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Journal of Cleaner Production 43 (2013) 20e26

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Journal of Cleaner Production

journal homepage: www.elsevier .com/locate/ jc lepro

Vanillin, a potential carrier for low temperature dyeing of polyesterfabrics

V. Pasquet a,b, A. Perwuelz a,b, N. Behary a,b,*, J. Isaad a,b

a ENSAIT-GEMTEX: ENSAIT, GEMTEX, Roubaix, FrancebUniv Lille Nord de France, USTL, F-59655 Villeneuve d’Ascq Cedex, France

a r t i c l e i n f o

Article history:Received 10 April 2012Received in revised form10 December 2012Accepted 12 December 2012Available online 11 January 2013

Keywords:Chemical substitutionDyeingPolyesterCarrierVanillin

* Corresponding author. Ecole Nationale Supérieure(ENSAIT), Laboratoire de Génie et Matériaux TextilesVictor Champier, BP 30329, 59056 Roubaix Cedex 01,64; fax: þ33 3 20 24 84 06.

E-mail address: nmassika.behary@ensait.fr (N. Beh

0959-6526/$ e see front matter � 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.jclepro.2012.12.032

a b s t r a c t

The potential use of vanillin for the chemical substitution of toxic carriers used in low temperaturedyeing of polyester fabrics, was assessed. Both para and ortho-vanillin were used to compare the dyeingof a woven polyester fabric with two different blue disperse dyes: a high molecular weight anthraqui-none dye D79 and a lowmolecular weight azoic dye D56. When 1 g of vanillin was used for dyeing with 3%of disperse dye, the dye uptakes increased for both vanillins, but were higher with ortho-vanillinespecially in the case of the low molecular weight dye. The impact of different dyeing parameterssuch as pH, o-vanillin concentration and use of ethanol co-solvent, on the dye uptake was also studied.Highest dye uptake was reached with 2 g of ortho-vanillin at pH 7, without use of the co-solvent.

Dye uptakes were compared to those of traditional carriers such as phenylphenol, dichlorobenzene,benzoic acid, and a commercial Levegal DTE carrier. With 2 g of vanillin, K/S of dyed fabric reached 16,which is equivalent to that obtained with 1 g of the commercial carrier. The study confirms that vanillincan be used as a chemical substitute to traditional carriers and leads to good wash and rub fastnessproperties.

At present, few literature data are available to compare toxicity of all carriers and apply the principle ofsubstitution. A toxicity analysis carried out using USEtox� model showed that both para and orthovanillins used in agro-food industries are not recognized as toxic for human health, unlike most tradi-tional carriers. Ortho-vanillin has however high ecotoxicity.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Environmental issues are being increasingly taken into accountin textile dyeing and finishing industries because of strict legisla-tions and a growing ecological concern. Main environmental im-pacts of textile dyeing & finishing industries involve high waterconsumption, high energy use and also input of a wide range ofchemicals (dyes, surfactants, carriers, etc.). Some of these chemicalsare hazardous for both human health and environment. In the lastfew years, researchers working in the field of wet textile processingare trying to implement natural and safer molecules, in line withthe principles of a more eco-friendly chemistry (Szente et al., 1998;Vankar et al., 2006; Montoneri et al., 2008). Meanwhile, the Sub-stitution Principle based on hazard assessments appear to justifythe use of safer chemical alternatives (Thorpe and Rossi, 2007;

des Arts et Industrie Textiles(GEMTEX), 2, allée Louise etFrance. Tel.: þ33 3 20 25 75

ary).

All rights reserved.

Ozturk et al., 2009; Lavoie et al., 2010; Hansonn et al., 2011). Thepurpose of our study was to assess the feasibility of substitutingtoxic molecules called carriers used for dyeing of polyester fabricsby vanillin which is an agro-sourced product.

