. In addition, it can be seen that the size of the cells is homogeneous throughout the sample.

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From FEG-SEM micrography of OG was possible to identify GO sheets as shown in Fig. 1(c).

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Photographs of developed sorbents are presented in Fig. 1(d,e). It was possible to verify a color change in PU foams surface after coating, from white to gray from GO color, which was added into the solution as a black powder. Both sorbents appearance were similar to PU foams modified with

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silica/graphene oxide developed by Lü et al. (2016). In addition, it was observed that PUGO.et sample presented more GO agglomerations than PUGO.pe, which had more uniform deposition than samples coated in ethanol. Li et al. (2015) correlates foams color to reduced graphene oxide

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concentration added. The higher amount added, darker the foam sample were. However, in this stud was added same amount of same carbon structure, which means that the difference between both sample are related to agglomeration of GO sheets. Furthermore, during the coating process of foams, petroleum ether suspension was homogeneous, i.e. there was a satisfactory dispersion of GO, which did not occur in ethanol suspension, where large particles could be observed in solution. This fact is directly related to coating homogeneity on the foams surface, since a particle containing several graphene sheets has a lower contact area than the same amount of single graphene sheets, influencing the sheets adhesion on solid fraction of the PU foam [20].

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Figure 1. Production scheme of GO coated PU foams: uncoated PU foam photography (a); PU foam optical micrography (b); FEG-SEM micrography of GO (c); PUGO.et (d); and PUGO.pe (e).

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Fig. 2 shows the FEG-SEM micrographs of the samples PU, PUGO.et and PUGO.pe. It can be seen in Fig. 2(a, b, c) that the PU foam has a fraction of solid well below the fraction of voids in its structure and has a smooth surface. Fig. 2(a, d, g) shows that after the coating process the foam

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structure and its cell morphology was maintained no changes in the foams cell morphology after

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coating, and GO sheets were identified on samples surface produced by both methods as presented in Fig. 2(e, h). Fig. 2(f, i) indicates that in PUGO.pe sample, GO sheets had a greater adhesion than when compared to the PUGO.et samples through the arrangement of the sheets on the surface of the

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foam. As shown in Fig. 2(e, f) the GO sheets were agglomerated, taking similar form to a particle instead of sheet, decreasing the area of contact with the foam surface. In Fig. 2(i) a satisfactory

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adhesion of GO sheets was observed on foam surface, possibly related to better dispersion of the GO in petroleum ether than ethanol, as previously commented and seen in Fig. 1(d, e). Tab. 2 presents sorbents developed density, which increasing of both coated foams was similar, between 13.85 and 14.28% over uncoated foam. However, PUGO.pe standard deviation was almost three times smaller than PUGO.et, which indicates that in PUGO.pe samples the GO was deposited more homogeneously than in the PUGO.et samples. This may be related to homogeneous GO dispersion in petroleum ether and in ethanol during coating process of PU foams. As GO sheets were agglomerated in suspension of ethanol, GO amount on the foams surface had greater variation compared to the samples produced on suspension in petroleum ether in which the GO sheets were

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ACCEPTED MANUSCRIPT well dispersed. In addition, as previously mentioned, single GO sheets tend to have higher adhesion on polyurethane surface. An increase of 1 kg.m-3 was presented by Liu et al. (2013) in graphene oxide coated foams over uncoated foam, which is close to that found in samples of the present

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work, which is not determinant amount.

Figure 2. FEG-SEM of samples: uncoated PU foam (a, b, c); PUGO.et (d, e, f); and PUGO.pe (g, h, i).

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ACCEPTED MANUSCRIPT Table 2. Density of developed sorbents: PUGO.et; and PUGO.pe.

Sample

Density (kg.m-3)

PUGO.et

11.84 ± 1.69

PUGO.pe

11.39 ± 0.60

The contact angle of PU foam and developed sorbents are shown in Tab. 3. Both coated samples

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presented hydrophobic characteristics since a material is considered hydrophobic when its contact angle is above than 90 ° [21, 22]. Regarding the uncoated foam there was WCA increase of 43.72

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and 71.56% to PUGO.et and PUGO.ep respectively. In addition, PUGO.et showed a considerably greater deviation than PUGO.pe, which indicates that the GO may not have adhered to the surface

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of the foam homogeneously. Some studies have reported a contact angle of 127 and 135° for foam with reduced graphene oxide and with (3-Mercaptopropyl)trimethoxysilane (MPS) functionalized

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graphene, respectively [12,24]. This indicates that, even having already obtained hydrophobic sorbents, it is still possible to increase their hydrophobicity by reducing or functionalizing the

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graphene oxide prior to its deposition on foam surface.

