Presence Of Dye Molecules Research Articles

Removal of Diazo Dye Direct Red 28 and Tetra Azo Dye Direct Black 22 Using Synthesized Magnetic Kaolin Supported Zinc Ferrite.

The presence of dye molecules in water resources has harmful effects on environment. Therefore, it is important to remove dyes from wastewater using eco-friendly materials. In this study, adsorptive removal of diazo dye Direct Red 28 (DR-28) and tetra azo dye Direct Black 22 (DB-22) was investigated by using a new composite, kaolin supported zinc ferrite (KZF) as adsorbent. Characteristics of the composite, KZF were determined using various techniques such as FTIR, SEM, XRD, VSM, and EDS/Mapping. The adsorption of DR-28 and DB-22 on KZF was studied as a function of contact time, initial dye concentration, adsorbent amount, temperature, initial pH of the solution as well as the heat treatment of the composite. The removal of DR-28 was found to be 92.4% for the KZF concentration of 1g/200mL, initial dye concentration of 20 mg/L, contact time of 120 min at original pH and 21°C. On the other hand the removal of DB-22 was found to be 91.7% under the same conditions at 40 °C. The results showed that Langmuir isotherm is suitable for the adsorption of DR-28 and DB-22 on KZF under given conditions. It was found that adsorption of DR-28 on KZF was exothermic while that of DB-22 was endothermic. The enthalpy changes (ΔH0) for the adsorption of DR-28 and DB-22 dyes on KZF were found to be -24.59 kJ/mol and 61.95 kJ/mol respectively. ΔS0 for the adsorption of DR-28 dye was found to be negative while ΔS0 for the adsorption of DB-22 was positive. The kinetic data fitted well to the pseudo second order model for the adsorption of DR-28 and DB-22 on KZF composite. These results showed that the prepared adsorbent KZF could be used as an adsorbent for the efficient removal of anionic dyes.

Thermal reduction of graphite oxide in the presence of nitrogen-containing dyes

Thermal reduction of graphite oxide (GO) is considered as a prospective method for the preparation of high-performance graphene-based materials. However, this method has certain limitations, and the major is that this exothermic process is difficult to control. In this research, we focused on the kinetic studies of the reduction of graphite oxide using non-isothermal differential calorimetry (DSC) method. Six GO nanocomposites with dyes were tested to study the shift in kinetic parameters. The apparent reaction order is determined to be ca 0.7 for the thermal decomposition of pure GO, while in the presence of dye molecules it increases sometimes reaching a value of 2.0 for higher dye concentrations. Decisively, the thermal decomposition of pure GO can be presented as an intermediate between a zero- and first-order reaction, while the introduction of dye molecules turns a certain part of the energy consumption via the bimolecular pathway. Our research revealed that the process of GO thermal decomposition can be operated and properties of the final product (reduced graphene oxide (rGO) and its derivatives) can be adjusted more precisely using additive molecules, which interact with GO sheets.

A study on structural, optical, thermal and electrical properties of the amaranth dye-doped KHOOD single crystal

Influence of amaranth dye on the potassium hydrogen oxalate oxalic acid dihydrate (KHOOD) single crystal is investigated. The structural studies were carried out to understand the crystal behavior after dye incorporation. Optical studies were performed to investigate the photon absorption of the crystal with or without the presence of dye molecule. The absorption of pure crystals were also compared with that of amaranth dye-doped crystals and the bandgap was estimated. The surface morphology and the presence of dye molecules are investigated using scanning electron microscope (SEM) and EDX analysis. The elemental mapping was carried out to understand the distribution of elements in the crystal surface. The thermal behavior of the crystal was studied and compared with that of KHOOD and dye-doped KHOOD crystals in detail. The emission properties of the crystals were studied and compared crystal. Field-dependent [Formula: see text]–[Formula: see text] studies were performed to study the conductivity of the crystals and results were discussed in detail.

