An adsorption study of alum-morin dyeing onto silk yarn

Silk yarn was dyed with morin (2′,3,4′,5,7-pentahydroxyflavone) by using alum as mordant. In order to optimize the process, three methods of dyeing involving: pre-mordanting, simultaneous mordanting, and post-mordanting were assessed and compared with a mordant-free process. The adsorption of alum-morin dye onto silk fibers indicated that the adsorption capacities were significantly affected by pH, the initial dye concentration, and temperature. The initial dye adsorption rates of alum-morin dye on silk before equilibrium was reached increased with higher dyeing temperatures. The pseudo second-order kinetic model was indicated for alum-morin dyeing (simultaneous mordanting) of silk at pH 4.0 with an activation energy (E _a ) of 45.26 kJ/mol. The value of the enthalpy of activation (ΔH ^#) for alum-morin dyeing on silk at pH 4.0 was −31.29 kJ/mol. Also, the free energy (ΔG ^o) and entropy changes (ΔS ^o) for alum-morin dyeing on silk were −17.73 kJ/mol and −45.7 J/molK, respectively, consistent with a spontaneous and exothermic adsorption process.     

Thermodynamics of adsorption of laccaic acid onto chitosan and associated dye toxicity studies

The thermodynamics of adsorption of laccaic acid (lac dye) onto chitosan were investigated under acidic condition over various concentrations (20–293 mg/l). Langmuir, Freundlich, and Temkin isotherms were used to analyze the equilibrium data at different temperatures, with the Freundlich isotherm fitting the experimental data significantly better than the other isotherms. The effect of temperature on the adsorption isotherm was studied by carrying out a series of isotherms at 10, 20, 40, and 60 °C. It was found that more dye was strongly adsorbed by chitosan when the temperature of the dye solution increased. Thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) were also evaluated. The negative value of ΔG° and positive value of ΔH° indicated that the laccaic acid adsorption process is a spontaneous and an endothermic one. Attenuated total reflectance Fourier transform infrared spectroscopy confirmed the functional groups of chitosan that affected the laccaic acid adsorption. Therefore, laccaic acid molecules could interact with the chitosan via electrostatic forces, hydrogen bonding, and ion-dipole interactions under acidic condition. From the toxicity study, the dye solution with the initial dye concentrations of 40 and 120 mg/l before dye removal showed significant mortality to earthworm Diplocardia communis (P<0.01).     

Tobacco stems as a low cost adsorbent for the removal of Pb(II) from wastewater: Equilibrium and kinetic studies

Adsorption of Pb(II) ions from aqueous solution onto tobacco stems has been investigated to evaluate the effects of initial lead ion concentration, adsorbent dosage, contact time, pH and temperature on the removal of Pb(II) systematically. The optimal pH value for Pb(II) adsorption onto the tobacco stems was found to be 5.0. The removal of lead ions for concentrations 10, 30 and 50 mg L⁻¹ using 0.8 g adsorbent at contact time of 120 min and at temperature of 299 K were 94.37%, 92.10% and 90.43%, respectively. Thermodynamic parameters such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were evaluated by applying the Van’t Hoff equation, which describes the dependence of equilibrium constant on temperature. The thermodynamics of Pb(II) adsorption onto the tobacco stems indicated that the adsorption was spontaneous and endothermic. Langmuir and Freundlich isotherms were used to analyze the equilibrium data at different temperatures and the equilibrium data were found to fit Freundlich isotherm equation better than Langmuir isotherm. The adsorption was analyzed using pseudo-second-order kinetic equation.     

Preparation and acid dye adsorption behavior of polyurethane/chitosan composite foams

We prepared a series of polyurethane(PU)/chitosan composite foams with different chitosan content of 5∼20 wt% and investigated their adsorption performance of acid dye (Acid Violet 48) in aqueous solutions with various dye concentrations and pH values. It was observed that PU/chitosan composite foams exhibited well-developed open cell structures. Dye adsorption capacities of the composite foams increased with the increment of chitosan content in composite foams, because amine groups of chitosan serve as the binding sites for sulfonic ions of acid dyes in aqueous solutions. In addition, dye adsorption capacities of composite foams were found to increase with decreasing the pH value, which stems from the fact that the enhanced chemisorption between protonated amine groups of chitosan and sulfonic ions of acid dye is available in acidic solutions. The dye adsoption kinetics and equilibrium isotherm of the composite foams were well described with the pseudo-second order kinetic model and Langmuir isotherm model, respectively. The maximum adsorption capacity (q _max) for the PU/chitosan composite foams with 20 wt% chitosan content is evaluated to be ca. 30 mg/g.     

