Polyfunctional cotton fabrics with catalytic activity and antibacterial capacity

Accepted Manuscript Polyfunctional cotton fabrics with catalytic activity and antibacterial capacity Bouazizi Nabil, El-Achari Ahmida, Campagne Christine, Vieillard Julien, Azzouz Abdelkrim PII: DOI: Reference:

S1385-8947(18)31088-X https://doi.org/10.1016/j.cej.2018.06.050 CEJ 19261

To appear in:

Chemical Engineering Journal

Received Date: Revised Date: Accepted Date:

13 March 2018 4 May 2018 9 June 2018

Please cite this article as: B. Nabil, E-A. Ahmida, C. Christine, V. Julien, A. Abdelkrim, Polyfunctional cotton fabrics with catalytic activity and antibacterial capacity, Chemical Engineering Journal (2018), doi: https://doi.org/ 10.1016/j.cej.2018.06.050

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Polyfunctional cotton fabrics with catalytic activity and antibacterial capacity.

Bouazizi Nabil a, b*, El-Achari Ahmida a, b, Campagne Christine a, b, Vieillard Julien c, Azzouz Abdelkrim d* a

Ecole Nationale Supérieure des Arts et Industries Textiles (ENSAIT), GEMTEX Laboratory, 2 allée Louise et Victor Champier BP 30329, 59056 Roubaix, France b Université Lille Nord de France, F-59000, Lille, France c Normandie Univ., UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), 55 rue Saint Germain, 27000 Evreux, France d Nanoqam, Department of Chemistry, University of Quebec at Montreal, QC H3C 3P8, Canada.

*Corresponding authors: Abdelkrim Azzouz; Email; [email protected]; Fax: +1-514-987-4054. And Nabil Bouazizi; Email; [email protected]; phone: +33 2.32.29.15.36

Abstract: A novel, eco-friendly and cost-effective method involving cotton fabric (CF) coating with copper oxide and grafting of 3-chloropropyltriethoxisilane and diethanolamine resulted in a multifunctional material (CF@CuO-Si-N(OH)2). The latter exhibited catalytic activity in 4nitrophenol (4-NP) reduction, methylene blue degradation and antibacterial activity. Scanning electron microscopy, energy dispersive X-Ray-fluorescence, Fourier transform infrared and UV– visible spectroscopies, contact angle and thermogravimetric analysis revealed the key-role of amine grafting in changes in wettability, stability, morphological and thermal properties. 4-NP catalytic reduction was found to obey 1st-order kinetics, affording 98 % conversion even after 7 successive reuses.

CF@CuO-Si-N(OH)2

also

exhibited

appreciable

antibacterial

capacity

against

Staphylococcus epidermidis (S.epidermidis) and Escherichia coli (E .Coli). These results open promising prospects for using textile fiber-based nanocomposites in diverse

technological

applications.

Keywords: Cotton fabric; Copper oxide; Diethanolamine; 4-nitrophenol reduction; dye degradation; antibacterial capacity.

1

1. Introduction A major environmental issue resides undoubtedly in water [1] more particularly by aromatic compounds (organic dyes, phenols, pesticides ,drugs and hormone disrupters,…), heavy metal ions and bacterial agents [2, 3]. Among these, a special interest was focused on Methylene-Blue (MB) and 4-nitrophenol (4-NP) exhibit intrinsic toxicity and/or harmful derivatives [4]. So far, some attempts have been devoted to the treatment of wastewaters containing such contaminants [5, 6]. Catalytic reduction of 4-NP on metal-loaded silica and graphene [6, 7] is a precise indicator that other porous supports such as textile materials also worth it to be investigated in this regard. Those intended for medical purposes are of particular interest owing to their high surface area, hydrophilic character and antibacterial properties [8-12]. Fabric surface modification often involves multi-step chemical treatments with negative environmental impacts [13, 14], and growing interest is now devoted to ecofriendly processes for surface functionalization [15, 16]. Innovative technologies have led to major developments in manufacturing, for instance, breathable waterproof fabrics, with easy-care properties, flame resistance, etc.

Cotton fiber (CF) is one of the most important natural textiles, being widely used

in the clothing industry because of its compatibility with human skin, hygroscopic properties and lack of environmental impact. CF has a large range of applications not only as clothing material but also as medical textiles with high hydrophilic character, ultraviolet protection properties and antibacterial activity . Textile coating with nano- and microparticles is a judicious route for inducing protection against UV radiation antimicrobial properties [17], flame retardancy capacity and other specific features such as water repellency and self-cleaning [18]. Nanoparticles of metals and metal oxides are nowadays prone to extensive research aiming the removal of hazardous organic pollutants and bacteria [19-22]. In this regard, CuO-based materials were already found to exhibit interesting catalytic and antibacterial activities [23-25]. CuO can be prepared through diverse procedures,

2

among which the hydrothermal method appears to be the simplest, most convenient cost-effective route . When deposited on solid surfaces, CuO can as effective interface for the chemical grafting through silanization of different organic molecules bearing diverse chemical functions such as amino and/or hydroxyl groups and others. Such a strategy already resulted in interesting polyfunctional materials for environmental applications, catalysis and antibacterial purposes [26]. Amine groups are known to act as powerful chelating agent, which can enhance the dispersion and stability of nanoparticles. Up today, CuO-coated fabrics with grafted amine have scarcely been studied for water treatments and antibacterial applications. In this work, we report for the first time the possibility to combine together two different approaches for preparing a cotton fabric (CF) displaying catalytic reduction of 4-NP, methyleneblue degradation and antibacterial activity against Staphylococcus epidermidis (S.epidermidis) and Escherichia coli (E .Coli). For this purpose, CF was coated by copper oxide, followed by chemical grafting of 3-chloropropyltrimethoxysilane (ClPTES) and chlorine substitution by diethanolamine (DEA(OH)2). The catalytic and antibacterial activities of the as-functionalized CF, along with its recyclability, durability and stability will be examined using diverse characterization techniques. The results obtained are expected to provide valuable findings for manufacturing high value-added CF with multiple functionalities.

