Dye System Research Articles

Synthesis of mesoporous-structured MIL-68(Al)/MCM-41-NH2 for methyl orange adsorption: Optimization and Selectivity

Here, we report a novel amino-modified mesoporous-structured aluminum-based metal-organic framework adsorbent, MIL-68(Al)/MCM-41-NH2, for dye sewage treatment. The introduction of molecular sieves overcomes the inherent defects of microporous MOFs in contaminant transfer and provides more active sites to enhance adsorption efficiency. Compared with using organic amino ligands directly, this strategy is ten times cheaper. The composite was well characterized and analyzed in terms of morphology, structure and chemical composition. Batch experiments were carried out to study the influences of essential factors on the process, such as pH and temperature. In addition, their interactions and the optimum conditions were examined using response surface methodology (RSM). The adsorption kinetics, isotherms and thermodynamics were systematically elucidated. In detail, the adsorption process conforms to pseudo-second-order kinetics and follows the Sips and Freundlich isothermal models. Moreover, the maximum adsorption capacity Qs of methyl orange (MO) was 477 mg g−1. It could be concluded that the process was spontaneous, exothermic, and entropy-reducing. Several binary dye systems have been designed for selective adsorption research. Our material has an affinity for anionic pigments. The adsorption mechanisms were discussed in depth. The electrostatic interaction might be the dominant effect. Meanwhile, hydrogen bonding, π-π stacking, and pore filling might be important driving forces. The excellent thermal stability and recyclability of the adsorbent are readily noticed. After five reuse cycles, the composite still possesses a removal efficiency of 90% for MO. Overall, the efficient and low-cost composite can be regarded as a promising adsorbent for the selective adsorption of anionic dyes from wastewater.

An experimental and theoretical investigation of cationic azine dye adsorption on natural sepiolite in single and multi-component systems

Adsorption kinetics and equilibria of the azine dyes onto natural sepiolite are investigated using Methylene Blue, Thionin and Safranin O. Experimental equilibrium results for three azine dyes are well predicted by the Freundlich, Langmuir and Redlich-Peterson isotherm models. The model parameters obtained for single solute systems at 298 K are used for the calculation of adsorption isotherms in binary and ternary dye solutions using multi-component isotherm models. Modified extended Langmuir model is satisfactorily fit to the adsorption in binary and ternary solutions. The diffuse-reflectance-infrared-Fourier-transforms technique was used to characterize the bare and dye loaded sepiolite surface. The kinetic results for single, binary and ternary dye systems have been analyzed according to the pseudo-first-order and Elovich models. Vermeulen approximation was also applied to the data for prediction of the diffusion behavior of the dyes. The molecular chemical reactivity of the dye molecules estimated based on the Density Functional Theory was well correlated to the sorption results. The energy gap between the highest-occupied molecular-orbital and lowest-unoccupied-molecular-orbital energies, chemical potential, chemical hardness, softness, global electrophilicity and global nucleophilicity values prove that Methylene Blue is more reactive than Thionine and Safranine O cationic dyes.

Optimizing wastewater heat recovery systems in textile dyeing processes using pinch analysis

• An optimal WWHR system for textile dyeing was developed using a two-step approach. • The two-step approach comprises the scenario definition and pinch analysis. • The cost-optimal WWHR system lowered the energy usage by 28.64% and TAC by 73.65%. • The PBP of the optimal WWHR system was 4.32 y. Textile manufacturing discharges large amounts of wastewater containing significant amounts of thermal energy. The textile dyeing process consists of several complex processes with different operating times, temperatures, and water usage. The absence of a suitable wastewater heat recovery (WWHR) system requires a large amount of energy for heating fresh water and cooling wastewater. Therefore, recovering wastewater while satisfying the operating conditions of each process is crucial. Herein, we suggest an optimal design for WWHR systems to maximize the energy efficiency in the textile dyeing process using pinch analysis by a novel two-step approach. First, the scenarios for all feasible WWHR methods were defined, and the WWHR systems were designed accordingly by integrating a heat pump and heat exchanger. Second, the heat exchanger network of the developed WWHR systems was modified based on pinch analysis to maximize the waste-heat recovery efficiency. Finally, to derive the cost-optimal WWHR system, a techno-economic analysis was conducted. The total annualized cost (TAC), based on the capital and operating cost, was determined based on current and potential future economies. The proposed energy-saving measures reduced the TAC by 28.6% and obtained a payback period of up to 4.3 y.

