improve of direct dye (direct orange 46) sorption on ...on the dye. the advantages of direct dyes...

Journal of Applied Chemical Research, 18, 7-14 (2011)

Journal of App l ied Chemical Research

www.jacr.k iau.ac. i r

Improve of Direct Dye (Direct Orange 46) Sorption on Pretreated Cotton Fabric by Cationic Agent

Y. Khanjani1, K. Farizadeh2*, S.Ahmadi2 1Young Researchers Club, Islamic Azad University, Shahr-e-Rey Branch, Tehran, Iran.

2Islamic Azad University, Shahr-e-Rey Branch, Tehran, Iran. (Received 27 April 2011; Final version received 12 May 2011)

AbstractThe sorption properties of direct dye on bleached cotton and cationized cotton (treated with Cibafix WFF) was studied. Cationization of cotton fabric at different conditions (time and cationic agent concentration) wasinvestigated. Nitrogen content of cotton samples pretreated with cationic agent were determined by Kjeldahl method. The results showed that at higher cationizing treatment time and initial cationic agent concentration lead to higher nitrogen content on cotton fabric. The adsorption isotherm of Direct Orange 46 (DO46) on cationized cotton was tested by fitting the adsorption data with Langmuir and Frendlich. Standard adsorption affinity of direct dyes on cationized cotton was measured. The results showed that standard affinity value is negative. This indicated that the adsorption of DO46 on cationized cotton is an exothermic process. According to results, the adsorption of direct dye on cationized cotton is more than bleached cotton. It is clear that the present of cationic group on cationized cotton fabric causes more attractionf or sorption of inionic dyes.Keywords: Cationized Cotton, Direct dyes, Adsorption isotherm, Standard affinity, Langmuir, Frendlich.

Introduction

Cotton is an abundant natural fiber which

consist of practically pure cellulose (about

88- 96 % )[1]. Cotton fibers due to hydroxyl

groups in its structure faces problem of fiber-

dye attraction. Many attempts have aimed

to improve dye bonding and dye adsorption

on materials through chemical modification

[2]. Cellulose fiber when comes in contact

with water produce slightly negative charge

(ξ=-11 Mv) that due to presence of hydroxyl

and carboxyl groups.Whereas common dyes

appropriate for cotton dyeing are anionic

(such as reactive and direct dyes) in dyeing

bath[3.4]. The slightly negative charge on the

fibers repels anionic dyestuff and hence the

efficiency of dye exhaustion and fixation on

cellulosic fiber is generally low[5].

The surface modification of textile fibers is

considered as the best process to obtain modern * Corresponding author: Dr. K. Farizadeh, Assistant Prof., Shahr-Rey branch, Islamic Azad University, Tehran, Iran. Email: [email protected]. Cell: 09121543906, Fax: 02122251140.

Y. Khanjani et al., J. Appl. Chem. Res., 18, 7-14 (2011)8

textile treatment [6]. In order to enhance the

dyeing capacity of the cotton fibers, inclusion of

an extensive functional compounds; for example

polyepichlorohydrin dimethyl amine (PECH-

amine), poly (4-vinylpridine) quaternary

ammonium compound, polyamidoamine

(PAMAM) and chitosan bio polymer on cotton

fibers has been reported.It was found that such

pretreatment increased the color strength of

the dyed cotton and improved wash fastness

properties [6]. Many substrates containing

quaternary ammonium groups or amino groups

have been used following this application [6].

Chemical modifications of cotton by reaction

with the functional groups (hydroxyl groups)

already present in the fiber are also investigated.

Etherification, esterification, grafting and

crosslinking reaction defined for chemical

modification of cotton have been extensively

studied [5]. By introduction of amino groups,

the cellulosic fiber will be cationized giving

high substantivity for anionic dyes due to the

columbic attraction between the positive charge

groups (NH2+) on the fiber and the negative

charge on the anionic dyes that is shown in

Figure 1.

Cell

Cell

OH + CH2CHCH2 CH2CHCH2

CH2CHCH2

Na2CO3N N

N

R2 R2

OH PA PA

PAOH

Fixation

O

O

Cl R1+ +

+

R1

R1

R2

Figure1. Chemical structure of Cibafix WFF compound and its reaction with cellulose.