In 2009, global production of polyester fibres reached 31.9million tonnes; about 45% of worldwide fiber production (Oerlikon,2010). Polyester (polyethylene terephtalate (PET)) fibers havea growing importance, and are mainly used in clothing, geotextileand automotive industries. PET has excellent tensile strength andchemical resistance. However as PET is hydrophobic and has nochemically active groups, its dyeing in aqueous conditions is quitedifficult. Dyeing is achieved with disperse dyes having good dif-fusivity and solubility in PET fiber. Moreover, the highly crystallinestructure of PET fiber slows down the rate of dye diffusion into thefiber (Trotman, 1970; Cegarra and Puente, 1967; Carrion, 1995).

Dyeing of polyester fabrics can be achieved using three differentmethods depending on the quantity of fabrics to be dyed (Dupont,2002; Dewez, 2008). Thermosol process used for continuousdyeing of thousands of meters of polyester fabrics, iscarried by impregnation of the PET fabric in the dye bathfollowed by squeezing of excess dye bath and then a prior drying

V. Pasquet et al. / Journal of Cleaner Production 43 (2013) 20e26 21

(at 100e140 �C) before dye fixation (at 200e225 �C during 12e25 s). This technique is however restricted to disperse dyes thatcan sublimate and penetrate inside the PET fiber in gaseous state.Thus, only a limited amount of color shades can be obtained.

When special shades are needed, dyeing of polyester fabricswith disperse dyes is achieved using exhaustion method (deepdyeing). The fabric to be dyed is immerged in the dye bath forlonger period (about 1 h) under high temperature and pressure,under agitation, with or without addition of a carrier to allow dyediffusion inside the polyester fiber. Exhaustion method is used fordyeing of smaller quantities of polyester fabrics or for dyeing ofpolyester textiles in the form of fibers, yarns or knitted fabrics. Twoexhaust dyeing methods are used: 1 - Dyeing under atmosphericconditions (below 100 �C) with the aid of carriers and 2 - Dyeingunder high-temperature and pressure conditions (125e135 �C). Thelast method is the most commonly applied but it requires highenergy consumption because of high temperature conditions.

Carriers are used for dyeing of PET fibers in order to improveadsorption and accelerate diffusion of disperse dyes into the fiber atlow temperature and pressure conditions. Nevertheless, most ofcarriers are toxic for humans and aquatic organisms (Murray andMortimer, 1971a; Shenai, 1998; Tavanaie, 2010). During dyeingand rinsing, a large amount of carriers is released into wastewater,but part remains entrapped in the fiber (Vigo,1994; Park, 2004) andis likely to be emitted into air during drying, thermofixation andlater use (eg. ironing).

Chemical carriers include: phenolics, chlorinated aromatics,aromatic hydrocarbons and ethers (Vigo, 1994). Some carriers aresaid “hydrophobic” and some are “hydrophilic”, and their mode ofaction differ accordingly. Hydrophobic carriers are more effectivethan hydrophilic ones (Burkinshaw, 1995). In textile industry, hy-drophobic carriers such as dichloro and trichloro-benzene arealready substituted by hydrophilic carriers such as benzoic acid(Vigo, 1994).

OH

OHH O

1.1. Action of carriers

During the first stage of dyeing, adsorption of carriers on PETfiber takes place in a manner which is similar to that of dispersedyes. Interactions between PET fiber and carrier involve primarilydispersive forces acting between aromatic parts of the carrier andthe PET polymer (Murray and Mortimer, 1971b; Ingamells andYabani, 1977; Burkinshaw, 1995).

As the carrier molecules are smaller in size than the dye mole-cules, they diffuse more rapidly into the amorphous regions of fiberafter their adsorption onto PET fiber. There is then a swelling of PETfiber and creation of spaces between PET macromolecular chains.Amorphous regions then become more easily accessible to the dyemolecules. This swelling phenomenon causes a plasticization ofPET and therefore a reduction of glass transition temperature Tg(Murray and Mortimer, 1971a; Vigo, 1994; Burkinshaw, 1995). Thecarrier has thus the effect of accelerating dye diffusion inside PETfiber.

