Combined ultrasound-laccase assisted bleaching of cotton

This study evaluates the potential of using ultrasound to enhance the bleaching efficiency of laccase enzyme on cotton fabrics. Ultrasound of low intensity (7W) and relatively short reaction time (30 min) seems to act in a synergistic way with the enzyme in the oxidation/removal of the natural colouring matter of cotton. The increased bleaching effect could be attributed to improved diffusion of the enzyme from the liquid phase to the fibres surface and throughout the textile structure. On the other hand inactivation of the laccase occurred increasing the intensity of the ultrasound. However, at the ultrasound power applied in the bleaching experiments the loss of enzyme activity was not significant enough to justify the use stabilizer such as polyvinyl alcohol. Furthermore, the polyvinyl alcohol appears to be a substrate for the laccase.     

A review on textile sonoprocessing: A special focus on sonosynthesis of nanomaterials on textile substrates

The chemical and physical effects of ultrasound with a frequency above 16 kHz, higher than the audible frequency of the human ear, have proven to be a useful tool for variety of systems ranging from the application of ultrasound in environmental remediation to the cooperation of ultrasound waves with chemical processing regarding as sonochemistry. Ultrasound opened up new advances in textile wet processing including desizing, scouring, bleaching, dyeing, printing and finishing and also nanoprocessing including nanopretreatment, nanodyeing, nanoprinting and nanofinishing. Use of ultrasound appears to be a promising alternative technique to reduce energy, chemicals and time involved in various operations. Over the past years there has been an enormous effort on using sonochemistry for the synthesis of nanomaterials on various textile materials. In situ sonosynthesis of nanoparticles and nanocomposites on different textiles is a pioneering approach driving future investigations. With such wide range of applications and vast ever increasing publications, the objective of this paper is presenting a comprehensive review on ultrasound application in textile from early time to now by the main emphasis on the sonosynthesis of nanomaterials outlining directions toward future research.     

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.     

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.     

Establishing an ultrasound-assisted activated peroxide system for efficient and sustainable scouring-bleaching of cotton/spandex fabric

This study presents a high-efficient and cost-effective ultrasound-assisted strategy for one-bath one-step scouring and bleaching of cotton/spandex fabric using sodium percarbonate (SPC) and tetraacetylenediamine (TAED) couple. SPC plays both roles of pH regulator and H₂O₂ donor to initiate the peracetic acid (PAA) release from TAED. The significance and interaction effects of operating parameters (TAED concentration, temperature and time) on the WI (Whiteness Index) of fabrics were investigated through a central composite design. The bleaching mechanism was studied by exploring the relationship between WI and PAA and hydroxyl radical (HO·) concentrations. The mechanical and dyeing performances of treated fabrics were also evaluated. Results show that temperature exerted a significant impact on WI followed by TAED concentration and time. The PAA concentration decreased and HO· concentration increased upon the temperature rise. Both PAA and HO· were significant to upgrade WI and ultrasound was effective in enhancing their bleaching efficiency. The fabric treated only with 15 mmol/L TAED and 10 mmol/L SPC at 40 °C for 40 min under ultrasound could achieve a WI of 68.6 (43% higher than greige fabric), which was almost equivalent to that of the fabric treated at 60 °C without ultrasound. This verifies the contribution of ultrasound technology in reducing bleaching temperature for energy-saving purpose. Moreover, the treated fabric displayed less than 5% tensile strength loss, having a marginal impact on the apparel performance. The wettability of fabric was greatly improved leading to a good dyeing performance. Encouraging results demonstrate the high efficiency of the ultrasound-assisted pre-treatment process of cotton/spandex fabric, which contributes to the sustainable production of textiles.     

Using ultrasound technology for the inactivation and thermal sensitization of peroxidase in green coconut water

Green coconut water has unique nutritional and sensorial qualities. Despite the different technologies already studied, its enzymatic stability is still challenging. This study evaluated the use of ultrasound technology (US) for inactivating/sensitizing coconut water peroxidase (POD). The effect of both US application alone and as a pre-treatment to thermal processing was evaluated. The enzyme activity during US processing was reduced 27% after 30 min (286 W/L, 20 kHz), demonstrating its high resistance. The thermal inactivation was described by the Weibull model under non-isothermal conditions. The enzyme became sensitized to heat after US pre-treatment. Further, the use of US resulted in more uniform heat resistance. The results suggest that US is a good technology for sensitizing enzymes before thermal processing (even for an enzyme with high thermal resistance). Therefore, the use of this technology could decrease the undesirable effects of long times and/or the high temperatures of the conventional thermal processing.     

