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.

Synthesis of Novel Acid Dyes with Coumarin Moiety and Their Utilization for Dyeing Wool and Silk Fabrics

This article describes the synthesis of some novel coumarin compounds to use as acid dyes by using compounds 1 - 4 as starting materials, which were prepared by interaction of 2-hydroxybenzaldehyde with ethyl 3-oxobutanoate, diethylmalonate, 4-nitrobenzenediazonium chloride and 4-sulfobenzenediazonium chloride, respectively. Compound 1 reacted with bromine and 2-cyanoacetohydrazide to give phenacyl bromide derivative 5 and 2-cyanoacetohydrazone derivative 6, respectively. Coupling of compound 6 with equimolar amount of 2-sulfo-4-((4-sulfophenyl) diazenyl)benzenediazonium chloride gave coumarin acid dye 8. Phenacyl bromide derivative 5 re-acted with potassium cyanide in refluxing ethanol to produce compound 7, which on coupling with equimolar amount of 8-hydroxy-6-sulfonaphthalene-2-diazonium chloride and 8-hydroxy-3,6-disulfonaphthalene-1-diazonium chloride gave coumarin acid dyes 9 and 10, respectively. Interaction of compound 2 with 2-amino-5-((4-sulfophenyl)diazenyl)benzenesulfonic acid, benzene-1,4-diamine and 3,3’-dimethoxy-[1,1’-biphenyl]-4,4’-diamine in refluxing ethanol afforded compounds 11, 12 and 14, respectively. Diazonium sulphate of compounds 12 and 14 coupling with 4-amino-5-hydroxynaphthalene-2,7-disulfonic acid gave compounds 13 and 15, respectively. Cyclocondensation of compound 3 with ethyl 3-oxobutanoate, diethyl malonate and malononitrile afforded derivatives of 3-acetyl-2H-chromen-2-one 16, ethyl 2-oxo-2H-chromene-3-carboxylate 17 and 2-imino-2H-chromene-3-carbonitrile 18, respectively. Reaction of sodium benzenesulfonate derivative 4 with ethyl 3-oxobutanoate and hydrazine hydrate gave compounds 19 and 20, respectively. The structures of the newly synthesized compounds were confirmed by elemental analysis, UV/ VIS, IR, 1H NMR and Ms spectral data. The suitability of the prepared dyestuffs for dyeing of wool and silk fabrics has been investigated. The dyed fabric shows good light fastness, very good rubbing, perspiration, washing and excellent sublimation fastness. These dyes have been color shade from blue to violet with very good depth and levelness on fabrics. The dye bath exhaustion and fixation on fabric has been found to be very good.

Sorption of Acid Dyes onto Silica Modified with Cetyltrimethylammonium Cations

The sorption behavior of acid dyes onto cetyltrimethylammonium bromide (CTAB)-modified silica as a function of pH in the aqueous medium was studied. Single-and multi-solute sorption equilibria of orange Ⅱ（OR), phenol red (PR) and Eriochrome Black T (EBT) were studied at pH 3, unbuffered water pH and pH 11. Sorption behavior of EBT could not be conducted at pH3 due to its aggregation in acidic medium. All the reaction conditions, experimental protocols and techniques remained the same throughout the sorption process. Sorption isotherms for single-solute system were fitted by the Langmuir model, while Langmuir competitive model (LCM) and the ideal adsorbed solution theory (IAST) coupled with Langmuir model (IAST/Langmuir) were used for the prediction of multisolute competitive sorption. Sorption affinities influenced by the factors like physical interactive forces between the molecules of CTA on silica and sorbate, structural limitations of the dyes based on their geometrical arrangement were investigated. Sorption affinity of OR was found to be higher than that of EBT and PR at all the pH values investigated. Magnitude of the sorption capacities was observed to be higher in acidic medium but lower in alkaline medium. Trends of the sorption affinities in multisolute system were simlar to those in single-solute system but magnitude of the sorption capacities was significantly reduced due to the prevailing competition among the sorbates.

Application of Acid Dyestuffs with Different Molecule Structure in Combined Dyeing and Finishing of Cotton Fabric

Simultaneous dyeing and durable press finishing of cotton fabrics with acid dyes bearing the different molecule structure and durable press finishing agent (DP agent abbr.) based on modified DMDHEU were investigated by using the pad-dry-cure process. Some factors affecting the process, such as structure of acid dyes, DP agent, catalysts and curing temperature were discussed. The dyed and finished fabrics were evaluated with respect to color strength, fixation, crease recovery angle, breaking strength and fastness properties. The results indicate that structure of acid dyes has a striking effect on the color strength of dyed and finished cotton fabric. The color strength and dry crease recovery angle of dyed and finished cotton fabric increases, whereas breaking strength decreases with increasing concentration of DP agent. It is necessary for ammonium nitrate to serve as catalyst. It is found that relatively satisfactory properties of dyed and finished cotton fabric can be obtained with appropriate adjustment of treating conditions.

