Pseudo single-bath process for ambient temperature bleaching and reactive dyeing of jute

Indian Journal of Fiore & Textile Research Vol. 28. December 2003, pp. 450-455 Pseudo single-bath process for ambient temperature bleaching and reactive dyeing of jute S N Chattopadhyay, N C Pan & A Day" Chemical & Biochemical Processing Division, National Institute of Research on Jute & Alli ed Fibre Technology. 12 Regent Park, Kolkata 700 040, India Received 19 Jlllle 2002; accepted 10 September 2002 Grey jute fi bre has been bleached at ambient temperature using hydrogen peroxide and then cold dyed with Procion Red M8B and Remazol Yellow FG dyes by four di ffe rent process sequences. namely conventi onal two-step process, trlle si ngle-bath process, pseudo single-bath process and pseudo si ngle-bath process using spent bleach bath. The effect of process sequences on colour yield of dyed j ute fi bre has been evaluated usi ng computer colour matching system. It is observed th at the colour yield by pseudo si ngle-bath process is well comparable with that of the conventional two-step ambient temperature bleaching and cold reactive dyeing process. It is also observed that the colour yield is max imum in case of pseudo si ngle-bath process and mi nimum in case of true single-bath process. The process of dyei ng has no effect on A """ value which confirms no alteration in the hue and tone of any sample dyed wi th reactive dye by different single-bath processes. The wash fas tness is satisfactory in all the processes. Keywords : Ambient temperature bleaching, Jute fi bre, Pseudo single-bath process, Reacti ve dyeing 1 Introduction Decreasing trend in the use of jute fibre in the traditional sector, like packaging, is being well compensated by the increasing use of jute in the di versified sectors. Jute is now finding its use in several di versified applications like curtains, upholstery, bags / luggage, handicrafts and even in apparel sector. So, the wet processing of jute has occupied very important position in jute industry as the diversified use needs attracti ve look where bleaching, dyeing and fi ni shing are must. But the processing of jute requires a lot of energy, water, chemicals, etc. which not only increases the cost of processing but also leads to environment pollution through effluents. Several works have been done in the recent past, like ambient temperature bleaching 1-4, foam application technology and singlebath bleaching-dyeing to combat the above problems. Considering the energy problem, environment pollution, ease of processing in the rural sector, etc., the present work has been devised in such a way that all the processings like bleaching and dyeing will be can-ied out at ambient temperature. Moreover, the attempts have also been made to carry out both the processes in the same bath. Also, the spent liquor after " To whom all the correspondence should be addressed. Phone : 242 12 11 5; Fax: 009 1-033-247 12583; E-mail: nirjaft @vsnl.net ambient temperature bleaching 5 has been reused for another batch of ambient temperature bleaching. This is an integrated approach suitable specifica ll y for rural small-scale sector where all the resources like thermal energy, electrical energy, skilled manpower, adequate finance, easy avail ability of chemicals, water, etc. are scare. 2 Materials and Methods 2.1 Materials Grey jute fibre of TD-3 vari ety having fineness of 2.4 tex was used for the ex peri ment. The following chemicals of anal ytical grade we re used for the study : hydrogen peroxide, tri sodium phosphate, sodium hydroxide, sodium carbonate. sodium hydrosulphite, sodium persulphate, sodium si licate, magnesium sulphate heptahydrate, non-i oni c detergent (Ultravon JU) and acetic acid. Reacti ve dyes Procion Red M 8B (nucleoph ilic substitution type) and Remazol Yell ow FG (nucleophilic addition type) were used for dyeing of jute fibre. 2.2 M ethods 2.2.1 Conventional Bleaching of G r ey Jute Fihre Bleaching of grey j ute fibre was carried out in a closed vessel at 90 C for 2 h, keeping the ma terial-toliquor rati o at 1: 20, using hydrogen peroxide ( I vo l).

