A novel heterogeneous Fenton photocatalyst prepared using waste wool fiber combined with Fe<Superscript>3+</Superscript> ions for dye degradation

Wool fiber Fe complex (Fe-Wool) was prepared with waste wool fiber and Fe³⁺ ions by a simple exhaust method, and characterized using SEM, FTIR, XRD, XPS, and diffuse reflectance UV-vis spectroscopy. The activity of Fe-Wool was tested as a novel heterogeneous Fenton catalyst for dye degradation in a wide pH range. Effect of Fe content, incorporation of Cu²⁺ ions, and light irradiation on its catalytic activity was also examined. The results indicated that amino and carboxylic groups or disulfide crosslinks from wool fiber as the ligand sites could react with Fe³⁺ ions to form Fe-Wool, and the Fe content in Fe-Wool was highly dependent on Fe³⁺ initial concentration and temperature. Fe-Wool showed a better catalytic activity on the dye degradation under light irradiation than in the dark because it was activated in the UV and visible regions. Incorporation of Cu²⁺ ions could significantly increase catalytic activity of Fe-Wool for the dye degradation, especially in neutral and alkaline pH range.     

Natural dyeing with black cowpea seed coat. I. Dyeing properties of cotton and silk fabrics

A new trial to determine the dyeing properties of cotton and silk fabrics with a black cowpea seed coat as crop waste was investigated. The natural dye anthocyanins were extracted from a black cowpea seed coat in an aqueous solution and used to dye silk and cotton. The optimal conditions for colorant extraction were an aqueous solution of a dried seed coat of black cowpea in a 1:10 liquor ratio at 70 °C for 4 hours with pH of 4. The best dye-uptake of silk and cotton fabric were obtained when the pH was 3.5 and 3.0 respectively, the temperature was 80 °C for 1 hour and the liquor ratio of black cowpea was 1:20. Different colors as dusky brown, brown, faint yellow, light green, reddish brown, cyan and green could be obtained using a various kind of mordants. The depth and brightness of color tones were affected by different dyeing and mordanting pH conditions. The colors of the fabrics were examined using a computer color matching system in terms of the K/S values and CIELAB color-difference values. The dyeing was evaluated using standard light, wash and heat fastness tests. Good wash and heat fastness were obtained but the poor light fastness indicated the need for improvement to fulfill the requirement for textile applications.     

Response surface optimization and artificial neural network modeling of microwave assisted natural dye extraction from pomegranate rind

The extracted dye from brown dry rind of the pomegranate has been used as natural colorant for textiles from ancient times. In this study, microwave assisted extraction (MAE) has been used for extraction for dye from dried pomegranate rind. The effect of three independent parameters namely extraction time (25–90 s), pH of solution (3.5–8) and amount of pomegranate rind (0.5–1.5 g) was considered. Response surface methodology (RSM) is applied to optimize the effects of processing parameters of extraction on the yield of dye and a computer-stimulated artificial neural network (ANN) model is developed to get a good correlation between the input variables responsible for extraction and the output parameter (concentration of dye) of extraction from pomegranate rind. Considering the yield of dye extraction and the feasibility of the experiment, the optimum conditions of dye extraction are extraction time 90 s, pH 3.5, amount of sample 1.48. Application of microwave irradiation method proved to be a rapid and improved technique for dye extraction and significantly reduced the extraction time. The optimization procedure shows a close interaction between the experimental and simulated values for dye extraction.     

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.     

Isolation, identification and dyeing studies of betanin on modified acrylic fabrics

Mature red fruits of Opuntia ficus-indica contain two soluble pigment, betanin and indicaxanthin. The optimal conditions for dye extraction were to mix 50 g of juice from cactus pears with 100 mL of acidified water as solvent for dye extraction. Two main dyes were purified from the pigment extract by chromatography and identified by UV-vis, HPLC and LC-MS techniques as indicaxanthin (15 mg per 100 g) and betanin (280 mg per 100 g). The effect of dye bath pH, salt concentration, dyeing time and temperature was studied. The optimal conditions for dyeing modified acrylic fabrics with betanin dye were carried out at 50 °C for 45 min at pH 5. Un-mordanted samples have good properties of water and washing fastness. Mordant CoSO₄ was found to give good light fastness (rating 5).     