2. Experimental 2. 1. Chemicals The

cotton

fabric

was

purchased

from

Subrenat

(Ref.

UB1-FROM/CR1.2).

3-

chloropropyltrimethoxysilane (ClPTES), anhydrous copper (II) sulfate (CuSO4), diethanolamine NH(CH2-CH2-OH)2, sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), absolute ethanol (EtOH) and trimethylamine were purchased from Sigma-Aldrich and used as received. All chemicals were used without further purification. 3

2.2. Cotton fabric purification and functionalization The cotton fabric (CF) was cleaned and further hydroxylated in a solution containing hydrogen peroxide, ammonium hydroxide and distilled water with a 1:1:5 as volumes ratio, under stirring at room temperature for 2 hours. The purified CF was washed and filtrated then dried at 60°C overnight. CuO dispersion on CF was achieved through immersion in 100 mL of a 0.2M aqueous solution of anhydrous copper (II) sulfate (CuSO4) under continuous stirring. Slow addition of 15mL NaOH (1 M) at 75 °C for 4 h produced CF@CuO precipitate. The latter was cooled down to room temperature, repeatedly washed with distilled water, recovered by filtration, and further dried overnight at 60 °C (Scheme 1-a). In a second step, 3-chloropropyltriethoxisilane (ClPTES) was chemically grafted on CF@CuO, though impregnation in 1:3 (Vol) water-ethanol mixture at 70°C for 6 hours. The obtained product (CF@CuO-ClPTES) (Scheme 1-b) was washed twice with the same water-ethanol mixture and then prone to chlorine substitution by diethanolamine was carried out at 50°C with the presence of nitrogen for 12 hours. The generated hydrogen chloride was removed from the cotton fabric by repeated washing with water/ethanol mixture. The final CF@CuO-ClPTES-N(CH2-CH2-OH)2 composite, denoted as CF@CuO-Si-N(OH)2, was washed, filtrated and then dried at 60°C (1-c).

2.3. Materials Characterization CF and modified CF samples were fully characterized through Fourier transform IR spectroscopy (Tensor 27 (Bruker) spectrometer with a ZnSe ATR crystal), scanning electron microscopy (SEM) and Energy dispersion X-ray fluorescence (ED-XRF) (ZEISS-EVO 15 equipment coupled to an ED-XRF analyzer, after sample metallization by a gold layer at 18 mA for 360 s with a Biorad E5200 device). Additional analyses were achieved through thermal gravimetric analysis (TGA-DTA, A6300R) and triplicate measurements of the water contact angle (DigidropGBX instrument using a goniometric method). 4

Scheme 1. Schematic illustration of cotton fiber hydroxylation before CuO particles incorporation (a), ClPTES grafting (b) and functionalization with diethanolamine (c).

5

2.4. Catalytic conversion of 4-NP and MB The catalytic performances of CF@CuO-Si-N(OH)2 were investigated in the reduction of 4nitrophenol (4-NP) (Scheme 2-a) and Methylene Blue (MB) (Scheme 2-b) in the presence of an excess amount of NaBH4 at room temperature. In each reaction, aqueous solutions of 4-NP (0.5 mM) or MB (1 mM) was added to a mixture containing different amounts of CT@CuO-Si-N(OH)2 (200-500 mg) and 5mL of NaBH4 (3 M) (Scheme 2).

Scheme 2. Catalytic reduction of 4-NP (a) and methylene-blue discoloration (b). 6

During the reactions, periodical samples were taken from the reaction mixture and analyzed by UV–vis spectroscopy (Shimadzu UV 1650 PC spectrophotometer) with distilled water as a reference solution. The reaction progress was expressed in terms of evolution in time of the relative absorbance (At/A0), A0 being that of the starting solutions of 4-NP and MB. After reach reaction, CF@CuO-Si-N(OH)2 catalysts were filtrated, repeatedly washed with distilled water and ethanol, dried at 60 °C and reused again in the same reaction under similar operating conditions. The influence of the reuse number on the catalytic activity was also examined.

2.6. Antibacterial activity The antimicrobial behavior of CF, CF@CuO, CF@CuO-ClPTES and CF@CuO-Si-N(OH)2 was evaluated by means of diffusivity and zone inhibitory tests against different Gram + and Grambacterial strains such as Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E .Coli). The test is a semi-quantitative method where samples (2.5 × 2.5 cm2) were directly contacted with a bacteria suspension spread on Mueller Hinton agar plates. After 24 h of incubation at 37 °C, the inhibition zone and diffusion disc in which bacteria did not proliferate was observed and analyzed.