Energy transfer kinetics in Basic Fuchsin dye sensitized CdS quantum dots

Sensitization of QDs (Quantum Dots) with a dye of good spectral overlap maximizes and extends the absorption range of incident photons. Interactions of Cadmium Sulfide Quantum Dots (CdS QDs) with Basic Fuchsin (BF) dye has been investigated in the present work using steady state and time resolved fluorescence emission techniques. The analysis has led to the inference that fluorescence resonance (Förster type) energy transfer (FRET) is the mechanism behind the fluorescence quenching of CdS QDs in the presence of dye molecules. An efficient energy transfer (~90%) from CdS donor to BF dye acceptor was observed and the FRET parameters such as Förster distance and spectral overlap integral were determined. The non-radiative energy transfer mechanism in QDs-dye binary mixtures holds great promise in analytical chemistry, biodetection system and in light harvesting systems.

Anion exchange membrane organic fouling and mitigation in salt valorization process from high salinity textile wastewater by bipolar membrane electrodialysis

To achieve a cleaner production, textile wastewater with high organic and salt content can be treated by using Bipolar Membrane Electrodialysis (BMED) to minimize acid and base consumption in a dyeing process. While the dye molecules may foul the ion exchange membranes and strongly affect the desalination process. This work aimed to investigate the performance and fouling mechanisms of BMED during desalination of sodium sulfate from Remazol Brilliant Blue R (RBBR). Results showed that maintaining the zeta potential of RBBR above −25 mV may mitigate fouling of AEM during the BMED process. This confirms that, zeta potential of charged foulants (RBBR) plays a key role in terms of controlling membrane fouling. Accordingly, a new parameter “critical salt concentration” was introduced to control membrane fouling. Furthermore, energy dispersive X-ray spectroscopy (EDS), FT-IR and electrochemical analysis confirmed that fouling of anion exchange membrane by RBBR was due to electrostatic interaction. Finally, it was calculated that 72.02% of sodium and 66.9% of sulfate in the feed were converted to NaOH and H2SO4, respectively. This study proves that BMED process may be an alternative way treating textile wastewater with high salinity and the presence of dye molecules.

Removal of hazardous basic dyes from aqueous solution by adsorption onto kaolinite and acid-treated kaolinite: kinetics, isotherm and mechanistic study

Presence of dye molecules in water causes various harmful effects for both human and aquatic species. Herein, we tried to remove two cationic dyes, namely Crystal violet and Brilliant green, from water by kaolinite clay mineral. The kaolinite clay mineral is further treated with 0.25 M and 0.05 M H2SO4 to increase its adsorption capacity. The structural changes due to acid treatment were analyzed by XRD, zeta potential, FTIR, SEM, cation exchange capacity, BET surface area, and pore volume measurements. Kinetic data were analyzed by using five different kinetic models and the data fitted best to pseudo-second-order model. Langmuir isotherm showed best fit to the adsorption of both Crystal violet and Brilliant green. Acid–treatment has slightly increased the adsorption capacities for both the dyes. The Langmuir monolayer adsorption capacity of raw kaolinite was found to be 47.17 and 25.70 mg g−1 for Crystal violet and Brilliant green, respectively, which increased to 49.50 and 50.51 mg g−1 for 0.25 M and 0.50 M acid-treated kaolinite in case of Crystal violet and to 26.45 and 26.88 mg g−1 in case of Brilliant green at 303 K. Crystal violet adsorption was exothermic with increase in ∆G values, whereas Brilliant green adsorption was endothermic in nature with decrease in ∆G in the temperature range 293–323 K. Reusability study showed the adsorbents could be successfully used up to 3rd cycle without much loss of adsorption capacity.

Fano resonance in a cholesteric liquid crystal with dye

In this paper, we consider the optical properties of cholesteric liquid crystals (CLCs) with a dye. We investigate the reflection, transmission, and absorption spectra peculiarities. We show that in the presence of dye molecules, in certain conditions, the photonic band gap (PBG) splits into two, three, etc., PBGs. A simple geometric method for determination of the Bragg frequencies and the widths of forbidden bands is proposed. It is shown that we can change the Bragg frequencies and the widths of forbidden bands by changing the parameters of dye molecules. We investigate the light localization peculiarities in the CLC layer in the presence of dye molecules. The peculiarities of the spectra of the photonic density of states and the spectra of light energy density in the CLC layer are also investigated. We show that in the presence of two types of resonances the observation of Fano resonance is possible. The peculiarities of Fano resonance in the CLC with dyes are investigated. We show that this system can be used for achieving a narrow bandwidth spectral response in transmission or reflection.

