Use of the ultrasonic cavitation in wool dyeing process: Effect of the dye-bath temperature.

The present work aims to study the effect of the liquid temperature on the performance of ultrasounds (US) in a dyeing process. The approach was both theoretical and experimental. In the theoretical part the simplified model of a single bubble implosion is used to demonstrate that the "maximum implosion pressure" calculated with the well known Rayleigh-Plesset equation for a single bubble can be correlated with the cavitation intensity experimentally measured with an Ultrasonic Energy Meter (by PPB Megasonics). In particular the model was used to study the influence of the fluid temperature on the cavitation intensity. The "relative" theoretical data calculated from the implosion pressure were satisfactorily correlated with the experimental ones and evidence a zone, between 50 and 60°C, were the cavitation intensity is almost constant and still sufficiently high. Hence an experimental part of wool dyeing was carried out both to validate the previous results and to verify the dyeing quality at low temperatures (40-70°C) in presence of US. A prototype dyeing equipment able to treat textile samples with US system of 600W power, was used. The dyeing performances in the presence and absence of US were verified by measuring ΔE (colour variation), Re,% (reflectance percentage), K/S (colour strength) and colour fastness. The US tests performed in the temperature range of 40-70°C were compared with the conventional wool dyeing at 98°C. The obtained results show that a temperature close to 60°C should be chosen as the recommended US dyeing condition, being a compromise between the cavitation intensity and the kinetics which rules the dyestuff diffusion within the fibres.

Mapping of cavitational activity in a pilot plant dyeing equipment.

A large number of papers of the literature quote dyeing intensification based on the application of ultrasound (US) in the dyeing liquor. Mass transfer mechanisms are described and quantified, nevertheless these experimental results in general refer to small laboratory apparatuses with a capacity of a few hundred millilitres and extremely high volumetric energy intensity. With the strategy of overcoming the scale-up inaccuracy consequent to the technological application of ultrasounds, a dyeing pilot-plant prototype of suitable liquor capacity (about 40 L) and properly simulating several liquor to textile hydraulic relationships was designed by including US transducers with different geometries. Optimal dyeing may be obtained by optimising the distance between transducer and textile material, the liquid height being a non-negligible operating parameter. Hence, mapping the cavitation energy in the machinery is expected to provide basic data on the intensity and distribution of the ultrasonic field in the aqueous liquor. A flat ultrasonic transducer (absorbed electrical power of 600 W), equipped with eight devices emitting at 25 kHz, was mounted horizontally at the equipment bottom. Considering industrial scale dyeing, liquor and textile substrate are reciprocally displaced to achieve a uniform colouration. In this technology a non uniform US field could affect the dyeing evenness to a large extent; hence, mapping the cavitation energy distribution in the machinery is expected to provide fundamental data and define optimal operating conditions. Local values of the cavitation intensity were recorded by using a carefully calibrated Ultrasonic Energy Meter, which is able to measure the power per unit surface generated by the cavitation implosion of bubbles. More than 200 measurements were recorded to define the map at each horizontal plane positioned at a different distance from the US transducer; tap water was heated at the same temperature used for dyeing tests (60°C). Different liquid flow rates were tested to investigate the effect of the hydrodynamics characterising the equipment. The mapping of the cavitation intensity in the pilot-plant machinery was performed to achieve with the following goals: (a) to evaluate the influence of turbulence on the cavitation intensity, and (b) to determine the optimal distance from the ultrasound device at which a fabric should be positioned, this parameter being a compromise between the cavitation intensity (higher next to the transducer) and the US field uniformity (achieved at some distance from this device). By carrying out dyeing tests of wool fabrics in the prototype unit, consistent results were confirmed by comparison with the mapping of cavitation intensity.

Washing off intensification of cotton and wool fabrics by ultrasounds.

Wet textile washing processes were set up for wool and cotton fabrics to evaluate the potential of ultrasound transducers (US) in improving dirt removal. The samples were contaminated with an emulsion of carbon soot in vegetable oil and aged for three hours in fan oven. Before washing, the fabrics were soaked for 3 min in a standard detergent solution and subsequently washed in a water bath. The dirt removal was evaluated through colorimetric measurements. The total color differences ΔE of the samples were measured with respect to an uncontaminated fabric, before and after each washing cycle. The percentage of ΔE variation obtained was calculated and correlated to the dirt removal. The results showed that the US transducers enhanced the dirt removal and temperature was the parameter most influencing the US efficiency on the cleaning process. Better results were obtained at a lower process temperature.