“Hydrophilic” carriers have a different mode of action: they actas powerful dispersing agent, increasing solubility of the dispersedye in water, (Burkinshaw, 1995; Arcoria, 1989), but their increasedsolubility in water decreases their diffusion inside the PET fiber.Carriers such as phenols have aromatic group which contributes totheir adsorption on the fiber (Balmforth et al., 1966).

Ortho-vanillin(b)Para-Vanillin(a)

O CH3OH

O CH3

Fig. 1. Chemical formula of the two vanillins used: (a) Para-Vanillin, (b) Orthovanillin.

1.2. Vanillin

Molecular structure of vanillin is similar to that of traditionalcarriers, which confers to all of them a solubility parameter close to

that of PET. Hence it would be interesting to study the possible useof vanillin to substitute traditional toxic carriers.

Naturally occurring vanillin in pods is very expensive and wasfor a long time replaced by petrochemical vanillin for its use in agri-food and perfumery. There is now a great concern for its productionusing biotechnological solution: Rhodia markets biosyntheticvanillin prepared by the action of microorganisms on ferulic acidextracted from rice bran and today lots of research is being un-dertaken to synthesize vanillin from agro-resources such as lignin(McShan, 2005). Moreover, vanillin is antioxidant (Tai et al., 2011)antimicrobial and anti-mutagenic effects (Walton et al., 2003).

In this article, the feasibility of substituting traditional carriersby 2 different types of vanillins: para and ortho-vanillin (seeFig. 1(a) and (b)) was assessed. PET fabric was dyed in atmosphericconditions using two different disperse dyes having differing mo-lecular weight. The toxicity risks related to the use of vanillincompared to the existing carrier molecules were also analyzedusing literature data.

2. Experimental

2.1. Dyeing methods

A 100% PET plain woven fabric, ready-to-dye (supplied by Sub-renat) density ¼ 167 g/cm2 was used.

The samples,weighing3g,weredyed in200mlbeakers (Labomatmachine) with two dyes, disperse dye blue D56 (M¼ 349.14 gmol�1)and disperse dye blue D79 (M¼ 639.41 gmol�1), see Fig. 2(a) and (b).For each dyeing the liquor volume was set to 150 ml. The amount ofdye usedwas 3% o.w.f. at a liquor ratio of 50:1. Dyeingwas carried outat 90 �C for 1 h at different pH values (3, 5, 7, 9, 11). pH was adjustedusing aqueous hydrochloric acid and potassium hydroxide. Then,dyed samples were reduction cleared using soda and sodiumhydrosulfite for 30 min at 50 �C, to remove all physi-sorbed dyemolecules on PET fabric surface. At the end, dyed samples werewashed twice at 30 �C for 10min in distilledwater and dried at roomtemperature.

Dyeing was carried out using vanillin as carrier and results werecompared to those of 5 traditional carriers (pure products), and toa commercial carrier Levegal DTE supplied by Bayer.

The chemical formula of the 5 chemical carriers used, are shownin Fig. 3.

2.2. Measurements and analysis

Reflectance of the cleaned dyed samples was measured witha spectraflash SF-650 spectrophotometer. Relative color strengthsK/Smax (at l ¼ 640 nm) were then determined using the KubelkaeMunk equation

K=S ¼ ð1� RÞ22R

� ð1� RÞ22R0

Fig. 4. K/Smax values of PET fabric dyed with 2 different disperse dyes(D56 ¼ 349.14 g mol�1 and D79 ¼ 639.41 g mol�) in presence of 1 g of the 3 differentcarriers (p-vanillin, o-vanillin and Levegal DTE) at 90 �C and pH 7 for 1 h, with LR¼ 1/50.

Fig. 2. Chemical formula of dyes used in this study: (a) Anthraquinone disperse dyeD56, (b) Azoic Disperse dye D79.

