Effects of ultrasonic energy on the wash fastness of reactive dyes

The field of ultrasonic is still making strides towards perfection, but already many applications of ultrasonic energy have been found in science and technology. There is also a field called sonochemistry where ultrasonic energy is used to create some chemical and mechanical effects on matter immersed or solved in liquids. It was presumed that ultrasonic textile washing could be a competitive alternative to conventional textile washing techniques; and as such the following experiments were conducted. In this study, the effects of ultrasonic energy on the wash fastness of reactive dyes, which have three different reactive groups, were investigated. After dyeing with the conventional method, the samples were applied with three types of washing processes simultaneously (conventional, ultrasonic probe and ultrasonic bath) and comparisons were made. Three different fixing agents were used in the washing processes. Colourfastness, staining fastness, magnitude of total colour difference (DeltaE) and lightness difference of the colour (DeltaL) values of dyed samples were measured.     

Cold Pad-Batch dyeing method for cotton fabric dyeing with reactive dyes using ultrasonic energy

Reactive dyes are vastly used in dyeing and printing of cotton fibre. These dyes have a distinctive reactive nature due to active groups which form covalent bonds with -OH groups of cotton through substitution and/or addition mechanism. Among many methods used for dyeing cotton with reactive dyes, the Cold Pad Batch (CPB) method is relatively more environment friendly due to high dye fixation and non requirement of thermal energy. The dyed fabric production rate is low due to requirement of at least twelve hours batching time for dye fixation. The proposed CPB method for dyeing cotton involves ultrasonic energy resulting into a one third decrease in batching time. The dyeing of cotton fibre was carried out with CI reactive red 195 and CI reactive black 5 by conventional and ultrasonic (US) method. The study showed that the use of ultrasonic energy not only shortens the batching time but the alkalis concentrations can considerably be reduced. In this case, the colour strength (K/S) and dye fixation (%F) also enhances without any adverse effect on colour fastness of the dyed fabric. The appearance of dyed fibre surface using scanning electron microscope (SEM) showed relative straightening of fibre convolutions and significant swelling of the fibre upon ultrasonic application. The total colour difference values ΔE (CMC) for the proposed method, were found within close proximity to the conventionally dyed sample.     

Ultrasonic dyeing of cellulose nanofibers

Textile dyeing assisted by ultrasonic energy has attained a greater interest in recent years. We report ultrasonic dyeing of nanofibers for the very first time. We chose cellulose nanofibers and dyed with two reactive dyes, CI reactive black 5 and CI reactive red 195. The cellulose nanofibers were prepared by electrospinning of cellulose acetate (CA) followed by deacetylation. The FTIR results confirmed complete conversion of CA into cellulose nanofibers. Dyeing parameters optimized were dyeing temperature, dyeing time and dye concentrations for each class of the dye used. Results revealed that the ultrasonic dyeing produced higher color yield (K/S values) than the conventional dyeing. The color fastness test results depicted good dye fixation. SEM analysis evidenced that ultrasonic energy during dyeing do not affect surface morphology of nanofibers. The results conclude successful dyeing of cellulose nanofibers using ultrasonic energy with better color yield and color fastness results than conventional dyeing.     

Ecofriendly laccase–hydrogen peroxide/ultrasound-assisted bleaching of linen fabrics and its influence on dyeing efficiency

This study evaluates the bleaching efficiency of enzymatically scoured linen fabrics using a combined laccase–hydrogen peroxide bleaching process with and without ultrasonic energy, with the goal of obtaining fabrics with high whiteness levels, well preserved tensile strength and higher dye uptake. The effect of the laccase enzyme and the combined laccase–hydrogen peroxide bleaching process with and without ultrasound has been investigated with regard to whiteness value, tensile strength, dyeing efficiency and dyeing kinetics using both reactive and cationic dyes. The bleached linen fabrics were characterized using X-ray diffraction and by measuring tensile strength and lightness. The dyeing efficiency and kinetics were characterized by measuring dye uptake and colour fastness. The results indicated that ultrasound was an effective technique in the combined laccase–hydrogen peroxide bleaching process of linen fabrics. The whiteness values expressed as lightness of linen fabrics is enhanced by using ultrasonic energy. The measured colour strength values were found to be slightly better for combined laccase–hydrogen peroxide/ultrasound-assisted bleached fabrics than for combined laccase–hydrogen peroxide for both reactive and cationic dyes. The fastness properties of the fabrics dyed with reactive dye were better than those obtained when using cationic dye. The time/dye uptake isotherms were also enhanced when using combined laccase–hydrogen peroxide/ultrasound-assisted bleached fabric, which confirms the efficiency of ultrasound in the combined oxidative bleaching process. The dyeing rate constant, half-time of dyeing and dyeing efficiency have been calculated and discussed.     