Coupling between Plasmonic and Molecular Excitations: TDDFT Investigation of an Ag-Nanorod/BODIPY-Dye Interaction.

A time-dependent density functional theory (TDDFT) computational approach is employed to study the optical coupling between a plasmonic system (a Ag50 nanorod) and a fluorescent dye (BODIPY). It is found that the BODIPY dye can interact with a plasmonic system in a rather different and selective way according to the mutual orientation of the fragments. Indeed, (i) the plasmon excitation turns out to be sensitive to the presence of the BODIPY transition and (ii) this can lead to amplify or suppress the resonance accordingly to the relative orientation of the corresponding transition dipoles. To understand the coupling mechanism, we analyze the shape of the induced density in real space and the Individual Component Map of the Oscillator Strength (ICM-OS) plots and achieve a simple rationalization and insight on the origin and features of the coupling. The resulting possibility of understanding plasmon/fluorophore interactions by simple qualitative arguments opens the way to a rational design of hybrid (plasmon + dye) systems with the desired optical behavior.

Migration and Chemical Characterization of Cyclic Oligomers from Polyester Fiber in Waterless Dyeing System

Migration and Chemical Characterization of Cyclic Oligomers from Polyester Fiber in Waterless Dyeing System

Correction to: Study of factors affecting the color fastness of high depth fiber dyed in silicon non-aqueous medium dyeing system

Correction to: Study of factors affecting the color fastness of high depth fiber dyed in silicon non-aqueous medium dyeing system

Graphene oxide incorporated chitosan/acrylamide/itaconic acid semi-interpenetrating network hydrogel bio-adsorbents for highly efficient and selective removal of cationic dyes

In recent years, polymeric bio-adsorbents offers high removal efficiency, superior adsorption capacity and selectivity against various pollutants in aqueous medium. While designing these adsorbents, their environmental friendliness, sustainability, renewability, easy accessibility, and cost-effectiveness should be considered. In this study, GO incorporated semi-interpenetrating network (semi-IPN) nanocomposite hydrogels (CS/AAm/IA/GO) were obtained by free radical copolymerization of acrylamide (AAm) and itaconic acid (IA) in the presence of chitosan (CS) as an environmentally friendly bio-adsorbent. GO significantly improved the thermal stability, compressive strength, and percentage swelling of the hydrogel. The selective adsorption studies demonstrated that methylene blue (MB) was the most efficiently removed dye from both individual and mixed dye systems with 99.8 % removal efficiency. The adsorption capacity was found to be 247.47 mg g−1 using 0.025 g hydrogel adsorbent containing 0.5 wt% of GO and an initial MB concentration of 5 mg L−1 at pH 8 over 90 min at room temperature. The kinetic and isotherm studies revealed that the adsorption process followed the pseudo-second-order kinetic model and Langmuir adsorption isotherm. Thermodynamic studies suggested the spontaneous and endothermic nature of MB adsorption. Also, the MB removal efficiency above 96 % was obtained after 7 consecutive adsorption-desorption cycles while maintaining the structural stability of the bio-adsorbent.

