Ultrasound-assisted dyeing of cellulose acetate

The possibility of reducing the use of auxiliaries in conventional cellulose acetate dyeing with Disperse Red 50 using ultrasound technique was studied as an alternative to the standard procedure. Dyeing of cellulose acetate yarn was carried out by using either mechanical agitation alone, with and without auxiliaries, or coupling mechanical and ultrasound agitation in the bath where the temperature range was maintained between 60 and 80 °C.The best results of dyeing kinetics were obtained with ultrasound coupled with mechanical agitation without auxiliaries (90% of bath exhaustion value at 80 °C). Hence the corresponding half dyeing times, absorption rate constants according to Cegarra–Puente modified equation and ultrasound efficiency were calculated confirming the synergic effect of sonication on the dyeing kinetics. Moreover the apparent activation energies were also evaluated and the positive effect of ultrasound added to mechanical agitation was evidenced by the lower value (48 kJ/mol) in comparison with 112 and 169 kJ/mol for mechanical stirring alone with auxiliaries and without, respectively.Finally, the fastness tests gave good values for samples dyed with ultrasound technique even without auxiliaries. Moreover color measurements on dyed yarns showed that the color yield obtained by ultrasound-assisted dyeing at 80 °C of cellulose acetate without using additional chemicals into the dye bath reached the same value yielded by mechanical agitation, but with remarkably shorter time.     

Investigation into dyeing acceleration efficiency of ultrasound energy

The acceleration efficiency of ultrasound was investigated by different application of ultrasound during dyeing process in an ultrasound cleaner. Actual energy dissipated into the dyeing bath was measured to ensure the formation of ultrasound cavatiation. The experimental findings showed ultrasound pretreatment could improve slightly the dye exhaustion and fixation, but failed to improve fastness of dyed fabrics. Obvious enhancement effects on dye exhaustion and fixation were achieved in continuous and intermittent ultrasound dyeing processes, and slight improvement effects on some fastness properties of fabrics dyed in ultrasound fields were observed. A comparison of the efficiencies in two ultrasound dyeing processes revealed the dyeing process in intermittent ultrasound field would benefit to making full use of ultrasound energy.     

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.     

Ultrasonic dyeing of cationized cotton fabric with natural dye. Part 1: cationization of cotton using Solfix E

The dyeing of cationized cotton fabric with Solfix E using colouring matter extracted from Cochineal dye has been studied using both conventional and ultrasonic techniques. Factors affecting dye extraction such as ultrasound power, particle size, extraction temperature and time were studied. The results indicated that the extraction by ultrasound at 300 W was more effective at lower temperature and time than conventional extraction. The effect of various factors of dye bath such as pH, salt concentration, ultrasound power, dyeing time and temperature were investigated. The colour strength values obtained were found to be higher with ultrasound than with conventional techniques. The results of fastness properties of the dyed fabrics were fair to good. The scanning electron microscope (SEM) images of the morphological and X-ray analyzes were measured for cationized cotton fabrics dyed with both conventional and ultrasound methods, thus showing the sonicator efficiency.     

Influence of temperature variations on the entropy and correlation of the Grey-Level Co-occurrence Matrix from B-Mode images

In this work, the feasibility of texture parameters extracted from B-Mode images were explored in quantifying medium temperature variation. The goal is to understand how parameters obtained from the gray-level content can be used to improve the actual state-of-the-art methods for non-invasive temperature estimation (NITE). B-Mode images were collected from a tissue mimic phantom heated in a water bath. The phantom is a mixture of water, glycerin, agar-agar and graphite powder. This mixture aims to have similar acoustical properties to in vivo muscle. Images from the phantom were collected using an ultrasound system that has a mechanical sector transducer working at 3.5 MHz. Three temperature curves were collected, and variations between 27 and 44 °C during 60 min were allowed. Two parameters (correlation and entropy) were determined from Grey-Level Co-occurrence Matrix (GLCM) extracted from image, and then assessed for non-invasive temperature estimation. Entropy values were capable of identifying variations of 2.0 °C. Besides, it was possible to quantify variations from normal human body temperature (37 °C) to critical values, as 41 °C. In contrast, despite correlation parameter values (obtained from GLCM) presented a correlation coefficient of 0.84 with temperature variation, the high dispersion of values limited the temperature assessment.     