Comparison of energy consumptions between ultrasonic, mechanical, and combined soil washing processes

Vigorous physical effects including micro-jet and micro-streaming can be induced in heterogeneous systems by acoustic cavitation. This can be useful for the removal of pollutants from contaminated soil particles. In this study, the diesel removal efficiencies in ultrasonic, mechanical, and combined soil washing processes have been compared considering the electrical energy consumptions for these processes. The combined process showed synergistic effects for both removal efficiency and effective volume also has the advantage of a short operation time compared to the sequential processes. Thus the ultrasonic soil washing process with mechanical mixing is considered a promising technology for industrial use.     

Ultrasonic-assisted dyeing of Nylon-6 nanofibers

We first time report ultrasonic dyeing of the Nylon 6 nanofibers with two disperse dyes CI Disperse blue 56 and CI Disperse Red 167:1 by utilising ultrasonic energy during dyeing process. The Nylon 6 nanofibers were fabricated via electrospinning and dyed via batchwise method with and without sonication. Results revealed that ultrasonic dyeing produce higher color yield (K/S values) and substantially reduces dyeing time from 60 min for conventional dyeing to 30 min can be attributed to breakage of dye aggregate, transient cavitation near nanofiber surface and mass transfer within/between nanofibers. Color fastness results exhibited good to very good dye fixation. SEM images exhibit insignificant effect of sonication on morphology of the nanofibers. Our research results demonstrate ultrasonic dyeing as a better dyeing technique for Nylon 6 nanofibers with higher color yield and substantially reduced dyeing time.     

Effect of sonochemical scouring on the surface morphologies,mechanical properties,and dyeing abilities of wool fibres

Ultrasonics has the potential to reduce the cost and environmental impact of textile processing. This work investigates the effects of ultrasonic irradiation during wool scouring on fibre surface morphologies, fibre mechanical properties, and fibre dyeing abilities. A range of ultrasonic frequencies were used in the scouring bath to examine the forms of fibre cuticle damage. It is observed that wool fibres underwent ultrasonic irradiation at a low frequency have severe modifications of the fibre surface structure. Despite some visible disruptions to the fibre scale structure however, ultrasonic irradiation has shown a negligible impact on the fibre mechanical properties, especially bending abrasion resistance which depends largely on the fibre surface conditions, and is responsible for the handle and pilling propensity of the resultant fabrics. Dyeing abilities were investigated on wool samples using commercially available acid dye and reactive dye. It is found that ultrasonically scoured wool has a quicker dye uptake in the early stage of low temperature dyeing for both acid dye and reactive dye, than the conventionally scoured wool.     

Ultrasound assisted enhancement in natural dye extraction from beetroot for industrial applications and natural dyeing of leather

There is a growing demand for eco-friendly/non-toxic colorants, specifically for health sensitive applications such as coloration of food and dyeing of child textile/leather garments. Recently, dyes derived from natural sources for these applications have emerged as an important alternative to potentially harmful synthetic dyes and pose need for suitable effective extraction methodologies. The present paper focus on the influence of process parameters for ultrasound assisted leaching of coloring matter from plant materials. In the present work, extraction of natural dye from beetroot using ultrasound has been studied and compared with static/magnetic stirring as a control process at 45 °C. The influence of process parameters on the extraction efficiency such as ultrasonic output power, time, pulse mode, effect of solvent system and amount of beetroot has been studied. The use of ultrasound is found to have significant improvement in the extraction efficiency of colorant obtained from beetroot. Based on the experiments it has been found that a mixture of 1:1 ethanol–water with 80 W ultrasonic power for 3 h contact time provided better yield and extraction efficiency. Pulse mode operation may be useful in reducing electrical energy consumption in the extraction process. The effect of the amount of beetroot used in relation to extraction efficiency has also been studied. Two-stage extraction has been studied and found to be beneficial for improving the yield for higher amounts of beetroot. Significant 8% enhancement in % yield of colorant has been achieved with ultrasound, 80 W as compared to MS process both using 1:1 ethanol–water. The coloring ability of extracted beet dye has been tested on substrates such as leather and paper and found to be suitable for dyeing. Ultrasound is also found to be beneficial in natural dyeing of leather with improved rate of exhaustion. Both the dyed substrates have better color values for ultrasonic beet extract as inferred from reflectance measurement. Therefore, the present study clearly offers efficient extraction methodology from natural dye resources such as beetroot with ultrasound even dispensing with external heating. Thereby, also making eco-friendly non-toxic dyeing of fibrous substances a potential viable option.     

