Tannins from Acacia mangium Bark as Natural Dyes for Textiles:Characteristics and Applications

Tannins are capable of producing natural dyes with antioxidant and antibacterial propertis,while synthetic dyes are commonly used in the textile industry,causing environmental issues like water pollution.This research aims to utilize waste tannins as natural dyes as an alternative to synthetic dyes.This study examined the effect of the extraction method on tannin properties such as phenolic content,antioxidants,and antibacterial activity.In addition,Pyrolysis Gas Chromatography‒Mass Spectrometry(Py-GCMS)analysis was used to identify the effect of extraction temperature on the chemical elucidation of tannin.The effect of tannin concentration was evaluated against four bacteria that are usually found on human skin:Staphylococcus epidermidis,Bacillus subtilis,Propionibacterium acnes,and Staphylococcus aureus.Extraction temperature significantly influences the chemical composition of tannin,which leads to different antioxidant properties.The maximum antibacterial properties of tannin were obtained at 90℃with the inhibition zone in the range of 0.9–1.0 mm against four bacteria,tannin yield of 26.59%,Gallic Acid Equivalents or total phenolic content(GAE)of 40.30 mg/g,and Radical Scavenging Activity or antioxidant activity(RSA)of 89.88%.Moreover,the concentration of tannin was significantly linear with its antibacterial properties.Tannin was successfully applied to the textile by using alum as a mordanting agent to create an antibacterial textile.The textile’s bacterial structure damage was analyzed under Field Emission Scanning Electron Microscopy(FESEM).After 50 washings,tannin-textiles with alum-modified properties remained stable compared to those without alum,with S.aureus and S.epidermidis being the most vulnerable bacteria,as confirmed by FESEM images.Hence,tannin is a feasible alternative to harmful and nondegradable synthetic dyes and antibacterial agents.

Bioremediation of Textile Azo Dyes Amido Black 10B, Reactive Black 5, Reactive Blue 160 by Lentinus squarrosulus AF5 and Assessment of Toxicity of the Degraded Metabolites

Bioremediation is an eco-compatible and economical approach to counter textile dye menace. The isolated Lentinus squarrosulus AF5 was assessed for decolourization of textile azo dyes, and had shown ~93%, 88% and 70% decolorization of Reactive blue 160 (RB160), Reactive black 5 (RB5) and Amido black 10B (AB10B) respectively. Further analysis using UV-vis, HPLC, and FTIR, 1H NMR had shown the degradation of the dyes. Toxicity analysis of the metabolites was performed using seed germination and plant growth on two agriculturally important plants Guar (Cyamopsis tetragonoloba) and wheat (Triticum aestivum) as well as cytotoxicity analysis using the human keratinocyte cell line (HaCaT). The dye mix appeared inhibitory for seed germination (20% - 40%), whereas metabolites were non-inhibitory for germination. Treatment of HaCaT cells with of dye mix and metabolites led into 45% and ~100% of cell viability of HaCaT cells respectively. Therefore, metabolites following degradation of the dye mix were observed to be non-toxic.

Biocatalytic enhancement of laccase immobilized on ZnFe_(2)O_(4) nanoparticles and its application for degradation of textile dyes

Efficient and convenient treatment of industrial dyeing wastewater is of great significance to guarantee human and animal health.This work presented the enhanced catalytic activity at pH 3.0 of laccase immobilized on amino-functionalized ZnFe_(2)O_(4) nanoparticles(ZnFe_(2)O_(4)-laccase)and its application for the degradation of textile dyes.Due to the existence of a large number of oxygen vacancies on the surface of the ZnFe_(2)O_(4) nanoparticles,negative ions accumulated on the magnetic carriers,which resulted in a harsh optimal pH value of the ZnFe_(2)O_(4)-laccase.Laccase activity assays revealed that the ZnFe_(2)O_(4)-laccase possessed superior pH and thermal stabilities,excellent reusability,and noticeable organic solvent tolerance.Meanwhile,the ZnFe_(2)O_(4) laccase presented efficient and sustainable degradation of high concentrations of textile dyes.The initial decoloration efficiencies of malachite green(MG),brilliant green(BG),azophloxine,crystal violet(CV),reactive blue 19(RB19),and procion red MX-5B were approximately 99.1%,95.0%,93.3%,87.4%,86.1%,and 85.3%,respectively.After 10 consecutive reuses,the degradation rates of the textile dyes still maintained about 98.2%,92.5%,83.2%,81.5%,79.8%and 65.9%,respectively.The excellent dye degradation properties indicate that the ZnFe_(2)O_(4)-laccase has a technical application in high concentrations of dyestuff treatment.