Development of copper coatings on ceramic powder by electroless technique

Electroless (EL) coating technique is one of the elegant ways of coating by controlling the temperature and pH of the coating bath in which there is no usage of electric current. EL nano-copper coating on ceramic particles of micron size is not reported. In this investigation, ceramic powders of ∼100 μm size have been coated with copper by EL technique in the pH and temperature ranges of 12-13.5 and 60-85 °C, respectively. The optimization of EL copper bath has been evaluated through the combination of process parameters like pH and temperature. The optimized value of pH is found to be 12.5 and temperature as 75 °C. The coated and uncoated powders have been subjected to microstructural studies by scanning electron microscope (SEM) and the phases present have been analyzed by X-ray diffraction. An attempt has been made to understand the bonding mechanism of coating. The adherence with the substrate is attributed to the chemical and mechanical bonding at the interface. A model has been suggested for the mechanical bonding effect at the interface.     

Improved mechanical properties of retorted carrots by ultrasonic pre-treatments

The use of ultrasound pre-processing treatment, compared to blanching, to enhance mechanical properties of non-starchy cell wall materials was investigated using carrot as an example. The mechanical properties of carrot tissues were measured by compression and tensile testing after the pre-processing treatment prior to and after retorting. Carrot samples ultrasound treated for 10 min at 60 °C provided a higher mechanical strength (P < 0.05) to the cell wall structure than blanching for the same time period. With the addition of 0.5% CaCl₂ in the pre-treatment solution, both blanching and ultrasound treatment showed synergistic effect on enhancing the mechanical properties of retorted carrot pieces. At a relatively short treatment time (10 min at 60 °C) with the use of 0.5% CaCl₂, ultrasound treatment achieved similar enhancement to the mechanical strength of retorted carrots to blanching for a much longer time period (i.e. 40 min). The mechanism involved appears to be related to the stress responses present in all living plant matter. However, there is a need to clarify the relative importance of the potential stress mechanisms in order to get a better understanding of the processing conditions likely to be most effective. The amount of ultrasound treatment required is likely to involve low treatment intensities and there are indications from the structural characterisation and mechanical property analyses that the plant cell wall tissues were more elastic than that accomplished using low temperature long time blanching.     

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.     

Ultrasound energy to accelerate dye uptake and dye–fiber interaction of reactive dye on knitted cotton fabric at low temperatures

Acoustic cavitation formed due to propagation of ultrasound wave inside a dye bath was successfully used to dye cotton fabric with a reactive dye at lower temperatures. The energy input to the system during sonication was 0.7 W/cm². This was within the energy range that contributes towards forming cavitation during ultra-sonication. The influence of ultrasound treatment on dye particle size and fiber morphology is discussed. Particle size analysis of the dye bath revealed ultra-sonication energy was capable of de-agglomeration of hydrolyzed dye molecules during dyeing. SEM micrograph and AFM topographical image of the fiber surface revealed fiber morphology remains unchanged after the sonication. The study was extended in understanding the contribution of ultrasound method of dyeing towards achieving good color strength on the fabric, compared to the normal heating method of dyeing. Study showed color strength obtained using ultra sound method of dyeing is higher compared to normal heating dyeing. Ultrasound energy was able to achieve the good color strength on cotton fabric at very low temperature such as 30 °C, which was approximately 230% more than the color strength achieved in normal heating method of dyeing. This indicates that energy input to the system using ultrasound was capable of acting as an effective alternative method of dyeing knitted cotton fabrics with reactive dye.     

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.     

Effects of ultrasonic energy on dyeing of polyamide (microfibre)/Lycra blends

Although ultrasonic energy is widely used cleaning and degreasing of parts and assemblies in automotive and other industries, the use of ultrasonic energy in an industrial scale for textile washing is very new. This is due to the complexity of controlling the combination of chemical and mechanical effects, whereas with degreasing of machine parts only the mechanical effects is applied. The use of ultrasonic energy in dyeing PA/Lycra fabrics with reactive dyes has been studied spectrophotometrically in this work. PA/Lycra (85/15) blends have been dyed using conventional and ultrasonic dyeing techniques with three reactive dyes containing different chromophore and reactive groups. The dyeing carried out conventionally and by the use of ultrasonic techniques. The results were compared in terms of percentage exhaustion; total dye transferred to the washing bath after dyeing and the fastness properties.     

Palm oil hydrolysis catalyzed by lipases under ultrasound irradiation--the use of experimental design as a tool for variables evaluation

Diacylglycerol oil has been increasingly recognized by its good nutritional properties and therefore, different technologies have been developed for obtaining it. The present work focuses on the diacylglycerol production by hydrolysis reaction of the palm oil using the PS IM and TL IM commercial lipases as biocatalysts under ultrasound irradiation. An experimental design (central composite rotatable design - CCRD) adopting surface response was applied as a tool to evaluate the optimal reaction conditions beyond a restrict number of experiments. Reactions were performed in an ultrasound equipment and different variables were investigated, such as temperature (30-55 °C), enzyme content (1-2 wt.% of oil mass), mechanical stirring (300-700 rpm) and reaction time. Both, PS IM and TL IM enzymes showed the best results after 1 h and 30 min of reaction under 30 °C and, applying 300 rpm as stirring. On these conditions, the diacylglycerol yield was around 34% and 39%, respectively; considering that 1% PS IM was applied for the first one and, 2% TL IM for the second one. Therefore, it was obtained good yield of a diacylglycerol-rich oil in shorter reaction times under sonication and soft conditions. The mathematic model proposed suggested a satisfactorily representation of the process and good correlation among the experimental results and the theoretical values predicted by the model equation were achieved.     

