Power Ultrasound-Assisted Cleaner Leather Dyeing Technique:  Influence of Process Parameters

Abstract

The application of power ultrasound to leather processing has a significant role in the concept of "clean technology" for leather production. The effect of power ultrasound in leather dyeing has been compared with dyeing in the absence of ultrasound and conventional drumming. The power ultrasound source used in these experiments was ultrasonic cleaner (150 W and 33 kHz). The effect of various process parameters such as amount of dye offer, temperature, and type of dye has been experimentally found out. The effect of presonication of dye solution as well as leather has been studied. Experiments at ultrasonic bath temperature were carried out to find out the combined thermal as well as stirring effects of ultrasound. Dyeing in the presence of ultrasound affords about 37.5 (1.8 times) difference as increase in % dye exhaustion or about 50% decrease in the time required for dyeing compared to dyeing in the absence of ultrasound for 4% acid red dye. About 29 (1.55 times) increase in % dye exhaustion or 30% reduction in time required for dyeing was observed using ultrasound at stationary condition compared with conventional dynamic drumming conditions. The effect of ultrasound at constant temperature conditions with a control experiment has also been studied. The dye exhaustion increases as the temperature increases (30-60 degrees C) and better results are observed at higher temperature due to the use of ultrasound. Presonication of dye solution or crust leather prior to the dyeing process has no significant improvement in dye exhaustion, suggesting ultrasound effect is realized when it is applied during the dyeing process. The results indicate that 1697 and 1416 ppm of dye can be reduced in the spent liquor due to the use of ultrasound for acid red (for 100 min) and acid black (for 3 h) dyes, respectively, thereby reducing the pollution load in the effluent stream. The color yield of the leather as inferred from the reflectance measurement indicates that dye offer can be halved when ultrasound is employed to promote dyeing. Scanning electron microscopy analysis of the cross section of the dyed leather indicates that fiber structure is not affected due to the use of ultrasound under the given process conditions. The present study clearly demonstrates that ultrasound can be used as a tool to improve the rate of exhaustion of dye, reduce pollution load in the spent effluent liquor, and improve the quality of leather produced. The study also offered provision to employ optimum levels of chemicals and increases percentage exhaustion for a given time, thereby limiting the pollution load in the tannery effluent, which is of great social concern.

Ultrasound assisted cleaner alternate emulsification method for oils and fats: tallow emulsion – fatliquor preparation for leather application

“…However, there is also a need for energy efficient ultrasound systems. The potential use of ultrasound in process industries such as leather with the aim to improve the quality, diffusion rate, reduce process time and pollution load have been investigated extensively for various processes such as leather dyeing (Sivakumar and Rao, 2003); analysis and review on leather processing as eco-friendly approach (Sivakumar and Rao, 2001); influence of process parameters on leather dyeing (Sivakumar and Rao, 2004) and on leather fatliquoring process (Sivakumar et al, 2005) for gaining possible environmental as well as process efficiency related benefits.…”

Towards cleaner degreasing method in industries: ultrasound-assisted aqueous degreasing process in leather making

“…Ultrasonic cleaner experimental set-up (Roop Telsonic Ultrasonics Ltd., India) generating ultrasound at 33 kHz frequency has been employed [17,19]. The power actually dissipated to the system was calculated to be 76 W, whereas the maximum available ultrasonic output power quoted by the manufacturer is 150 W [17].…”

“…The application of power ultrasound in leather processing has been studied elsewhere [13]. The uses of ultrasound in soaking [14,15], liming [16], dyeing [17][18][19][20][21], tanning [22,23] and fatliquoring [6,11,24] have been reported. In the present work, the influence of ultrasound in fat removal with different solvent systems has been studied.…”

Reactions of nonsymmetrical bidentate linkers having a phthalimidoyl and acid chloride group or a 2-benzothiazole group with α-d-glucoside derivatives and their application for the modification of cellulose

“…The desired product, methyl 2, (10) was obtained by the reaction of 9 with linkers 1 or 2 in the presence of pyridine in high yields. The results are shown in Table 4.…”

“…Then, this paper was dipped in protein (albumin) phosphate buffer solution for 1 h. To confirm protein conjugation, the Acid Black 10B dye method was used. 10 The treated paper was washed with phosphate buffer solution to remove excess protein, dipped into the dye (Acid Black 10B) solution, and washed with AcOH/H 2 O in order to remove unreacted dye. These treatments have appeared to colorize in deep blue a part of the paper marked as the S type with linkers 1 or 2.…”