Micellization, aggregation, and molecular interactions involved in CTAB‐Alizarin Red S complexation

AbstractSurfactant–dye complexation between anionic dye: Alizarin Red S (ARS) and cationic surfactant:cetyltrimethylammonium bromide (CTAB) was investigated in an aqueous medium at 303.15 K employing various physicochemical characterization to offer an understanding of the micellization conduct. Here, micellization and thermodynamic parameters have been calculated using the tensiometry and conductivity approach. The critical micelle concentration (CMC) of CTAB is observed to decrease in presence of ARS. The Gibbs energy of micellization () remains be negative on increasing the ARS content which indicated the spontaneity of the overall micellization process. Cyclic voltammetry (CV) reflected the impact of interactions between CTAB and ARS. ARS solubilization in CTAB micelles caused a red (bathochromic) shift in the ultraviolet–visible spectrum below the CMC thereby inferring that ARS undergoes J‐type aggregation in the pre‐micellar region. The intercept drawn following the Job's (corrected absorbance vs. CTAB volume ratio plot) method depicted the volume fractions of (equimolar) ARS (VARS) and CTAB (VCTAB) expressed in v/v occurring at VARS/VCTAB = 0.52/0.48, suggesting their stoichiometric ratio of 1:1 amid each molecule of ARS and CTAB leading to CTAB‐ARS ion‐pair complexation. A computational simulation method using molecular orbital energy calculations was used to evaluate the successive correlation between CTAB and ARS to comprehend the binding mechanism. The lower energy gap (ΔE) value of CTAB‐ARS indicated the favorable interaction of ARS with CTAB. Thus, the present work will reflect the significance of surfactant–dye systems in analytical and biochemistry research; and may open novel possibilities in dye absorption and their applications in the removal of dyes using surfactants.

Preparation of a 3D flower-like spherical structure g-C3N4/CuBi2O4/Bi2MoO6 photocatalyst for efficient removal of antibiotics under visible light

For the remediation of antibiotic-contaminated water bodies, this study synthesized g-C3N4/CuBi2O4/Bi2MoO6 3D flower-like spherical photocatalysts by a solvothermal method. The tetracycline antibiotics were used as the target pollutants and degraded under visible light to evaluate the photocatalytic performance of the prepared photocatalysts. Notably, the g-C3N4/CuBi2O4/Bi2MoO6 photocatalyst achieved 84.6 % and 91.6 % for the degradation of tetracycline hydrochloride and chlortetracycline (100 mL, 20 mg/L), respectively, within 2 h under visible light irradiation. Furthermore, we found that the composites showed very low degradation rates for dye-based contaminants, but still exhibited excellent photocatalytic activity for antibiotics in a mixed contaminant system of dyes and antibiotics. And the intermediate was detected by gas chromatography-mass spectrometry (GC–MS), suggesting a possible photo-degradation pathway for tetracycline. Finally, biochemical experiments were carried out to further illustrate the effective degradation of antibiotics in water after photocatalytic degradation by observing and comparing the growth of mung bean seeds.

Study of Factors Affecting the Color Fastness of High Depth fiber Dyed in Silicon Non-aqueous Medium Dyeing System

Study of Factors Affecting the Color Fastness of High Depth fiber Dyed in Silicon Non-aqueous Medium Dyeing System

Sustainable silk dyeing in a silicon non-aqueous dyeing system with Reactive Red 195: salt-free and less alkali

Conventional dyeing processes usually generate a huge amount of wastewater, and in general, silk dyeing with reactive dyes using large amounts of salt and alkali has a great environmental impact. Herein, a green approach for a new dyeing system involving silk fabric dyed with reactive dyes in a silicon non-aqueous dyeing system without salt was reported. The optimal dyeing parameters of silk fabric dyed in this green dyeing system without alkali were 90°C for 75 minutes and with alkali were 70°C for 75 minutes, and the Reactive Red 195 exhibited good dye permeability, superior exhaustion, high fixation rate, and good dyeing depth, indicating the high utilization of dye and less effluent discharge. The color fastness of silk fabric dyed in the silicon non-aqueous dyeing system was comparable to silk fabric dyed in the conventional water bath. In addition, the fixation rate and K/ S value were improved by the addition of 0.4% (o.w.f) NaHCO3, which cannot be obtained in a conventional water bath, and all silk fabrics showed better tensile strength dyed in the green dyeing system. Therefore, the sustainable green dyeing method with a silicon non-aqueous system achieved a salt-free, less alkali or alkali-free, and simple process, which has the potential to solve the problems of wastewater, high salt, and high alkali in conventional dyeing processes.

