Vera Vivod

Cyclodextrins in Textile Finishing

Cyclodextrins can act as hosts and form inclusion compounds with various small molecules. Such complexes can be formed in solutions, in a solid state as well as when cyclodextrins are linked to various surfaces where they can act as permanent or temporary hosts for small molecules that provide certain desirable attributes. This characteristic makes cyclodextrin a promising reagent in textile finishing.

New findings about the lipase acetylation of nanofibrillated cellulose using acetic anhydride as acyl donor.

The acetylation efficiency of nanofibrillated cellulose (NFC) with acetic anhydride as acetyl donor was studied using lipase from Aspergillus niger in a mixture of dimethyl sulphoxide (DMSO) and phosphate buffer solution at ambient conditions and in supercritical carbon dioxide (scCO2). The chemical acetylation of NFC with comparable ester content was carried out for comparison. The ATR-FTIR, solid-state CP/MAS (13)C NMR and DSC analyses revealed that, besides the enzyme-catalysed acetylation, predominantly appearing at the C-6 position of cellulose hydroxyls, a strong and stable acyl-enzyme intermediate attachment also occurred on the NFC via Maillard reaction. Enzymatic acetylation via attached acyl-enzyme complex on NFC yielded high hydophobicity (contact angle of 84±9°), whereas the chemical acetylation with comparable ester content resulted in a much lower hydrophobic surface with a contact angle of 33±3°. Finally, the adsorption capacity profiles of lysozyme and BSA proteins on native, chemically and enzymatically acetylated NFC as a function of the pH medium were determined.

Enhanced catalytic activity of the surface modified TiO2-MWCNT nanocomposites under visible light.

Fusing multiwall carbon nanotubes (MWCNTs) with TiO2 at the nano-scale level promotes the separation of those electron-hole charges generated upon UV and daylight irradiation. In this study, we investigated facile sonochemical synthesis, combined with the calcination process for the preparations of TiO2-MWCNT composites with different mole ratios of titanium and carbon. In order to produce stable nano dispersions we exploited an innovative biotechnology-based approach for the covalent functionalizations of TiO2-MWCNTs with in-situ synthesized soluble phenoxazine dye molecules. The none and functionalized TiO2-MWCNTs composites were analyzed by a range of analytical techniques including XRD, Raman, XPS, SEM and UV-vis diffuse reflectance spectroscopy (DRS), and dynamic light scattering (DLS). The photocatalytic activity was evaluated toward the liquid-phase degradation of MB in aqueous solution under both UV and visible light irradiation. TiO2-MWCNTs with optimized mole ratio exhibit much higher photocatalytic activity and stability than bare TiO2. The as-prepared TiO2-MWCNTs photocatalyst possessed good adsorptivity of dyes, extended light absorption range and efficient charge separation properties simultaneously. The results indicated that the soluble phenoxazine dyes and amino-benzenesulfonic acid monomers were covalently grafted on to the surfaces of TiO2-MCNTs, which promoted good aquatic dispersibility and extended light absorption, resulting in increased photocatalytic efficiency.

Highly efficient film-like nanocellulose-based adsorbents for the removal of loose reactive dye during textile laundering:

Cellulose nanofibrils (CNFs) were surface functionalized with hexamethylenediamine (HMDA) and, further, integrated with native CNFs in various weight mass ratios to fabricate water-stable films by the solvent casting method, to be used for the removal of tri-chromatic and anionic black reactive dye with the highest bleeding effect in the very first minutes of textile laundering, and in a weight mass compared to a commercial color-catcher sheet (Delta Pronatura (DP)). The effects of CNF-HMDA content on film bath absorption, surface potential and contact angle properties, as well as dye removal kinetics from different laundering baths (A – without and B – with a detergent) in up to 140 min were studied at 20℃ versus 60℃ and using different dye concentrations (0.1–1 g/L). It was found that bath absorption is decreased significantly (up to 60%) by increasing the CNF-HMDA content in the films, as compared to using a DP color-catcher sheet, due to a morphologically denser structure with surface-positioned hydrophobic ethylene moieties of HMDA, as well as reducing electrostatic attraction groups of CNF and HMDA. Such a surface interacts kinetically faster with anionic and hydrophobic dye molecules already at 20℃, reaching up to 37–80% removal of all dye colorants in the first 20 min. In contrast, the dye removal efficacy of the DP color-catcher sheet is due to it interacting with a cationic polymer being released from the surface, which is better only for a bluish color, and at 60℃, while being between 30% and 48%, as its release is hindered and reduced by the deposition of surfactants from the detergent.