On the other hand, the exhaustion of anionic

dyes (reactive, direct and acid dyes) on cationic

modified cotton can be improved greatly [5].

Direct dyes are used on cellulose fibers such

as cotton, rayon, and linen. The name “direct

dye” alludes to the fact that these dyes do not

require any form of “fixing”. They are almost

always azo dyes. They also have sulphonate

functionality, but in this case, it is only to

improve solubility and the negative charges

on the dye. The advantages of direct dyes are

resistance to faiding in the light and easy to

handle. The chemical structure of DO46 is

shown in Figure 2.

N N NH2SO3Na

Figure 2. C.I.Direct orange 46 (DO46).

The dyeing of cotton fabrics with anionic dyes

such as direct and reactive dyes require the

presence of large concentration of electrolyte

such as Glauber̕ s salt or sodium chloride and

alkaline to increase dye uptake, resulting in

critical environmental problems. The best

solution to avoid this problem is to cationized

the cotton fiber with cationic agent that promote

the colour strength of the dyed samples and

improve wash fastness properties [7-8]. In this

paper, we compared the adsorption isotherm of

DO46 and standard affinity of direct dyeing of

cotton pretreated with cationic agent (Cibafix

WFF) with untreated cotton.

Y. Khanjani et al., J. Appl. Chem. Res., 18, 7-14 (2011) 9

Experimental

Materials

Woven cotton fabric was provided free of

charge by a local producer in Iran. Direct

Orange 46 (DO46)(Sirius Orange K-CFN)

was from Dystar representative in Iran. The

purification of DO46 was by re-crystallization

with acetone. The Cibafix WFF (a Polyamino

Chlorohydrin Quaternary Ammonium

Compound), as a cationic agent, was obtained

from Ciba representative in Iran.

Instrumentation

A Unico 4802 UV-Visible spectrophotometer

was used for absorbance measurements using

quartz cell of 1 cm path length. A Shimadzu

1601 PC UV-Visible spectrophotometer was

employed for measuring of L*a*b* values. A

shaker bath equipped with thermostat, Shirley

(SDL–D403/1-3), operated at 75 rpm, was used to

study the adsorption of DO46 onto cotton samples.

Methods

Preparation of Fabric

Desizing

Before being used, the grey cotton fabric was

desized in solution containing 2% amylase

enzyme under slightly acidic pH at 60oC for

1 hour in laboratory mill. The enzyme was

deactivated with boiling of suspension at 90oC

for 15 min and the degraded starch products

was tested with potassium iodide and then

thoroughly washed out.

Scouring

The desized cotton fabric was scoured

in solution containing 1 g/lit Non- ionic

detergent, 5% Na2 CO3 at 100°C for 1 hr. Then

the samples were washed by cold water.

Bleaching

The desized and scoured fabric was bleached

with 5% hydrogen peroxide, 3% sodium

hydroxide and 1% sodium silicateat 100°C.

After that samples were rinsed with cold water

and neutralized with 1% acetic acid and then

it was washed thoroughly and dried in 50°C.

Cationizing of Cotton Fabric

The pretreatment of cotton fabric was carried

out by exhaust method in solution containing

20% o.w.f (% on weight of fabric) Polyamino

Chlorohydrin Quaternary Ammonium

Compound (Cibafix WFF), 15 g/l soda ash

(pH=9) for well- prepapred cotton, in L:G

20:1 for 60 min at 70°C.Then the fabric was

neutralized and washed thoroughly and dried

at ambient temperature.

Nitrogen Percentage

The nitrogen content was determined by the

Cole and Parks modification of the semimicro

Kjeldahl method [3].

UV-Visible Spectrometric

The UV-visible spectra of visible region (400-

800 nm) of DO 46 is shown in Figure 3.


Figure 3. UV- visible spectrum of DO46.

The wavelength of maximum absorbance (λmax)

of DO 46 was measured using Shimadzu 1601

PC UV-Visible spectrophotometer. In order

to determine λmax, the diluted dye solution

(0.05 g/lit) was prepared and absorption of

dye solution at visible region was measured.