CHATTOPADHYAY el al. : AMBIENT TEMPERATURE BLEACHING & REACTIVE DYEING OF JUTE 451 trisodium phosphate (5 gil), sodium hydroxide (1 gil), sodium silicate (10 gil) and non-ionic detergent (2 gil). After bleaching, the fibre samples were washed thoroughly in cold water, neutralized with acetic acid (2mJlL), again cold washed and finally dried in air. 2.2.2 Ambient Temperature Bleaching of Grey Jute Fibre Jute fibre intended for ambient temperature bleaching was dipped in a solution containing hydrogen peroxide (10 vol), sodium silicate (20 gil), sodium hydroxide (20 gil), trisodium phosphate (5glL), sodium persulphate (logll), magnesium sulphate heptahydrate(0.5 gil) and Ultravon JU (10 gil), keeping the material-to-liquor ratio at 1 :3, and queezed to give 100 % wet pick-up. The samples were put in a plastic bag and kept as such for overnight. The samples were then washed, neutralized with acetic acid (2 mjll) and washed again in cold water before drying at room temperature. 2.2.3 Dyeing of Ambient Temperature Bleached Jute Fibre Ambient temperature bleached jute fibres were dyed with two different reactive dyes, namely Procion Red M88 and Remazol Yellow FG, using the following procedure : Pracion Red M8B - Dye bath was made with dye (4%) and Glauber' s salt (60 gil), keeping the material-to-liquor ratio at 1:20. The bleached fibre samples were dipped into the dye bath and kept for 1 h with stirring at 30 C. After this treatment, sodium carbonate (20 gil) was added in the same bath and kept for 45 mjn under the same condition. Thereafter, the samples were washed with cold water, soaped with Ultravon JU (2 gil) for 15 min at boil followed Rernazo! Yellow FG - Dye bath was made with dye (4%) and Glauber' s salt (80 gil), keeping the material-to-liquor ratio at 1:20. The bleached fibre samples were dipped into the dye bath and kept for 20 min with stilting at 30 C. After this treatment, the sodium hydroxide (4 gil) was added in the same bath and kept for Ih under the same condition. Thereafter, the samples were washed with cold water, soaped with Ultravon JU (2 gil) for 15 min at boil followed 2.2.4 Single-Bath Bleaching - Dyeing of Jute Fibre Ambient temperature bleaching and reactive dyeing of jute fibre was carried out by using three different process sequences, namely true single-bath process, pseudo single-bath process and pseud o single-bath process using spent bleach bath. 2.2.4.1 True Single-Bath Process For ambient temperature bleaching, grey jute fibre was dipped in a solution containing hydrogen peroxide 00 vol), sodium silicate (20 gil ), sodium hydroxide (20 gil), tri sodium phosphate (5g/L ). sodium persulphate (10 gil), magnesium sulphate heptahydrate (0.5 gil) and Ultra von JU ( 10 gil ). keeping the material-to-liquor ratio at 1:3. After keeping the bath as such for 2 h, sodium hydrosulphite ( 10 gil) was added to it and the solution was stirred for 15 min. Procion Red M8B (4%) and Glauber' s salt (60 gil ) were added to the above bleach bath and kept for I h with stirring at 30 C. After this treatment, the sodium carbonate (20 gil) was added in the same bath and kept for 45 min under the same condition. Thereafte r. the samples were washed with cold water. soaped with Ultravon JU (2 gil) for 15 min at boil fo ll owed Remazol Yellow FG (4%) and Glauber's salt (80 gil) were added to the above bleach bath and kept for 20 min with stirring at 30 C. After this treatment. the sodium hydroxide (4 gil) was added in the sa me bath and kept for 1 h under the same condition. Thereafter, the samples were washed with cold water. soaped with Ultravon JU (2 gil) for 15 min at boil followed 2.2.4.2 Pseudo Single-Bath Process For ambient temperature bleaching, grey jute fi bre was dipped in a solution containing hydrogen peroxide (10 vol), sodium silicate (20 gil), sodium hyd rox ide (20 gil), trisodium phosphate (5glL), sodium persulphate (10 gil), magnesium sulphate heptahydrate (0.5 gil) and Ultravon JU (10 gil), keeping the material- to- liquor ratio at 1:3, and squeezed to give 100% wet pick-up. The samples were put in a pl asti c bag and kept for 2 h.the bleached fibre (without washing) was then put in a separate bath containing ten times its volume of water (M:L :: 1:10). Sodium hydrosulphite (3 gil) was added to the bath and kept for 15 min with continuous stirring. Procion Red M8B dye (4%) and Glauber's salt (60 gil) were added to the above bath and kept for I h with stirring at 30 C. After this treatment, the sodium carbonate (20 gil) was added in the same bath and kept for 45 min under the same condition. Thereafter. the samples were washed with cold water, soaped