One-step crosslinking preparation of tannic acid particles for the adsorption and separation of cationic dyes

In this study,a new tannic acid adsorbent(ethylene glycol diglycidyl ether crosslinked tannic acid,TAEGDE)for adsorptive removal of dyes from water was prepared using EGDE as a cross-linking agent.The resultant TA-EGDE was in particulate form with rough surface morphology and a diameter ranging from 10 to 30μm.The adsorption performance of the TA-EGDE was evaluated in a flow-through mode using water samples contaminated with methylene blue(MB)and two-component mixed dyes,respectively.The TA-EGDE provided adsorption capacity up to 721.8 mg·g^(-1)at 65°C for MB.It showed a high removal efficiency(99%)of MB(50 mg·L^(-1))from the water sample and could recovery 90%of the adsorbed MB by eluting with acidic ethanol aqueous solution.The excellent adsorption of MB and neutral red on the TA-EGDE may be the result of the synergy of electrostatic interaction andπ-πinteraction.Furthermore,the TA-EGDE could separate dyes from water samples contaminated with twocomponent mixed dyes with a separation coefficient ranging from 1.8 to 36.5.The anionic TA-EGDE would be an effective adsorbent to remove and recycle dyes from the contaminated water.

Design of the reactive dyes containing large planar multi-conjugated systems and their application in non-aqueous dyeing

The development of pollution-free dyeing technology, including anhydrous dyeing and non-aqueous dyeing technologies, has always been an important way and research hot in energy conservation and emission reduction. Designing new structural dye molecules is the key to water-saving dyeing processes.Herein, three reactive dyes were designed and synthesized, which contained large planar multiconjugated systems and multi-reactive groups. The designed reactive dyes are expected to have high affinity and high fixations in non-aqueous or small bath dyeing processes. The reactive dyes were applied in the decamethylcyclopentasiloxane(DMCS) reverse micelle dyeing for cotton fabric. High exhaustion rate of 99.35%, 98.10% and 98.80%, and fixation rate of 95.15%, 96.34% and 94.40% for three dyes, R1,R2 and R3, could be respectively obtained. The dyes can be fully utilized and had excellent dyeing performance, fastness and levelling properties under the revere micelle dyeing. The cotton fabric is like an oil-water separator in the dyeing process, where the dye micelles rapidly absorb and permeate into the cotton fibers. DMCS circulates around the fabric to transfer mass and energy. After dyeing, the solvent can be separated quickly and reused. The new reactive dyes containing large planar and multi-conjugated systems have potential application in green and sustainable dyeing technology with less wastewater and higher utilization.

Visible-light degradation of azo dyes by imine-linked covalent organic frameworks

Covalent organic frameworks(COFs)are nanoporous crystalline polymers with densely conjugated structures.This work discovers that imine-linked COFs exhibit remarkable photodegradation efficiency to azo dyes dissolved in water.Visible light generates different types of radicals from COFs,and superoxide radicals break N=N bonds in dye molecules,resulting in 100%degradation of azo dyes within 1 h.In contrast,these dyes cannot be degraded by conventionally used photocatalysts,for example,TiO2.Importantly,the COF photocatalysts can be recovered from the dye solutions and re-used to degrade azo dyes for multiple times without loss of degradation efficiency.This work provides an efficient strategy to degrade synthetic dyes,and we expect that COFs with designable structures may use as new photocatalysts for other important applications.

States of graphene oxide and surface functional groups amid adsorption of dyes and heavy metal ions

Water pollution regarding dyes and heavy metal ions is crucial facing the world.How to effectively separate these contaminants from water has been a key issue.Graphene oxide(GO)promises the greenwater world as a long-lasting spotlight adsorbent material and therefore,harnessing GO has been the research hotspot for over a decade.The state of GO as well as its surface functional groups plays an important role in adsorption.And the way of preparation and structural modification matters to the performance of GO.In this review,the significance of the state of existence of stock GO and surface functional groups is explored in terms of preparation,structural modification,and adsorption.Besides,various adsorbates for GO adsorption are also involved,the discussion of which is rarely established elsewhere.