3. Results and discussions 3.1. Morphology and structure SEM images (Fig. 1) showed smooth and clean surface of the untreated CF (a) which markedly contrasts with that of CF@CuO fibers (b). Quite heterogeneous dispersion of CuO appeared as white aggregate-like deposit. Further chemical grafting of ClPTES and DEA(OH)2 on CF@CuO resulted in much rougher fiber surface with weaker dispersion of bulkier aggregates (c, d). CuO incorporation was confirmed by FTIR analysis which revealed the appearance of a band at 880–800 cm−1. The latter was attributed to Cu-O-Cu lattice vibration. In addition, the formation of copper oxide was confirmed by the peaks around 640 and 560 cm-1 corresponding to the stretching vibrations of the monoclinic phase of CuO [27]. The absorption bands observed at 1450 cm-1 might 7

be due to the bending and stretching vibrations of the surface hydroxyl groups of the surface of CuO particles [28].

a)

b)

c)

d)

Fig. 1. SEM images of (a) CF, (b) CF@CuO, (c) CF@CuO-ClPTES and (d) CF@CuO-Si-N(OH)2.

a)

b)

8

c)

d)

Fig. 2. EDX spectra of (a) CF, (b) CF@CuO, (c) CF@CuO-ClPTES and (d) CF@CuO-Si-N(OH)2.

9

1,01

4

Transmittance (a.u.)

1 1,00 3

1 0,99

0,98

0,97

0,96

1 2 3 4

CF CF@CuO CF@CuO-ClPTES CF@CuO-Si-N(OH)2

2

4

0,95 4000

3500

3000

2500

2000

1500

1000

-1

Wavenumber (cm )

Fig. 3. FTIR spectra of CF (a), CF@CuO (b), CF@CuO-ClPTES (c) and CF@CuO-Si-N(OH)2 (d).

The marked decay in the 3400 cm-1 band must be due to a depletion of available hydroxyl groups, presumably as a result of physical surface blocking and/or even chemical interaction with the incorporated CuO. No intensity increase was noticed around 700 cm-1, where specific Cu-O vibrations to Cu(OH)2 usually occur [29-31] suggests that no Cu(OH)2 was formed. In addition, the low intensity of the broad 3600-3200 cm-1 indicates that not additional hydroxyls including those belonging to Cu(OH)2 were formed on the surface. Apparent evidence of the selective formation of CuO is that the initially blue color of Cu2+ solution turned black. Additional evidence resides in the total disappearance the specific blue-green color of Cu(OH)2 even elsewhere around CuO aggregates. FTIR analysis of CF@CuO-ClPTES and (d) CF@CuO-Si-N(OH)2 show the appearance of a band at 1200 cm−1 attributed to the vibrations of Si-O bond and at 800 cm-1 assigned to Si-O-C stretching vibration (Fig. 3), which indicates the formation of an interface of the grafted of ClPTES on the surface of CF [32]. This is in agreement with the XRD (Fig. 4) which revealed a slight of two characteristic peaks of cellulose at 2Ɵ = 22.8° and 29.5°[33] towards higher 2-theta values after CuO incorporation (Fig. S1). Such a phenomenon was progressively more pronounced after 10

silanization and DEA(OH)2 grafting (c, d). This can be explained by a weak CF structure compaction in agreement with the weaker dispersion of bulkier aggregates revealed by previous SEM observations. Such a compaction must arise from not only the formation of Si-O-C bridges on the surface, but also from hydrophobic interaction of ClPTES and strong Lewis acid-base (LAB)

Intensity (a,u,)

interactions between amino and surrounding OH groups.

(d) (c) (b)

(a) 20

30

40

50

60

70

80

2 (°)

Fig. 4. XRD patterns of (a) CF, (b) CF@CuO, (c) CF@CuO-ClPTES and (d) CF@CuO-Si-N(OH)2 structures

Deeper insights in the IR spectra of CF@CuO-Si-N(OH)2 revealed the rise of an intense band at ca. 1025 cm-1 at the expense of the 3440 and 1674 cm-1 bands, which markedly decreased in intensity (Fig. S2). The latter were attributed to stretching and bending vibrations of the N-H bond, respectively [34]. This is due to effective chemical grafting of diethanolamine groups. Since, no change in the OH density on the surface was noticed after further ClPTES grafting, it appears that silanization occurred selectively on CuO. However, the slight intensity increase of the 3600-3200 cm-1 band after functionalization by DEA(OH)2 provides evidence of the appearance of additional hydroxyl groups. The latter should induce higher hydrophilic character at the fiber surface, in agreement with the contact angle measurements. 11

3.2. Hydrophilic character and thermal stability Contact angle measurements at different times after drop deposition under ambient conditions resulted in significant changes in drop shape in time and according to CF modification step (Fig. S3). A first overview of the results gave higher values of the contact angle for CF@CuO (121o) and CF@CuO-ClPTES (80.5o) after 30 s as compared to the starting CF (56.7o) (Table 1). This account for a decay of the hydrophilic surface in agreement with previous FTIR observations regarding the disappearance of OH stretching bond. However, as expected DEA(OH)2 grafting appears to revive the hydrophilic character, given the consecutive decrease in the contact angle down to 75.7o after 60 s, 68.2 after 90 s until total disappearance after 120 s. The contact angle did not disappear after 120 s for the three other samples.