Mutagenic activity of isoxazolylnaphthoquinoneimines assayed by micronucleus bone marrow test.

Studies were undertaken to evaluate the ability of various quinoneimines to induce micronuclei in bone marrow cells as a measure of their genotoxicity. Accordingly, 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (I), its 2-acetyl derivative (II) and 2-[(5-methyl-3-isoxazolyl)amino]-N-(5-methyl-3-isoxazolyl)-1 ,4- naphthoquinone-4-imine (III), as well as two of their precursors, 2-hydroxynaphthoquinone (NQ-2-OH) and 3,4-dimethyl-5-aminoisoxazole (DMAI) were given by intraperitoneal injection at 5, 50, 100 and 200 mg/Kg doses to S.J.L. Swiss mice with 24 h sampling time. Compounds I and II displayed highly significant differences at 50, 100 and 200 mg/kg doses (p < 0.01) and their mutagenic dose response curves correlated closely with an inverted U-shaped form whose interpretation is still the subject of controversy. NQ-2-OH only produced a significant increase in micronucleus frequency at 50 mg/kg, whereas no mutagenic activity was found for compound III and DMAI at the doses assayed. At 50 mg/kg the order of relative mutagenic potencies was I > II > NQ-2-OH. Mechanisms advanced to explain loss of drug activity at high doses include capture saturation, enzymatic induction during metabolism and participation of an independent defense system.

Mutagenic and analgesic activities of aniline derivatives.

Phenacetin (1), acetaminophen (2), acetanilide (3), 4-aminophenol (4), and aniline (5) were tested in S.J.L. Swiss mice for their mutagenic and analgesic activities. The S-analogues of 1 and 2, 4-mercaptoacetanilide (6) and 4-ethylthioacetanilide (7), respectively, were synthesized and tested in the same way to define if both activities could be separated by molecular modification. All the compounds tested exhibited analgesic activity with ED50 values ranging from 12.6 to 158.5 mg/kg. The compounds could be arranged in a decreasing order of analgesic activity as follows: 3 greater than 4 congruent to 5 congruent to 6 greater than 1 congruent to 7 greater than 2. All the compounds, except 6, were positive mutagens in the micronucleus test (statistically significant). The order of relative mutagenic potencies was 1 congruent to 7 greater than 4 greater than 2 congruent to 3 congruent to 5. A narrow dose-response curve relationship was found for 5 and its metabolite 4, the relative mutagenic potencies of which suggest ring hydroxylation as the major pathway of biotoxification. No parallelism was found between analgesic and mutagenic activities, so they could be separated by pharmacomodulation: 6 was more effective as an analgesic in the acetic acid test than 2, and no mutagenic activity was found at the doses assayed.

Studies on antimicrobial agents. 1. Synthesis and relation between the antimicrobial activities and certain physicochemical properties of some N'-(pyridinoacetyl) fatty acid hydrazides.

A new series of N'-(pyridinioacetyl)alkanoic and -benzoic acid hydrazides, as chloride salts, and some cyclic analogues produced ring closure have been synthesize and tested in a search for more effective germicides. Physicochemical parameters, such as surface tension, critical micelle concentration, and thermodynamic activity. (Ferguson values), were also determined. Staphylococcus aureus and Streptococcus pyogenes were the most susceptible of the organisms tested. N'-(Pyridinoacetyl)hexadecanoic acid hydrazide exhibited the highest toxicity to Staph. aureus and fungi. The mean surface tension of the equitoxic solutions is 59.8 +/- 0.3 dyn/cm for bacteria and 51.65 +/- 0.1 dyn/cm for fungi. N'-(Pyridinoacetyl)octadecanoic acid hydrazide and N'-(pyridinoacetyl)-9-ocadecenoic acid hydrazide exhibit the highest toxicity to S. pyogenes (1.1 x 10(-6) M). The surface tension of their equitoxic solutions and their Ferguson values indicate that these compounds may act through a different mechanism.