Ultrasonic preparation of cationic cotton and its application in ultrasonic natural dyeing

Cationization of cotton fabric was conferred by the sonicator reaction of cellulose with bromoacetyl bromide, followed by substitution of the terminal bromo groups by triethylamine. Experiments showed that the optimal volume of bromoacetyl bromide necessary to succeed the first stage was 0.4 mL. The order of weight gain for various processes indicates, ultrasound, 25 kHz > ultrasound, 40 kHz > mechanical stirring. Also, for the second stage the order of nitrogen contents indicates ultrasound, 25 kHz > ultrasound, 40 kHz > mechanical stirring. The structures of both untreated and cationic fibres were investigated by FTIR spectroscopy. Modified cotton fabric was subsequently dyed in both conventional and ultrasonic techniques with isosalipurposide dye isolated from Acacia cyanophylla yellow flowers. The effect of dye bath pH, ultrasonic power and frequency, dyeing time and temperature were studied and the order of K/S values indicates ultrasound, 25 kHz > ultrasound, 40 kHz > CH. ultrasound was also found to enhance the dye uptake and the overall fastness properties. Analysis of the sorption isotherms of isosalipurposide dye on cationic cotton fabric shows that the Languimir isotherm equation is best able to correlate the data.     

Investigation of the effect of power ultrasound on the nucleation of water during freezing of agar gel samples in tubing vials

Nucleation, as an important stage of freezing process, can be induced by the irradiation of power ultrasound. In this study, the effect of irradiation temperature (−2 °C, −3 °C, −4 °C and −5 °C), irradiation duration (0 s, 1 s, 3 s, 5 s, 10 s or 15 s) and ultrasound intensity (0.07 W cm⁻², 0.14 W cm⁻², 0.25 W cm⁻², 0.35 W cm⁻² and 0.42 W cm⁻²) on the dynamic nucleation of ice in agar gel samples was studied. The samples were frozen in an ethylene glycol-water mixture (−20 °C) in an ultrasonic bath system after putting them into tubing vials. Results indicated that ultrasound irradiation is able to initiate nucleation at different supercooled temperatures (from −5 °C to −2 °C) in agar gel if optimum intensity and duration of ultrasound were chosen. Evaluation of the effect of 0.25 W cm⁻² ultrasound intensity and different durations of ultrasound application on agar gels showed that 1 s was not long enough to induce nucleation, 3 s induced the nucleation repeatedly but longer irradiation durations resulted in the generation of heat and therefore nucleation was postponed. Investigation of the effect of ultrasound intensity revealed that higher intensities of ultrasound were effective when a shorter period of irradiation was used, while lower intensities only resulted in nucleation when a longer irradiation time was applied. In addition to this, higher intensities were not effective at longer irradiation times due to the heat generated in the samples by the heating effect of ultrasound. In conclusion, the use of ultrasound as a means to control the crystallization process offers promising application in freezing of solid foods, however, optimum conditions should be selected.     

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.     

The effect of deposition temperature on the surface coverage and morphology of iron-phosphate coatings on low carbon steel

The influence of deposition temperature and concentration of NaNO₂ in the phosphating bath on the surface morphology and coverage of iron-phosphate coatings on low carbon steel was investigated. The phosphate coatings were chemically deposited on steel from phosphate bath at different temperatures (30-70 °C) and with the addition of different amounts of accelerator, NaNO₂ (0.1, 0.5 and 1.0 g dm⁻³). The morphology of phosphate coatings was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The composition of iron-phosphate coatings was determined using energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Surface coverage was evaluated by the voltammetric anodic dissolution (VAD) technique.It was shown that the increase in temperature of the NaNO₂-free phosphating bath up to 70 °C caused an increase in surface coverage. The addition of NaNO₂ in the phosphating bath significantly increased the surface coverage of phosphate coatings deposited at temperatures lower than 50 °C. The phosphate crystals were of laminated and needle-like structures for deposits obtained at temperatures lower than 50 °C, while at higher temperatures needle-like structure was transformed to laminated structure. The increase in NaNO₂ concentration in the phosphating bath from 0.1 to 1.0 g dm⁻³ did not significantly increase the surface coverage, but decreased the crystals size, consequently favouring the phosphate nucleation and better packing of the crystals.     