Study of Electrical Output in Photogalvanic Cell for Solar Energy Conversion and Storage: Lauryl Glucoside-Tartrazine-D-Fructose System

Objective: The present study is focusing on the role of surfactant in photogalvanic cells and how photons from sunlight can be used as a driving force for energy solar energy conversion and storage. Methods: An H shaped cell was designed for study of electrical output in solar transformations. Electrical circuit was proposed by using of dye, reductant, surfactant, NaOH, double distilled water (DDW), multi-meter, calomel electrode, 250 k roistered, saturated calomel electrode, platinum electrode, carbon pot, resistance key, digital pH meter, microammeter, and 200 W tungsten bulb. A detailed reaction mechanism for the proposed photogalvanic cell (PG Cell) for generating photocurrent and photocurrent has been studied. PG Cells were studied for the solar energy transformation system. Findings: PG Cells were studied by using different parameters via photocurrent, photopotential, conversion efficiency, fill factor and cell performance. The above values are as follows: 388.0 □A, 1141.0 mV, 0.7995%, 0.5389 and 129.0 minutes. Electrical output of the cell has also been observed for tartrazine, D-Fructose and lauryl glucoside systems. Potential at power point, Potential at open circuit, power point of cell (pp) and current at short circuit were also studied. The obtained values are as follows: 1133 mV, 1523 mV, 435.321 and 544mA. Novelty: The photogalvanic is an emerging field of research for conversion and storage of solar energy. This study employs lauryl glucoside-tartrazine-D-fructose system for better electrical output which is also an eco-friendly natural dye system. The observed results are better in cell performance (t1=2) and reduction in cost (INR 9531.38 / USD 125) of the photogalvanic cell for its commercial viability. Keywords: Photogalvanic cells; solar energy conversion; storage; lauryl glucoside; tartrazine

Adsorption Behaviors of Cationic Methylene Blue and Anionic Reactive Blue 19 Dyes onto Nano-Carbon Adsorbent Carbonized from Small Precursors.

In this work, an innovative nano-carbon material (N-CM) adsorbent was reported for exploring its adsorption behaviors toward cationic methylene blue (MB) and anionic reactive blue 19 (RB19) pollutants. The proposed N-CM was synthesized by a one-step solvothermal treatment of citric acid and zinc gluconate small precursors. N-CM consists of nanosheets that have an advantageous specific surface area, large sp2/sp3 hybridized domains, and abundant nitrogen/oxygen-containing surface functional groups. The synergistic effects of these features are conducive to the MB and RB19 adsorption. Different from anionic RB19 adsorption (79.54 mg/g) by the cooperative π-π stacking and hydrogen bonding, cationic MB adsorbed onto N-CM mainly by the electrostatic attraction at the natural pH solution (> pHpzc), with an adsorption capacity up to 118.98 mg/g. Interestingly, both MB and RB19 adsorption conformed to the pseudo-second order kinetic (R2 ≥ 0.995) and Langmuir isothermal (R2 ≥ 0.990) models, accompanied by similar maximum monolayer adsorption capacities of 120.77 and 116.01 mg/g, respectively. Their adsorption processes exhibited spontaneously endothermic characteristics. Moreover, N-CM showed superior selective capability toward MB in different mixed dye systems, with high removal efficiencies of 73–89%. These results demonstrate that the high-performance carbon adsorbent prepared from small precursors via low-temperature carbonization shows great potentials in wastewater treatment.

Spectroscopic, conformational analysis, structural benchmarking, excited state dynamics, and the photovoltaic properties of Enalapril and Lisinopril