Effect of Biopolishing on Dye ability of Cotton Fabric - A Review

The effect of biopolishing treatment on color yield of cotton is of great importance to the dyers. Such treatment using cellulase has an influential role on dye ability of the fabric. Research into this area of dyeing has yielded apparently contradictory results. Cellulase treatment prior to dyeing can facilitate the dyeing process resulting in the higher color yield. However, zero impact or negative influence on the color yield of dyed fabric has also been reported. On the other hand, cellulase treatment after dyeing can be retarded by the presence of dye molecules or due to the interaction between dye molecules and cellulose. Though lots of research works have been done on bio polishing and as the application of the process in the textile industry has increased to a greater extent, the information on the effects of this process on color yield, both in cases of cellulase pre-treatment and posttreatment are absolutely necessary. Considering this the paper mainly focuses the previous works regarding the effects of cellulase action (Both before and after dyeing) on the color yield of dyed cotton.

Effect of Ag Nanoparticles Doped in Polymethyl Methacrylate Matrix for Luminescent Solar Concentrator

Metal-enhanced fluorescence (MEF) of Ag nanoparticles (NPs) in the presence of dye molecules has been studied for application in luminescent solar concentrator (LSC) devices. The LSC was prepared from bulk polymerization reaction of methyl methacrylate (MMA), which was the matrix for the LSC devices. The polymethyl methacrylate (PMMA) sheets doped by different dye concentrations were produced. The optical properties were characterized by absorption, emission and transmission spectroscopy measurements. Effects of dye concentrations on the photovoltaic performance of LSCs were investigated and discussed. Moreover, different concentrations of Ag nanoparticles were dispersed in the matrix in the presence of dye molecules in order to study the metal-enhanced fluorescence in material. The optimal concentration of Ag NPs resulting in a maximum fluorescence emission enhancement (almost 90 %) has been obtained which induced by the particular dye/Ag NPs composite materials. It depends on the coupling and spacing between neighboring dyes and Ag NPs. The result showed that the continuous transition from fluorescence enhancement to quenching, depending on Ag NPs concentration in the LSC device. The highest efficiency (1.96%) was achieved in solar cells which were assembled by the side of the PMMA sheets with dye concentration at 20 ppm.

Enhanced sensing of anthraquinone dyes using multiwalled carbon nanotubes modified electrode

The voltammetric behaviour of two anthraquinone dyes such as Alizarin Red S (ARS) and Reactive blue 4 (RB4) was investigated at plain glassy carbon electrode (GCE), multiwalled carbon nano tube modified GCE (MWCNT/GCE) and zeolite modified GCE (ZE/GCE) using cyclic voltammetry. Effects of pH, scan rate and concentration were studied. The surface morphology of the modified electrode in the absence and presence of dye molecules was characterized by scanning electron microscopy (SEM). A systematic study on the variation of experimental parameters with differential pulse stripping voltammetry (DPSV) was carried out and the optimized experimental conditions were arrived. MWCNT/GCE performed well among the three electrode systems and the limit of detection (LOD) was 0.036 µg mL−1 for ARS and 0.05 µg mL−1 for RB4 on this modified system. Suitability of the differential pulse stripping voltammetric method for the trace determination of textile dyes in effluents was also realized.