V. Pasquet et al. / Journal of Cleaner Production 43 (2013) 20e2622

where R is the decimal fraction of reflectance of dyed fabric (atl ¼ 640 nm), R0 is the decimal fraction of reflectance of undyedfabric, K is the absorption coefficient, and S is the scatteringcoefficient.

Dye concentrations inside PET fiber was quantified by colori-metric analysis after dye extraction with dimethylformamide(DMF) using a Kumagawa extractor. Calibration curves (of absorb-ance v/s dye concentration) using pure dye solutions were used todetermine the dye concentration inside PET fiber.

Dyed samples were tested according to ISO standard methods.Specific tests used were ISO 105-C10 for color fastness to washingand ISO 105-X12 test for color fastness to rubbing.

For the fastness to washing, a specimen of dyed polyester fabricwas washed at 50 �C for 45 min. Color degradation was evaluatedby comparison with a non-washed specimen. Color difference wasmeasured to assess the wash color fastness: 1 e poor, 2 e fair, 3 e

moderate, 4 e good, 5 e excellent.For dry rubbing test, dyed polyester fabric was placed on the

base of a crockmeter, a white squared cotton testing fabric wasallowed to slide on the dyed polyester fabric back and forth twentytimes. The staining on white cotton sample was assessed on a greyscale: 1 e poor, 2 e fair, 3 e moderate, 4 e good, 5 e excellent. Forwet rubbing test, white cotton samples were thoroughly dampedwith distilled water before performing the test.

3. Results

3.1. Effect of the blue dye molecule size

Fig. 4 shows the color strength expressed in terms of K/Smax (atl ¼ 640 nm) of polyester fabrics dyed separately with two dispersedyes: D56 and D79, in presence of o-vanillin, p-vanillin and thecommercial carrier Levegal DTE.

Fig. 3. Chemical formula of chemical traditional carriers used in the study: (a) phenyl-phenol, (b) para and ortho-dichlorobenzene, (c) benzoic acid, (d) biphenyl.

The smaller disperse dye molecule D56 yields a higher K/Smax

value compared to the larger disperse dye D79. Several studies haveshown that disperse dye uptake by PET fabrics depends on the sizeof dye molecules (Lee and Kim, 1998; Dhouib et al., 2006). Both o-vanillin and p-vanillin increase the K/Smax values but o-vanillinyields a higher color strength value. However, the highest K/Smaxvalue is obtained with the commercial carrier Levegal DTE. Thus,with the smaller dye D56, K/Smax value increases from 1 to 4 withp-vanillin, reaching K/Smax ¼ 8 with o-vanillin, and K/Smax ¼ 16with the commercial conventional carrier.

Moreover, Table 1 shows that with the larger dye D79, washfastness is not very good (3.5) especially when o-vanillin or thecommercial carrier is used.

3.2. Influence of pH

Fig. 5 shows the variation of K/Smax values as a function of pH fordyeing with disperse dye D56, with 1 g of each vanillin carrier. Atlow pH values (pH 2e7), K/Smax does not vary significantly but atbasic pH values (9e11), K/Smax values decrease sharply for bothvanillins. We used Marvin software to identify species chargedistribution according to pH values. The pKa of p-vanillin isaround 7.4 and that of o-vanillin is around 9. For pH valueshigher than the pKa values, predominant species are anionicforms of p-vanillin and o-vanillin because alcohol groups losea hydrogen ion. As far as the disperse dye D56 is concerned, itacquires an anionic form for pH > 9.8. At basic pH, it has alreadybeen shown that PET was negatively charged (Ran et al., 2011). Athigh pH values, electrostatic repulsion between negatively charged

Table 1Fastness properties of dyed polyester fabrics with 3% dye owf.

Washing Dry rubbing Wet rubbing

D56 D79 D56 D79 D56 D79

No carrier 4.5 4 5 4.5 4.5 41 g p-vanillin 4.5 4 5 4.5 4.5 41 g o-vanillin 4.5 3.5 4.5 4.5 4.5 41 g commercial carrier

(Levegal DTE)3.5 3.5 4.5 3.5 4 4.5

0

1

2

3

4

5

6

7

8

9

0 2 4 6 8 10 12pH

K/S

max

o-vanillin

p-vanillin

Fig. 5. K/Smax values of PET fabric dyed with D56, (at 90 �C, 1 h, LR 1/50, 1 g of p-vanillinor 1 g of o-vanillin) at different pH values.