Progress in research and application of vital dyes in chromovitrectomy

Chromovitrectomy is a surgical method that uses intraocular dyes during vitreoretinal surgery to stain transparent tissues in the eye such as the posterior vitreous cortex,epiretinal membrane and inner limiting membrane for easy operation.It can avoid the intraocular complications associated with incomplete vitrectomy,incomplete epiretinal membrane peeling and incomplete internal limiting membrane peeling.At present,the commonly used vital dyes in clinic are as follows:indocyanine green,infracyanine green,triamcinolone acetonide,trypan blue,brilliant blue G.Indocyanine green was first used for intraocular staining,which can show the inner limiting membrane well.Following indocyanine green,trypan blue is used to identify idiopathic epiretinal membranes and triamcinolone acetonide is used to stain the vitreous.Recently,it has been discovered that natural dyes extracted from fruits,such as lutein and anthocyanins,are also used in intraocular vitrectomy.The main purpose of this review is to explore the research status and prospects of various intraocular stains in stained vitrectomy.

Adsorption of Anionic and Cationic Dyes from Textile Effluents by Activated Carbon Prepared from Sawdust and Fish Scale

In Bangladesh, there are thousands of textile-dying industries spread across the country’s many regions, the majority of which involve knitting and dying. The dyeing industry uses an enormous quantity of water, as well as colors and chemicals. After the dying process has been completed, they also release a significant amount of wastewater. Cotton, wool, and polyester fiber are typically dyed with textile dyes such as reactive, acid, and disperse dyes. These dyes are utilized most frequently in the respective sectors. The dyes’ colorants are extremely poisonous and dangerous to all forms of life, including aquatic life and living things. The present work has been intended to investigate whether or not it is practicable to remove commonly used textile dyes simultaneously from an aqueous dye solution using an adsorption technique that makes use of a variety of different adsorbents. This study focuses on the removal of color from two distinct types of dyes—Methylene Blue and Reactive Blue-250 which are cationic and anionic in nature respectively, using two different types of activated carbon adsorbents prepared from sawdust and fish scale. Dye removal capacity was tested as a function of contact time, the dosage of the adsorbent, pH during the treatment process, temperature and initial concentration of dye. The applicability of the Langmuir and Freundlich adsorption isotherms in describing experimental data was investigated. The micro and mesoporous activated carbon prepared from sawdust and fish scale identified by Scanning Electron Microscopy (SEM) images indicated that such adsorbents with a large surface area have more dye adsorption potential whereas the variation in dye adsorption occurs due to variation in surface area. From the overall experimental data, maximum removal of 95.39% and 87.92% was found for Methylene Blue and Reactive Blue-250 respectively by sawdust, and 90.64% removal of Methylene Blue by using fish scale.

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.

Synthesis of 6-chloro and 6-fluoro-4-hydroxyl-2-quinolone and their azo disperse dyes

In this study,6-chloro-4-hydroxy-2-quinolone and 6-flouro-4-hydroxy-2-quinolone were synthesized from corresponding dianilides.These compounds were coupled with some diazotized aromatic amines to give the corresponding azo disperse dyes.The structures of the quinolone derivatives and new azo dyes were confirmed by UV-vis,FT-IR,;H NMR and elemental analysis.

Innovation and application of dyes with high fixation

Reactive dyes are the main species for cotton dyeing due to their wide range of hue, satisfactory color fastness and facile application method. Aiming at increasing fixation on cotton fibers, benzimidazolone yellow reactive dyes, sulfonamide red reactive dyes and anthraquinone azo blue reactive dyes are designed. The preparation, characterization and application properties of these dyes with high fixation are introduced in detail. In order to achieve dye fixation to near 100%, macromolecular crosslinking reactive dyes are designed, their dyeing and fixing mechanism are discussed. These novel reactive dyes show promising application prospect in dyeing and printing of cotton fibers.

Synthesis of Some New Diazo Disperse Dyes and Their Application on Dyeing of Polyester

The synthesis of some new diazo disperse dyes containing a pyrazol-5-one was described. The structures of the new products have been deduced from elemental analysis and spectral dada such as UV-Vis absorption, IR, ^1H NMR, and MS spectroscopy. These dyestuffs gave satisfactory results when applied as disperse dyes to polyester fabric. The dyeing properties such as light fasmess, washing fastness and exhaustion studies have been investigated.

Charge and Energy Transfer in the Metal-free Indoline Dyes for Dye-sensitized Solar Cells

Metal-free indoline dyes for dye-sensitized solar cells were studied by employing quantum chemistry methods. Comparative study of the properties of both ground and excited states of metal-free indoline dyes for dye-sensitized solar cells revealed： （i） as the number of rhodanine rings increases, the energy difference between HOMO and LUMO decreases and there is a red shift in the absorption spectrum with the binding energy increased, and the transition dipole moment decreased; （ii） Based on an analysis of charge differential density, we observed that the charge and energy are transfered from the phenylethenyl to the indoline and rhodanine rings; （iii） The electron-hole coherences are mainly on the indoline and rhodanine rings, and the exciton sizes are 30 and 40 atoms for indoline dyes with one and two rhodanline rings, respectively. These results serve as a good example of computer-aided design in metal-free indoline dyes for dye-sensitized solar cells.