Table 3. Water contact angle of samples: PU, PUGO.et; and PUGO.pe.

Photography test

WCA

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Sample

66.1° ± 2.1

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PU.OGC.et

95.0° ± 24.9

PU.OGC.ep

113.4° ± 12.2

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ACCEPTED MANUSCRIPT The selectivity tests are presented in Fig. 3(a, b), in which the sorbent selectivity to nonpolar fluids is confirmed. Both samples were deposited in the nonpolar phase (heptane) and only one of its tips remained in the polar phase (water), for both coated foams. Furthermore, both developed sorbents presented fluctuating capacity as Fig. 3(c, d) shows, which is an important property that makes possible to remove the sorbent from the ocean after saturated with oil. Considering a practical application, if the sorbent does not have this characteristic, it can go down to seabed,

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graphene oxide, after 20 seconds the sorbent reach bottom beaker.

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damaging the marine environment. In the study of Liu et al. (2013) PU foams with reduced

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Figure 3. Selectivity of samples: PUGO.et (a); and PUGO.pe (b); and Fluctuating capacity of samples: PUGO.et (c); and PUGO.pe (d).

Fig. 4(a) shows the sorption capacity results of petroleum for the samples PU, PUGO.et and PUGO.pe, and also pictures of samples during sorption test. Both coated samples, PUGO.et and PUGO.pe, present similar values of sorption capacity, 61.456 ± 3.557 and 64.465 ± 4.278 g.g-1, respectively. In addition, both coated samples have a sorption capacity three times the sorption capacity of the uncoated PU sample, which corresponds to 17.761 ± 6.546 g.g-1. As shown in Fig. 4(b, c, d), during sorption test the uncoated foam did not submerge and both coated foams submerged completely, so the high difference in the amount of collected oil between coated samples and uncoated sample. This phenomenon may be related to the surface tension between

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ACCEPTED MANUSCRIPT sorbent and fluid, which has been reduced with GO coating. Zhou et al. (2016) obtained sorption capacity in n-hexane, diesel oil, lubricating oil and crude oil from 21.6 to 36.3 g.g-1 for uncoated foam and 25.8 to 44.1 g.g

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for coated foam, which was approximately 43% lower oil sorption

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capacity than sorbents developed in present study.

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Figure 4. Sample sorption capacity of petroleum (a); and pictures during sorption test samples: PU (b); PUGO.et (c); and PUGO.pe (d).

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Figure 5. Reusability of samples: PUGO.et; and PUGO.pe.

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Fig. 5 shows sorption capacity per cycle PUGO.et and PUGO.pe samples. It was verified that, at the start of the test (cycle 1), sorption capacity is similar to the static sorption capacity as shown in Fig. 4(a) until the samples reach a maximum sorption capacity, cycle 3 for PUGO.et and cycle 4 for

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PUGO.pe, which was higher than static sorption capacity, 70.34 and 74.03 g.g-1 respectively.

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Possibly this was due to foam structure have mixture of open and closed cells, by forcing the oil removal by compression, the film in the pore of the cell split increasing number of connected cells, thus favoring the passage of oil through the structure as well as filling it with oil. In addition, the

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compressive stress suffered by the samples possibly contributed to the forced transfer of the oil into the foam.

After reaching maximum capacity, the sorption capacity began to decrease until stabilization,

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this interval being related to the deformation suffered by the foam during the compression process for the sorvato removal. The values of sorption capacity at the end of test (cycle 100) showed a decrease from the highest values found during test, which was 7.28% for PUGO.et and 6.17% for PUGO.pe. In this way, it is possible to reuse the sorbent for several sorption cycles and possibly the oil collected as well. Nguyen et al. (2012) developed graphene coated foams with high sorption capacity in motor oil, soybean oil, pump oil and used pump oil, but the sorption capacities decreased to 20% of their initial value after the second cycle.

4. Conclusions

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ACCEPTED MANUSCRIPT In summary, it was reported a facile and inexpensive method with addiction of TDI to fabricate graphene oxide foams sponges with hydrophobic and oleophilic properties and their practical use for separation and petroleum sorption from water, considering its fluctuating capacity and reusability. From the obtained results, it was possible to conclude that PU foams have a structure favorable for use as sorbents because they present a structure composed by a solid fraction and high fraction of empty spaces. In both samples the presence of GO on the surface was identified, but on

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petroleum ether method the GO sheets were deposited more homogeneously and also presented superior adhesion on the foam surface when compared to the ethanol method. In the sorption

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capacity tests, the coated samples presented similar values, which was 3 times higher than uncoated sample, reaching 61.5 and 64.5 grams of oil per grams of sorbent. In addition, the coated foams

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exhibited selectivity to nonpolar fluids and fluctuating capacity. The developed sorbents were reusable and after a few sorption cycles their capacity increased to 70.34 and 74.03 g.g-1. Thus, the

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sorbents produced in this work have high potential for application in the remediation of disasters

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involving oil spillage in aqueous environment, as well as in earthy environment.