There have been numerous attempts to theoretically design a better photovoltaic property with much interest on how to improved absorption and emission parameters of most reactive compounds in respect to dye – sensitized solar cells (DSSCs). This is regardless of the promising futures of the photovoltaic properties. However, for such effective design, it is necessary to understand the electronic and photophysical properties of the dye systems. Herein detailed density functional theory (DFT) and time – dependent DFT (TD-DFT) investigation of the excited state characteristics and the influence of various solvents: water, acetone, ethanol and chloroform on the photophysical properties of enalapril and lisinopril were investigated along with the experimental spectral (UV–vis and FT-IR) analysis. The electronic structure calculations were conducted using the 6–311++G(d,p) basis set in combination with B3LYP, M06-2X, and ꞷB97XD DFT functionals for the structural benchmarking investigations of the studied compounds. Results of the excitation electronic analysis of enalapril was observed to have wavelength absorption in the order gas > chloroform > ethanol > water which correspond to 229.19, 228.81, 228.85, 229.03 nm respectively while Lisinopril have the order of chloroform > gas > water > ethanol which present ethanol have the highest transition energy. In all the studied structured, the transition assignment corresponds to π → π* all corresponding to the Frank -Condon local excitation. It can be inferred from the photovoltaic properties that among the studied compounds in four different phases enalapril have the highest oscillator strength, but the values of light-harvesting efficiency (LHE) varies and show greater stability in Lisinopril. Lisinopril was observed to have the highest value of VOC compared to Enalapril this further confirmed the result obtained from the frontier molecular orbitals.

Salt-free dyeing of cotton fabric and adsorption of reactive dyes in non-aqueous dyeing system: equilibrium, kinetics, and thermodynamics

Salt-free dyeing of cotton fabric and adsorption of reactive dyes in non-aqueous dyeing system: equilibrium, kinetics, and thermodynamics

Distribution mechanism of disperse dyes with similar substituents in a waterless dyeing system based on molecular dynamic simulation

In this paper, starting from the dye molecular structure activity relationship, the effect of substituents on the coloration process, such as dissolution, adsorption and diffusion behaviors, was investigated by molecular dynamics simulations in a waterless dyeing (D5) system. Related dyeing experiment test were performed to verify the accuracy of the simulation results. The results showed that the diffusion coefficient of disperse dyes decreased gradually due to an introduction of one ortho-substituent cyano group compared with unsubstituted dyes. Meanwhile, using the substituent N-cyanoethyl group instead of N-ethyl group in coupling component further decreased the diffusion coefficient, which was attributed to an increase of aggregation capacity. Simultaneously, the solubility of disperse dyes containing bis N-cyanoethyl groups in D5 media also decreased obviously due to the low dye-D5 interaction energy, which was consistent with their aggregation behavior. Additionally, the growing strong interaction energy between dye molecules and polyester fibers due to an introduction of cyano group or N-cyanoethyl group contributed to increasing the adsorption efficiency and dyeing uptake. It will be an effective and labor-saving method to select and develop the special disperse dyes for the sustainable D5 dyeing system.

A review on reverse micellar approach for natural fiber dyeing

AbstractThis study reviews the need and importance of non‐aqueous dyeing systems in the chemical processing industry, especially using the reverse micellar system in the dyeing of natural fibres. When it comes to conventional dyeing systems, which use large quantities of water, chemical, and energy, cause a lot of effluent load to the environment. Again the effluent water has to be treated well to eliminate all the harmful substances in it. To overcome the issues, a lot of research has been carried out in this area to minimise the use of water and chemicals in the dyeing process. Like use of low material to liquor ratio (M:L) in dyeing, dyes with high fixation at lower temperatures, low/salt less dyeing in case of reactive dyeing with cotton, cottonseed oil dyeing, microwave‐assisted dyeing, and use of supercritical carbon dioxide in case of polyester dyeing and many more. All the above said methods are aqueous‐based and, after the completion of dyeing, results in wastewater generation, which requires further treatment to reduce the harmful chemicals. Therefore, to further minimise the use of water and chemicals in the dyeing of natural fibres reverse micellar system has been introduced with the help of surfactants of both Ionic and nonionic in nature. As of today, a lot of work has been carried out in the dyeing of natural fibres with this system by employing ionic, nonionic, and mixed surfactants. Fascinating results were obtained in the dyeing with good levelness, high exhaustion, and fixation values, and results were compared with conventional dyeing. Computer colour matching studies were also done better to understand the applicability of these systems in the industry and found nearer results.