STUDIES ON CROWN ETHER CYANINE DYES (X). THE SYNTHESIS OF BENZOXAZOLE CROWN ETHER CYANINE DYES

A simple method for synthesis of benoxazole crown ether cyanine dyes is described.

STUDIES ON CROWN ETHER CYANINE DYES(XI)THE SYNTHESIS OF BENZOTELLURAZOLE CROWN ETHER CYANINE DYES

Three methods for synthesis of benzotellurazole crown ether(6)are described.The cyanine dye(8)can be easily obtained by treating(6) with CH_3I and CH(OEt)_3.

Chitosan and chemically modified chitosan beads for acid dyes sorption

The capabilities of chitosan and chitosan-EGDE （ethylene glycol diglycidyl ether） beads for removing Acid Red 37 （AR 37） and Acid Blue 25 （AB 25） from aqueous solution were examined. Chitosan beads were cross-linked with EGDE to enhance its chemical resistance and mechanical strength. Experiments were performed as a function ofpH, agitation period and concentration of AR 37 and AB 25. It was shown that the adsorption capacities of chitosan for both acid dyes were comparatively higher than those of chitosan- EGDE. This is mainly because cross-linking using EGDE reduces the major adsorption sites -NH3＋ on chitosan. Langmuir isotherm model showed the best conformity compared to Freundlich and BET. The kinetic experimental data agreed very well to the pseudo second-order kinetic model. The desorption study revealed that after three cycles of adsorption and desorption by NaOH and HCl, both adsorbents retained their promising adsorption abilities. FT-IR analysis proved that the adsorption of acid dyes onto chitosan-based adsorbents was a physical adsorption. Results also showed that chitosan and chitosan-EGDE beads were favourable adsorbers and could be employed as low-cost alternatives for the removal of acid dyes in wastewater treatment.

Decolorization of reactive dyes by laccase immobilized in alginate/gelatin blent with PEG

To achieve effective decolorization of reactive dyes,laccase immobilization was investigated.Laccase 0.2%(m/V)(Denilite IIS) was trapped in beads of alginate/gelatin blent with polyethylene glycol(PEG),and then the supporters were activated by cross-linking with glutaraldehyde.The results of repeated batch decolorization showed that gelatin and appropriate concentration of glutaraldehyde accelerated the decolorization of Reactive Red B-3BF(RRB);PEG had a positive effect on enzyme stability and led to an inc...

Preparation of activated carbon from cattail and its application for dyes removal

Activated carbon was prepared from cattail by H3PO4 activation. The effects influencing the surface area of the resulting activated carbon followed the sequence of activated temperature 〉 activated time 〉 impregnation ratio 〉 impregnation time. The optimum condition was found at an impregnation ratio of 2.5, an impregnation time of 9 hr, an activated temperature of 500℃, and an activated time of 80 min. The Brunauer-Emmett-Teller surface area and average pore size of the activated carbon were 1279 m^2/g and 5.585 nm, respectively. A heterogeneous structure in terms of both size and shape was highly developed and widely distributed on the carbon surface. Some groups containing oxygen and phosphorus were formed, and the carboxyl group was the major oxygen-containing functional group. An isotherm equilibrium study was carried out to investigate the adsorption capacity of the activated carbon. The data fit the Langmuir isotherm equation, with maximum monolayer adsorption capacities of 192.30 mg/g for Neutral Red and 196.08 mg/g for Malachite Green. Dye-exhausted carbon could be regenerated effectively by thermal treatment. The results indicated that cattail-derived activated carbon was a promising adsorbent for the removal of cationic dyes from aqueous solutions.

Photocatalytic Degradation of Water-Soluble Dyes by LaCoO_3

Pervoskite type oxides LaCoO 3 was prepared by citrate method with the granula of 20 nm-30 nm. With a fluorescent Hg lamp or sunlight as irradiator, the degradation experiments of various water soluble dyes were carried out in the suspension system of LaCoO 3 . The results show that the pervoskite type oxide LaCoO 3 has good photocatalytic activity.Studied by X ray photoelectron spectroscopy and photoacoustic spectra, its photocatalytic activity is found to be related with factors such as the d electron structure of ion Co 3+ ,Co—O binding energy and adsorbed oxygen on the surface etc.