452 IND IAN J. FIBRE TEXT. RES., DECEMBER 2003 with Ultravon JU (2 gil) for 15 min at boi l fo llowed Re mazol Yell ow FG dye (4%) and G lauber's salt (80 gil) were added to the above bath and kept for 20 min with stirring at 30 C. After this treatment, the sodium hydroxide (4 gil) was added in the same bath and kept for 1 h under the same condition. Thereafter, the sa mples were washed with cold water, soaped with U ltravon JU (2 gil) for 15 min at boil followed 2.2.4.3 Pseudo Single-Bath Process using Spent Bleach Bath The liquor left out after ambient temperature bleaching, as described in section 2.2.2, was re used for the preparation of second batch of the sample. Grey jute fibre intended for ambient temperature bleaching using spent liquor was dipped in the above liquor and squeezed to give 100% wet pick-up. The samples were put in a plastic bag and kept for 2 h. The bleached fibre (without washing) was the n put in a separate bath containing ten times its volume of water (M:L:: I: 10). Sodium hydros ul phite (2 gil) was added to the bath and kept for 15 min with continuous stirring. The dyeing was carried out in the same way as mentioned in section 2.2.4.2. 2.3 Determination of Physico-chemical Properties 2.3.1 Whiteness, Yellowness and Brightness Indices Whiteness index (HUNTER scale), yellowness index (ASTM D 1925 scale) and brightness index (TAPPI 45 scale) of grey, conventional bleached and ambient temperature bleached jute fibre samples were measured by the Spectrascan-5100 (R) computer colour matching system using relevant softwares. Table I - 2.3.2 A 1IIax> Reflectance and KIS Values Spectrascan-5100 (R) computer colour matching system was also used to measure A. max> re fl ectance and KIS va lues of different types of reacti ve dyed jute fib re samples using relevant softwares and following formula: K I S = l (J -R) 2 I 2R ] DC C where K is the coeffi c ient of absorption ; S. the coefficient of scattering ; R, the re fl ectance of substrate at A. max; and C, the concentration of dye. T he K I S value is viewed as an index of dye uptake. 2.3.3 Wash Fastness All the reactive dyed jute fibre samples we re subjected to wash fastness tests in a launder-o-meter as per IS:3361-1979 (ref.6). Wash fastness ratings of a ll the dyed jute fibre samples were evaluated with the help of computer colour matching system. 3 Resul ts and Discussion Table 1 shows that both the whiteness and brightness indices are poor in case of grey jute fibre but after bleaching both the indices improve considerably. There is a substanti al decrease in yellowness index after bleaching. Conventi onal bleaching process produces better bleaching effect compared to ambient temperature bleaching process. The whiteness and brightness achieved after ambient te mperature bleaching are sa ti sfactory enough fo r subsequent dyeing operation. Table 2 shows that the ambient temperature bleached jute fibre produces higher KIS value as compared to conventional bleached jute fibre, indicating that the Evaluati on of fibre quality Sample Bleaching Bleach ing Wh iteness Yellowness Brightness agent uscd process index index index (HUNTER) (ASTM 0 1925) (TA PPI45) Grey Nil Nil 53.99 46.21 23.96 Bleached Hydrogen peroxide Conventional 83 17 18.82 64.59 Bleached Hydrogen peroxide Ambient temperatu re 76.27 2 1.9 1 53.99 Table 2 - Effect of different bleaching processes on dyeing behav iou r of jute fibre Parameter Procion Red M8B Remazol Yellow FG Conventional Ambient Conventional Amoi ent bleaching temperature bleaching temperature bl eaching bleaching A Illax, nm 550 550 420 420 Refl ectance 5.5 1 4.93 14.14 13.3 I KIS value 8. I I 9. 16 2.6 1 2.91 Wash fastness 3-4 4 3-4 3-4