Fe2+/Fe3+ based MOIFs + dye interaction study: Thermodynamic and kinetic analysis estimated through spectrophotometrically

Herein, the interaction study of organic dyes with newly reported metal organic ionic frameworks (MOIF) based on [Fe(CN)6]3-/[Fe(CN)6]4-/[Fe(CN)5NO]2- and cetylpyridinium cation, investigated through spectrophotometric method. Measurements were carried out at 303.15, 308.15 and 313.15 K where interaction found to be decreased with increase in temperatures. The 60–90% maximum interaction was noted for [Fe(CN)5NO]2- based MOIF with all chosen dyes at 303.15 K inferring the high interaction ability associated with dissymmetry of this MOIF due to presence of different ligands. The oxidation state and hydrophilicophobic domains of MOIFs have been found accountable for the stronger interaction where Fe2+ with high hydrophobicity was found more interacting as compared to Fe3+ with less hydrophobicity. The activation parameters ΔG0, ΔH0 have been found greater for MOIFs and methylene blue dye systems due to stronger interaction of their hydrophobic domains. The ΔS0 noted greater for [Fe(CN)5NO]2- based MOIF showing the impact of availability of interacting sites and distortion in symmetry. The isotherm analysis has inferred about the maximum uniform distribution of binding energy, favorability of interaction, interaction capacity and intensity, was associated with methylene blue and MOIFs systems. The positive slope (2.303/K) of a plot of log(Ao/At) vs t (time) inferred the first order kinetic of MOIF and chosen dyes.

FeOOH quantum dot decorated flower-like WO3 microspheres for visible light driven photo-Fenton degradation of methylene blue and acid red-18

In this study, nano-flower WO3 hollow microspheres were synthesized by calcining SrWO4 precursors at 300 °C. The WO3-FeOOH-X series photocatalysts were synthesized by successfully anchoring the amorphous FeOOH quantum dots uniformly on the WO3 nanoflower petals. Azo dyes in single system (MB, AR-18) and mixed system (MB+AR-18) were treated synergistically by light and Fenton. The reusability of WO3-FeOOH-3 samples at ambient temperature was investigated. Active species removal experiments were conducted to reveal their photo-Fenton degradation mechanism of organic pollutants. The results showed that the degradation rate of WO3-FeOOH-3 was 98.69% for MB within 5 min. The degradation rate of AR-18 was 92.55%. The mixed dye system (MB+AR-18) became clarified within 5 min. The efficient degradation rate was attributed to the homogeneous dispersion centers and the multiple active sites provided by the WO3 petals for FeOOH anchoring. In conclusion, WO3-FeOOH-X provides a new pathway and applicability for the efficient degradation of MB and AR-18 azo dyes.

Delineating molecular interactions within surface active ionic liquids + tartrazine dye solutions: A comparative study with conventional surfactant-DTAC

Surface active ionic liquids (SAILs) have been used in various technological fields. Moreover, the deep understanding of interactions exist in SAIL and dye systems will enhance their utility in various fields. In this study, the interactions of cationic Ionic liquids/surfactant 1-Methyl-3-octylimidazoilum chloride [C8mim][Cl], 1-Methyl-3-decylimidazolium chloride[C10mim][Cl], Dodecyl trimethylammonium chloride (DTAC) with anionic dye tartrazine were investigated by state of the art techniques i.e., conductivity, UV–visible spectroscopy, fluorescence spectroscopy and surface tension. The Critical micelle concentration (CMC) of tartrazine-added aqueous ILs/surfactant solutions were obtained, and a decrease is observed after addition of dye. Further, with the increase in alkyl chain length of ILs, the CMC is considerably reduced. Spectroscopic studies reveal a change in spectra of dye which hints ILs/surfactant dye interaction. The binding constant (Kb) is calculated by conductivity, UV-visible, fluorescence methods, which follows the order DTAC>[C10mim][Cl]>[C8mim][Cl]. Computational studies give an idea of the HOMO – LUMO energy gap between the donor and acceptor orbitals of ILs/surfactant and dye, which can be useful in the prediction of the feasibility of interaction between two entities.