Halochromic (pH-responsive) material was obtained by dyeing functionalized viscose fabric with a crude extract from
Streptomyces sp
. strain NP4. The functionalization of the fabric before dyeing was ...performed to make cellulose susceptible to coloration with NP4 extract. Two combined pre-treatment steps were used, oxidation to obtain dialdehyde cellulose and chitosan deposition after oxidation. Chitosan was deposited onto untreated fabric as well, while only oxidized viscose was also investigated for dyeing. Functionalization by both protocols made viscose susceptible to dyeing with the notion that the deposition of chitosan onto oxidized viscose produced the darkest shade on the material. Dyed fabrics showed visual pH responsiveness in the range pH 4–10, with a color change from pink to red (pH 4–pH 7) and a major color change from red to blue (pH 7–pH 10) whereby fabric was tested and could withstand 10 color-changing cycles. Cytotoxicity assay confirmed the non-toxic nature of dyed material, which indicates its possible use as wound dressing’s indicators.
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A convenient and efficient approach toward the synthesis of seven aromatically substituted xanthendiones 1?7 and one structurally-related xanthenone 8 through condensation of dimedone and the ...appropriate aromatic aldehyde is reported. Further, their chemical structure was confirmed by melting points, elemental analysis, FT-IR, 1H-, 13C-NMR and UV?Vis spectroscopic methods. The relationship between the chemical structure and pharmacological activity was determined empirically using appropriate software packages and in vitro using the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method. The results of in silico prediction suggested that all investigated compounds possess good oral bioavailability. The results of the ABTS assay indicate that five compounds possess the ability to scavenge the ABTS?+ radical cation. Based on the comparison of the IC50 values, the activity of the compounds was found to be as follows: 6 > 1 > 7 > 2 > 8. The effects of solvent dipolarity/ polarizability and solute solvent?hydrogen-bonding interactions on the shifts of the absorption maxima were rationalized by means of the linear solvation energy relationship concepts proposed by Kamlet?Taft and Catal?n.
Green, black, rooibos, and hibiscus tea (GT, BT, RT, and HT) aqueous extracts were prepared and characterized in terms of total flavonoids (TFC) and total phenolic (TPC) contents and antioxidant and ...antimicrobial activities. BT has the highest, while HT has the lowest TFC (1213 vs. 415 mg l–1), while the extracts’ TPCs (2283 – 7251 mg l–1) decreased in the following order: BT > GT > RT > HT. Their antioxidant activities of 78.1 – 93.1% and 97.8 – 100% were determined according to DPPH and ABTS methods, respectively. BT and especially GT aqueous extracts possessed mild effects against several microorganisms. All examined extracts have an affinity for dyeing wool, cellulose acetate, polyamide, and cotton, which is proven by the color strength values of 1.65–19.12. Wool, polyacrylonitrile, polyester, polyamide, cotton, and cellulose acetate functionalized with GT aqueous extract inhibited the growth of S. aureus and E. coli, while polyacrylonitrile and cotton also inhibited the growth of E. faecalis, and C. albicans, respectively. Wide inhibition zones for S. aureus were observed for fabrics functionalized with BT aqueous extract. Generally, the investigated fabrics showed very high (81.60 – 100%) ABTS radical scavenging ability independent of the extract used. TPCs have good linear correlations with the antioxidant activities of wool and polyacrylonitrile determined by the DPPH method. Fabrics with different chemical compositions dyed and/or functionalized with GT or BT aqueous extracts can be used to produce high-value-added medical textiles with therapeutic, prophylactic, and protective functions. They can find potential applications in wound treatment, especially in skin wounds that are susceptible to infection with S. aureus. Moreover, wool and cotton functionalized with GT or BT aqueous extract can also be considered for use in disposable medical textiles like bandages and gauze used in the wound-healing process.