Acknowlegments

This research was supported by the National Council for Scientific and Technological Development

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(CNPq), the Foundation for Research Support of the State of Rio Grande do Sul (FAPERGS), the

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Secretariat of Economic Development, Science and Technology (SDECT) of Rio Grande do Sul and Union of plastics industries in the northeast of the state of Rio Grande do Sul (SIMPLAS-RS). The experiment was assisted by Polymers Laboratory, Central Laboratory of Microscopy and

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References

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Laboratory of Materials Chemical Reasearch at University of Caxias do Sul.

[1] L. Peng, S. Yuan, G. Yan, P. Yu, Y. Luo. Hydrofobic sponge for spilled oil absorption. Journal of Applied Polymer Scince, v. 131, pp. 40886–40893, 2014. DOI: 10.1002/app.40886. [2] L. Shenkmann, E. Stokstad. Gulf oil disaster. American Association for the Advancement Scince (AAAS), v. 328, pp. 1214–125, 2010. [3] T.T. Lim, X. Hunag. Evaluation of kapok (Ceibapentandra (L.) Gaertn.) as a natural hollow hydrophobic–oleophilic fibrous sorbent for oil spill cleanup. Chemosphere, v. 66, pp. 955–963, 2007. DOI: 10.1016/j.chemosphere.2006.05.062. [4] B. Li, X. Liu, X. Zhang, W. Chai, Y. Ma, J. Tao. Facile preparation of graphene–Coated polyurethane sponge with superhydrophobic/superoleophilic properts. Journal of Polymer Research, v. 22, pp. 190–195, 2015. DOI: 10.1007/s10965-015-0832-1.