Binary catalyst system dye degradation using photocatalysis

In this paper, soy meal hull activated carbon (SMHAC) and titania nanoparticle (TiO₂) were used as catalysts to degrade dyes. Activated carbon was prepared using soy meal hull. Degradation of dyes using single and binary catalyst systems was studied. Textile dyes were used as model pollutants. Photocatalytic dye degradation and mineralization were studied using UV-Vis spectrophotometer and ion chromatography (IC). The effects of pH, initial dye concentration, and salt on dye degradation were investigated. Dye solutions were decolorized completely (100 %). The presence of salts decreased dye degradation rate. Degradation of dyes followed first order kinetics model. Formate, acetate, and oxalate were detected as dominant aliphatic intermediates during dye degradation process. Nitrate, sulfate, and chloride anions were detected as dye mineralization products.     

Load of Ag<Subscript>3</Subscript>PO<Subscript>4</Subscript> Particles on Sulfonated Polyphenylene Sulfide Superfine Fibre with High Visible-light Photocatalytic Activity

Ag₃PO₄ was loaded on sulfonated polyphenylene sulfide (SPPS) superfine fibre by a facile precipitation method. Both the structure and properties of the as-synthesized Ag₃PO₄/SPPS composites were characterized via XRD, SEM, EDS, XPS, FTIR, and UV-vis. The photocatalytic performance of Ag₃PO₄/SPPS composites was investigated via degradation of Methylene blue(MB) solution under visible light irradiation. The degradation results revealed that the photocatalytic activity of Ag₃PO₄/SPPS composites was greatly enhanced by the incorporation of Ag₃PO₄ with SPPS superfine fibre. For concentrations of AgNO₃ and Na₂HPO₄ solutions of 0.3 M and 0.06 M in the preparation process, the Ag₃PO₄/SPPS composite showed higher photocatalytic activity under visible light irradiation.     

Preparation of amidoxime-modified polyacrylonitrile nanofibers immobilized with laccase for dye degradation

A novel approach to preparing multifunctional composite nanofibrous membrane was developed. Polyacrylonitrile (PAN) nanofibrous membrane was fabricated by electrospinning and then the nitrile groups in PAN copolymer was chemically modified to obtain amidoxime modified PAN (AOPAN) nanofiber membrane which was further used as a functional support for laccase immobilization. During the process of reactive dye degradation catalyzed by the AOPAN nanofiber membrane immobilized with laccase, metal ion adsorption occurred at the same time. The chemical modification was confirmed by Fourier transform spectroscopy (FTIR). Scanning electron microscope (SEM) was employed to investigate the surface morphologies of the electrospun nanofibers before and after laccase immobilization. The effects of environmental factors on laccase activity were studied in detail. It was found that the optimum pH and temperature for the activity of immobilized laccase was 3.5 and 50 °C. The relative activity retention of the immobilized laccase decreased dramatically during the initial four repeated uses. After 20 days’ storage, the activity retention of immobilized laccase was still high above 60 %. It has also proved that laccase immobilized on AOPAN nanofiber membrane performed well in dye degradation and metal ion adsorption.     

Removal of benzidine-based azo dye from aqueous solution using amide and amine-functionalized poly(ethylene terephthalate) fibers

In this study, amide and amine groups bound to poly(ethylene terephthalate) fibers are used to remove the colored toxic Congo red dye from aqueous solution. The effects of process variables like pH, contact time, graft yield, and initial dye concentration on the adsorption were investigated. The maximum adsorption of Congo red to amide and amine groups was observed at pH 3 and 5 respectively. Equilibrium was attained at approximately 60 min for the amine group. The adsorption capacity of amine group on the poly(ethylene terephthalate) fiber was 46.5 mg g⁻¹ at 25 °C, which was higher than that of the amide group on the poly(ethylene terephthalate) fiber. Desorption was done using 0.1 M NH₃, and recovery was measured at 58.2 %. The used adsorbent was regenerated and recycled six times. The results showed that the amine-functionalized fiber could be considered as potential adsorbents for removal of Congo red from aqueous solution.     