Fig. 6. K/Smax values of PET fabric dyed at 90 �C during 1 h at pH 7, with a LR 1/50, and3% owf of disperse dye D56) with different amounts of o-vanillin at two differentconcentrations of ethanol.

V. Pasquet et al. / Journal of Cleaner Production 43 (2013) 20e26 23

PET, and negatively charged dye and vanillins, would make dyeadsorption more difficult and would thus decrease the dye uptake.

Dye fastnesses were almost the same (Table 2) whatever the pHused. However, to reduce the input of chemical additives in dyebath, all dyeings in the following parts were carried out at pH 7,where dye uptake was maximal.

Also, the impact of vanillin on dye uptake being higher for thesmaller disperse dye D56, only this dye was retained for the fol-lowing part of the study.

3.3. Influence of vanillin concentration and presence of ethanolsolvent on dye uptake

The dashed curve in Fig. 6 shows that increasing the concen-tration of o-vanillin leads to a higher dye uptake (K/Smax values).Burkinshaw (Burkinshaw, 1995) showed that the amount of carrierincreased the amount of dye inside the fiber to a certain value. Here,we can see that as the concentration of vanillin increases from 0 to2 g, the K/Smax value increased proportionally. 2 g of vanillin wasthe optimum quantity necessary for optimum dyeing, with K/Smaxvalue reaching 16. Beyond 2 g, there is no further significantincrease in dye uptake, and unlevel dyeing took place.

A recent study (Ferrero et al., 2011) showed the benefits of usingethanol as co-solvent for dyeing fibers such as polyester. Indeed,disperse dyes and vanillin are not (or little) water soluble. Thus, theinfluence of ethanol when dyeing with vanillin as carrier wasstudied. K/Smax values were recorded for dyeing with differentconcentrations of vanillin carrier without and with 1 ml/l or 2 ml/lof ethanol. Fig. 6 shows that for quantities of vanillin �1 g, verylittle increase in K/Smax values was measured with 5 ml/l of ethanolonly (DK/S w 1). Indeed, Arcoria et al. (1985) showed that ethanolhas an effect on the dyeing of PET with disperse dyes, but the effectis highly dependent on the structure of dye.

Table 2Fastness properties of PET fabric dyed with D56, (90 �C, 1 h, LR 1/50, 1 g of p-vanillinor 1 g of o-vanillin) at different pH, with 3% dye owf.

Washing Dry rubbing Wet rubbing

p-vanillin o-vanillin p-vanillin p-vanillin o-vanillin p-vanillin

pH 3 4.5 5 4.5 5 4.5 5pH 5 5 4.5 4.5 4.5 4.5 4.5pH 7 4.5 4.5 5 4.5 4.5 4.5pH 9 4.5 4.5 5 4.5 4 4.5pH 11 5 4 5 4.5 5 4.5

The presence of ethanol did not influence the wash and rubfastness values which were similar to those obtained withoutethanol (values not shown here).

3.4. Comparison of vanillin with other chemical traditional carriers

After studying the influence of several parameters on the dyeingof PET with vanillin, dye uptake in presence of vanillin was com-pared to 5 other chemical carriers.

Fig. 7 shows the measured K/Smax values of fabrics dyed inpresence of 1 g of carrier and 3% of dye D56.

Indeed, compared to the 5 conventional carriers, o-vanillinyields a K/Smax value which is similar to that of benzoic acid. Theother 4 conventional carriers yield very high K/Smax values whichare 5e6 times higher than that obtained with o-vanillin. P-vanillinyields the smallest K/Smax. However when fastness (Table 3) resultsare compared, the wash fastness of polyester fabrics dyed using anyof the two vanillins is better than that using chemical carriers suchas the two dichlorobenzenes or the commercial Levegal DTE.

