Fabio Rombaldoni

Study of Methylene Blue adsorption on keratin nanofibrous membranes.

In this work, keratin nanofibrous membranes (mean diameter of about 220nm) were prepared by electrospinning and tested as adsorbents for Methylene Blue through batch adsorption tests. The adsorption capacity of the membranes was evaluated as a function of initial dye concentration, pH, adsorbent dosage, time and temperature. The adsorption capacity increased with increasing the initial dye concentration and pH, while it decreased with increasing the adsorbent dosage and temperature, indicating an exothermic process. The adsorption results indicated that the Langmuir isotherm fitted the experimental data better than the Freundlich and Temkin isotherm models. A mean free energy evaluated through the Dubinin-Radushkevich model of about 16kJmol(-1), indicated a chemisorption process which occurred by ion exchange. The kinetic data were found to fit the pseudo-second-order model better than the pseudo-first-order model. The obtained results suggest that keratin nanofibrous membranes could be promising candidates as dye adsorption filters.

Morphological and structural investigation of wool-derived keratin nanofibres crosslinked by thermal treatment

Mats of wool-derived keratin nanofibre have been prepared by electrospinning solutions of keratin in formic acid at 20 and 15 wt.%, and obtaining nanofibres with mean diameter of about 400 and 250 nm, respectively. These mats can find applications in tissue engineering (they can mimic the native extracellular matrix) and in wastewater treatment (they can trap small particles and adsorb heavy-metals). A drawback to overcome is their solubility in water. A stabilization method, based on a thermal treatment alternative to the use of formaldehyde, is proposed. The solubility test in the dithiothreitol/urea extraction buffer, the amino acid composition analysis and studies on keratin secondary structures suggest that the improved stability in water of thermally treated mats can be ascribed to the formation of amide bonds between acid and basic groups of some amino acid side chains.

Antibacterial efficacy of polypyrrole in textile applications

This paper describes application and evaluation of polypyrrole as an antibacterial polymer. Polypyrrole was produced embedding two doping agents: chloride and dicyclohexyl sulfosuccinate ions. Stability of the antibacterial efficacy of polypyrrole deposited on cotton fabrics was assessed before and after three different kinds of washing (namely, laundering with anionic and non-ionic detergents and dry-cleaning). Polypyrrole showed excellent antibacterial properties (100 % of bacterial reduction) against Escherichia coli for both doping agents. Treated fabrics were further characterised by scanning electron microscopy, energy dispersive X-ray analysis and infrared spectroscopy. The antibacterial efficacy diminished after launderings with anionic and non-ionic detergents because of two different mechanisms: the neutralisation of positive charges under alkali conditions (dedoping), and a partial removal of polypyrrole by abrasion and surfactant action. After dry-cleaning, polypyrrole embedding chloride and dicyclohexyl sulfosuccinate ions still showed excellent antibacterial efficacy. Moreover, scanning electron microscopy investigations were used to intuitively explain the bactericidal mechanism of polypyrrole on Escherichia coli bacteria.

Wool-derived keratin nanofiber membranes for dynamic adsorption of heavy-metal ions from aqueous solutions

Membranes made of randomly oriented wool-derived keratin nanofibers (∼240 nm mean diameter), were prepared by electrospinning process, and tested for the Cu(II), Ni(II), and Co(II) metal ion removal from aqueous solutions, through dynamic adsorption tests. The Cu(II) ion adsorption was studied from the isotherm and kinetic point of view, both in non-competitive and competitive conditions. As regards the non-competitive condition, the experimental data had a very good fit with both Langmuir and Freundlich isotherm models. The maximum adsorption capacity obtained from the Langmuir model was about 11 mg/g and the high correlation coefficient of the BET model indicates that the adsorption was a multilayer process. The mean free energy of adsorption, evaluated through the Dubinin–Radushkevich model, was 14.1 kJ/mol, indicating that the adsorption of Cu(II) ions on keratin nanofiber membranes occurred by ion exchange reactions. The process kinetics was evaluated by pseudo-first and pseudo-second order models, the latter showing the highest correlation with the experimental data. The competitive adsorption tests evidenced that the keratin nanofiber membranes maintained a good adsorption capacity for Cu(II) ions and also with the coexistence of Co(II) and Ni(II) metal cations. As regards the selectivity studies, the results showed that the adsorption of metal ions by keratin nanofiber membranes followed the order Cu(II) > Ni(II) > Co(II).