Influence of water hardness on acid dyeing with silk

In this paper, the effect of water hardness, expressed in CaCO₃ equivalent, on the dyeing silk with acid dye under acid, alkaline and isoelectric point dyeing conditions was studied by zeta potential method. Under acid condition and in the presence of calcium ion, the positive zeta potential of silk was found to decrease with a reduction in the dye adsorption. Such a phenomenon might be due to the presence of cation which increased the dyeing potential barrier at the interface between fibre and dye solution. This would result in a higher resistance of dye anions passing through the interface. Under alkaline condition, the zeta potential on silk was negative and resulted in a strong potential barrier for the dye anions. The presence of calcium ion would result in a decrease in the absolute value of zeta potential of silk fibre with an overall increase in dye absorption. Under isoelectric point, the zeta potential of silk fibre was found to be near zero and dye adsorption was not influenced by the cations. When studying the effect of calcium ion on the silk dyeing with acid dye under acid, alkaline and isoelectric point dyeing conditions, it was found that calcium ions influenced dye exhaustion and fixation greatly under acidic and alkaline dyeing conditions, which such influence became much smaller when the pH of dyebath was at the isoelectric point of the fibre. These results showed that calcium ion could produce strong electrolytic effect on dyeing even under very low concentrations.     

Sonicator dyeing of natural polymers with <Emphasis Type="Italic">Symplocos spicata</Emphasis> by metal chelation

Symplocos spicata (local name: Dom sheng) belonging to Family Symplococeae produces yellowish brown natural dye which has been used for dyeing textiles since ancient times by the Monpas tribe of Arunachal Pradesh. Symplocos spicata (Dom Sheng) was found in the Lumla area of Tawang district. Leaves of the plant are used by the Monpas and Tibetans for extraction of dye. Innovative sonicator dyeing with S. spicata showed that pretreatment with 2–4% metal mordant of the weight of the fabric is optimum showing very good fastness properties for dyed natural polymers such as cotton, wool, and silk. CIELab and K/S of the dyed fabrics were also evaluated. The superiority of sonicator dyeing over conventional dyeing has been established through this study.     

Dyeing properties and antimicrobial activity of silk fabric with extract of unripe Citrus Unshiu fruits

This study was carried out to optimize dyeing conditions of unripe Citrus Unshiu extract on silk fabric and to evaluate antimicrobial activity of the dyed fabric for its potential use as a functional natural dye. Unripe fruits of Citrus Unshiu in Jeju Island, Korea, extracted in 80 % Ethanol solution to final solid dye powder were dyed on silk fabric under a variety of conditions such as dye bath concentrations, temperature, and dyeing duration together with mordanting. Dyeing fastness properties to washing, rubbing, perspiration, and light were tested and the antimicrobial activities of the dyed fabric against Staphylococcus aureus and Klebsiella pneumoniae were investigated quantitatively. As results, the fabric showed the maximum dye uptake (K/S) under the conditions of 80 °C for temperature, 30 min for duration, and 600 % (o.w.f.) for dye concentration. Both pre- and post-mordanting seemed not to be effective on increasing K/S values of the dyed silk fabrics under the optimum dyeing conditions. Fastness ratings to washing, rubbing, and perspiration were all very good (4–5 grades) for both 300 and 600 % dyed silk fabrics. Excellent antimicrobial activities over 99 % reduction rate against two both bacteria were exhibited for all of dyed fabrics undergone more than 300 % of dye concentration. From these results, it was concluded that the dye concentration of 300 % of unripe Citrus Unshiu could be employed to produce antimicrobial silk fabric. Furthermore, to get more saturated shades on the fabric by the citrus, higher dye concentration such as 600 % was available as well.     

Psychoacoustic characteristics of fibers

In order to investigate psychoacoustic characteristics of fibers, and to compare them with sound physical parameters, each sound of 25 different fabrics consisted of a single fiber such as wool, cotton, silk, polyester, and nylon was recorded. Sounds of specimens were transformed into critical band diagram and psychoacoustic characteristics including loudness and sharpness for each sound were calculated based on Zwicker’s models. Physical parameters such as the level pressure of total sound (LPT), level ranges (ΔL), frequency differences (Δf), AR coefficients (ARC, ARF, ARE) were obtained in fast fourier transform (FFT) spectrum. Nylon taffeta showed higher values for loudness than 2.5 sone corresponding to human low conversation, while most silk fibers generated less louder showing lower values for loudness than 1.0 sone. Wool fibers had higher loudness mean value than that of cotton, while the two fibers didn’t differ in LPT. Loudness showed high positive correlation coefficients with both LPT and ARC. Sharpness values were higher for wool fiber group than other fibers. Sharpness was not concerned with loudness, LPT, and ARC, but the fabrics with higher values for sharpness tended to show higherΔL.     