Synthesis and characterization of water-soluble phthalocyanine Copper(II) complex and its coloration on acrylic fibers

Herein, we report the synthesis and dyeing property of cationic copper phthalocyanine (cationic CuPc). The synthesized cationic CuPc was characterized using UV-Vis spectra and it showed good solubility in aqueous solution over a wide pH range. The dyeing of cationic CuPc was successfully employed onto acrylic fiber. The dyeing of acrylic fiber using cationic CuPc was achieved using conventional method. The effects of five important variables such as liquor ratio, dye concentration, dyeing time, temperature and pH were examined on the color strength (K/S) of dyed acrylic fiber. The maximum color strength was obtained at lower liquor ratio (100:1), higher dye concentration (6 %), longer dyeing time (60 min), 120 °C and alkaline condition (pH 11).     

Dyeing properties and colour fastness of wool dyed with indicaxanthin natural dye

This research work involves the dyeing of wool with indicaxanthin, a natural dye extracted from fruits of Opuntia ficus-indica. The optimal conditions for dye extraction were to mix 50 g of Juice from cactus pears with 100 mL of 80% aqueous ethanol as solvent for dye extraction. Liquid chromatography was applied for the separation. Two main dyes were obtained, which were identified as indicaxanthin (75 mg per 50 g) and betanin (5 mg per 50 g). The effect of dye bath pH, salt concentration, dyeing time and temperature were studied. The optimal conditions for wool dyeing with indicaxanthin dye were carried out at 70 °C for 90 min with the pre-treatment of various metal salts as mordant. The colour yields of the dye on the wool were found to be highly dependent of the pH, optimum results being obtained at pH 4. The K/S of wool increased in the order of the dyeing using KAl (SO₄)₂ > MnSO₄ > CoSO₄ > FeSO₄ > none > ZnSO₄ > CuSO₄. Un-mordanted samples have good properties of water and washing fastness. Mordants KAl (SO₄)₂ and CoSO₄ were found to give good light fastness (rating 5).     

Extraction of natural dye from <Emphasis Type="Italic">Coreopsis tinctoria</Emphasis> flower petals for leather dyeing − An eco-friendly approach

This study evaluated the extraction of two colors of dye (yellow and brown) from Coreopsis tinctoria flower petals using ultrasound and the dyeing of leather with the extracted dyes as a source of nontoxic and eco-friendly dye. The results showed an increase in the dye extraction values with increasing time at 100 W ultrasonic power at 80 °C for 1 h. Leather dyeing was optimized with the aid of ultrasound and magnetic stirring. The optimum leather dyeing conditions, with respect to the dye uptake, dye penetration and intensity of the color, were determined to be 12 % dye concentration, 100 W power, 1,000 rpm, and pH 7.0 for 60 min at 80 °C. It was shown that sonication improves dye exhaustion from a 90 % to 60 % rating for 1 h of dyeing time. The dyed leather was assessed by reflectance measurements and compared with visual assessment data. The fastness properties of dyed leather samples showed good fastness against washing, light, and dry and wet rubbing. The strength properties were not significantly altered and the bulk properties, such as softness, were found to be improved by the use of Coreopsis tinctoria yellow and brown dyes using an ultrasonic and magnetic stirring dyeing process.     

枯草芽孢杆菌Natto3的筛选及其降解黄曲霉毒素B_1的初步研究

从可食用的纳豆中筛选出一株能够高效降解黄曲霉毒素B1(aflatoxin B1,简称AFB1)的细菌,该细菌的发酵上清液经浓缩后制成的粗酶液对AFB1降解率达到91.4%。对该菌进行了分类地位鉴定并初步研究了粗酶液的酶学性质。结果表明,该菌经生理生化和16S r DNA序列比对鉴定为枯草芽孢杆菌,并命名为Natto3。Natto3的粗酶液降解AFB1的最适培养时间为72h,最适反应温度为37℃,最适p H值是8.5,Zn2+、Mn2+、Mg2+、Cu2+、Li+五种金属离子均会不同程度地抑制降解活性。此外,将该粗酶液添加在被黄曲霉毒素高度污染的花生样品中进行脱毒实验,可使花生中AFB1的浓度从192μg/kg降至43μg/kg。     