13

ACCEPTED MANUSCRIPT

AC

CE

PT E

D

MA

NU

SC

RI

PT

[5] C. Cantagallo, J.C.C. Milanelli, D. Dias-Brito. Limpeza de ambientes costeiros brasileiros contaminados por petróleo: uma revisão. Pan-American Journal of Aquatic Sciences, v. 2, pp. 1–12, 2007. [6] A.P.L. Graig, E. Sena, L. Magalhães, M.C. Krause. Técnicas de limpeza de vazamentos de petróleo em alto mar. Cadernos de Graduação – Ciências Exatas e Tecnologia, v. 1, pp. 75–86, 2012. [7] M.O. AdebajO, R.L. Frost, J.T. Kloprogge, O. Carmody, S. Kokot. Porous materials for oil spill cleanup: a review of synthesis and absorbing properties. Journal of Porous Materials, v. 10, pp. 159–170, 2003. DOI: 10.1023/A:1027484117065. [8] Y. Liu, J.K. Ma, T. Wu, X.G. Wang, G.R. HuanG, Y. Liu, H.X. Qiu, Y. LI, Y. WanG, J.P. Gao. Cost-effective reduced graphene oxide-coated polyurethane sponge as a highly efficient and reusable oil-absorbent. ACS Applied Materials Interfaces, v. 5, pp. 10018–10026, 2013. DOI: 10.1021/am4024252. [9]. L.S. Miranda, J.A.S.A. Anjos, I.T.A. Moreira. Avaliação de tecnologias de remediação em zonas costeiras impactadas pela indústria de petróleo. Revista eletrônica de Energia, v. 4, pp. 19–37, 2014. [10] A. Asthana, T. Maitra, R. Büchel, M.K. Tiwari, D. Poulikakos. Multifunctional Superhydrophobic Polymer/Carbon Nanocomposites: Graphene, Carbon Nanotubes, or Carbon Black? ACS Applied Materials & Interfaces, v. 6, pp. 8859–8867, 2014. DOI: 10.1021/am501649w. [11] D. Wu, L. FanG, Y. Qin, W. Wu, C. Mao, H. Zhu. Oil sorbents with high sorption capacity, oil/water selectivity and reusability for oil spill cleanup. Marine Pollution Bulletin, v. 84, pp. 263– 267, 2014. DOI: 10.1016/j.marpolbul.2014.05.005. [12] Z. Niu, J. Chen, H.H. Hng, J. Ma, X. Chen. A leavening strategy to prepare reduced graphene oxide foams. Advanced Materials, v. 24, pp. 4144-4150, 2012. DOI: 10.1002/adma.201200197. [13] A. Keshavarz, H. Zilouei, A. Abdolmaleki, A. Asadinezhad. Enhancing oil removal from water by immobilizing multi-wall carbon nanotubes on the surface of polyurethane foam. Journal of Environmental Management, v. 157, pp. 279–286, 2015. DOI: 10.1016/j.jenvman.2015.04.030. [14] M.V.G. Zimmermann, B.R. Fenner; R.M.C. Santa, A.J. Zattera. Sistemas Sorvente de Óleos em Ambientes Marinho e Terrestre Baseado em Espumas de Poliuretano Modificadas Quimicamente. BR 10 2016 003722 0, 2016. [15] R.F. Johnson, T.G. Manjrekar, J.E. Halligan. Removal of oil from water surfaces by sorption on unstructured fibers. Environmental Science & Technology, v. 7, pp. 439–443, 1973. DOI: 10.1021/es60077a003. [16] V. Singh. Crude oil sorption by raw cotton. Industrial & Engineering Chemistry Research, v. 52, pp. 6277–6281, 2013. DOI: 10.1021/ie4005942. [17] M. Toyoda, M. Inagaki. Sorption and recovery of heavy oils by using exfoliated graphite. Spill Science & Technology Bulletin, v. 8, pp. 467–474, 2003. DOI: 10.1016/S1353-2561(03)00131-2. [18] X. Qi, Z. Jia, Y. Yang, H. Liu. Sorption capacity of new type oil adsorption felt for potential application to ocean oil spill. Procedia Environmental Sciences, v. 10, part A, pp. 849–853, 2011. DOI: 10.1016/j.proenv.2011.09.137. [19] H. Li, L. Liu, F. Yang. Hydrofobic modification of polyurethane foam for oil spill cleanup. Marine Pollution Bulletin, v. 64, pp. 1648–1653, 2012. DOI: 10.1016/j.marpolbul.2012.05.039. [20] S. Kim, J. Lee, S. Lee. Fractionation of graphene oxides by size-selective adhesion with spherical particles. Macromolecular Research, v. 24, pp. 1098-1105, 2016. DOI: 10.1007/s13233016-4146-x. [21] A.G. Cunha, C. Freire, A. Silvestre, C.P. Neto, A. Gandini, M.N. Belgacem, D. Chaussy, D. Beneventi. Preparation of highly hydrophobic and lipophobic cellulose fibers by a straightforward gas-solid reaction. Journal of Colloid and Interface Science, v. 344, pp. 588-595, 2010. DOI: 10.1016/j.jcis.2009.12.057.

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[22] L. Feng, S. Li, Y. Li, H. Li, L. Zhang, J. Zhai, Y. Song, B. Liu, L. Jiang, D. Zhu. Superhydrophobic surfaces: From natural to artificial. Advanced Materials, v. 14, pp. 1857-1860, 2002. DOI: 10.1002/adma.200290020. [23] X. Lü, Z. Cui, W. Wei, J. Xie, L. Jinag, J. Huang, J. Liu. Constructing polyurethane sponge modified with sílica/graphene oxide nanohybrids as a ternary sorbent. Chemical Engineering Journal, v. 284, pp. 478-486, 2016. DOI: 10.1016/j.cej.2015.09.002. [24] S. Zhou, G. Hao, X. Zhou, W. Jiang, T. Wang, N. Zhang, L. Yu. One-pot synthesis of robust superhydrophobic, functionalized graphene/polyurethane sponge for effective continuous oil-water separation. Chemical Engineering Journal, v. 302, pp. 155-162, 2016. DOI: 10.1016/j.cej.2016.05.051. [25] D.D. Nguyen, N.H. Tai, S.B. Lee, W.S. Kuo. Superhydrophobic properties of graphene-based sponges fabricated using a facile dip coating method. Energy & Environmental Science, v. 5, pp. 7908-7912, 2012.

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ACCEPTED MANUSCRIPT COMPARATIVE ANALYSIS AMONG COATING METHODS OF FLEXIBLE POLYURETHANE FOAMS WITH GRAPHENE OXIDE

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The GO dispersion in petroleum ether was more homogeneous than the GO dispersion in ethanol; Flexible PU foams developed presents a three-dimensional porous structure with high fraction of voids; After application of GO coating, the sorption capacity was tripled relative to uncoated PU foams; The method of obtaining the sorbents in petroleum ether GO suspension had a sorption capacity of 64.5 g.g-1.

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