The K/Smax values of the dyed fabrics were then compared to the% of dye from the dye bath which penetrates inside PET fiber. Dyeextraction method described in part 2 was used to quantify theamount of dye inside the PET fiber. Fig. 8 shows that without anycarrier, only 7.5% of the dye from the dye bath solution penetratesthe PET fiber. With the chemical carriers, dye penetration inside thefiber is highly increased especially with p-dichlorobenzene, where63.8% of dye in dye bath penetrates the PET fiber. Only 13.8% and18.3% of the dye penetrates the fiber with the p-vanillin and o-vanillin respectively, but with o-vanillin, dye penetration inside PETfiber is slightly higher than that with benzoic acid. Indeed when allK/Smax values are plotted against the % of dye inside the PET fiber,a linear regression curve appears (see Fig. 7), indicating that theK/Smax values are proportional to the concentrations of dye insidethe fiber, and this is true for all carriers studied here. This wouldmean that the kinetics of dye penetration inside the PET fiber issimilar for all carriers used in this study. This result also confirmsthat the small size dye D56 diffuses uniformly inside the PET fiberwhatever is the nature of the carrier used.

To better understand the differences in dye uptakes with thedifferent carriers, the K/Smax values were compared to the Hoy

Fig. 7. K/Smax values of PET dyed fabric plotted against the % of dye from dye bath which penetrates inside PET fiber.

Fig. 8. K/Smax values of PET fabric dyed (at 90 �C, 1 h, pH 7, LR 1/50) with 3% of dispersedye D56 and 1 g of carrier, compared to the solubility limit in water, of each carrier.

V. Pasquet et al. / Journal of Cleaner Production 43 (2013) 20e2624

solubility parameter and to the solubility limit in water, of eachcarrier. As specified in literature, carrier molecules which aresmaller in size than dye molecules, diffuse more rapidly into theamorphous regions of PET causing a swelling of PET and creation ofspaces between PET macromolecular chains facilitating thus, theaccess to dye molecules. Penetration of carrier molecules in PETwill depend on the solubility of the carrier in the PET (Tavanaie,2010). Indeed, several studies have shown (Slark and O’Kane,1997) correlation between good absorption of a molecule bya polymer and proximity of the solubility parameter. Using groupcontribution method for each chemical group, the Hoy solubilityparameter of the two vanillins and of polyethylene terephtalatewere calculated, and compared to that of the other carriers. Table 4shows that though the Hoy solubility parameter of all carriers isclose to that of PET, there is no real correlation between the carrierHoy parameter and K/Smax of dyed fabrics.

The measured K/Smax values were also compared to the solubi-lity limit of each carrier in water (see Fig. 8). The higher is thesolubility limit in water, the lower is the K/Smax value of the PETdyed fabric The values of the solubility limit in water of the twovanillins are even higher than that of the hydrophilic carrier-benzoic acid. The very low dye uptake with p-vanillin would thusbe explained by its very high solubility in water. However, thoughthe solubility limit in water of the o-vanillin is higher than that ofbenzoic acid, the dye uptake (K/Smax values) in presence ofo-vanillin is slightly higher than that with the benzoic acid.

3.5. Summary on the potential use of vanillin as a carrier for dyeingPET fabric

All the study carried here showed that when compared tochemical carriers, both vanillins seem to allow a uniform distri-bution of the small dye D56 in the fiber, just as the other chemicalcarriers. However, though the Hoy solubility parameters of the two

Table 3Fastness properties of fabrics dyed using 1 g of different carriers, with 3% dye D56

owf.