According to the graph, the λmax of direct

orange 46 (DO46) is 558 nm.

Kinetic Studies

One gram of cotton samples (bleached

andcationized cotton) were dyed with DO46

at 40°C at different times, keeping the L.R. of

100:1 and an initial dye concentration of 1 %.

The quantity of dye adsorbed on cotton samples

were estimated using the following equation (1):

qt = (C0 – Ct)V/W Equation (1)

whereqt is the quantity of dye adsorbed on

cotton sample (mg/g cotton) at any time,

C0 and Ct are the initial and concentrations

(mg/L) after dyeing time t, respectively. V

is the volume of dye bath (mL) and W is the

weight of cotton sample (g).

The DO46 concentrations graph for standard

solution versus absorbance at 558 nm

wavelength, (maximum absorbance), was

plotted and used to determine the concentration

of an unknown solution. For each dyeing, the

absorbance of dye solution was monitored.

Then, the concentrations of dye in the residual

bath and the dye uptake were calculated using

the standard graph. Subsequently, the dyeing

rate of DO46 on cotton sample was plotted.

Equilibrium Studies

One gram of cotton sample (bleached

andcationized cotton) was dyed with different

dye concentrations (0.5- 4%) at 40˚C for 120

min. The quantity of dye adsorbed on cotton

samples at equilibrium were estimated using

the following equation (2):

qe= (C0 – Ce)V/W Equation (2)

where qe is the quantity of dye adsorbed on

cotton sample (mg/g cotton) at equilibrium,

C0 and Ce are the initial and equilibrium dye

concentrations (mg/l), respectively. V is the

volume of dye bath (mL) and W is the weight

of cotton sample (g).

Results and Discussion

Effect of Different Concentrations of Cibafix

WFFThe content of nitrogen in pretreated

cotton with different concentrations of Cibafix

WFF (10, 20 and 25% o.w.f) is summurized

in Table1.The results show that increase in

concentration of cationic agent leads to higher

nitrogen content in cationized cotton fabric.

Although nitrogen of cotton sample increase


at higher Cibafix WFF concentration and also

25% o.w.f Cibafix WFF shows better result

(Table 1).

Effect of Cationizing TreatmentTimeThe content of nitrogen in cotton pretreated at different times with Cibafix WFF are listed in Table 1. The results show that increase in thecationizing treatment leads to increase in nitrogen content. Although nitrogen content increase with increase of the time and 60 min shows better result (Table 1).

Table 1. The effect of treatment time and cationic agent concentration on nitrogen content in cotton pretreated with Cibafix WFF.

Parameters Nitrogen percent(%)Time(min)

15 0.0530 0.0860 0.12

Cationic agent (%)15 0.0920 0.1225 0.14

Rate of Dyeing

Determining of equilibrium time is one of the

most important characteristics which represent

the adsorption of DO46 on cotton samples

(either bleached cottonor cationized cotton).

The adsorption of dye on cationized cotton

is more than bleached cotton (Figure 4). It is

clear that presence of cationic group on cotton

fabric leads to more attractive site of sorption

for anionic dye.

Time (min)Figure 4. Effect of dyeing time of cotton samples (bleachedandcationizedcotton) dyeid with Direct Orange 46 (DO46). Dyeing conditions: initial dye concentration 1%, 40 °C andL.R.100:1.

The adsorption of dye increased at 120 min,

of dyeing and then reached the equilibrium

gradually. The L*a*b* values of cotton

samples are listed in Table 2.

Table2. The CIE Lab values of cotton samples (bleached andcationized cotton) dyed with Direct Orange 46 (DO46) at different times. Dyeing conditions: initial dye concentration 1%, 40 °C and L.R. 100:1.