Treatment of dyeing solution by NF membrane for decolorization and salt reduction

A synthesized dyeing solution consisted of reactive dye, salts, and polyvinyl alcohol was prepared and treated by two different types of commercial nanofiltration (NF) membranes, i.e. NF90 and NF270 under various process conditions. These NF membranes were evaluated for permeate flux, salt, and color rejection as well as fouling propensity for a certain period of operation. Results revealed that NF90 suffered significant flux decline compared to NF270 after four operation cycles of treatment process, indicating its high sensitivity to foulant attachment. With respect to color removal, it is found that NF270 demonstrated greater stability in maintaining its separation efficiency (between 94 and 98% rejection) regardless of the feed properties and number of operation cycles. Though the salt rejection of NF270 was not as high as NF90, its consistent separation performance throughout the study period proved its reliability in long run. Recommended chemical cleaning process was also conducted in an effort to recover the membrane water flux due to the fouling. The results revealed that 90% of the initial water flux of NF270 was retrieved after a chemical cleaning. The water flux of NF90, however, was not able to be recovered. A water flux coefficient of 1.74 l/m2 h bar was reported after a chemical cleaning process in comparison to its virgin state of 5.43 l/m2 h bar. The irreversible fouling on NF90 was strongly linked to the pore blockage resulted from the presence of dye molecules in the feed solution. Based on these findings, it is showed that NF270 is more reliable and sustainable to be used in treating industrial dyeing wastewater. The high water productivity of NF270 coupled with high resistance against dye absorption may outweigh its relatively low rejection rate of salt in industrial applications.

Surface anchoring effect on guest–host ferroelectric liquid crystal response time – an electro-optical investigation

The effect is reported of surface anchoring on various electro-optical parameters of a pure ferroelectric liquid crystal (FLC) and five mixtures with different concentrations of dye. The Anthraquinone D5 dye was used as guest entity, whereas Felix 17-000 was used as host in this investigation. The presence of dye molecules in the FLC dramatically affects the electro-optical properties compared with those of the pure system. Electro-optical parameters such as spontaneous polarization and rotational viscosity not only change with the addition of dye but they are also strongly dependent on the concentration of dye in pure FLC. The effect of dye molecules on the anchoring energy of the pure FLC system was also investigated. Due to strong anchoring energy on FLC substrate, its effect on response time was also studied. An improvement in the contrast ratio after dye doping was observed. The value of spontaneous polarization increases due to addition of dye, suggesting that molecular alignment improves, which is very useful from the application point of view.

A novel route to synthesis of photoluminescent dye/polypyrrole nanoparticles: Effects of intermolecular energy transfer on nucleation and growth of polypyrrole

Photoluminescent dye/polypyrrole nanoparticles were prepared by one-step polymerization of pyrrole monomer in the presence of the dye molecules under UV light illumination. Oxygen in the air was selected as an oxidant in this method. Optical properties of the nanoparticles were investigated, revealing that the nanoparticles exhibited higher photostability than pure RhB. In addition, it was found that the presence of both dye molecules and UV light played the important role in the formation of the nanoparticles. And then the mechanism for the formation of well-confined nanoparticles was explained via the effects of intermolecular energy transfer between the dye molecules and pyrrole monomer on nucleation and growth of polypyrrole.

Variation of the morphology of electrodeposited copper thiocyanate films

Crystalline CuSCN films can be obtained by cathodic electrodeposition from solutions containing Cu(II) cation and thiocyanate anion. The change in film structure and morphology due to variation of the deposition conditions is investigated in view of applications of CuSCN in dye-sensitized p–n solar cells. Smaller grain sizes were obtained towards more negative deposition potentials, with higher ethanol fraction in the solvent and in the presence of dye molecules and surfactants as structure-directing additives. The largest effect was seen when varying the anion of the copper(II) salt and the cation of the thiocyanate salt in the deposition bath. While Cu(ClO 4) 2 and LiSCN lead to the formation of compact films, plate-like structures are seen with CuCl 2 and NH 4SCN and rod-like structures with NaSCN.

Synthesis of anionic water‐borne polyurethane with the covalent bond of a reactive dye