Ultrasound assisted intensification of biodiesel production using enzymatic interesterification

Ultrasound assisted intensification of synthesis of biodiesel from waste cooking oil using methyl acetate and immobilized lipase obtained from Thermomyces lanuginosus (Lipozyme TLIM) as a catalyst has been investigated in the present work. The reaction has also been investigated using the conventional approach based on stirring so as to establish the beneficial effects obtained due to the use of ultrasound. Effect of operating conditions such as reactant molar ratio (oil and methyl acetate), temperature and enzyme loading on the yield of biodiesel has been investigated. Optimum conditions for the conventional approach (without ultrasound) were established as reactant molar ratio of 1:12 (oil:methyl acetate), enzyme loading of 6% (w/v), temperature of 40 °C and reaction time of 24 h and under these conditions, 90.1% biodiesel yield was obtained. The optimum conditions for the ultrasound assisted approach were oil to methyl acetate molar ratio of 1:9, enzyme loading of 3% (w/v), and reaction time of 3 h and the biodiesel yield obtained under these conditions was 96.1%. Use of ultrasound resulted in significant reduction in the reaction time with higher yields and lower requirement of the enzyme loading. The obtained results have clearly established that ultrasound assisted interesterification was a fast and efficient approach for biodiesel production giving significant benefits, which can help in reducing the costs of production. Reusability studies for the enzyme were also performed but it was observed that reuse of the catalyst under the optimum experimental condition resulted in reduced enzyme activity and biodiesel yield.     

Ultrasonic pilot-scale reactor for enzymatic bleaching of cotton fabrics

The potential of ultrasound-assisted technology has been demonstrated by several laboratory scale studies. However, their successful industrial scaling-up is still a challenge due to the limited pilot and commercial sonochemical reactors. In this work, a pilot reactor for laccase-hydrogen peroxide cotton bleaching assisted by ultrasound was scaled-up. For this purpose, an existing dyeing machine was transformed and adapted by including piezoelectric ultrasonic devices. Laboratory experiments demonstrated that both low frequency, high power (22 kHz, 2100 W) and high frequency, low power ultrasounds (850 kHz, 400 W) were required to achieve satisfactory results. Standard half (4 g/L H₂O₂ at 90 °C for 60 min) and optical (8 g/L H₂O₂ at 103 °C for 40 min) cotton bleaching processes were used as references. Two sequential stages were established for cotton bleaching: (1) laccase pretreatment assisted by high frequency ultrasound (850 kHz, 400 W) and (2) bleaching using high power ultrasound (22 kHz, 2100 W). When compared with conventional methods, combined laccase-hydrogen peroxide cotton bleaching with ultrasound energy improved the whitening effectiveness. Subsequently, less energy (temperature) and chemicals (hydrogen peroxide) were needed for cotton bleaching thus resulting in costs reduction. This technology allowed the combination of enzyme and hydrogen peroxide treatment in a continuous process. The developed pilot-scale reactor offers an enhancement of the cotton bleaching process with lower environmental impact as well as a better performance of further finishing operations.     

Optimization of ultrasonic extraction of 23 elements from cotton

Optimization of ultrasonic extraction of 23 elements from cotton was performed with different solvent volume ratios. For this purpose nitric acid, hydrochloric acid and water were mixed and applied in a mixture for the extraction of elements adsorbed on cotton material. The elements chosen for the extraction procedure (Al, As, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, Sb, Si, Sn, Tl and Zn) were those that are important in textile processing. Some of them cause problems during fiber processing, dyeing or bleaching. The removal of elements from the processed fabric can be successfully done with ultrasonic extraction in the ultrasonic bath. Extraction procedure was optimized by software package Design Expert 6 (DX6) and the optimum of ultrasonic extraction was achieved with the mixture of 1M HCl-1M HNO(3)-H(2)O=3.32/2.83/93.85 (v/v). Ultrasonic extraction was a fast and efficient extraction procedure easily applied on cotton textile material.     