Cationized cottonBleached cottonParametersb*a*L*b*a*L*Time (min)

54.5520.5667.2650.3714.9470.081556.2720.5666.1052.8316.1769.193057.3221.4865.6953.0117.9868.566057.5921.7664.9053.7518.2167.679058.1122.0063.3254.5819.6267.2712058.6022.1263.1055.1719.8366.5215058.8122.5863.2155.6220.1566.4118059.1022.9863.0755.4720.5566.53210


The results reveal that, L* values decreases and

a*, b* values increases as the time increases to

120 min and then the L*a*b* remains almost

constant. Therefore, time of dyeing was set at

120 min.

Adsorption Isotherms

Several models have been published to describe

the adsorption isotherms. The Langmuir and

Freundlich models are the most frequently

employed models [9]. In this research, to

describe the relation between the amount of dye

adsorbed on cotton samples and the amount of

dye in residual dyeing bath at 40°C, Langmuir

and Freundlich models were used. The most

widely used equation describing the adsorption

process is Langmuir equation, which has the

linear form (equation 3) [10]:

Where Q is the maximum amount of the dye

adsorbed on cotton samples to form a complete

monolayer coverage bond to the surface at

high equilibrium dye concentration Ce, qe is

the amount of dye adsorbed on cotton samples

at equilibrium, and b is Langmuir constant

related to the affinity of the binding sites.

The value of Q represents practical limit of

adsorption capacity when the surface is fully

covered with dye molecules and provides

the comparison for adsorption performance.

The values of Q and b can be calculated from

intercepts and slops of the straight lines of plot

of 1/q against 1/Ce [11]. The values of Q and b

are calculated and listed in Table 3.

Table 3. Langmuir and Freundlich values of adsorption of Direct Orange 46 (DO46) on cotton samples (bleached and cationized cotton).

Isotherm modelsParametersBleached cottonCationized cotton

LangmuirQ( mg\g fiber)26.3231.28

B9.513.30R20.9330.978

FreundlichQf( mg\g fiber)42.7364.32

N1.651.73R20.9570.912

Correlation coefficients of Langmuir and

Freundlich models are also listed in Table 3.

The results show that experimental data for

adsorption of DO46 on bleached cotton does

not fit the Langmuir model but experimental

data for adsorption of DO46 on cationized

cotton fit the Langmuir model. The Freundlich

equation is another model which is often used to describe adsorption data. The linear form of the Freundlich isotherm can be represented in equation 4:

where Qf is roughly an indicator of the


adsorption capacity and 1/n is the adsorption

intensity. Therefore, Qf and 1/n can be

determined from the linear plot of lnqe against

lnCe. The Qf and n values are listed in Table 3.

Correlation coefficients show that experimental

data for adsorption of DO46 on bleached

cotton fitted by this model. The magnitude

of the exponent 1/n gives an indication of the

favorability of adsorption. Values of n > 1

represent favorable adsorption conditions [11].

Standard Affinity

The standard affinity (-∆µ˚) was determined

using equation 5 [12]:

-∆µ˚= RT lnK (5)

Where R is the gas constant, T is the absolute

temperature (K) and K is the partition ratio.

The values of partition ratio (K) and standard

affinity (-∆µ˚) are presented in Table 4.

Table 4. Standard affinity (∆µ˚) and partition ratio (K) for the adsorption of Direct Orange 46 by cotton samples (bleached and cationized cotton).

-∆µ˚(kj/mol)KSample12.1957.83Bleached cotton12.5196.58Cationized cotton

It can be observed from Table 4 that the

standard affinity are negative which means

that the adsorption of DO46 on cotton samples

(bleached and cationized cotton) are an

exothermic process.

Conclusion

The adsorption of Direct Orange 46(DO46)

on cotton samples (bleached and cationized

cotton) was studied. The results indicated that

the adsorption of DO46 on cationized cotton

is more than bleached cotton. It is clear that

presence of cationic group on cotton fabric

leads to more attractive sites for sorption

of dye. The adsorption isotherm of DO46

oncationized cotton and bleached cotton are

Langmuir and Freundlich types, respectively.

The partition ratio (K), the standard affinity

(∆µ˚) was determined. It was noted that the

adsorption of DO46 on cotton samples is

exothermic process.

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improve of direct dye (direct orange 46) sorption on ...on the dye. the advantages of direct dyes...

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