Ultrasonic assisted dyeing: Dyeing of acrylic fabrics C.I. Astrazon Basic Red 5BL 200%

The dyeing of acrylic fabrics using C.I. Astrazon Basic Red 5BL 200% has been studied with both conventional and ultrasonic techniques. The effect of dye concentration, dye bath pH, ultrasonic power, dyeing time and temperature were studied and the resulting shades obtained by dyeing with both techniques were compared. Colour strength values obtained were found to be higher with ultrasonic than with conventional heating. The results of fastness properties of the dyed fabrics were studied. X-ray and Scanning Electron Microscope SEM were carried out on dyed samples using both methods of dyeing to find out an explanation for the better dyeability of acrylic fabrics with (US) method. Dyeing kinetics of acrylic fabrics using C.I. Astrazon Basic Red 5BL 200% using conventional and ultrasonic conditions were compared. The time/dye-uptake isotherms are revealing the enhanced dye-uptake in the second phase of dyeing. The values of dyeing rate constant, half-time of dyeing and standard affinity and ultrasonic efficiency have been calculated and discussed.     

Studies on the use of power ultrasound in leather dyeing

Uses of power ultrasound for acceleration/performing the chemical as well as physical processes are gaining importance. In conventional leather processing, the diffusion of chemicals through the pores of the skin/hide is achieved by the mechanical agitation caused by the paddle or drumming action. In this work, the use of power ultrasound in the dyeing of leather has been studied with the aim to improve the exhaustion of dye for a given processing time, to reduce the dyeing time and to improve the quality of dyed leather. The effect of power ultrasound in the dyeing of full chrome cow crust leather in a stationary condition is compared with dyeing in the absence of ultrasound as a control experiment both in a stationary as well as conventional drumming condition. An ultrasonic cleaner (150 W and 33 kHz) was used for the experiments. Actual power dissipated into the system was calculated from the calorimetric measurement. Experiments were carried out with variation in type of dye, amount of dye offer, temperature and time. The results show that there is a significant improvement in the percentage exhaustion of dye due to the presence of ultrasound, when compared to dyeing in absence of ultrasound. Experiments on equilibrium dye uptake carried out with or without ultrasound suggest that ultrasound help to improve the kinetics of leather dyeing. The results indicate that leathers dyed in presence of ultrasound have higher colour values, better dye penetration and fastness properties compared to control leathers. The physical testing results show that strength properties of the dyed leathers are not affected due to the application of ultrasound under the given process conditions. Apparent diffusion coefficient during the initial stage of dyeing process, both in presence and in absence of ultrasound was calculated. The values show that ultrasound helps in improving the apparent diffusion coefficient more for the difficult dyeing conditions such as in the case of metal-complex dyes having bigger aggregate size compared to less difficult dyeing conditions.     

Empirical rheological model for rough or grooved bonded interfaces

In the industrial sector, it is common to use metal/adhesive/metal structural bonds. The cohesion of such structures can be improved by preliminary chemical treatments (degreasing with solvents, alkaline, or acid pickling), electrochemical treatments (anodising), or mechanical treatments (abrasion, sandblasting, grooving) of the metallic plates. All these pretreatments create some asperities, ranging from roughnesses to grooves. On the other hand, in damage solid mechanics and in non-destructive testing, rheological models are used to measure the strength of bonded interfaces. However, these models do not take into account the interlocking of the adhesive in the porosities. Here, an empirical rheological model taking into account the interlocking effects is developed. This model depends on a characteristic parameter representing the average porosity along the interface, which considerably simplifies the corresponding stress and displacement jump conditions. The paper deals with the influence of this interface model on the ultrasonic guided modes of the structure.     