Preparation of Acid Dyeable Polypropylene Fiber

A series of basic copolyamides has been synthesized withadipic acid(AA),hexamethylene diamine(HMDA)anddiethylenetriamine(DETA).Intrinsic viscosity determi-nation,thermal analysis and infrared spectrum analysisof the copolyamide indicates that molecular weight,ther-mal stability reduce whereas alkalinity increase with theincreasing fraction of DETA.Then acid dyeable polypro-pylene fibers are prepared by admixing polypropylene(PP)with those copolyamides prior to extrusion.Lowconcentration of the additive affects slightly on the crys-tallinity and the mechanical property of PP fiber.Themodified PP fibers have a nice acidic dyeability.

Sorption Behaviour of Acid Dyes by Soybean Protein/Poly(vinyl alcohol) Blend Fibre

The sorption behaviour of acid dyes by soybean protein/poly(vinyl alcohol) blend fibre was studied. The quantity of dye sorbed by the fibre increased markedly with the decrease in the pH of dyebath and reduced with the addition of neutral electrolyte when the pH was below 4.5. Acid dyes exhibited higher sorption rate constant and lower half dyeing time for the fibre than for spun silk and wool, which was related to the special morphological structure of the fibre. At pH 4, the sorption of disulphonated acid dyes with higher molecular weight followed the dual sorption mechanism of Langmuir plus Nernst-type partitioning well as they interacted with the fibre through electrostatic forces, hydrophobic forces and hydrogen bonds. It is considered that soybean protein and PVA components should be simultaneously dyed by disulphonated acid dyes with higher molecular weight.

THE COMPATIBILITY OF MIXED ACID DYES ON SILK

The compatibility of mixed acld dyes on silk has been surveyed by means of ascheme for compatibility rating.Experiments on the Influence of different dyeconstltutions,the ratio of dye concentrations,and dyeing processes oncompatibility have been made.The compatibility or some productive reclpesformed mainly by Lanasyn Blue GL(Cl Acid Blue 127:1)and Milling Navy 5R(Cl Acid Blue 113)has also been measured.The paper indicates that the dyeswith the approximate affinities and diffusion coefficients,high ratio of dyeconcentrations,and reasonable dyeing processes make the good compatibillty ofmixed acid dyes on silk.It may be served as a guide to production in reasonablyselecting dyes and dyeing processes.

Inhibitive Effect of NaCl and Citric Acid on the Colour Yield of Acid Dye on Nylon Fabric

Nylon 6 fabric was dyed with C.I. Acid Yellow 23 at a temperature 50?°C using sodium chloride (NaCl) and citric acid as auxiliaries. The adsorption kinetic mechanism was studied using two models. Results of the UV-Vis spectroscopy indicated that colour yield of C.I. Acid Yellow 23 reduced when more than 1% (acid) and 5% (salt) concentration were used respectively for dyeing. NaCl however had the most inhibitive effect on the dye colour yield. The adsorption kinetics mechanism result fitted the pseudo-second-order-kinetic model with R2 of 0.993.

CI Acid Orange 52 Dye Removal Using Natural and Formulated Clay-Lime Materials: Isotherm, Kinetic and Thermodynamic Studies

The main objective of the study is to improve the removal efficiency of Ourlago-kaolin (Kao), sodium montmorillonite (Na-MMT), and two formulated clay-lime (F13 and F23) towards CI Acid Orange 52 dye (AO52). F13 and F23 were obtained by chemical stabilization through thermal treatment at 300°C. Fourier Transform Infrared spectra showed different surface functional groups on the clay materials, X-ray diffraction patterns revealed the raw materials contain many crystalline phases, scanning electron microscopy micrographs showed the variation of the layered structures of different clay materials, energy dispersive X-Ray analysis micrographs revealed compositional information and thermogravimetric-differential scanning calorimetry curves indicated the higher weight loss of 11.26% and 11.38% were observed for F13 and F23 respectively. BET surface area analyzed gave 133.0071 m2•g−1 for F13 and 132.34803 m2•g−1 for F23. The optimum pH value was 2.0 for Kao and Na-MMT. The adsorption experiments indicated that F13 and F23 have the maximum uptake abilities of 7.8740 and 3.1645 mg•g−1, respectively, compared to Kao (0.8761 mg•g−1) and Na-MMT (2.6178 mg•g−1). The pseudo-second-order model well described the adsorption kinetic model of AO52 dye onto the overall samples;Langmuir and Freundlich’s isotherms appropriately described the uptake mechanism. The positive values of ∆G° and negative value ∆H° indicated that the adsorption process was spontaneous and endothermic for Na-MMT, and non-spontaneous and exothermic for Kao, F13, and F23 because of their positive values of ∆G° and negative value of ∆H°. The modified clays have higher adsorption capacities and better life cycles compared hence opening new avenues for efficient wastewater treatment.