Biocompatible antimicrobial electrospun nanofibers functionalized with ε-poly-l-lysine

&NA; The antimicrobial polypeptide &egr;‐poly(L‐lysine) (&egr;‐PL) was electrostatically incorporated to poly(acrylic acid) (PAA)/poly(vinyl alcohol) (PVA) electrospun nanofibers. &egr;‐PL loading and distribution was assessed by infrared spectra, &zgr;‐potential measurements and the primary amino reactive dye fluorescamine. Functionalized fibers with 485 ± 140 nm diameter, could be loaded with 0.57–0.74 g &egr;‐PL (g dressing)−1 that released at a constant rate of 5.4 ± 2.8 mg &egr;‐PL (g dressing day)−1. Such a dressings resulted in two orders of magnitude lower bacterial colonization than non‐functionalized PAA‐PVA after 14 days of incubation. Bacterial impairment was attributed to the damage of cell membranes and the formation of intracellular reactive oxygen species. &egr;‐PL functionalized nanofibers did not display cytotoxicity to human corneal epithelial cells, HCEpC, in 24 h MTT assays. However, the viability of rapidly growing tumoral HeLa cells decreased >50% under the same conditions. The prepared biocompatible nanofibrous dressings with durable antibacterial activity show potential application as wound dressings and other biomedical uses.

Zeolite Integrated Nanocellulose Films for Removal of Loose Anionic Reactive Dye by Adsorption vs. Filtration Mode during Textile Laundering

Water stable, flexible and ecological acceptance composite films were prepared by the solvent casting process using native, dealuminated (treated with HCl to affect the surface chemistry and pore structure) and/or surface modified (coated with a cationic surfactant PDADM of different molecular weights) H-ZSM-5 type zeolite of different shapes (spherical vs. rod) and Si/Al ratios (P26 vs. P371) as adsorbents and cellulose nanofibrils (CNFs) as a networking matrix (in a weight ratio of 4:1). The films were tested for removal of the black anionic reactive dye with the highest bleeding effect at the first rinsing cycle of textile laundering. The effects of zeolite structure and surface chemistry on films dye’ removal kinetics from a standardised rinsing bath were investigated for up to 140 min at room temperature and using 0.1 g/l of dye concentration, depending on the film-to-bath weight-to-volume ratios (from 1:10 to 1:1000), thus simulating different rinsing conditions. The results show that up to 80 % of the dye was removed in the first 20 min in the lowest weight-to-volume ratio (1:10), fitting the Langmuir isotherm, and the process followed the pseudo-second order kinetic, yielding a multi-layer adsorption mechanism with a monolayer capacity of ~11 mg/g and ~21 vs. ~30 mg/g by films prepared from native or HCltreated and PDADMA100 vs. PDADMA400 coated P371 zeolites, respectively. Such efficacy was due to the more densely and fully surface-covered longitudinal P371 with PDADM400, given the huge electrostatic attraction sites for dye molecules, compared to the partly interpenetrated PDADM into relatively larger pore-sized (~450 nm vs. 220 nm) of P26. The filtration performance of the films was also examined, be used for the removal of the dye from the rinsing bath, released from the washing drum. An ultra-high flux rate (11.000 kL/m2 h MPa) with 45 % of dye removal efficacy and capacity of ~24 mg/g was provided by films prepared from spherical and aggregated P26PDADMA-400, showing its high potential also as a filter membrane.

Non-Formaldehyde Polyfunctional Crosslinking System for Cotton

Crosslinking of cotton with polycarboxylic acid, applied with catalysts based on phosphorus-containing inorganic acids, produces fabrics with excellent smooth-drying properties, which release no formaldehyde at any stage of preparation or on storage. If polycarboxylic acid has three or more carboxylic acid groups, the formation of such an anhydride can occur more than once and crosslinking of the cellulose molecule occurs. In our research work the use of an unsaturated bifunctional acid (maleic acid) and a phosphorus-containing inorganic compound (sodium hydroxyphosphinite) to obtain durable press finishing properties and flame retardant properties was studied.