CHATTOPADHYAY el at.: AMBIENT TEMPERATURE BLEACHING & REACTIVE DYEING OF JUTE 453 colour yield is more in case of ambient temperature bleached jute fibre. This finding is true for both Procion Red M8B ( substitution type of reactive dye) and Remazol Yellow FG ( addition type of reactive dye). The higher dye uptake may be due to the high alka line condition used during ambient temperature bleaching. Wash fastness property is found to be good in all the cases. In true single-bath process (Table 3), the colour yield is very poor when sodium hydrosulphite is not added for counteracting the oxidising effect of hydrogen peroxide bleached bath and alkali is not added during the fixation stage of reactive dye. Some minor improvement in colour yield is observed when sodium hydrosulphite or alkali is added alone. But more improvement in colour yield is observed when both sodium hydrosulphite and alkali are added in the bath. This finding is true for both the reactive dyes studied. In all the cases, the colour yield is very poor when true single-bath process is followed. Wash fastness of all the samples is moderate. Low liquor ratio, high alkali concentration and very hi gh oxidising agent concentration may be responsibl e fo r poor colour yield. Hence, it was decided that the true single-bath process wi ll not serve the purpose and the idea of pseudo single-bath process was emerged. In pseudo single-bath process, as the fibre was not washed after bleaching, it carried a portion of excess alkali to the dye bath. So, alkali was not added in the bath during fixation stage of reactive dyes. The colour yield of dyed samples was found to be poor in both types of pseudo single-bath processes. For the improvement in fixation of dyes, the alkali was added to the dye bath during fixation stage and the colour yield was found to be satisfactory in all the cases whether it is pseudo single-bath process or pseud o single-bath process using spent bleach bath (Table 4). To optimize the concentration of reducing agenl after bleaching both in case of pseudo single-bath process (Table 5) and pseudo single-bath process Table 3 - Effect of intermediate addition of reducing agent after bleaching and alkali during fixation stage of reacti ve dye ing on dyc ing behaviour of jute fibre using true single-bath process at ambient temperature Addition Addition Procion Red MSB Remazol Yello w FG of sodium of alkali A. ma" RFL KIS Wash A IIll' RFL KIS hydrosulphite nm fastness nm No No 550 37.34 0.53 3 420 47.39 0.29 No Yes 550 33.76 0.65 2-3 420 43.47 0.37 Yes No 550 32.SS 0.69 3 420 43.42 0.3 7 Yes Yes 550 26.46 1.02 3-4 420 3 1.24 0.76 W a~h ras t nc s~ 3-4 :1 2-3 3-4 RFL - Reflectance <- Table 4 - Effect of alkali during fixation stage of reactive dye in pseudo single-bath process and pseudo singlc-bath process using spent bleach bath at ambient tempcrature Parameter Pseudo single-bath process Pscudo single-bath process usi ng spent bleach hath Procion Remazol Procion Remazol Red MSB Yellow FG Red MSB Yellow FG With Without With Without With Without With Without alkali alkali alkali alkali alkali alkali alkali alkali A max, nm Rc l1ectancc KIS 550 550 420 420 550 550 420 420 6.19 23.S2 10.05 27.02 S.44 34. 17 13.07 4645 7. 11 1.22 4.02 0.99 4.97 0.63 2.S9 0.3 1 Table 5 - Effect of reducing agent after bleaching on dyeing behaviour of reacti ve dyes using pseudo single-bath process at ambi ent temperature Parameter Procion Red MSB Rcmazol Yellow FG 0" 2.0" 3.0" 5.0" 0" 2.0" 3.0" 5.0" A max' nln 550 550 550 550 420 420 420 420 Reflectance 23.S2 12. 11 6.19 6.97 34.42 2609 10.05 12. 13 KIS 1.22 3. 19 7. 11 6.21 0.62 1.05 4.02 3. IS a Sodium hydrosulphite concentration in gil

454 INDIAN 1. FIBRE TEXT. RES., DECEMBER 2003 Table 6 - Effect of reducing agent after bleachi ng on dyeing behaviour of reactive dyes following pseudo single-bath process using spent bleach bath at ambient temperature Parameter Procion Red M8B Remazol Yellow FG 0" 1.5" 2.0" 3.0" 0" 1.5" 2.0" 3.0" Am;.t.'