Table 1. Evolution in time of the contact angle for CF and modified counterparts. Samples CF CF@CuO CF@CuO-ClPTES CF@CuO-Si-N(OH)2

30s 56.5 121 80.5 134.5

Contact angle Ɵ(°) 60s 90s 49.0 48.0 74.0 72.1 75.3 71.4 75.7 68.2

120s 35.4 69.0 53.6 0.0

The surprisingly high value of the contact angle (134.5o) registered after 30 s must be due to the slight structure compaction already demonstrated by SEM observations and shifts of the XRD lines towards higher 2-theta values. This can be explained by the formation of Si-O-C bridges on the surface, hydrophobic interaction of ClPTES propyl entanglement and strong Lewis acid-base (LAB) interactions between amino and surrounding OH groups. Such interactions impose diffusion hindrance that causes slow initial wettability without affecting the hydrophilic character. A confirmation in this regard was provided by the low weight loss of 5% of CF@CuO-Si-N(OH)2 in the temperature range of 50–160 °C, as measured by TGA analysis in air at a 20 °C.min-1 heating

12

rate (Fig. 5). This weight loss mainly accounts for dehydration and at most ethanol volatilization , and is paradoxically in the same magnitude order as compared to the three other samples.

CF CF@CuO CF@CuO-ClPTES CF@CuO-Si-N(OH)2

100

Weight (%)

80

60

40

20

0 100

200

300

400

500

Temperature (°C)

600

700

Fig. 5. TGA patterns of treated and untreated cotton fabrics.

A much higher weight loss of ca. 60-90% occurred in the range 200–360 °C, and was attributed to diverse processes according the sample. As expected CF exhibited slightly higher thermal stability up to ca. 210-220oC as compared to CF@CuO-ClPTES and CF@CuO-Si-N(OH)2 (190-200oC). Their almost similar thermal stability must be mainly due to that of their common propyl bridges incorporated by silanization. This stability is sufficient for their catalytic activity in reactions occurring at and around ambient temperature. The slightly higher weight loss of CF@CuO-SiN(OH)2 (80% versus 75% for CF@CuO-ClPTES) can be explained by additional water release from the compacted structure as the propyl degradation progresses. CF@CuO displayed the lowest stability which barely reached 120-150oC, presumably due to early and slow dehydroxylation. A third weight loss was noticed at ca. 360-370oC for CF@CuO, and can be due to CuO oxidation. This still remains to be elucidated and research is still in progress in this direction. The third weight loss observed at 460-480oC for CF can be explained in terms of volatilization of products resulting from CF combustion in air . 13

3.3. Catalytic activity in 4-NP and MB reduction Attempts to 4-NP and MB reduction were monitored through UV-Vis spectrophotometry (Fig. S4 and S5). The intensity decay of the 400 nm, a characteristic absorption band of 4-NP and rise of the 295 nm associated to 4-aminophenol (4-AP) [35] were reflected by color changes in the reaction mixture from light yellow to darker yellow and then colorless (Scheme 3-a) due to the formation of 4-nitrophenolate ions in alkaline condition by the action of NaBH4 [36]. During the reaction, the absorption peak of 4-NP was found to shift from 400 nm to 385 nm. Similarly, the characteristic absorption peak of MB at 663 nm also decreased in intensity up to total disappearance after 12 min for CF@CuO-Si-N(OH)2. This was reflected by the blue color of the reaction mixture which also quickly turned colorless (Scheme 3-b) during MB reduction into leuco-methylene blue, a less toxic reaction product [37]. The decay in time of the [instant /initial] absorbance ratio (At/A0) of this band accounts for similar decrease of the corresponding concentration ratio (Ct/C0) (Fig. S6). This allowed plotting the increase in time of the conversion yield (Conversion yield = (1 - Ct/C0) X 100%) [35]. Almost total conversion of 4-NP ((98-99%) was registered after only 10 min in the presence of CF@CuO-SiN(OH)2, but after 24 min with CF@CuO-ClPTES and 36 min with CF@CuO (Fig. 6-a).

a

b

Scheme 3. Color changes in time during the reduction of 4-NP (a) and MB (b).

14

Fig. 6. Evolution of the conversion yield in time at room temperature for 4-NP (a) and MB (b). 4-NP0 = 0.5 mM; NaBH40 = 0.1 M; m catalyst =500 mg.

The relatively higher catalytic activity of CF@CuO-Si-N(OH)2 must arise from the capacity of its diethanolamine groups to enhance to the electron transfer from BH4− ions to the nitro group of 4-NP [38]. Though 4-NP reduction into 4-AP by aqueous NaBH4 is thermodynamically favorable, the occurrence of a kinetic barrier due to large potential difference between donor and acceptor molecules is expected to limit the reaction feasibility [35]. Attempts to reaction kinetics in order to apply the pseudo first-order were achieved using NaBH4 excess as compared to 4-NP. Plotting Ln(Ct/C0) as a function of time for the 400 nm band showed linear evolution in time only for CF@CuO-ClPTES and CF@CuO-Si-N(OH)2 (Fig. 7), as supported by their R2 values beyond 0.98 (Table 2). CF modification induced a marked increase in the rate constant 0.001 min−1 up to 0.401 min−1. So far, CF@CuO-Si-N(OH)2 exhibited higher catalytic activity expressed in terms of rate constant than many catalysts constant in the reduction of 4-NP [6, 7, 39-43] and of MB under similar conditions [42, 44-47]. The beneficial role of CuO incorporation on the catalytic activity was already explained in terms of enhanced interaction that improves 4-NP adsorption . 15

Fig. 7. Ln(Ct/C0) as a function of time for the characteristic band of 4-NP (a) and MB (b).. 4-NP0 = 0.5 mM; NaBH40 = 0.1 M; m catalyst =500 mg.