Dyeing of modified acrylic fibers with curcumin and madder natural dyes

Hydrophobic fibers are highly crysta lline and non-polar polymers hence pose a big problem for dyers. Modified acrylic fiber containing different amounts of amidoxime groups as a function of the nitrogen content was obtained and dyed with curcumin and madder natural dyes. The dyeing parameters, such as dye concentration, dye bath pH, salt concentration, temperature, and time and the effect of alum and ferrous sulfate used as mordants were investigated. Compared with the dyeings obtained from modified acrylics, those of blank samples appeared less in color strength values. The color strength was proportional to the nitrogen content of the sample and the maximum value was obtained at pH 2 and pH 5 using madder and curcumin, respectively. The fixation of the dye molecules to the modified acrylic fibers was investigated to show mainly ionic and physical bonds. The washing, perspiration, and rubbing fastness properties for the dyed samples were enhanced by application of alum. The light fastness ratings were also improved using ferrous sulfate especially for the case of the samples dyed with madder.     

Sorption of Yellow 59 on Posidonia oceanica,a non-conventional biosorbent: Comparison with activated carbons

Posidonia oceanica, an endemic marine magnoliophyta found in the Mediterranean Sea, is used as a biosorbent for dye wastewater treatment. The ability of P. oceanica to remove the dye C.I. Acid Yellow 59 from an aqueous solution was compared to that of two commercial activated carbon forms: powdered (PAC) and granular (GAC) activated carbon. The effect of initial pH, mass concentration, contact time and initial dye concentration were investigated for the three sorbents. Equilibrium uptake was found to be pH dependent and maximum uptake was observed at an acid pH (2–3) for all materials. Kinetic studies for initial dye concentration of 20, 50 and 100 mg L^?1 showed that dye uptake followed the pseudo-second order model for all materials and equilibrium was reached in 10, 400 and 600 min for PAC, GAC and P. oceanica, respectively. The equilibrium data tend to fit Freundlich isotherm model for all materials, the best retention of C.I. Acid Yellow 59 was found to be on PAC followed by P. oceanica and then GAC. This comparative study indicates that sorption onto P. oceanica is an effective, cheaper alternative for dye removal.     

Functionalization of the aquatic weed water hyacinth <Emphasis Type="Italic">Eichhornia crassipes</Emphasis> by using zinc oxide nanoparticles for removal of organic dyes effluent

In this study, purified Eichhornia crassipes dead biomass, coated biomass with ZnO nanoparticles (NPs) and one coated with both ZnO NPs and polyethylenimine (PEI) were successfully fabricated as a bioadsorbent and biodegradent of organic dyes from the textile dye effluent. These ZnO NPs are capable of enhancing the dispersability and adsorption capacity of PEI and the anionic dyes. The surface analyses of Eichhornia crassipes, Eichhornia crassipes/ZnO NPs and Eichhornia crassipes/ZnO NPs/ PEI were characterized by SEM, specific surface area and micropore volume. The effect of three parameters including Eichhornia crassipes concentration, dye concentration and contact time on the color removal percent and degradation percent were evaluated. The results showed that the bleached Eichhornia crassipes was an efficient adsorbent for cationic dyes. Also, the effectiveness of Eichhornia crassipes/ZnO NPs was employed as photocatalytic agent for the degradation of C.I. Direct Red 23 in the presence and absence of UV irradiation. Moreover, Eichhornia crassipes/ZnO NPs/PEI shows a high adsorption capacity toward the anionic dyes C.I. Acid Red 40 and C.I. Reactive Orange 91. It was found that, Eichhornia crassipes/ZnO NPs was completely degraded C.I. Direct Red 23 by >90 % within 90 min of UV irradiation time, whereas in the absence of UV irradiation it required a substantially longer time (120 min) to achieve a similar degradation percent. In addition, Eichhornia crassipes/ZnO NPs/PEI was most effective and show the maximum adsorption capacity for C.I. Reactive Orange 91 and C.I. Acid Red 40 and its efficiency for the color removal percent was 100 % for C.I. Reactive Orange 91 and 95 % for C.I. Acid Red 40 in less than 60 min processing time.     