Ultrasound assisted three phase partitioning of a fibrinolytic enzyme

The present investigation is aimed at ultrasound assisted three phase partitioning (UATPP) of a fibrinolytic enzyme from Bacillus sphaericus MTCC 3672. Three phase partitioning integrates the concentration and partial purification step of downstream processing of a biomolecule. Three phase system is formed with simultaneous addition of ammonium sulfate to crude broth and followed by t-butanol. UATPP of a fibrinolytic enzyme was studied by varying different process parameters such as ammonium sulfate saturation concentration, pH, broth to t-butanol ratio, temperature, ultrasound frequency, ultrasonication power, and duty cycle. The optimized parameters yielding maximum purity of 16.15-fold of fibrinolytic enzyme with 65% recovery comprised of 80% ammonium sulfate saturation, pH 9, temperature 30 °C, broth to t-butanol ratio 0.5 (v/v), at 25 kHz frequency and 150 W ultrasonication power with 40% duty cycle for 5 min irradiation time. SDS PAGE analysis of partitioned enzyme shows partial purification with a molecular weight in the range of 55–70 kDa. Enhanced mass transfer of UATPP resulted in higher fold purity of fibrinolytic enzyme with reduced time of operation from 1 h to 5 min as compared to conventional TPP. Outcome of our findings highlighted the use of UATPP as an efficient biosepartion technique.     

Design parameter investigation of industrial size ultrasound textile treatment bath

Design requirements for industrial size ultrasound bath for textile treatments have been determined. For this purpose, effects of sound pressure level, bath temperature, bath volume, textile material type and hydrophility degree of fabric were examined extensively. Finite element analysis (FEA) was used to investigate spacing and alignment of the ultrasound source transducers to reach effective and homogenous acoustic pressure distribution in the bath. It was found that textile material type, bath temperature and volume led to significant changes at sound pressure level. These parameters should be taken into consideration in designing of industrial size ultrasound bath for textile treatments. Besides, wettability of textiles is highly dependent to the distance from the transducers.     

超声辐照对酶促反应影响的研究进展

综述了超声辐照对于酶活性和酶催化反应的影响,以及各种超声参数对反应的影响,并展望了超声辐照在酶促反应中的应用前景。     

Stability and decolourization ability of Trametes villosa laccase in liquid ultrasonic fields

We report in this study that the sonication of laccase from Trametes villosa and bovine serum albumin promotes the formation of protein aggregates with high molecular weight. The formation of aggregates leads to the deactivation of the enzyme, fact that was confirmed by the analysis of the enzyme stability (half-life time) upon ultrasound treatment. This inactivation was mainly caused by the radicals formed by the cavitation phenomenon. It was verified that the addition of polyvinyl alcohol to laccase had a protecting effect against enzyme inactivation. The performance of laccase in the decolourization of indigo carmine was studied. It was observed that the best results were attained when the dye solution was treated with ultrasound and enzyme stabilized with polyvinyl alcohol, where more than 65% of decolourization was achieved. This value is remarkably higher than that attained for the enzyme alone, which was only able to decolourize 20% of the dye solution within 1h of treatment. These results have important implications for the exploitation of sonication in textile industry, where the pollution caused by the release of dyes into effluents is one of the major concerns.     

Ultrasound assisted enzymatic conversion of non edible oil to methyl esters

Conventional and ultrasound-assisted hydrolysis and subsequent esterification of Nagchampa oil under mild operating conditions have been investigated with an objective of intensification of methyl esters production using a sustainable approach. The effect of ratio of reactants, temperature, enzyme loading, pretreatment of enzyme (using ultrasonic irradiations) on the hydrolysis and esterification reaction has been studied. Optimum conditions for hydrolysis were observed to be 1:1 weight ratio of oil: water for Lip Z and 1:3 for Lip 2 enzymes, enzyme loading of 400 units for Lip Z and 800 mg for Lip 2 enzymes and reaction time of 6 h. In the case of esterification reaction, optimum conditions obtained were oil to methanol molar ratio of 1:2, enzyme loading of 1000 mg and reaction time of 20 h. Use of pretreated enzyme (using ultrasonic irradiations) was found to increase the extent of esterification reaction from 75% to 92.5%. It was observed that use of ultrasound in the reaction significantly intensified the esterification reaction with time requirement reducing from 20 h for conventional stirring based approach to only about 7.5 h in the presence of ultrasound. The extent of esterification obtained with sonicated enzyme also increased to 96% from 75% with unsonicated enzyme.     

