Dye Reuse Research Articles

Facile and rapid synthesis of novel hybrid pigments and their application as colorants in high-performance polymer

Facile and efficient synthesis of hybrid pigments by removing common synthetic dyes, e.g., Rhodamine (RhB), Acid Yellow 17 (AY17), and Acid Violet 7 (AV7), from the water via adsorption process utilizing Cucurbit[6]uril, CB[6], (a major by-product formed during CB[n] synthesis) as an adsorbent is described. The influence of various parameters on the adsorption process is investigated. The adsorption mechanism is studied by performing ATR-FTIR and TGA analyses. Subsequently, The obtained hybrids pigments RhB@CB[6] (P1), AY17@CB[6] (P2), and AV7@CB[6] (P3) were used as thermoplastic colorants. All the hybrid pigments are processed into Polystyrene (PS) at 250 °C with good color intensity, color brightness, and homogeneous dispersion. The hybrid pigments exhibit better photostability, heat resistance, and migration resistance to acid, alkali, and organic solvents. This protocol provides a potential alternative to traditional inorganic pigments via dye wastewater treatment and reuse of dye by absorbing onto major by-product CB[6] as hybrid pigment colorants for various thermoplastics.

Separation of Some Anionic Dyes Using Reverse Micelles of CTAB and SDS as Efficient Surfactants Adsorbents from Aqueous Medium

Extractive removal of anionic dyes, namely, Color Index (CI) Reactive Blue 222 and Reactive Yellow 145, using reverse micelles based on liquid-liquid extraction (LLE) was carried out from aqueous solutions using different anionic and cationic surfactants (e.g., sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB), resp.), which dissolved in ethyl acetate as solvent. The reverse micelle principal acts on the dye encapsulated in the solvent in an aqueous micropool. The experiments were carried out by mixing in a simple mixer a given amount of dyes and surfactants dissolved in a solvent in an aqueous process. Due to gravity, the dye is separated from water after the solvent phase is separated from the aqueous phase, including dye encapsulated in reverse micelles. Under various experimental conditions, extraction efficiency was studied, including solution pH, extraction time, initial dye concentration, extractant concentration, temperature, stripping agent, and solvent reusability. Dyes extracted were stripped quantitatively with NaOH solution. Recovery of the solvent and the reuse of dyes and surfactants after extraction of dye molecules from reverse micelles surfactant core considered are very important from an economic point of view. The optimized conditions were 7 ± 0.2 solution pH, 9 × 10−2 mol/L extractant concentration, 1M NaOH stripping agent concentration, 60 min extraction time, 6 × 10−5 mol/L dye concentration, and 1 : 1 aqueous to organic (A/O) ratio. 87–93% of dyes were extracted at experimental optimum conditions.

Efficient removal and separation of anionic dyes from aqueous medium by the application of reverse micelles of cationic surfactants

A new protocol based on liquid/liquid extraction using reverse micelles is proposed. The recovery of solvent and reuse of dye and surfactant, after extracting the dye molecules from the core of reverse micelles of surfactant is related to the economic viability of the process. Experiments were conducted by mixing a known quantity of dye in aqueous phase and solvent-containing surfactants in a simple mixer. The separation of solvent phase, containing encapsulated dye in reverse micelles, from aqueous phase due to gravity results in separation of dye from water. The removal of different anionic dyes (methyl orange, congo red and aniline blue) from aqueous phase in amyl alcohol solvent using different cationic surfactants was studied. The percentage removal of dye depends upon the size of the reverse micelle of the surfactant. The solvent used for the dye removal can be recovered by distillation method and can be reused. The dye is separated from reverse micelles by lowering the temperature below the Kraft point by using the solvent depending upon the solubility of the two. Hence all the components of the experiment can be recovered and reused.

Study on Reuse of Dyes from Wastewater

Through putting protein additives in reactive dyes wastewater and decolorization, both of the additives and dye wastewater changed into a kind of complex compound. Protein additives with amorphous loose micelle structure which has -NH2, -COOH, -OH and -CONH- produce electrostatic attraction, hydrogen bonding, van der Waals force and hydrophobic interaction between dye ions and dye molecules. Thereby, absorptive dye can embed dyes in micelles by adsorption, flocculation, coagulation to achieve the collecting of dye in dye wastewater. In this paper, we mainly discussed the performance and reuse of decolorized dyes. Further we studied on the reuse of the protein blends dye and the use of WLS for cotton fabrics pretreatment. By researching on the influence of WLS amount, optimal process conditions including pretreatment, dyeing, were both determined. The effect of WLS modification was also evaluated. It was found that the dyeing rate in decolorized dye increased after cotton was modified by WLS. Therefore, it is necessary to explore the decolorization of reactive dyes wastewater and the reuse in order to save dyes, chemicals and reduce emission.

Dye and Solvent Recovery in Solvent Extraction Using Reverse Micelles for the Removal of Ionic Dyes

Among the several methods, dye removal from water by solvent extraction using reverse micelles is promising in terms of the simplicity and efficiency of the process. The recovery of solvent and reuse of dye after its removal is related to the economic viability of the process. In the present study, backward extraction or recovery of dye into an aqueous phase from the solvent phase by using a counterionic surfactant after forward extraction is experimentally studied using a simple mixer and settler arrangement. The backward extraction of dye also resulted in the recovery of solvent. The effects of different parameters, such as the surfactant concentration, pH, and KCl concentration on the recovery of methyl orange and methylene blue dyes, are investigated. The percentage of both cationic and anionic dyes recovered increases with an increase in the counterionic surfactant concentration or with a decrease in the KCl concentration. The percentage of recovery of anionic methyl orange increases with a decrease in pH, whereas that for cationic methylene blue increases with an increase in pH. Selective removal of dye from a cationic and anionic dye mixture was experimentally studied by treating the dye mixture with reverse micelles of anionic and cationic surfactants in a stepwise manner. The results obtained are explained based on electrostatic interaction between the surfactant and dye.

Removal of ionic dyes from water by solvent extraction using reverse micelles.

Several methods (e.g., UV/H2O2 oxidation, adsorption, flocculation-precipitation) are normally employed to remove dye from water. A new technique based on liquid/liquid extraction using reverse micelles is proposed whereby recovery of solvent and reuse of dye is possible. Experiments were conducted by mixing a known quantity of dye in aqueous phase and solvent-containing surfactants in a simple mixer. The separation of solvent phase, containing encapsulated dye in reverse micelles, from aqueous phase due to gravity results in separation of dye from water. The removal of different ionic dyes (e.g., eosin yellow, methylene blue, malachite green, methyl orange, orange G) from aqueous phase in the presence of different cationic and anionic surfactants [e.g., sodium dodecylbenzene sulfonate, sodium bis(2-ethylhexyl) sulfosuccinate, hexadecyltrimethylammonium bromide, and cetyl pyridinium chloride] in different solvents (e.g., amyl alcohol, benzyl alcohol, methyl benzoate, and isooctane) were studied by conducting experiments. The percentage removal of dye from aqueous phase increases with the decrease in dye concentration or with the increase in surfactants concentration. Furthermore, the percentage COD removal of dye is increased with the increase in surfactant concentration. The nature of solvent has minimal effect on percentage removal of dye. The ratio of solventto aqueous phase volume required for the removal of dye decreases with the increase in surfactant concentration. It is possible to back-extract dye into aqueous phase and recover solvent by using counterionic surfactants. The separation of aqueous phase from the aqueous-phase solvent dispersion is faster for amyl alcohol as compared to benzyl alcohol and methyl benzoate. A theoretical model based on ion-exchange reaction between surfactants and dye is used to analyze the experimental data.