Multifunctional finishing of wool fabrics by chitosan UV-grafting: An approach

The aim of this study was the surface modification of wool fibers to confer a multifunctional finishing to the fabrics, improving the textile value and its applications without damage of comfort properties. The attention was focused on an economical and environmental friendly process to obtain an effective treatment with good durability to washing. Chitosan in acetic acid solution was applied by padding, and grafted by ultraviolet radiation, through radical reactions promoted by a photoinitiator. 2% chitosan grafted was enough to confer satisfactory antimicrobial activity (67% reduction of Escherichia coli) after an oxidative wool pre-treatment and 1h impregnation at 50 °C. Moreover treated wool fabrics showed a strong dyeability increase toward acid dye. However the evaluation of the treatment durability to laundering showed different behavior depending on the nature of the surfactants. Finally, anti-felting properties with respect to untreated fabrics were revealed, while no effect was shown toward anti-pilling properties.

Characterization of Plasma-coated Wool Fabrics

(Si : Ox : Cy : Hz) thin films were deposited on knitted wool fabrics by plasma-enhanced chemical-vapor deposition using hexamethyldisiloxane as a monomer and argon and oxygen as feed gases in low-pressure equipment. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed the presence of the siloxane coating. The pilling tendency of treated samples was investigated for different deposition powers, ranging from 30 to 50 W. A reduction on pill formation was observed for all treated samples. A silicone-based wet chemical treatment was taken as the reference method for pilling reduction and plasma treatments were compared with it. The pilling grade of treated fabrics was also tested after washing and the results confirmed a good pilling behavior of plasma-treated fabrics. Changes were observed in the bursting resistance of plasma-treated wool samples compared with untreated ones, while no significant differences were found in the whiteness index.

KES-F Characterization and Hand Evaluation of Oxygen Plasma-Treated Wool Fabrics Dyed at Temperature Below the Boil

In our previous works, we investigated the possibility of reducing the dyeing temperature of wool fabrics with oxygen low-temperature plasma pre-treatment. Fabrics were dyed replicating an industrial process on a laboratory-scale machine, and it was found that pre-treated fabrics could be dyed at 85°C with no worsening of their dyeing performances compared with fabrics conventionally dyed at the boil. In this work, the physical, low-stress mechanical and surface properties of untreated fabrics, untreated fabrics conventionally dyed at 98°C, and plasma-treated fabrics dyed at 85°C, were measured using Kawabata’s Evaluation System for Fabrics. In particular, there were significant increases in bending and shearing characteristic values for plasma-treated fabrics dyed below the boil (85°C). Moreover, subjective hand tests highlighted that these fabrics were stiffer and crisper than the other two types of fabric, thus confirming the results of objective measurements.

Effect of Carbon Dioxide Dry Cleaning on Low-stress Mechanical Properties, Air Permeability and Crease Pressing Performance of Men’s Suit Fabrics

Carbon dioxide (CO2) is becoming a promising alternative to perchloroethylene in dry cleaning. In this work, the effect of CO2 dry cleaning on some physical and mechanical properties of six different pure wool and wool/cashmere fabrics was investigated in order to detect any possible fabric modification. It was found that the CO2 dry cleaning process especially affected the thickness and compressional energy, making the fabrics thicker and fuller. A marked increase in shear hysteresis was detected, while no particular variations in bending and tensile properties or crease pressing performance were noted. Finally, there was a significant decrease in the air permeability of three of the six fabrics involved.