Washing Dry rubbing Wet rubbing

p-vanillin 4.5 5 4.5o-vanillin 4.5 4.5 4.5Benzoic acid 4.5 4.5 4.5Biphenyl 4.5 5 4Phenylphenol 4 4.5 4p-dichlorobenzene 3.5 4 4o-dichlorobenzene 3.5 4 4Levegal DTE 3.5 4.5 4

vanillins are similar to that of PET, their diffusion inside the PETfiber would be reduced due to their increased affinity with respecttowater molecules in the dye bath. Our study showed that the coloryield (K/Smax value) is higher with ortho-vanillin than with para-vanillin. With 1 g of o-vanillin, dye uptake is slightly higher thanthat with 1 g of hydrophilic benzoic acid carrier (K/Smax ¼ 7.5), andwith 2 g of o-vanillin, dye uptake value is doubled (K/Smaxvalue ¼ 16), which is a value obtained with 1 g of commercialLevegal carrier.

4. Toxicity assessment

A further study, based on literature data was conducted tocompare toxicity of these molecules to show the interest of using

Table 4Solubility parameters of different carriers used.

Solubility parameter(Hoy) en Cal1/2 cm�3/2

p-vanillin 9.9o-vanillin 10.17Benzoic acid 10.87p-dichlorobenzene 9.31o-dichlorobenzene 9.31Biphenyl 9.24Phenyl-phenol 12.12PET 11.18

Table 5Different parameters of toxicity for the different carrier molecules.

Acute toxicityb,d Cancerogenicityc Neuro-toxicityb Developmental orreproductive harma,b

Endocrinedisruptora,b

Ecotoxicitya,d

p-vanillin Slight Not listed No ? ? Not acutely toxico-vanillin Slight to moderate Not listed No ? ? ?Benzoic acid Slight Not listed No ? ? Not acutely toxicp-dichloro-benzene Slight 2B No ? ? Moderateo-dichloro-benzene Slight 3 No ? ? Slight to moderateBiphenyl Slight 3 No ? Suspected ModeratePhenyl-phenol High 2Be3 No Yes Suspected Moderate to high

a Hazardous Substances Data Bank (HSDB).b Pesticide Action Network (PAN).c International Agency for Research on Cancer (IARC).d Material Safety Data Sheets (MSDS).

Table 6Characterization factors of ecotoxicity and human health calculated by USEtox� model.

Freshwater ecotoxicological characterization factor inCTUe [PAF m3 day/kg emitted]

Human health characterization factor inCTUh [cases/kg emitted]

Emission to Emission to

Water Air Soil Water Air Soil

p-vanillin 528 31 108 n/a n/a n/ao-vanillin 5050 242 969 n/a n/a n/aBenzoic acid 49 5.30 3.62 1.43$108 7.82$10�9 5.77$10�8

Phenylphenol 8300 163 13.4 9.03$10.�8 8.10$10�10 3.55$10�8

Biphenyl 1730 12 2.3 2.32$10�8 1.45$10�9 5.52$10�8

o-dichlorobenzene 613 3 22 1.52$10�8 1.13$10�8 2.65$10�8

p-dichlorobenzene 1030 4.1 34 9.19$10�8 6.88$10�8 1.74$10�7

The characterisation factor for aquatic ecotoxicity (ecotoxicity potential) is expressed in comparative toxic units (CTUe) and provides an estimate of the potentially affectedfraction of species (PAF) integrated over time and volume per unit mass of a chemical emitted (PAF m3 day kg�1).

V. Pasquet et al. / Journal of Cleaner Production 43 (2013) 20e26 25

vanillin as a carrier. We attempted to apply principles of chemicalsubstitution advocated in literature (Hansonn et al., 2011) to justifythe use of vanillin. The toxicity risks involved at different stages(dyeing and final use) in the life cycle of PET textile product dyedusing a carrier, were considered. Carriers can come in direct contactwith human being when inhaled by workers or when they are indirect contact with the user’s skin. They can also be released inwater or in air, causing water or air pollution and inducing thus,some ecotoxicity. So, parameters such as human toxicity and eco-toxicity have to be taken into account when assessing the toxicityrisks of two vanillins.