近红外技术在自然纺织纤维品种鉴别及成分预测上的应用

近红外光谱技术由于其检测方便、信息量大、无损等特性受到人们越来越多的关注,并且与化学计量学结合时能在一定程度上抵消其光谱峰重叠、信息弱等缺点。在纺织纤维的品种鉴别及化学性质鉴定方面,国家标准中较为常见的主要有电镜目测法及化学溶解法,但这些方法的测试周期长,测试步骤烦琐,不适宜大批量样本的分析,也不适用于在线检测。文章着重就近红外在自然纤维中的应用进行了综述,包括自然纺织纤维的品种鉴别、纤维内杂质检验以及生产过程中染料的鉴别等。     

基于近红外光谱和变量优选的棉麻混纺织物棉含量快速检测

纺织品纤维成分的快速检测对其生产过程质量监控、贸易和市场监督均具有重要的意义。利用近红外光谱技术联合变量优选对棉麻混纺织物中的棉含量进行快速检测研究。采用NIRFlex N-500型傅里叶近红外光谱仪在4 000～10 000 cm-1光谱范围内采集样本的反射光谱,对样本光谱进行范围初选和预处理分析。在此基础上,利用UVE(uninformative variables elimination),SPA(successive projections algorithm)及CARS (competitive adaptive reweighted sampling)方法对光谱变量进行优选,再应用PLS(partial least squares)建立棉麻混纺织物中的棉含量预测模型。最后,采用最优预测模型对未参与建模的样本进行预测。研究结果表明,4 052～8 000 cm-1光谱范围为棉含量较优的建模光谱范围。CARS变量选择方法能较为有效地提高预测模型的精度,CARS-PLS模型的校正集、预测集相关系数和均方根误差分别为0.903,0.749和8.01%,12.93%。因此,近红外光谱联合CARS变量优选可以用于棉麻混纺织物棉含量的快速检测,CARS方法可以有效简化预测模型,提高预测模型性能。     

Ultrasound assisted enzyme catalyzed hydrolysis of waste cooking oil under solvent free condition

The present work demonstrates the hydrolysis of waste cooking oil (WCO) under solvent free condition using commercial available immobilized lipase (Novozyme 435) under the influence of ultrasound irradiation. The process parameters were optimized using a sequence of experimental protocol to evaluate the effects of temperature, molar ratios of substrates, enzyme loading, duty cycle and ultrasound intensity. It has been observed that ultrasound-assisted lipase-catalyzed hydrolysis of WCO would be a promising alternative for conventional methods. A maximum conversion of 75.19% was obtained at mild operating parameters: molar ratio of oil to water (buffer pH 7) 3:1, catalyst loading of 1.25% (w/w), lower ultrasound power 100 W (ultrasound intensity – 7356.68 W m⁻²), duty cycle 50% and temperature (50 °C) in a relatively short reaction time (2 h). The activation energy and thermodynamic study shows that the hydrolysis reaction is more feasible when ultrasound is combined with mechanical agitation as compared with the ultrasound alone and simple conventional stirring technique. Application of ultrasound considerably reduced the reaction time as compared to conventional reaction. The successive use of the catalyst for repetitive cycles under the optimum experimental conditions resulted in a loss of enzymatic activity and also minimized the product conversion.     

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.     

Ultrasound induced green solvent extraction of oil from oleaginous seeds

Ultrasound-assisted extraction of rapeseed oil was investigated and compared with conventional extraction for energy efficiency, throughput time, extraction yield, cleanness, processing cost and product quality. A multivariate study enabled us to define optimal parameters (7.7 W/cm² for ultrasonic power intensity, 40 °C for processing temperature, and a solid/liquid ratio of 1/15) for ultrasound-assisted extraction of oil from oilseeds to maximize lipid yield while reducing solvent consumption and extraction time using response surface methodology (RSM) with a three-variable central composite design (CCD). A significant difference in oil quality was noted under the conditions of the initial ultrasound extraction, which was later avoided using ultrasound in the absence of oxygen. Three concepts of multistage cross-current extraction were investigated and compared: conventional multistage maceration, ultrasound-assisted maceration and a combination, to assess the positive impact of using ultrasound on the seed oil extraction process. The study concludes that ultrasound-assisted extraction of oil is likely to reduce both economic and ecological impacts of the process in the fat and oil industry.