Adsorption characteristics of humic acid-immobilized amine modified polyacrylamide/bentonite composite for cationic dyes in aqueous solutions

Humic acid-immobilized amine modified polyacrylamide/bentonite composite （HA-Am-PAA-B） was prepared and used as an adsorbent for the adsorption of cationic dyes （Malachite Green （MG）, Methylene Blue （MB） and Crystal Violet （CV）） from aqueous solutions. The polyacrylamide/bentonite composite （PAA-B） was prepared by intercalative polymerization of acrylamide with Nabentonite in the presence of N,N＇-methylenebisacrylamide as a crosslinking agent and hexamethylenediammine as propagater. PAA-B was subsequently treated with ethylenediammine to increase its loading capacity for HA. The surface characterizations of the adsorbent were investigated. The adsorbent behaved like a cation exchanger and more than 99.0% removal of dyes was detected at pH range 6.0-8.0. The capacity of HA-Am-PAA-B was found to decrease in the following order： MG〉MB〉CV. The kinetic and isotherm data were interpreted by pseudo-second order rate equation and Freundlich isotherm model, respectively. Experiments were carried out using binary solute systems to assess the competitive adsorption phenomenon. The experimental isotherm data for each binary solute combination of MG, MB and CV were analyzed using Sheindrof-Rebhun-Sheintuch （SRS） （multicomponent Freundlich type） equation.

Biodegradability of terephthalic acid in terylene artificial silk printing and dyeing wastewater

As the characteristic pollutant, terephthalic acid(TA)was in charge of 40%—78% of the total COD of terylene artificial silk printing and dyeing wastewater(TPW-water). The studies on biodegradability of TA were conducted in a serial of activated sludge reactors with TPW-water. TA appeared to be readily biodegradable with removal efficiency over 96.5% under aerobic conditions, hardly biodegradable with removal efficiency below 10% under anoxic conditions and slowly biodegradable with a turnover between 31.4% and 56.0% under anaerobic conditions. TA also accounted for the majority of BOD in TPW-water. The process combined by anoxic, anaerobic and aerobic activated sludge reactor was suitable for TA degradation and TPW-water treatment. Further, the aerobic process was essentially much more effective than the anaerobic or anoxic one to degrade TA in TPW-water.

COLOUR SYSTEMS OF MIXED POLYNUCLEAR COMPLEXES OF LANTHANUM-2,7-BISAZOCHROMOTROPIC ACID DYES-ZINC-O-PHENANTHROLINE

In the preceding work we discussed the formation of mixed polynuclear complexes (MPC) of rare earth-arsenazo Ⅲ-copper-o-phenanthroline. This note reports the action rule of various 2, 7-bisazochromotropic acid dyes with different structures in this kind of colour reactions. The experiments showed that only those symmetric 2, 7-bisazochromotropic

Adsorption behavior of Azo Dye C. I. Acid Red 14 in aqueous solution on surface soils

Azo dyes have received considerable attention because of their association with various human health problems. The aim of the investigation is to determine the adsorption behavior ofazo dyes in aqueous solution on DG06, GSE17200, and GSE17201 soils using C. I. Acid Red 14 （AR14） as example. The experimental results indicate that the Freundlich model expresses the adsorption isotherm better than the Langmuir model and the pseudo-second-order model achieves adsorption of AR14 on the three soils well. Based on the pseudo-second-order model, the adsorption thermodynamic of AR14 on DG06 soil have been studied and the thermodynamics parameter of AGO is determined and AGO value shows the adsorption process of AR14 on DG06 is mainly physical in nature. Furthermore, the effects of temperature, pH and salinity （NaC1） on adsorption have been investigated. The decrease in pH or the increase in salinity enhances the adsorption of AR14 by DG06, GSE17200, and GSE17201.

Comparing the Effect of Different Concentration of Sulfuric Acid Differentiation Solution on Acid Fast Dyeing

Objective: In the acid-fast staining experiment of pathological tissues, sulfuric acid and hydrochloric acid were used to evaluate the staining results, so as to get the best staining method. Methods: Using sulfuric acid differentiation solution and hydrochloric acid differentiation solution, the paraffin blocks of pathological tissues known to contain Mycobacterium tuberculosis were compared to evaluate the staining effect. Results: When 0.5% hydrochloric acid differentiation solution is used and the differentiation time is 6 s, the dyeing effect is better than that of sulfuric acid differentiation solution.