Photocatalytic degradation of formaldehyde by silk mask paper loading nanometer titanium dioxide

Silk mask paper with different adsorbability was prepared by changing the beating degree of silk pulp and the basis weight of silk paper, and photocatalytic silk mask paper was prepared by loading nanometer titanium dioxide (nano-TiO₂) on the silk mask paper, then degradation of formaldehyde by silk mask paper loading nano-TiO₂ under daylight lamps and ultraviolet lamps were investigated, respectively. Results showed that silk mask paper could adsorb formaldehyde and had higher adsorption efficiency in the initial stage, and the adsorption/desorption equilibrium could be basically achieved in 60 minutes. The adsorption capacity of silk mask paper made from silk pulp with beating degree of 45 ^oSR was relatively low, and it increased with the increase of beating degree, but there was little change in adsorption when the beating degree of silk pulp exceeded 65 ^oSR. Under daylight lamps, 26.61 %, 31.42 % and 38.21 % of formaldehyde could be degraded in 180 minutes by silk mask paper loading 1 wt%, 3 wt% and 5 wt% nano-TiO₂, respectively. However, under ultraviolet (UV) lamps, 46.23 %, 55.47 % and 66.38 % of formaldehyde could be degraded within the same time, respectively. More formaldehyde could be degraded by photocatalytic silk mask paper under UV lamps than under daylight lamps, and the more the load of nano-TiO₂ on the silk mask paper, the higher the degradation rate of formaldehyde within the same time.     

Dyeing properties and colour fastness of cotton and silk fabrics dyed with<Emphasis Type="Italic">Cassia tora L.</Emphasis> extract

A natural colorant was extracted fromCassia tora L. using buffer solutions (pH: 2–11) as extractants. The dyeing solution (Cassia tora L. extract) extracted using pH 9 buffer solution was found to give the highest K/S values of dyed fabrics. Cotton and silk fabrics were dyed withCassia tora L. extract at 60°C for 60 min with pre-treatment of various metal salts as mordants. It was found thatCassia tora L. extract was polygenetic dyestuffs and its major components were anthraquinones. Studies have been made on the effects of the kind of mordant on dyeing properties and colour fastnesses of cotton and silk fabrics. The K/S of cotton fabrics increased in the order of the dyeing using FeSO₄>CuSO₄>ZnSO₄>MnSO₄≅Al₂(SO₄)₃>NiSO₄>none, however, the K/S of silk fabrics increased in the order of the dyeing using FeSO₄>CuSO₄>ZnSO₄≅Al₂(SO₄)₃>MnSO₄≅NiSO₄>none. It was found that the K/S values of dyed fabrics were largely affected by the colour difference (ΔE) between mordanted fabric and control fabric. However, they were not depended on the content of mordanted metal ion of the fabrics. Mordants FeSO₄ and CuSO₄ for cotton fabric, FeSO₄, CuSO₄, and Al₂(SO₄)₃ for silk fabric were found to give good light fastness (rating 4).     

Synthesis,spectral characterization of azo dyes derived from calix[4]resorcinarene and their application in dyeing of fibers

Seven new upper rim functionalized azocalix[4]resorcinarene dyes have been synthesized by coupling calix[4]resorcinarene with different diazo compounds of p-chloroaniline, p-nitroaniline, p-toludine, p-anisidine, p-aminobenzoic acid, o-aminophenol, and aniline. The characterization of these dyes has been carried out by elemental analysis, FT-IR, ¹H- and ¹³C-NMR. Effect of solvents of varying dielectric constants on the absorption spectra of substituted and unsubstituted azocalix[4]resorcinarene dyes have been examined by UV-vis spectrophotometer. These azocalix[4]resorcinarene dyes have also been used for dyeing textile fibers like cotton, silk, and wool. Their dyeing and fastness properties have also been discussed.     