Toxicity risks of the two vanillins were compared to those oftraditional carriers. The following toxicity risks were considered:acute toxicity, carcinogenic potential, toxicity on reproductionor development of a species, neurotoxicology, and endocrinedisruption.

Several reports give information on safety data of moleculesused in our study. There is however still a lack of data for all tox-icities considered here (Hansonn et al., 2011). Thus data on thefollowing toxicities are still missing: toxicity on reproductive sys-tem or development of a species and endocrine disruption (seeTable 5). Moreover, the different toxicity risk parameters are notnecessarily related to each other, and each of them yields to dif-ferent conclusions. For example, although ortho-vanillin is not lis-ted as a potentially cancerigenous molecule when compared todichlorobenzene, it has nevertheless, a higher acute toxicity.

Finally, the USEtox�model was used to carry out a comparativestudy on the different molecules used as carrier. Indeed, USEtox�model is an environmental model for characterization of humanhealth and ecotoxic impacts in comparative assessment and forranking of chemicals according to their inherent hazard charac-teristics (Ralph et al., 2008). It has been developed by a team ofresearchers and has already been applied to several thousands ofchemicals. In particular, emissions to air and water are considered.Table 6 shows that it is not proved that the two vanillins are toxic

for human health. Moreover, Lirdprapamongkol et al. (2009) con-firmed the antimutagenic properties of the two vanillins. Howeversafety data sheet from suppliers does point out that o-vanillin maycause eye irritation, skin inflammation and respiratory irritationwhen inhaled. Ecotoxicity in terms of emissions to air, of p-vanillinis higher than that of benzoic acid, while o-vanillin has the highestecotoxicity.

In spite of its high ecotoxicity, o-vanillin seems to be a promisingcarrier molecule to improve disperse dye uptake by PET fibres. Inaddition, both vanillins present antibacterial and antifungal char-acteristics and would probably impart these properties to thepolyester fabric, too.

5. Conclusion

Conventional carriers having high toxicity are gradually beingreplaced byother processes, which are not always environmentally-friendly. This study was carried out to study the potential use of anagro-sourced vanillin molecule for substituting carriers used forpolyester fabric dyeing process. Increased disperse dye uptake isobserved when o-vanillin or p-vanillin is used, but for small sizedisperse dye only. Our experiments showed that both vanillins seemto allow a uniform distribution of the small disperse dye in the fiber,just as other chemical carriers. Our study showed that in the dyeingconditions used (3% of dye solution), the color yield (K/Smax value) ishigher with o-vanillin than with p-vanillin. With 1 g of o-vanillin,color yield is slightly higher than thatwith 1 gof hydrophilic benzoicacid carrier (K/Smax ¼ 7.5), and with 2 g of o-vanillin, dye uptakevalue is doubled (K/Smax value ¼ 16), which is a value obtainedwith 1 g of commercial Levegal carrier. Moreover dyeing withvanillin can be carried at neutral pH without addition of otherchemicals to adjust pH.

The study confirms that vanillin may substitute traditional car-riers used in the dyeing of polyester with disperse dyes of smallsizes.

V. Pasquet et al. / Journal of Cleaner Production 43 (2013) 20e2626

USEtox model shows that both vanillins do not present anyproved human toxicity, however o-vanillin which gives the highestdye uptake has a high fresh water ecotoxicity.

These results highlight the perspective of studying other agro-sourced products as substitutes for chemicals used in textileprocessing.

However, in the framework of a life cycle assessment, severaltoxicity data are missing. Environmental and toxicity risks of usingcarriers are mainly due to their inhalation, their cytotoxicity andecotoxicity. The quantity of vanillin present or which may bereleased (during use) at the fabric surface or emitted in air or watershould be evaluated for similar dye uptake values.

Acknowledgments

This work was realized within the framework of ACVTEX projectwhich is financed by Europe (Interreg and FEDER), Conseil Régionaldu Nord e Pas-de-Calais, ADEME, DIRECCTE and Région Wallone.The authors also would like to thank Christian Catel for his kindhelp.

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