Polyester Fabric’s Fluorescent Dyeing in Supercritical Carbon Dioxide and its Fluorescence Imaging

As one of the most important coumarin-like dyes, disperse fluorescent Yellow 82 exhibits exceptionally large two-photon effects. Here, it was firstly introduced into the supercritical CO₂ dyeing polyester fabrics in this work. Results of the present work showed that the dyeing parameters such as the dyeing time, pressure and temperature had remarkable influences on the color strength of fabrics. The optimized dyeing condition in supercritical CO₂ dyeing has been proposed that the dyeing time was 60 min; the pressure was 25 MPa and the temperature was 120 °C. As a result, acceptable products were obtained with the wash and rub fastness rating at 5 or 4–5. The polyester fabrics dyed with fluorescent dyes can be satisfied for the requirement of manufacturing warning clothing. Importantly, the confocal microscopy imaging technology was successfully introduced into textile fields to observe the distribution and fluorescence intensity of disperse fluorescent Yellow 82 on polyester fabrics. As far as we know, this is the first report about supercritical CO₂ dyeing polyester fabrics based on disperse fluorescent dyes. It will be very helpful for the further design of new fluorescent functional dyes suitable for supercritical CO₂ dyeing technique.     

Ultrasonic washing of textiles

We present the results of experimental investigation of ultrasonic washing of textiles. The results demonstrate that cavitation bubbles oscillating in acoustic fields are capable of removing soils from textiles. Since the washing performance is mitigated in a large washing bath when using an ultrasonic transducer, we propose a novel washing scheme by combining the ultrasonic vibration with a conventional washing method utilizing kinetic energy of textiles. It is shown that the hybrid washing scheme achieves a markedly enhanced performance up to 15% in comparison with the conventional washing machine. This work can contribute to developing a novel laundry machine with reduced washing time and waste water.     

Measuring vibration characteristics at large amplitude region of materials for high power ultrasonic vibration system

This study proposes a method of estimating the mechanical quality factor of materials for high-power ultrasonic vibration systems under large vibration amplitude conditions. The quality factors of several metals as well as some polymers are measured by this method. In this method, the quality factor is calculated as the ratio of the reactive energy stored in a specimen to the dissipated energy. The dissipated energy is estimated from the input/output mechanical energy to the specimen by measurement of the vibration intensity, while the reactive energy is measured as the kinetic energy of the vibration. Then, the quality factor for the specified part can be extracted using this method. In this report, quality factors for torsional vibration were measured at about 30 kHz as functions of the vibration strain.     

Sono-leather technology with ultrasound: a boon for unit operations in leather processing - review of our research work at Central Leather Research Institute (CLRI), India

Ultrasound is a sound wave with a frequency above the human audible range of 16Hz to 16kHz. In recent years, numerous unit operations involving physical as well as chemical processes are reported to have been enhanced by ultrasonic irradiation. There have been benefits such as improvement in process efficiency, process time reduction, performing the processes under milder conditions and avoiding the use of some toxic chemicals to achieve cleaner processing. These could be a better way of augmentation for the processes as an advanced technique. The important point here is that ultrasonic irradiation is physical method activation rather than using chemical entities. Detailed studies have been made in the unit operations related to leather such as diffusion rate enhancement through porous leather matrix, cleaning, degreasing, tanning, dyeing, fatliquoring, oil-water emulsification process and solid-liquid tannin extraction from vegetable tanning materials as well as in precipitation reaction in wastewater treatment. The fundamental mechanism involved in these processes is ultrasonic cavitation in liquid media. In addition to this there also exist some process specific mechanisms for the enhancement of the processes. For instance, possible real-time reversible pore-size changes during ultrasound propagation through skin/leather matrix could be a reason for diffusion rate enhancement in leather processing as reported for the first time. Exhaustive scientific research work has been carried out in this area by our group working in Chemical Engineering Division of CLRI and most of these benefits have been proven with publications in valued peer-reviewed international journals. The overall results indicate that about 2-5-fold increase in the process efficiency due to ultrasound under the given process conditions for various unit operations with additional benefits. Scale-up studies are underway for converting these concepts in to a real viable larger scale operation. In the present paper, summary of our research findings from employing this technique in various unit operations such as cleaning, diffusion, emulsification, particle-size reduction, solid-liquid leaching (tannin and natural dye extraction) as well as precipitation has been presented.     