A promising biosorbent for biosorption of a model hetero-bireactive dye from aqueous medium

In this study, residual shell biomass of Corylus avellana L. was used as potential biosorbent for biosorption of a model industrial hetero-bireactive dye. The biosorbent was characterized by FTIR and SEM. The batch biosorption studies were performed as a function of dye concentration and contact time. The biosorption of dye was found to be very quick. Various kinetic and isotherm models were used to evaluate the obtained experimental data. The biosorption kinetic was best represented by the pseudo-second-order model while the biosorption equilibrium was best described by Langmuir model. The maximum dye biosorption capacity of biosorbent based on Langmuir isotherm was obtained as 74.527 mg g^-1. These results showed that the use of such plant waste biomass in biosorption system could be a feasible method for the removal of such recalcitrant dye from industrial effluents to reduce operating costs.     

Eco-friendly dyeing using natural mordant extracted from <Emphasis Type="Italic">Emblica officinalis G</Emphasis>. Fruit on cotton and silk fabrics with antibacterial activity

Emblica officinalis G. dried fruit tannin was extracted and applied as a natural mordant alone and in combination with metal mordant namely copper sulphate for dyeing on cotton and silk fabrics using natural dyes. The color strength, color-coordinates, wash and light fastness were also evaluated for cotton and silk fabrics with and without mordanting. The pre-mordanted cotton and silk fabrics on dyeing gave better color strength, wash and light fastness than those dyeing obtained without mordanting. The total phenolic content of the extract was calculated. Cotton and silk fabrics resulted in good antibacterial activity using the Emblica officinalis G. mordant. When mordant was used along with 0.5 and 1 % copper sulphate mordant and the activity enhanced and was active up to 20 washes.     

Removal of methylene blue by amidoxime polyacrylonitrile-grafted cotton fabrics: Kinetic,equilibrium, and simulation studies

In this study, an amidoxime-grafted cotton fabric ion exchanger was developed for methylene blue (MB) removal from wastewater. The ability of the amidoxime-grafted cotton fabrics to remove MB ions from an aqueous solution was investigated in equilibrium, kinetics and thermodynamics studies. Equilibrium data agreed well with the Freundlich and Langmuir isotherm models. The result indicated that, based on the Langmuir coefficient, the maximum capacity (monolayer saturation at equilibrium) of the amidoxime-grafted cotton fabric was 22.27 mg/g. The kinetic data were found to follow the pseudo-second-order model, and intra-particle diffusion is the sole rate-controlling factor. Negative values of ΔG ⁰, ΔH ⁰, and ΔS ⁰ revealed the spontaneous, exothermic and entropy-driven nature of the process.     

Cellulose-based porous adsorbents with high capacity for methylene blue adsorption from aqueous solutions

A novel cellulose-based porous adsorbent with high adsorption capacity for methylene blue (MB) was prepared by free radical polymerization methods. The obtained polymer grafting rate and dye removal efficiency are as high as 338.64 % and 97.74 %, respectively, when the dosage of monomer is 4.5 g, the polymerization condition is 3 h at 70 °C. The cellulose-based adsorbent showed high mechanical properties and good flexibility. The Langmuir isotherm model revealed that the maximum theoretical adsorption capacity of this material for methylene blue was 1734.816 mg g-1 at pH 9.0 at 313 K, which is higher than the values observed for other adsorbents. Scanning electron microscopy (SEM) showed that the cellulose-based adsorbent exhibits a typical well-defined porous and interconnected three-dimensional framework structure, which is benefits to dye adsorption. The adsorption kinetics (pseudo first-order, pseudo-second-order, and intraparticle diffusion models) was also studied, and the pseudo-second-order model fitted MB adsorption better than the pseudo-first-order and intraparticle diffusion models at different initial dye concentrations (500-3000 mg l ^-1). The novel polyacrylic acid-grafted quaternized cellulose (PAA-g-QC) adsorbent is thus potentially useful for the treatment of dye-contaminated wastewater.     

Synthesis, characterization and application of quinazolinone based reactive dyes for various fibers

Seven hot brand heterocyclic mono azo reactive dyes (7a–g) have been synthesized by coupling diazotized 2-phenyl-3{4′-[(4″-aminophenyl)sulphonyl]phenyl}-quinazoline-4(3H)-one-6-sulphonic acid (4) with various 2-chloro-4-nitro anilino cyanurated coupling components (6a–g) and their dyeing performance on silk, wool, and cotton has been assessed. The purity of dyes was checked by thin layer chromatography. These dyes were identified by recording IR and ¹H-NMR spectra. The λ _max, R _f value, %exhaustion, %fixation, light fastness, wash fastness, rubbing fastness, reflectance (%R) value, and K/S value have also been studied.     