Table 2. Pseudo-first-order kinetics study for the catalytic reduction of 4-NP and MB with NaBH4. 4-Nitrophenol Methylene Blue Samples Time (min)a *k(min-1) **R2 Time (min) *k(min-1) CF >70 0.001 0.561 >60 0.000 CF@CuO 36 0.110 0.820 41 0.132 CF@CuO-ClPTES 24 0.170 0.975 30 0.201 CF@CuO-Si-N(OH)2 10 0.401 0.981 12 0.490 a Reaction time for maximum conversion yields *K is the rate constant for the 1st order kinetics, and is expressed in min-1. **R2 is the correlation coefficient of the linear regression.

**R2 0.654 0.770 0.981 0.990

The reaction times required for maximum reduction of MB were in the same magnitude order (>60 for CF, 41 min for CF@CuO, 30 min for CF@CuO-ClPTES and 12 for CF@CuO-Si-N(OH)2 than those registered for 4-NP(>70, 36, 24 and 10 min, respectively). This indicates a slightly higher catalytic activity of CF@CuO-Si-N(OH)2 in 4-NP reduction. Diethanolamine grafting is supposed to enhance to the electron transfer from BH4− ions to the nitro group of 4-NP [38]. The much shorter reaction time for achieving maximum conversion yield with CF@CuO-Si-N(OH)2 (10 min) as compared to CF@CuO (36 min) and CF@CuO-ClPTES (24 min) suggests a synergistic between CuO and DEA(OH)2. This remains to be elucidated.

16

3.4. Parameter effects and surface interactions Parameters such as pH, catalyst concentration and temperature appear to strongly influence the catalytic reduction of 4-NP (Fig. 8). A first overview showed that decreasing pH induced an intensity decrease of the 400 nm band. This accounts for a beneficial role of acidic media on 4-NP reduction, which should be H+-dependent. Similar effect was observed with increasing catalyst concentration, suggesting a contribution of the extent of the material surface to 4-NP adsorption. The positive effect of increasing temperature was somehow expected, and must involve mainly the barrier of the activation energy in this temperature range.

Fig. 8. Effect of pH (a), catalyst concentration (b) and temperature (c) on the UV-Vis spectra of the reaction mixture. These spectra were recorded after 10 min of 4-NP reduction in the presence of CF@CuO-Si-N(OH)2. Reaction conditions. [4-NP] = 0.5mM; [NaBH4] = 0.1 M; RT. The key role of pH is strongly related to that of -DEA(OH)2 group, which acts as a hydrogen carrier in reduction reactions. At acidic pH, -N-(OH)2 groups (pKa=8.52-8.88) should be prone to protonation, thereby promoting 4-NP adsorption through Lewis acid-base interaction with the oxygen atom of the nitrate group of 4-NP. In addition, the positive charge of the –NH+-(OH)2 group may also favor interaction with BH4- anion. Both phenomena are expected to be enhanced by decreasing pH, which explains the beneficial effect of acidic media. Here, 4-NP adsorption appears to be an essential requirement for electron transfer. Similar reaction pathway should be involved in the reduction of MB molecule, which also possesses amino groups in the form of tertiary amine 17

(pka > 8) that do not protonate in acidic media. However, the mere presence of a positive charge on the S atom of MB and the more difficult protonation of its pyridine cycle (pKa= 5.25) are supposed to attenuate adsorption on positively charged –NH+-(OH)2 group. This explains somehow the slightly weaker catalytic activity of CF@CuO-Si-N(OH)2 in MB reduction as compared to that of 4NP. Once adsorbed, electron transfer to both 4-NP and MB may cause reduction of CuO, affecting thereby the catalytic activity. That is why the reusability of CF@CuO-Si-N(OH)2 was evaluated for the reduction of both substrates. The reusability involves two factors: (i) the recyclability through complete recovery of the catalyst from the reaction mixture; (ii) the stability of its catalytic activity. The latter was found to slightly decrease from 98% down to 92-93% after five cycles for the reduction of both substrates (Fig. 9). This can be regarded as being an appreciable stability for potential use in practical applications. The catalytic activity reached 86% after cycles in the reduction of 4-NP for 10 min.

Fig. 9. CF@CuO-Si-N(OH)2 catalyst recyclability in the reduction of 4-NP(a) and MB (b). Reaction conditions: 4-NP = 0.5mM, NaBH4 = 0.1 M, m catalysts= 500 mg, T = RT.

The catalysts used in both reduction reactions were fully characterized and no significant structural change was found to take place. However, a weak decrease in CuO content was noticed along with traces of brown powder on the bottom of the reactor identified by XRF as being Cuo particles. 18

Therefore, the slight activity appears to originate mainly from a progressive CuO reduction into metal Cuo particles and probably Cu2O. Deeper insights through XPS analyses are still in progress.

3.7. Antibacterial activity The antibacterial activity of all samples was evaluated for E. coli and S. epidermidis. The results obtained showed no response for the untreated CF sample (Fig. 10). No inhibition zone was observed and bacteria remained on the entire surface, suggesting the absence of a resistance to bacteria. However, CF@CuO-Si-N(OH)2 showed a positive response and an inhibition zone with a diffusion process around the sample for both bacteria (Fig. S7).