清末传世纺织品的材质鉴别和所用染料的微量分析

从早期纺织品保护的视角出发,通过对这一行业国内外大量文献资料梳理分析,对比了织物的常规系统分析方法,结合现代的科学技术方法,对早期纺织品的面料种类、所用染料种类以及染色工艺进行测定分析。面对目前服饰博物馆清末传世朱红女袄保藏面临的严峻考验,运用傅里叶变换红外光谱仪鉴定该纺织品的材质,以萃取法提取纺织品上的染料,用反射分光色度仪对提取前后的纺织品进行表面颜色分析,并用高压液相色谱和质谱对色素进行结构分析,尝试确定分析早期纺织品上染料的结构成分和上染方式。将现代分析技术（液质联用）和理念（色度学）融入传统研究中,使用客观科学技术获取更多有效数据和信息,佐证以主观目鉴方法得出的结论,弥补这一研究领域的空白,使对于传统服饰的研究更具深度。与传统的纺织品鉴别方法横向比较,现代的科学技术方法获得的相关信息更加详尽可靠。有利于根据不同染料特性和不同纤维种类特性提出具有针对性的保藏措施,对博物馆馆藏纺织品的保护和保存具有重要的意义。采用傅里叶变换红外仪对样品的面料进行简单分析,通过不同的特殊特征峰确定了样品为蚕丝面料。该研究建立了一种普遍适用的染料提取方法,采用丙酮、乙腈、吡啶：水（1∶1）、N,N-二甲基甲酰胺、0.1%乙二胺四乙酸水溶液/N,N-二甲基甲酰胺（1∶1）、甲醇六种不同的溶剂提取样品上的染料,采用反射分光光度仪对样品表面剥色前后的颜色进行色度测量分析。结果表明,吡啶的水溶液对染料具有最佳的提取效果;发现提取染料时加入少量乙二胺四乙酸,会提高剥色效率,即染色方式可能是媒染法,因为乙二胺四乙酸可以破坏染料和媒染金属离子间的络合作用。从染料提取前后织物的颜色变化可以推断样品的颜色可能是由染料拼色得到,利用液质联用技术（LC-MS）对提取的染料进行检测,根据染料上染方式和分子量推测分析,纺织品上染料可能含有小檗碱。经过标准小檗碱染料进行验证,进一步证明了染色纺织品上其中一种染料为小檗碱。     

Ultrasound-assisted soil washing processes using organic solvents for the remediation of PCBs-contaminated soils

Ultrasonic soil washing processes using organic solvents were investigated for the development of novel remediation technologies for persistent organic pollutants (POPs)- contaminated soils. Aluminum foil erosion was first tested to understand sonophysical activity in water, methanol (polar) and n-hexane (nonpolar) in a 28 kHz double-bath-type sonoreactor. Significant sonophysical damage on the aluminum foil was observed at the antinodes for all solvents, and the order of degree of sonophysical damage was as follows: water > methanol > n-hexane. Subsequently, conventional (mechanical mixing only) and ultrasonic soil washing (mechanical mixing and ultrasound) techniques were compared for the removal of polychlorinated biphenyls (PCBs) from soil. Two types of contaminated soils, fresh (Soil A, C₀ = 2.5 mg/kg) and weathered (Soil B, C₀ = 0.5 mg/kg), were used and the applied soil-to-liquid (S:L) ratio was 1:5 and 1:10 for methanol and n-hexane, respectively. The polar solvent significantly increased washing efficiencies compared to the nonpolar solvent, despite the nonpolar nature of the PCBs. Washing efficiency was significantly enhanced in ultrasonic soil washing compared to conventional washing, owing to macro- and micro-scale sonophysical actions. The highest washing efficiencies of 90% for Soil A and 70% for Soil B were observed in the ultrasonic washing processes using methanol. Additionally, a single operation of the ultrasonic washing process was superior to two sequential processes with conventional mixing in terms of washing efficiency, consumption of washing agents, treatment of washing leachate, and operation time. Finally, the removal of PCBs in an organic solvent (methanol) was investigated in photolytic and sonolytic processes for the post-treatment of soil washing leachate. A photolysis efficiency of 80% was obtained within 60 min of UV exposure for intensities of 1.0, 2.0, and 4.0 W/cm². The primary mechanism of PCBs degradation is photolytic dechlorination. In contrast, no degradation was detected in the sonolytic process, as the excess organic solvent acted as a strong radical scavenger.     