Ultrasound assisted copolymerization of acrylonitrile with N-amino phenyl maleimides and N-amino phenyl 2,3 dimethyl maleimides

The N-amino phenyl maleimide (N-APhM) and N-amino phenyl 2,3 dimethyl maleimide (N-APhDiMeM) derivatives were prepared by the condensation of phenyl hydrazine with maleic anhydride and 2,3 dimethyl maleic anhydride respectively. (13)C NMR spectroscopy proved the formation of the symmetric amino maleimide structure and not the pyridazinone or aminoisomaleimides. The copolymerization of acrylonitrile with the (N-APhM) and (N-APhDiMeM) were prepared using ultrasound. The thermal behavior of the prepared copolymers, under nitrogen atmosphere, was investigated using thermogravimetry (TG) techniques. The dyeing of the copolymers formed has been studied using both conventional and ultrasonic techniques. The effect of dye bath pH, ultrasonic power, dyeing time and temperature were studied. Color strength values obtained were found to be higher using ultrasound than with conventional heating. The results of fastness properties of the dyed copolymers were also studied.     

A novel polyol method to synthesize colloidal silver nanoparticles by ultrasonic irradiation

A polyol synthesis of silver nanoparticles in the presence of ultrasonic irradiation was compared with other configurations (at ambient temperature, 120 °C, and 120 °C with injected solutions) in the absence of ultrasonic irradiation in order to obtain systematic results for morphology and size distribution. For applying ultrasonic irradiation, rather fine and uniform spherical silver particles (21 ± 3.7 nm) were obtained in a simple (at ambient temperature without mechanical stirring) and fast (within 4 min, 3.61 × 10⁻³ mol min⁻¹) manner than other cases (at ambient temperature (for 8 h, 0.03 × 10⁻³ mol min⁻¹): 86 ± 16.8 nm, 120 °C (for 12 min, 1.16 × 10⁻³ mol min⁻¹): 64 ± 14.9 nm, and 120 °C with injected solutions (during 12 min): 35 ± 6.8 nm; all other cases contained anisotropic shaped particles). Even though the temperature of polyol reaction reached only at 80 °C (<120 °C) in the presence of ultrasonic irradiation, a uniform mixing (i.e. enhanced collision between silver particle and surrounding components) by ultrasonic irradiation might induce a better formation kinetics and morphological uniformity.     

Ultrasound-assisted lipase-catalyzed transesterification of soybean oil in organic solvent system

This work reports the transesterification of soybean oil with ethanol using two commercial immobilized lipases under the influence of ultrasound irradiation. The experiments were performed in an ultrasonic water bath, following a sequence of experimental designs to assess the effects of temperature, enzyme and water concentrations, oil to ethanol molar ratio and output irradiation power on the reaction yield. Results show that ultrasound-assisted lipase-catalyzed transesterification of soybean oil with ethanol might be a potential alternative route to conventional alkali-catalyzed method, as high reaction yields (∼90 wt.%) were obtained at mild irradiation power supply (∼100 W), and temperature (60 °C) in a relatively short reaction time, 4 h, using Lipozyme RM IM as catalyst. The repeated use of the catalyst under the optimum experimental condition resulted in a decay in both enzyme activity and product conversion after two cycles. The use of Novozym 435 led to lower conversions (about 57%) but the enzyme activity was stable after eight cycles of use, showing, however, a reduction in product conversion after the forth cycle.     

Molecular interaction of oxazine dyes in aqueous solution: Temperature dependent molecular disposition of the aggregates

Temperature dependent molecular interaction of oxazine dyes, viz., brilliant cresyl blue (C.I. Basic dye), cresyl violet (C.I. Basic violet 3) and nile blue (C.I. Basic blue 12) are studied in aqueous media within a concentration range of 5.0 × 10^− 6 M to 8.0 × 10^− 4 M by UV-visible absorption spectroscopy. The effect of temperature on the geometrical structure of the dimer in solution along with the dimerization equilibria is explained in terms of electrostatic and hydrophobic interactions. Modified non-covalent interaction between two monomer molecules in a dimer as a function of temperature affects the extinction coefficient as well as the geometrical disposition of the dimers and this is well manifested in the exciton splitting of the dimer spectra. The angle θ between main oscillators of the two monomer molecules in a dimer increases by 1.94° for brilliant cresyl blue, whereas an increase of 4.32° and 1.73° were observed for cresyl violet and nile blue respectively due to the increase of temperature from 20 °C to 60 °C.