Fig. 10. Inhibition zones revealing the antibacterial activity at 37 °C of CF (a, a’), CF@CuO (b, b’), CF@CuO-ClPTES (c, c’) and CF@CuO-Si-N(OH)2: (a, b, c and d for E. Coli and a’, b’, c’ an,d c’ for S.

epidermidis). 19

The diameter of the inhibition zone (DIZ) against E. coli and S. epidermidis (Table 4) was found to vary according to the material and bacteria. Based on the DIZ value, it clearly appears that CF showed no resistance against bacteria unlike its modified counterparts. DEA(OH)2 grafting induced the strongest diffusion rate and antibacterial activity with higher efficiency against S. epidermidis than E. coli.

Table 4. Zone of inhibition (mm) of each sample against E. coli and S. epidermidis. Samples CF CF@CuO CF@CuO-ClPTES CF@CuO-Si-N(OH)2

E. coli 1 5 4 6

Zone of inhibition (mm) S. epidermidis 0 0 1 3

As observed, the Gram-negative bacteria E. coli was less affected by CF@CuO-Si-N(OH)2 than the Gram positive bacteria S. epidermidis. The nature of the cell wall structure was one of possible reasons for the sensitivity. S. epidermidis is less resistant, being composed of multilayers of peptidoglycan with an abundant amount of pores that renders them more sensitive to reactive species. In contrast, the cell wall of E. coli is relatively thin which would be less vulnerable to the attack of reactive species [48]. A possible explanation of the antibacterial activity should consist in partial CuO dissolution with Cu+ cation release. The latter is well known to be harmful for bacteria once inoculated inside. Besides, CuO nanoparticles are also supposed to have the capacity to generate hydrogen peroxide (H2O2) in aqueous media, inducing damage in the cell membrane [58]. Therefore, CF@CuOClPTES was found to behave as interesting material with appreciable antibacterial activity, notwithstanding that terminal DEA(OH)2 group may restrict the release of Cu+ cation [49]. A judicious strategy should consist in the grafting of digestible terminal groups than can penetrate the cell and release the cation inside. Research is still in progress in this direction.

20

In addition, protonated amino groups of CF@CuO-ClPTES may also contribute to this antibacterial activity by promoting sufficiently strong electrostatic interaction with bacteria membranes that are negatively charged, resulting in an inhibition of bacteria growth [50].

4. Conclusion Cotton fabric functionalization by CuO loading and chemical grafting of ClPTES/DEA(OH)2 produced a polyfunctional material, CF@CuO-Si-N(OH)2 , displaying high catalytic activity in the reduction of 4-nitrophenol and methylene blue. Conversion yields of 99-98% and 97% were achieved in only in 10 min and 12 min, respectively. The catalytic activity was due mainly to terminal diethanolamine group that protonates in acidic media, favoring adsorption via electrostatic interactions. CF@CuO-Si-N(OH)2 also exhibited antibacterial activities against S.epidermidis and E .Coli. This property is assumed to arise from CuO dispersion, which act as Cu+ cation reservoir and protonated diethanolamine group that behaves as cell membrane inhibitor. These findings allow envisaging improvements to adapt cotton fiber modifications for potential uses in wastewater treatment and practical applications in biomedical textiles.

Acknowledgments We are grateful to Christian CATEL, GEMTEX, Roubaix, France for the support in the antibacterial parts.

References [1] V. Thavasi, G. Singh, S. Ramakrishna, Electrospun nanofibers in energy and environmental applications, Energy & Environmental Science 1 (2008) 205-221. [2] L. Liu, Z.Y. Gao, X.P. Su, X. Chen, L. Jiang, J.M. Yao, Adsorption Removal of Dyes from Single and Binary Solutions Using a Cellulose-based Bioadsorbent, ACS Sustainable Chemistry & Engineering 3 (2015) 432442. [3] N. Ghasemi, F. Jamali-Sheini, R. Zekavati, CuO and Ag/CuO nanoparticles: Biosynthesis and antibacterial properties, Materials Letters 196 (2017) 78-82. [4] J. Zhang, G. Chen, D. Guay, M. Chaker, D. Ma, Highly active PtAu alloy nanoparticle catalysts for the reduction of 4-nitrophenol, Nanoscale 6 (2014) 2125-2130. [5] F. Ghanbari, M. Moradi, Application of peroxymonosulfate and its activation methods for degradation of environmental organic pollutants: Review, Chemical Engineering Journal 310 (2017) 41-62. 21

