► Ultrasonic assisted dyeing of wool with an acid dye was studied at 60–80
°C. ► Dyeing kinetics with mechanical stirring, ultrasound and both were compared. ► Ultrasound increased the absorption ...rate constants by at least 50%. ► Fastness tests yielded good values for samples dyed with ultrasound even at 60
°C.
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 assisted dyeing of cellulose acetate with disperse dye was studied at 60–80°C.•Stirring with and without auxiliaries were compared with stirring coupled with ultrasound.•Ultrasound ...increased absorption rates and yielded 90% bath exhaustion in 90min at 80°C.•Fastness tests and color yields were good for samples dyed with ultrasound even without auxiliaries.
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 (48kJ/mol) in comparison with 112 and 169kJ/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.
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•Graphene oxide were used as nanoplatelets into UV-curable epoxy resin.•Cationic UV–curing was performed for the different formulations.•A clear enhancement of the water vapor ...transmission rate was measured for composites coatings.
In this paper we investigated the improvement of water-vapor barrier properties of an UV-cured epoxy film containing graphite oxide nanoplatelets. Graphene platelets were successfully dispersed in the epoxy resin and cured by UV-irradiation. Good performances in increasing water vapor barrier properties at a very low filler loading are obtained: the permeability decreased of about 40% with a 0.5wt.% of GOx and of about 60% with a 1.0wt.% of GOx. These good results are attributed to a homogeneous filler dispersion, as clearly shown by TEM microscopy.
Greasy raw wool, as sheared, was proposed as natural, cost effective adsorbent material for oil recovery and remediation of marine surface contaminated by oil spills. In this way, an effective ...cleaning of sea surface can be coupled with the revaluation of a sheep breeding waste, suitable for the purpose thanks to its oilphilic behaviour. A characterization of wools of different origin was carried out by sorption test of IFO 380 oil, either pure or mixed with Diesel, layered on a water surface. The wool has been characterized in terms of humidity, lipids, adherent and not adherent dirt while viscosity, density and surface tension were evaluated for the different oil mixes. Preliminary tests on the process efficiency, performed with reduced volumes of water and oil in a static system, assessed the sorption kinetics, the yield of the process for fresh wool and the number of sorption- regeneration cycles at which the wool can be submitted without reduction of the original adsorption properties. The obtained results were used to set a scaled up series of tests, on a pilot prototype, suitable for reproduce the real recovery conditions of a ship on the sea. The possible destination of the exhausted wool was also taken into account. The obtained results suggest that wool wastes can be a suitable sorbent material for spilled oil recovery on marine surfaces, with performance that are competitive with the materials of synthetic origin proposed for similar applications.
Wastewater effluents from textile industry mainly contain dyes used in the dyeing or printing of textiles yarns or fabrics. A lot of technologies can be adopted for dye removal from wastewaters, ...including biological treatments based on activated sludge, adsorption on activated carbon, or membrane processes. Nevertheless, none of these methods is performing toward all classes of dyes; treatment plants of great dimensions and difficult handling can be required, while costs can be prohibitive. In a previous work we cationized cotton obtaining a strong improvement of dyes adsorption. In the present work, a cotton fabric was more eco-friendly functionalized by chitosan UV grafting and used as dyes adsorbent. The process parameters for the fabric treatment were optimized in terms of chitosan add-on, impregnation time, temperature, pH, radiation time and curing intensity. The cotton grafted by chitosan was characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared analysis in Attenuated Total Reflection (FTIR-ATR) and X-ray Photoelectron Spectroscopy (XPS). The material was then tested towards different dye classes: acid, reactive and direct dyes. Batch, kinetic as well as continuous flow assessment tests were carried out, evaluating the adsorption capacity by spectrophotometric measurements. Moreover the influence of pH as well as temperature on the adsorbent capacity of the functionalized cotton were investigated. The material showed good adsorption capacity and very high adsorption rate toward all the investigated dyes. Moreover, by assembling the functionalized cotton in a filter form, good adsorption capacity is ensured even at 25 °C, with good behaviour in terms of filter exhaustion and pressure drop while a positive influence on adsorption capacity was displayed in acid conditions. Finally, regeneration tests by NaOH solution were carried out, with a good release of the adsorbed dye. In conclusion, obtained results show good perspectives for chitosan treated cotton use in wastewater filtration.
Communicable diseases can be transmitted by contaminated water and water decontamination process is fundamental to eliminate micro-organisms. In this work, cotton gauzes were coated with chitosan, ...using an UV-curing process, or cationized by introduction of quaternary ammonium groups and tested, in static and dynamic conditions, as water filter for biological disinfection against both Gram-negative and Gram- positive bacteria. With both treatments 100% microorganisms reduction was reached in static assessment, while in dynamic conditions better results were obtained by chitosan treated gauze, reaching 100% S.Aureus and K. Pneumoniae reduction with 4 s and 8 s contact time respectively. This substrate could be a good candidate for application as biological filter.
A class of metal-doped polyanilines (PANIs) was synthesized and investigated as electrocatalysts for the carbon dioxide reduction reaction (CO
2
RR). These materials show good affinity for the ...electrode substrate and allow to obtain stable binder-free electrodes, avoiding the utilization of expensive ionomer and additives. The emeraldine-base polyaniline (EB-PANI), in absence of metal dopant, shows negligible electrocatalytic activity and selectivity toward the CO
2
RR. Such behavior significantly improves once EB-PANI is doped with an appropriate cationic metal (Mn, Cu or Sn). In particular, the Sn-PANI outperforms other metal-doped samples, showing a good turnover frequency of 72.2 h
−1
for the CO
2
RR at − 0.99 V vs the reversible hydrogen electrode and thus satisfactory activity of metal single atoms. Moreover, the Sn-PANI also displays impressive stability with a 100% retention of the CO
2
RR selectivity and an enhanced current density of 4.0 mA cm
−2
in a 10-h test. PANI, a relatively low-cost substrate, demonstrates to be easily complexed with different metal cations and thus shows high tailorability. Complexing metal with conductive polymer represents an emerging strategy to realize active and stable metal single-atom catalysts, allowing efficient utilization of metals, especially the raw and precious ones.
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