(. nm 550 550 550 550 420 420 420 420 ReOectance 30.82 9.61 8.44 8.73 43.44 14.24 13.07 13.68 KIS 0.79 4.25 4.97 4.76 0.37 2.58 2.89 2.69 a Sodium hydrosulphite concentration in gil Table 7 - Effect of different single-bath bleaching-dyeing processes at ambient temperature on colour yield using two reactive dyes Process A",,, nm Procion Red M8B RFL KIS fastness Remazol Yell ow FG Wash A max RFL KIS Wash nm fastness True single-bath process Pseudo single-bath process Pseudo single-bath process using spent bleach bath 550 550 550 26.46 1.02 6.19 7.11 8.44 4.97 using spent bleach bath (Table 6), different concentrations of sodium hydrosulphite (0,1.5, 2.0, 3.0, and 5.0 gil) were used. The colour yield increased with the increase in sodium hydrosulphite concentration up to 3 gil in pseudo single-bath process and up to 2 gil in pseudo single-bath process using spent bleach bath. Thereafter, a decreasing trend in colour yield was observed. Sodium hydrosulphite reacts with the active hydrogen peroxide remaining inside the fibre and in the bath up to the optimized concentration. The higher concentration, than the optimized one, acts on the dyestuff in addition to its action with oxidising agent, thereby reducing the colour yield. Dyeing properties of jute fibre dyed with Procion Red M8B and Remazol Yellow FG at optimized condition using different processes are given in Table 7. It is evident that the colour yield is maximum in case of pseudo single-bath process and minimum in case of true single-bath process. By comparing the colour yield s from Table 2 and Table 7, it is revealed that the pseudo single-bath process is well comparable with the conventional two-step process using ambient temperature bleaching and cold reactive dyeing. Pseudo single-bath process using spent bleach liquor produces higher colour yield than that produced by true single-bath process but lower than that produced by pseudo single-bath process. 4 420 31.24 0.76 3-4 4 420 10.05 4.02 4 3-4 420 13.07 2.89 3-4 4 Conclusions 4.1 Whiteness index produced by ambient temperature process is slightly lower than that produced by conventional hot bleaching process. The whiteness and brightness achieved after ambient temperature bleaching is satisfactory enough for subsequent dyeing operation. 4.2 Dyeing of ambient temperature bleached jute fibre produces higher colour yield as compared to conventional bleached jute fibre. This finding is true for both Procion Red M8B (substitution type) and Remazol Yellow FG (addition type) dyes. High alkaline condition during ambient temperature bleaching results in swelling of fibre which ultimately gives better colour yield. 4.3 In true single-bath process, the addition of reducing agent (sodium hydrosulphite) after bleaching and that of alkali during fixation stage is must. But the colour yield is very poor when true si ngle-bath process is followed for ambient temperature bleaching and cold reactive dyeing. Low liquor ratio, high alka li concentration and very high oxidizing agent concentration may be responsible for poor colour yield. So. the true single-bath process was not found to serve the purpose and the idea of pseudo single-bath process was emerged. 4.4 In pseudo single-bath process, the addi ti on of 3 gil sodium hydrosulphite after bleaching and the..

CHATTOPADHYAY el al.: AM BIENT TEMPERATURE BLEACHING & REACTIVE DYEI NG OF JUTE 455 required amount of alkali for fixation of reactive dye is must. Colour yield produced by pseudo single-bath process is well comparable with that produced by conventional two-step process using ambient temperature bleaching and cold reactive dyeing. 4.5 Pseudo single-bath process using spent bleach bath produced higher colour yield than that produced by true single-bath process but it is lower than that produced by pseudo single-bath process. In this case, the optimized concentration of sodium hydrosulphite is 2 gil to achieve maximum colour yield. As the spent bleach bath can be reused, thi s process becomes simple and economic with minimum effluent disposal problem as after spent liquor bleaching there is hardl y any liquor left out in the bath for disposa l. 4.6 Wash fastness ratings are sati sfactory In a ll the processes. References I Pandey S N, Chattopadh yay S N & Basu G. Indian.I Fibre Text Res, 20 (1995) 102. 2 Basu G & Chattopadhyay S N, Indian J Fibre TexT Res. 2 1 ( 1996) 2 17. 3 Chattopadhyay S N, Pan N C & Day A. TexT Trends. XLlII(200 I) 23. 4 Pan N C. Chattopadhyay S N & Day A. TeXT Asia. XXXII (2001 ) 40. 5 Pan N C, Chattopadhyay S N & Day A, TexT Ind Trade.I. 39(200 I )37. 6 IS: 3361-1979, lsi Handbook oj TeXTile TeSTing ( Bureau of Indi an Standards, New Delhi ), 1982.