Ultrasound for low temperature dyeing of wool with acid dye

The possibility of reducing the temperature of conventional wool dyeing with an acid levelling dye using ultrasound was studied in order to reach exhaustion values comparable to those obtained with the standard procedure at 98 °C, obtaining dyed samples of good quality. The aim was to develop a laboratory method that could be transferred at industrial level, reducing both the energy consumption and fiber damage caused by the prolonged exposure to high temperature without the use of polluting auxiliary agents.Dyeings of wool fabrics were carried out in the temperature range between 60 °C and 80 °C using either mechanical or ultrasound agitation of the bath and coupling the two methods to compare the results. For each dyeing, the exhaustion curves of the dye bath were determined and the better results of dyeing kinetics were obtained with ultrasound coupled with mechanical stirring. Hence the corresponding half dyeing times, absorption rate constants according to Cegarra-Puente modified equation and ultrasonic efficiency were calculated in comparison with mechanical stirring alone. In the presence of ultrasound the absorption rate constants increased by at least 50%, at each temperature, confirming the synergic effect of sonication on the dyeing kinetics. Moreover the apparent activation energies were also evaluated and the positive effect of ultrasound was ascribed to the pre-exponential factor of the Arrhenius equation. It was also shown that the effect of ultrasound at 60 °C was just on the dye bath, practically unaffecting the wool fiber surface, as confirmed by the results of SEM analysis.Finally, fastness tests to rubbing and domestic laundering yielded good values for samples dyed in ultrasound assisted process even at the lower temperature. These results suggest the possibility, thanks to the use of ultrasound, to obtain a well equalized dyeing on wool working yet at 60 °C, a temperature process strongly lower than 98 °C, currently used in industry, which damages the mechanical properties of the fibers.     

Ultrasonic system for continuous washing of textiles in liquid layers

The use of ultrasonic energy for washing of textiles has been tried several times without achieving practical development. In fact, the softness of the fibres makes the cavitation to produce small erosion effect and the reticulate structure of the fabric favours the formation of air bubble layers which obstruct wave penetration. In addition, a high proportion of water with respect to the wash load and a certain water degassing is required to assure efficiency and homogeneity in the wash performance. Such requirements have hindered the commercial development of the ultrasonic washing machines for domestic purposes. For specific industrial applications, a great part of these limitations may be overcome. This article deals with a new process in which the fabric is exposed to the ultrasonic field in a flat format. Such process has been implemented at laboratory and at semi-industrial stage by using specially designed power ultrasonic transducers with rectangular plate radiators. The cleaning effect is produced by the intense cavitation field generated by the plate radiator within a thin layer of liquid where the fabric is introduced. The homogeneity of such effect is achieved by the successive exposure of all the fabric areas to the intense acoustic field. In this paper the structure and performance of the developed system are shown.     

Ultrasounds: an industrial solution to optimise costs, environmental requests and quality for textile finishing

Ultrasounds are widely used at industrial scale for cleaning of mechanical pieces for example. Potential applications exist for finishing of textiles. This work aimed to improve traditional textile finishing processes thanks to ultrasound. The technical objective was to develop specific applicators of ultrasonic energy which could be adapted on jigger, a widespread textile finishing machine. Laboratory studies have allowed to define the conditions for application of ultrasounds and check their effects on fibre structure, validated by trials in dynamic conditions. Ultrasound technology makes it possible to intensify the phenomena of diffusion and washing by the effect of cavitation and improves effectiveness of traditional washing treatments. Industrial ultrasound processes need further optimisation on industrial machines.