[6] H. Guan, C. Chao, Y. Lu, H. Shang, Y. Zhao, S. Yuan, B. Zhang, PtNi nanoparticles embedded in porous silica microspheres as highly active catalysts for p-nitrophenol hydrogenation to p-aminophenol, Journal of Chemical Sciences 128 (2016) 1355-1365. [7] F. Zhao, W. Kong, Z. Hu, J. Liu, Y. Zhao, B. Zhang, Tuning the performance of Pt-Ni alloy/reduced graphene oxide catalysts for 4-nitrophenol reduction, RSC Advances 6 (2016) 79028-79036. [8] A.S. Maryan, M. Montazer, T. Harifi, Synthesis of nano silver on cellulosic denim fabric producing yellow colored garment with antibacterial properties, Carbohydrate Polymers 115 (2015) 568-574. [9] F. Ferrero, M. Periolatto, C. Vineis, A. Varesano, Chitosan coated cotton gauze for antibacterial water filtration, Carbohydrate Polymers 103 (2014) 207-212. [10] S. Afzal, W.A. Daoud, S.J. Langford, Superhydrophobic and photocatalytic self-cleaning cotton, Journal of Materials Chemistry A 2 (2014) 18005-18011. [11] A. Hou, G. Sun, Multifunctional finishing of cotton with 3,3′,4,4′-benzophenone tetracarboxylic acid: Functional performance, Carbohydrate Polymers 96 (2013) 435-439. [12] J. Zhuo, G. Sun, Antimicrobial Functions on Cellulose Materials Introduced by Anthraquinone Vat Dyes, ACS Applied Materials & Interfaces 5 (2013) 10830-10835. [13] J. Zhuo, G. Sun, Light-induced surface graft polymerizations initiated by an anthraquinone dye on cotton fibers, Carbohydrate Polymers 112 (2014) 158-164. [14] R. Dastjerdi, M. Montazer, S. Shahsavan, A new method to stabilize nanoparticles on textile surfaces, Colloids and Surfaces A: Physicochemical and Engineering Aspects 345 (2009) 202-210. [15] A. El-Shafei, M. ElShemy, A. Abou-Okeil, Eco-friendly finishing agent for cotton fabrics to improve flame retardant and antibacterial properties, Carbohydrate Polymers 118 (2015) 83-90. [16] I. Shahid ul, M. Shahid, F. Mohammad, Green Chemistry Approaches to Develop Antimicrobial Textiles Based on Sustainable Biopolymers—A Review, Industrial & Engineering Chemistry Research 52 (2013) 52455260. [17] D. Klemenčič, B. Tomšič, F. Kovač, M. Žerjav, A. Simončič, B. Simončič, Antimicrobial wool, polyester and a wool/polyester blend created by silver particles embedded in a silica matrix, Colloids and Surfaces B: Biointerfaces 111 (2013) 517-522. [18] J. Alongi, M. Ciobanu, G. Malucelli, Sol–gel treatments for enhancing flame retardancy and thermal stability of cotton fabrics: optimisation of the process and evaluation of the durability, Cellulose 18 (2011) 167-177. [19] B. Gutarowska, W. Machnowski, Ł. Kowzowicz, Antimicrobial activity of textiles with selected dyes and finishing agents used in the textile industry, Fibers and Polymers 14 (2013) 415-422. [20] S. Singh, K.C. Barick, D. Bahadur, Functional Oxide Nanomaterials and Nanocomposites for the Removal of Heavy Metals and Dyes, Nanmaterials and nanotechnology 3 (2013) 3-20. [21] D. Malwal, P. Gopinath, Enhanced photocatalytic activity of hierarchical three dimensional metal oxide@CuO nanostructures towards the degradation of Congo red dye under solar radiation, Catalysis Science & Technology 6 (2016) 4458-4472. [22] K.V. Ragavan, N.K. Rastogi, Graphene–copper oxide nanocomposite with intrinsic peroxidase activity for enhancement of chemiluminescence signals and its application for detection of Bisphenol-A, Sensors and Actuators B: Chemical 229 (2016) 570-580. [23] A.A. Alswat, M.B. Ahmad, T.A. Saleh, Zeolite modified with copper oxide and iron oxide for lead and arsenic adsorption from aqueous solutions, Journal of Water Supply: Research and Technology - Aqua 65 (2016) 465. [24] S. Athar, H. Asilian, Catalytic oxidation of carbon monoxide using copper-zinc mixed oxide nanoparticles supported on diatomite, Health scope 1 (2012) 52-56. [25] T.A. Saleh, M.M. Al-Shalalfeh, A.A. Al-Saadi, Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment, Scientific Reports 6 (2016) 32185. [26] G. Sharmila, M. Thirumarimurugan, V.M. Sivakumar, Optical, catalytic and antibacterial properties of phytofabricated CuO nanoparticles using Tecoma castanifolia leaf extract, Optik - International Journal for Light and Electron Optics 127 (2016) 7822-7828. [27] N. Bouazizi, R. Bargougui, P. Thebault, T. Clamens, F. Desriac, F. Fioresi, G. Ladam, S. Morin-Grognet, N. Mofaddel, O. Lesouhaitier, F. Le Derf, J. Vieillard, Development of a novel functional core-shell-shell 22