Dyeing of cotton and polyester/cotton blend with disperse dyes using sodium 2-(2,3-dibromopropionylamino)-5-(4,6-dichloro-1,3,5-triazinylamino)-benzenesulfonate

The cotton fabrics were pretreated by sodium 2-(2,3-dibromopropionylamino)-5-(4,6-dichloro-1,3,5-triazinylamino)-benzenesulfonate (DBDCBS) at alkaline condition of room temperature and then dyed with four disperse dyes having amino groups (C.I. Disperse Yellow 9, C.I. Disperse Red 11, C.I. Disperse Blue 56 and C.I. Disperse Violet 1) at acidic condition of high temperature. A novel hetero-bifunctional bridge compound,DBDCBS, has two reactive groups such as dichloro-s-triazinyl group andα, β-dibromopropionylamido group. The first has reactivity towards hydroxy group of cellulosic fiber and the second shows reactivity towards amino groups of disperse dye containing amino groups. The results indicate that it is possible to dye polyester/cotton blend at one-bath dyeing using one kind of disperse dye containing amino groups. Therefore, two kinds of dyeing methods such as two-bath process one-bath dyeing and one-bath process one-bath dyeing were investigated and their dyeabilities were compared. The differences between these two methods were negligibly small so that perfect one-bath one-step dyeing of polyester/cotton blend by one kind of disperse dye was achieved.     

Surface modification and ternary system dye removal ability of manganese ferrite nanoparticle

In this paper, the surface of magnetic manganese ferrite nanoparticles (MFN) was modified using cetyl trimethylammonium bromide (CTAB). The modified MFN was studied using Fourier transform infrared spectroscopy (FTIR). The adsorption capacity of surface modified MFN (MFN-CTAB) was investigated for dye removal for single and ternary systems. Three anionic dyes, C.I. Direct Red 80 (DR80), C.I. Direct Red 31 (DR31), and C.I. Acid Blue 92 (AB92), were used as model compounds. The effects of operational parameters on dye removal (i.e. adsorbent dosage, dye concentration and salt) and the kinetic and isotherm of dye adsorption were studied. The adsorption kinetic for the dyes was found to be well described by the pseudo-second order model. The maximum dye adsorption capacity (Q ₀) of MFN-CTAB for DR80, DR31 and AB92 was 83 mg/g, 59 mg/g and 70 mg/g, respectively. The adsorption isotherm data were analyzed using the Langmuir, Freundlich, and Temkin equations. The results revealed that the Langmuir model fitted the adsorption data better. The results showed that the MFN-CTAB as a magnetic adsorbent might be a suitable alternative to remove dyes from colored aqueous solutions.     

An approach to the influence of particle size distribution of leuco vat dye converted by a reducing agent

Three vat dyes have been applied to regular viscose rayon and their dyeing and wash fastness properties were evaluated. Particle size determination was undertaken to obtain information about the size of dye particles converted by a reducing agent, to see if dye particle size has an affect on dyeing properties of regular viscose rayon. It is observed that viscose rayon exhibits more dyeability with reducing agent concentrations between 5–7.5 g/l. Also, we found that the vat dyeing system is greatly affected by the particle size of the vat dye converted to leuco form by a reducing agent.     

Coloration and Decoloration of Textiles Using a TiO<Subscript>2</Subscript> Composite Pigment

A colorable pigment was prepared by dye adsorption onto titanium dioxide and subsequent silane coating. The effects of pH value, dye concentration, and adsorption times on dye adsorption were discussed. Large adsorption capacity of an anionic dye was obtained at pH value of 2 and the adsorption process was well described by the Langmuir isotherm model. Good dyeability and color fastness of pigment dyed fabric were achieved in the normal life cycle under sunlight. The decoloration of pigment was realized through photocatalytic degradation of dye molecules by titanium dioxide under ultraviolet irradiation when reusing the pigment dyed textiles after disposal. The new absorption peaks in the FTIR spectrum at 2924.95 cm^-1, 1714.91 cm^-1, 1461.17 cm^-1, and 1289 cm^-1 verified silane modification. Silane modification improved fixation of dyes onto the pigment and immobilization of pigments onto substrates. The close attachment of silane coating layer to titanium dioxide was conducive to photodegradation of dye molecules in the pigment.