The tautomerism of 8-(phenyldiazenyl)quinolin-5-ol has been studied by a combination of theoretical (DFT calculations) and experimental (UV–Vis and NMR) methods. The detailed study of neutral ...molecules has shown that the hydrazone tautomeric form, stabilized by an intramolecular N–H⋯N hydrogen bond, is solely present in most of the solvents. In strong proton acceptor solvents, besides the dominant hydrazone form, the deprotonated form also appears. Solvent effects on the absorption maxima of the hydrazone form are interpreted by the linear solvation energy relationship concept, using Kamlet-Taft and Catalán models. Upon deprotonation, a substantial structural transformation is observed in the studied compound leading to a slow rotation around the Cquin-N bond. The process, as monitored by 1H NMR, is strongly solvent assisted and facilitated by proton acceptor solvents. Consequently, the investigated dye could be considered as a base-activated rotary switch.
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•Tautomerism of quinoline azo dye is studied by combination of theory and experiment.•Hydrazone form observed in solutions is stabilized by intramolecular hydrogen bond.•Upon deprotonation, slow rotation around the Cquin-N bond is observed.•Deprotonation is solvent assisted and facilitated by proton acceptor solvents.•The studied dye could be considered as rotary switch activated by addition of base.
The present paper demonstrates a simple way for revalorization of differently softened cotton and cotton/elastane knitted fabric waste collected from the textile industry. Such waste was used as an ...adsorbent for Congo Red (CR) dye, whereby up to 96% removal efficiency was reached. The CR adsorption process onto cationic and silicone softened fabrics is in conformity with Langmuir (with maximum adsorption capacity of 12.533 mg/g) and Freundlich isotherms, respectively. Different adsorption of CR onto cationic and silicone softened fabrics is ascribed to the different softeners’ fixation to them, while the adsorption of CR operates in the same manner, via hydrophobic interactions. The adsorption kinetic data follow the pseudo-second-order model, while the equilibrium was reached after 90 min. Additionally, this study proposed a new circular economy solution for the disposal of fabric waste with adsorbed CR generating additional revenues. The volume electrical resistivity measurements confirmed that the knitted fabric wastes with adsorbed CR have 169–737 times lower resistivities (0.008–0.037 GΩ·cm) than before the adsorption. The inversely proportional correlation between fabrics’ adsorption efficiencies and their volume electrical resistivities after CR adsorption was found. Such knitted fabric waste with adsorbed CR could be defined as dissipative materials and could be used for providing antistatic protection.
This paper outlines a novel simple protocol for tuning the structure and properties of jute using sodium periodate (NaIO
) oxidation and coating with alginate. When compared to the raw jute, fabrics ...oxidized with a 0.2 or 0.4 % NaIO
solution for 30-120 min exhibited an increased aldehyde group content (0.185 vs. 0.239-0.398 mmol/g), a significantly increased negative zeta potential (from -8.57 down to -20.12 mV), a slight disruption of fiber crystallinity, 15.1-37.5 % and 27.9-49.8 % lower fabric maximum force and stiffness, respectively. Owing to the removal of hydrophobic surface barrier, decreased crystallinity index and the presence of micropores on the fabrics' surfaces, oxidized fabrics have a 22.3-29.6 % improved ability for moisture sorption compared to raw fabric. Oxidized fabrics characterized by very long wetting times and excellent antioxidant activities (> 98 %), can find applications as hydrophobic packaging materials. To further extend the utilization of jute in biocarpet engineering such as water-binding geo-prebiotic supports, oxidized fabrics were coated with alginate resulting in 7.9-24.9 % higher moisture sorption and 352-660 times lower wetting times than their oxidized counterparts. This modification protocol has never been applied to lignocellulosic fibers and sheds new light on obtaining jute fabrics with tuned structure and properties intended for various applications.
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•Theoretical and experimental study of solvatochromism of pyridone dyes is performed.•LSER models used for quantification of intermolecular solvent–solute interactions.•Benchmark of 4 ...common DFT methods for the study of solvent effects on λmax is done.•New polylinear equations for more accurate prediction of UV–Vis maxima developed.•Empirical solvent parameters are used as additive corrections of solvent effects.