AbstractWe successfully synthesized an anionic water‐borne polyurethane (PU) capable of reacting with a reactive dye to form a covalent bond with the dye molecule. The anionic water‐borne PU was synthesized and grafted with the reactive dye to form a dyed PU. First, the PU prepolymer was synthesized from 4,4′‐methylene bis(isocyanatocyclohexane), poly(tetramethylene glycol), 2,2′‐bis(hydroxymethyl) propionic acid (as an anionic center), and triethyleneamide (as a neutralizer). Then, pure water was added to emulsify and disperse the prepolymer to form an anionic water‐borne PU prepolymer. Finally, the extender N‐(2‐hydroxyethyl) ethylene diamine was used to extend the anionic water‐borne prepolymer to form a PU polymer with hydroxyl groups that could further react with the reactive dye molecule. With respect to the heating properties, the dyed PU polymers exhibited higher glass‐transition temperatures of the hard segment than those without dye molecules. However, neither the glass‐transition temperature of the soft segment nor the melting temperature of the soft segment varied in the presence of dye molecules, but they were changed with various chain lengths of the soft segment. As for the mechanical properties, the modulus and strength of the dyed PU polymers decreased because of the bulkiness of their dye molecules, but the breaking elongation increased. Moreover, the inherent viscosity decreased in the presence of the dye molecules. As for the dyeing properties, the percentage of dye grafting was greater than 90%. The dye‐grafted PU exhibited a lower percentage of migration than PU extended with ethylene diamine (without hydroxy groups) and also showed a higher grade of colorfastness to light. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 797–805, 2002; DOI 10.1002/app.10336

Influence of organic dyes on potassium sulfate crystal growth: a joint morphological and atomic force microscopy analysis

In situ atomic force microscopy (AFM) was used to study potassium sulfate crystal growth in the presence of acid fuchsin and pyranine. These polysulfonated dyes are able to adsorb onto the {1 1 0} and {0 1 0} (pyranine only) crystal faces producing strong habit modifications. Using AFM, we analyzed the changes in surface micromorphology induced by the additives on advancing steps for the {1 1 0} and {0 1 0} surfaces. Evolution of micromorphology with time showed that at low supersaturations, layers grow by step flow at preexisting steps by the addition of growth units at the step edges. During growth, the presence of dye molecules at concentrations as low as ∼2×10−6 and ∼4×10−4 M for pyranine and acid fuchsin, respectively, produces significant changes in the step morphology and growth rates. Indeed, the additive molecules attach to the terraces pinning the growing front; as a consequence, the edges of the growing steps become jagged. At critical dye concentrations, crystal growth is heavily encumbered or even blocked along certain crystallographic directions. Concurrently, on a macroscopic scale strong habit modifications are observed. Comparison of our in situ AFM experiments with previous habit modification studies showed that acid fuchsin is also able to enter the {0 1 0} surfaces, a previously unnoticed phenomenon.

The Relationship between Hygral Expansion and Measured Set of Piece-Dyed Worsted Fabrics

The influence of applied dye on the dimensional and setting properties of 100% wool fabrics is examined. The presence of dye molecules and hydrophobic groups reduces hygral expansion independent of measured fabric set. A mechanism is proposed to explain these observations.

Resonance Energy Transfer from the Lowest Excited Triplet State of Diphenylcarbene to Dye Molecules: Utilization for the Characterization of the Triplet−Triplet Fluorescence

Triplet−triplet (T1 → T0) fluorescence spectra and decay curves of diphenylcarbene (DPC) in the absence and in the presence of dye molecules such as Rhodamine 6G and Rhodamine B were measured in several organic glasses at 77 K. In the absence of dye molecules, the T1 → T0 fluorescence signals exhibit biexponential decay with the lifetimes of ∼30 and ∼140 ns, which are attributable to the independent T1 → T0 emission from the individual T1 sublevels of DPC. In the presence of dye molecules, fluorescence decay signals of both fast and slow components were well analyzed in terms of resonance energy transfer of Forster type from DPC to dye molecule. The reaction scheme of the energy transfer and their various parameters are discussed on the basis of the independent T1 → T0 emission from the individual T1 sublevels of DPC at low temperature.

The effect of dyeing on the hygral expansion of worsted fabrics. Part 3ndashreactive dyeing

The influence of different types of reactive dye on fabric set and hygral expansion is detailed. Lanasol (α‐bromoacrylamide) reactive dyes were found to inhibit the development of set during dyeing, resulting in lower dimensional instability. The low hygral expansion is attributable to set inhibition by the fibre reactive group and to water exclusion by the presence of dye molecules. An alkaline aftertreatment is shown to result in increased fabric set and dimensional instability.