UV-A Activated ZnO Mediated Photocatalytic Decolorization of Nigrosine (Acid Black 2) Dye in Aqueous Solution

The present study deals with studied the essential requirements for photo-decoulorization of nigrosine dye with suspension solution of photocatalyst (ZnO), under 250 Watt UV-A light (Io = 1.47 10-7 ensien s-1). A kinetics study of photo-decolourization for this dye was obeyed to pseudo-first order. The best initial pH of decolorization at 25 mg/L of dye solution with 300 mg of ZnO was given a fast reaction at 8.17. The calculated activation energy for this photoreaction was found to be 31.549 kJ·mol-1. Thermodynamically, the reaction is exothermic and spontaneously. The efficiency of decolorizatio E% was 97.077 at 15 min that decreased with addition oxidant reagents such as H2O2, Fe2+ and mixture from them.

Study on Dyeing of a Novel,Pro-environment Polylactic Acid (PLA) Fiber Yarn

Seventeen disperse dyes including anthraquinone, azo, methine, nitro, and quinoline dyes were applied to dye the Polylactic Acid (PLA) yarns at different conditions, and the dyebath exhaustion was determined. The result shows that C.I. disperse red 167, C.I. disperse orange 30, and C.I. disperse blue 284 have dye-uptakes greater than 80%. Therefore, they can be used as the three principal dyes for PLA yarns. The experiment discovered that the dyes, because of their Monoazo and ester group contents, have a higher dye-uptake for the PLA fiber. The research on the optimization of dyeing techniques suggests that PLA yarn can obtain a high level of dyeing effectiveness at the following conditions: pH 4-5, dyeing temperture 110℃ for 30-40 min. Color fastness to perspiration, and water-washing fastness increased 1-1.5 by the addition of the abstergent FB during the reduction clearing.

Dyeability of Polyester and Polyamide Fabrics Employing Citric Acid

The employment of sustainable chemicals, such as citric acid, represents a possibility for the development of textile dyeing processes. This study aimed to analyze the possibility of replacement of acetic acid (commonly used in textile processing) by citric acid in polyester and polyamide 6 dyeing processes. The utilization of citric acid as leveling agent for disperse dyestuffs was also investigated. Dyeing processes in turquoise color for these fabrics were performed employing citric and acetic acid. Color differences between dyeing processes and color fastness to water were evaluated. All the color dyeing differences were not significant and there was no transference in color fastness tests (grade 5). Otherwise, the differences among polyamide dyeing processes could be related to the efficiency of citric acid solution as sequestering agent. Notwithstanding citric acid to be more expensive than acetic acid and the need of previous dissolution by stirring, it could be advantageous for some formulations.

Poly (Acrylamide-co-Acrylic Acid) Hydrogel Induced by Glow-Discharge Electrolysis Plasma and Its Adsorption Properties for Cationic Dyes

In this paper, poly （acrylamide-co-acrylic acid） （P（AM-co-AA）） hydrogel was pre- pared in an aqueous solution by using glow-discharge electrolysis plasma （GDEP） induced copoly- merization of acrylamide （AM） and acrylic acid （AA）, in which N,N＇-methylenebisacrylamide （MBA） was used as a crosslinker. A mechanism for the synthesis of P（AM-co-AA） hydrogel was proposed. To optimize the synthesis condition, the following parameters were examined in detail： the discharge voltage, discharge time, the content of the crosslinker, and the mass ratio of AM to AA. The results showed that the optimum pH range for cationic dyes removal was found to be 5.0-10.0. The P（AM-co-AA） hydrogel exhibits a very high adsorption potential and the ex- perimental adsorption capacities for Crystal violet （CV） and Methylene blue （MB） were 2974.3 mg/g and 2303.6 mg/g, respectively. The adsorption process follows a pseudo-second-order kinetic model. In addition, the adsorption mechanism of P（AM-co-AA） hydrogel for cationic dyes was also discussed.

基于核酸杂交反应的荧光生物传感器的制备及在黄曲霉毒素B_1检测中的应用

采用核酸适配体作为特异性识别元件,SYBR Green I(SGI)荧光染料为信号输出单元,构建了黄曲霉毒素B_1(AFB_1)生物传感器,并对试验条件进行了优化。优化的试验条件如下:适配体互补链与适配体的物质的量比为1.5,SGI加入量为10μL,适配体双链与SGI的作用时间为2 min,适配体与AFB_1作用时间为14 min。结果表明,在AFB_1质量浓度为0.1~1 000μg·L^(-1)时,荧光强度变化量与其质量浓度对数呈线性关系,检出限(3S/N)为0.081μg·L^(-1)。对实际玉米样品进行加标回收试验,回收率为95.2%~105%,测定值的相对标准偏差(n=7)均小于6.0%。与其他适配体传感器进行比较,该方法所构建的荧光适配体传感器对AFB_1的检测具有操作简便、检测范围宽、灵敏度高、特异性强、成本低廉等优点,适合现场快速测定。