Dyeing of cotton and silk yarn with the extracted dye from the fruit hulls of mangosteen,<Emphasis Type="Italic">Garcinia mangostana</Emphasis> linn

The extracted dye from the dried fruit hulls of mangosteen was used as a natural dye for the dyeing of cotton and silk yarn. The optimal conditions for dye extraction were to extract the dried fruit hulls of mangosteen at 80°C for 1 hour with a 15 % w/v citric acid solution in a 1:4 ratio of mangosteen powder to solvent. Cotton dyeing with the extracted dye from the dried fruit hulls of mangosteen was carried out at 60°C for 60 minutes with a material to liquor ratio of 1:25. The effect on dyeing of mordant type with different mordanting methods was studied. The results showed that the dyeing of cotton using the post-mordanting method with ferrous sulfate and calcium hydroxide not only provided better depth of shade but also provided better wash fastness and light fastness than with other mordants (alum; zinc tetrafluoroborate) or without a mordant. Good fastness properties were also obtained using a post-mordanted silk with calcium hydroxide.     

Use of 1,6-diaminohexane-functionalized glycidyl methacrylate-g-poly(ethylene terephthalate) fiber for removal of acidic dye from aqueous solution

In this study, removal of Congo red (CR) from aqueous solution by 1,6-diaminohexane-functionalized glycidyl methacrylate-g-poly(ethylene terephthalate) (HMDA-GMA-g-PET) fiber was investigated. A new aminated fibrous adsorbent was prepared by a reaction between amine and epoxy group in GMA-g-PET fiber prepared by grafting GMA monomer onto poly (ethylene terephthalate) (PET) fiber. Effects of various parameters such as pH, treatment time, initial, dye concentration, and reaction temperature on the adsorption amount of dye onto reactive fiber were investigated. The adsorption rates of CR were much higher on the HMDA-GMA-g-PET fiber than on GMA-g-PET and ungrafted PET fiber. The effective pH was 2.0 for adsorption on grafted PET fiber. It was found that the sufficient time to attain equilibrium was 60 min. The maximum adsorption capacity of the reactive fiber for CR is 16.6 mg/g fiber. The rates of adsorption were found to conform to the pseudo-second order kinetics with good correlation. It was found that the adsorption isotherm of CR fitted Freundlich type isotherm.     

Sorption properties of iron impregnated activated carbon web for removal of methylene blue from aqueous media

In this study, impregnation of iron chloride was carried out on needle punched web of waste acrylic fibers, which was subsequently carbonized under layer of charcoal by physical activation in high temperature furnace to produce iron impregnated activated carbon (FeAC). For comparison purpose, one more sample of activated carbon (AC) was prepared without impregnation of iron chloride. Both the webs were carbonized at 1200 °C with no holding time, and characterization of BET surface area, SEM morphology, EDX elemental analysis, XRD crystalline structure was performed. The FeAC web was used as adsorbent for the removal of methylene blue from aqueous solution. The dye removal percentage was investigated at different experimental parameters like different dye concentrations, adsorbent dosage, stirring speed and different pH. The obtained results were analyzed using linear and non-linear forms of Langmuir and Freundlich isotherms and adsorption kinetics (i.e. pseudo first order and pseudo second order model).     

Copper oxide-carbon nanotube (CuO/CNT) nanocomposite: Synthesis and photocatalytic dye degradation from colored textile wastewater

In this paper, CuO/CNT nanocomposite was synthesized and its photocatalytic dye degradation ability for colored textile wastewater was studied. The characteristics of the nanocomposite were investigated by XRD, SEM and FTIR. The photodegradation of Direct Red 31 (DR31) and Reactive Red 120 (RR120) by CuO/CNT in presence of H₂O₂ was investigated. Photocatalytic dye degradation was determined by UV-vis spectrophotometer. Effects of catalyst dosage, initial dye concentration and salt on photodegradation performance were studied. The photocatalytic dye degradation ability of pure CuO and CuO/CNT nanocomposite is 78 % and 89 % for DR31 and 70 % and 87 % for RR120, respectively. The results showed that CNT increased the photocatalytic activity of CuO. The presence of salt decreases dye degradation efficiency. The dye degradation kinetics by nanocomposite followed first-order kinetic model. The reaction rate at 0.005 g catalyst was 0.0137 and 0.0105 min^-1 for DR31 and RR120, respectively. It was found that the CuO/CNT nanocomposite as a photocatalyst could be used to degrade dyes from colored wastewater.