nanoparticles: From design to anti-bacterial applications, Journal of Colloid and Interface Science 513 (2018) 726-735. [28] K.R. Reddy, Green synthesis, morphological and optical studies of CuO nanoparticles, Journal of Molecular Structure 1150 (2017) 553-557. [29] M.U. Anu Prathap, B. Kaur, R. Srivastava, Hydrothermal synthesis of CuO micro-/nanostructures and their applications in the oxidative degradation of methylene blue and non-enzymatic sensing of glucose/H2O2, Journal of Colloid and Interface Science 370 (2012) 144-154. [30] X. Liu, Z. Li, Q. Zhang, F. Li, T. Kong, CuO nanowires prepared via a facile solution route and their photocatalytic property, Materials Letters 72 (2012) 49-52. [31] J. Xia, H. Li, Z. Luo, H. Shi, K. Wang, H. Shu, Y. Yan, Microwave-assisted synthesis of flower-like and leaflike CuO nanostructures via room-temperature ionic liquids, Journal of Physics and Chemistry of Solids 70 (2009) 1461-1464. [32] M.N. Sepehr, H. Kazemian, E. Ghahramani, A. Amrane, V. Sivasankar, M. Zarrabi, Defluoridation of water via Light Weight Expanded Clay Aggregate (LECA): Adsorbent characterization, competing ions, chemical regeneration, equilibrium and kinetic modeling, Journal of the Taiwan Institute of Chemical Engineers 45 (2014) 1821-1834. [33] Z. Khatri, R.A. Arain, A.W. Jatoi, G. Mayakrishnan, K. Wei, I.-S. Kim, Dyeing and characterization of cellulose nanofibers to improve color yields by dual padding method, Cellulose 20 (2013) 1469-1476. [34] L. Maurizi, A. Claveau, H. Hofmann, Polymer Adsorption on Iron Oxide Nanoparticles for One-Step Amino-Functionalized Silica Encapsulation, Journal of Nanomaterials 2015 (2015) 6. [35] Q. Geng, J. Du, Reduction of 4-nitrophenol catalyzed by silver nanoparticles supported on polymer micelles and vesicles, RSC Advances 4 (2014) 16425-16428. [36] N. Bingwa, R. Meijboom, Kinetic Evaluation of Dendrimer-Encapsulated Palladium Nanoparticles in the 4-Nitrophenol Reduction Reaction, The Journal of Physical Chemistry C 118 (2014) 19849-19858. [37] B.R. Ganapuram, M. Alle, R. Dadigala, A. Dasari, V. Maragoni, V. Guttena, Catalytic reduction of methylene blue and Congo red dyes using green synthesized gold nanoparticles capped by salmalia malabarica gum, International Nano Letters 5 (2015) 215-222. [38] S. Bae, S. Gim, H. Kim, K. Hanna, Effect of NaBH4 on properties of nanoscale zero-valent iron and its catalytic activity for reduction of p-nitrophenol, Applied Catalysis B: Environmental 182 (2016) 541-549. [39] Z. Li, Z. Jia, T. Ni, S. Li, Green and facile synthesis of fibrous Ag/cotton composites and their catalytic properties for 4-nitrophenol reduction, Applied Surface Science 426 (2017) 160-168. [40] E. Akbarzadeh, M. Falamarzi, M.R. Gholami, Synthesis of M/CuO (M = Ag, Au) from Cu based Metal Organic Frameworks for efficient catalytic reduction of p-nitrophenol, Materials Chemistry and Physics 198 (2017) 374-379. [41] A. Bhattacharjee, M. Ahmaruzzaman, Green synthesis of 2D CuO nanoleaves (NLs) and its application for the reduction of p-nitrophenol, Materials Letters 161 (2015) 79-82. [42] M.T. Islam, N. Dominguez, M.A. Ahsan, H. Dominguez-Cisneros, P. Zuniga, P.J.J. Alvarez, J.C. Noveron, Sodium rhodizonate induced formation of gold nanoparticles supported on cellulose fibers for catalytic reduction of 4-nitrophenol and organic dyes, Journal of Environmental Chemical Engineering 5 (2017) 41854193. [43] A. Elfiad, F. Galli, A. Djadoun, M. Sennour, S. Chegrouche, L. Meddour-Boukhobza, D.C. Boffito, Natural α-Fe2O3 as an efficient catalyst for the p-nitrophenol reduction, Materials Science and Engineering: B 229 (2018) 126-134. [44] D. Xu, P. Diao, H. Baida, T. Jin, X. Guo, M. Xiang, Y. Yang, H. Li, J. Wang, Photochemical synthesis of iridium submicroparticles and their application in catalytic reduction of methylene blue, Applied Catalysis A: General 516 (2016) 109-116. [45] Y. Xie, B. Yan, H. Xu, J. Chen, Q. Liu, Y. Deng, H. Zeng, Highly Regenerable Mussel-Inspired Fe3O4@Polydopamine-Ag Core–Shell Microspheres as Catalyst and Adsorbent for Methylene Blue Removal, ACS Applied Materials & Interfaces 6 (2014) 8845-8852. [46] T. Yao, T. Cui, H. Wang, L. Xu, F. Cui, J. Wu, A simple way to prepare Au@polypyrrole/Fe3O4 hollow capsules with high stability and their application in catalytic reduction of methylene blue dye, Nanoscale 6 (2014) 7666-7674. 23

[47] Y. Liu, Y. Zheng, B. Du, R.R. Nasaruddin, T. Chen, J. Xie, Golden Carbon Nanotube Membrane for Continuous Flow Catalysis, Industrial & Engineering Chemistry Research 56 (2017) 2999-3007. [48] F. Fu, L. Li, L. Liu, J. Cai, Y. Zhang, J. Zhou, L. Zhang, Construction of Cellulose Based ZnO Nanocomposite Films with Antibacterial Properties through One-Step Coagulation, ACS Applied Materials & Interfaces 7 (2015) 2597-2606. [49] O.G. Nik, B. Nohair, S. Kaliaguine, Aminosilanes grafting on FAU/EMT zeolite: Effect on CO2 adsorptive properties, Microporous and Mesoporous Materials 143 (2011) 221-229. [50] H.Z. Zardini, A. Amiri, M. Shanbedi, M. Maghrebi, M. Baniadam, Enhanced antibacterial activity of amino acids-functionalized multi walled carbon nanotubes by a simple method, Colloids and Surfaces B: Biointerfaces 92 (2012) 196-202.

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A novel polyfunctional cotton fabric was prepared firstly. Functionalized cotton fabric with excellent catalytic activity toward the reduction of 4-NP. High conversion efficiency of the Methylene Blue degradation. An excellent new catalyst for with good stability and recyclability. Development of cotton fabrics with antibacterial activity.