In order to improve the performance of theoretical UV–Vis spectra predictions, a theoretical and experimental study of solvatochromic properties of ten azo pyridone dyes has been performed. For quantitative estimation of intermolecular solvent–solute interactions, a concept of the linear solvation energy relationships has been applied using Kamlet-Taft and Catalán models. Theoretical UV–Vis spectra for all dyes have been calculated using four TD-DFT methods in nine different solvents with the aim to define the most reliable model. Finally, new polylinear equations for more accurate theoretical prediction of UV–Vis maxima are developed using empirical Kamlet-Taft and Catalán solvent parameters as additive corrections for specific and nonspecific solvent–solute interactions.
The raw jute fabric was oxidized with 0.2% or 0.4% NaIO4 for 60 or 120 min to obtain valuable adsorbents for the textile dye Congo Red (CR). Batch adsorption experiments were carried out as a ...function of solution pH, contact time, initial CR concentration, and temperature. At an initial CR concentration of 25 mg/L, the raw jute possessed the lowest adsorption due to the lowest availability and content of carboxyl and aldehyde groups capable of binding dye. The fabrics oxidized for 60 min with 0.2% NaIO4 and 120 min with 0.4% NaIO4 reached equilibrium adsorption after 240 and 330 min, respectively. The adsorption of CR onto studied fabrics followed the pseudo-second-order model indicating that the chemisorption process is primarily represented. Within the studied range of CR concentrations (25–100 mg/L), its adsorption onto fabric oxidized for 120 min with 0.4% NaIO4 obeys the Langmuir isotherm model (i.e. adsorption occurs at specific, energetically equivalent adsorbent sites with monolayer coverage of CR over a homogeneous surface), wherein the calculated maximal adsorption capacity is 12.863 mg/g. A thermodynamic study revealed the spontaneous and endothermic character of CR adsorption onto jute fabric. Based on the recorded ATR-FTIR spectra before and after CR adsorption, it is suggested that repulsion, hydrogen bonds, and π-π stacking interactions are involved in the binding of CR onto jute fabrics.
This study is aimed at extending the soybean hulls’ lifetime by their utilization as an adsorbent for metal ions (Cd2+ and Cu2+) and dyes (Reactive Yellow 39 (RY 39) and Acid Blue 225 (AB 225)). ...ATR-FTIR spectroscopy, FE-SEM microscopy, and zeta potential measurements were used for adsorbent characterization. The effect of the solution’s pH, peroxidase extraction, adsorbent particle size, contact time, the pollutant’s initial concentration, and temperature on the soybean hulls’ adsorption potential was studied. Before peroxidase extraction, soybean hulls were capable of removing 72% Cd2+, 71% Cu2+ (at a pH of 5.00) or 81% RY 39, and 73% AB 225 (at a pH of 3.00). For further experiments, soybean hulls without peroxidase were used for several reasons: (1) due to their observed higher metal ion removal, (2) in order to reduce the waste disposal cost after the peroxidase (usually used for wastewater decolorization) extraction, and (3) since the soybean hulls without peroxidase possessed significantly lower secondary pollution than those with peroxidase. Cd2+ and Cu2+ removal was slightly increased when the smaller adsorbent fraction (710-1000 μm) was used, while the adsorbent particle size did not have an impact on dye removal. After 30 min of contact time, 92% and 88% of RY 39 and AB 225 were removed, respectively, while after the same contact time, 80% and 69% of Cd2+ and Cu2+ were removed, respectively. Adsorption of all tested pollutants follows a pseudo-second-order reaction through the fast adsorption, intraparticle diffusion, and final equilibrium stage. The maximal adsorption capacities determined by the Langmuir model were 21.10, 20.54, 16.54, and 17.23 mg/g for Cd2+, Cu2+, RY 39, and AB 225, respectively. Calculated thermodynamic parameters suggested that the adsorption of all pollutants is spontaneous and of endothermic character. Moreover, different binary mixtures were prepared, and the competitive adsorptions revealed that the soybean hulls are the most efficient adsorbent for the mixture of AB 225 and Cu2+. The findings of this study contribute to the soybean hulls’ recovery after the peroxidase extraction and bring them into the circular economy concept.
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