جستجوی مقالات مرتبط با کلیدواژه « Dye » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

The textile dyeing industries' wastewater is classified as a highly toxic composition of toxic compounds, and their release into the environment causes a severe biotic risk to the ecosystem. Microbial fuel cell (MFC) is a promising technology for treating textile wastewater and corresponding electricity generation. This work studied the decolorization mechanism of Reactive Blue 4 (RB4) and acid Red 88 (AR88) dyes in the binary mixture in an MFC using baker's yeast. The decolorization of dyes was analyzed using spectrophotometry methods UV-Vis, FTIR, and COD measurements. The results showed that the decolorization on the first day was taken place very fast, which can be attributed to biosorption and bioaccumulation mechanisms. Analyzing the FTIR spectrum revealed that the decolorization was also caused by biological decomposition on the fourth and fifth days. The decolorization efficiency for the two dyes differed after the fifth day, and the final decolorization of AR88 and RB4 was 96 % and 85 %. The COD removal of synthetic wastewater from treatment was 87 %.

Since the population has increased and various industries have developed in recent years, concerns and challenges related to water and the environment have been raised. A large part of water pollution is caused by effluents and sewage of various industries, including dyes, heavy metals, radionuclides, etc. MXenes are emerging two-dimensional nanomaterials, often known from the family of carbides or nitrates of intermediates with the general formula  The high surface area of these nanomaterials has increased the adsorption efficiency and removal of contaminants. Also, MXenes remove and absorb dyes and heavy metals, due to different functional groups on the surface. In some cases, with the help of ultraviolet radiation, increased efficiency and photocatalytic degradation have been observed. Some of these materials remove environmental pollutants by electrostatic absorption. Heavy metal ions can be trapped in the space between the thin layers of MXene plates. The reusability of these materials is often a perfect feature, as they can often be recovered and used for several cycles. MXenes are promising for water treatment membranes due to their hydrophilicity, high specific surface area, and excellent mechanical and electrical properties. In this study, these materials firstly introduced. Then the application in removing dyes, heavy metals, and radionuclides have been investigated.

Various methods have been used to treat industrial effluents from dyes. In this study, the removal of two xanthene dyes using laccase enzyme was investigated. Lacases are oxidizing enzymes and have been studied in many studies due to their wide range of substrates. One of the capabilities of laccase is the bleaching of synthetic dyes. In this study, the removal of two dyes, erythrosine B and rhodamine 6G, which are members of the xanthene group, as well as neutral red dye by spore laccase from Bacillus sp KC2 in approximately 24 hours using spectrophotometry, Spectrofluorometry and Z-scan methods were studied. The results of Z-scan showed removal of erythrosine B from aqueous solvent by 45%, rhodamine 6G by 49% and neutral red by 68%.

Methylene blue and crystal violet dyes are the most widely used dyes in some industries such as textiles, silk, and wood. Accumulation of cationic dyes in water resources is harmful to humans, animals, and the environment, so their removal from the effluents of the dyeing industry is essential. Among all the treatment methods, adsorption is one of the most attractive routes for the treatment of polluted water due to its low cost and simplicity of design. According to the studies, it can be seen that zeolites modified with iron nanoparticles show a high adsorption capacity in the removal of dyes. However, the use of adsorbents in the form of fine powders is still difficult and their use in continuous systems is limited due to the cracking and the pressure drop.

To solve the problems of adsorbents in powder form, the ionic gelation method was used to prepare a granular adsorbent based on natural zeolite clinoptilolite modified with Fe3O4 nanoparticles. In order to prepare granules with suitable appearance and high adsorption percentage, the effect of various parameters such as initial pH of the solution, type and concentration of the crosslinking solution and initial ratio of alginate to nanocomposite was investigated. The synthesized granules were investigated by XRD, SEM-EDX and BET analysis.

The results showed that the pH was ineffective and the iron (III) chloride solution was optimal with a concentration of (2 w/v%) and an initial ratio of 1:4 alginate to nanocomposite. The maximum adsorption capacity of the prepared granules towards methylene blue and crystal violet adsorption was determined as 12.484 mg/g and 11.904 mg/g by Langmuir isotherm, respectively, which indicated to a high ability of the prepared granules to remove these cationic dyes.

Dyes have many uses due to their variety and complex structure.In recent years, wastewater from the production or consumption of dyes in various industries have increased and become a serious threat to the environment and human health.The effect of cold plasma as a new and advanced technology for the treatment of dye from wastewater is presented in this review paper. This method can be used for various applications such as treatment and pre-treatment of effluents, removal of pigments, and hazardous chemicals from effluents.In this wastewater treatment system, different cases such as characteristics of effluent, target materials, type of suitable plasma discharge, reactor type, toxicity experiments, biodegradability tests of plasma generated intermediates, environmental compatibility assessment of combined technologies, and economic estimation were considered. According to the studies, the results indicated the positive effects of cold plasma for decolorization of wastewater and also increased efficiency of modern wastewater treatment systems.  

Photophysics of nano-micelles containing crystal violet dye using water-in-oil microemulsion at molar ratio of water- to-surfactant of 10 (W = 10) and different values of mass fraction of water nano-droplets (MFD) by means of spectroscopy was studied. Spectroscopy results showed that in 0.002 concentrations of crystal violet within the microemulsion system, the absorption spectrum of dye was deviated from the Beer's law. The fluorescence emission intensity of the dye at high concentrations of the molecules dye within the AOT microemulsion decreased. The Stokes shift of dye at 0.002 concentrations within the AOT nano-droplet decreased and at 0.00003125 concentrations, behavior of fluorescence was not regular. The polarity parameter (ET(30)) for dye molecules at high concentrations often  indicated a decrease, while in lower concentrations of dye, it generally remained constant. The ratio of the dipole moment ground state to the excited state of dye at high concentration decreased but for the low concentration, it often increased.

Nowadays, the use of sensitive and selective fluorescent sensors for biological and clinical applications has been important for the early detection and control of various diseases. Since saccharides play an important role in biological processes, their detection is one of the particular importance and there is an urgent need to develop of technology for the continuous control of glucose in patients. Bronic acids, can be reversed and covalently formed by the diols in aqueous solution to form five or six ring esters. Based on this phenomenon, compounds containing bronic acid have been used as receptors in sensors. In this paper, fluorescent sensors based on dyes with bronic acids are introduced.

Phenothiazine is a butterfly shaped molecule based on indoline use as a starting material to synthesis organic dyes. These dyes have significant properties and performance in optoelectronic devices. Many optical and electrical properties such as photoluminescence, electroluminescence and electro-chemical properties can be modified by placing appropriate moiety on the parent phenothiazine group. In the last few decades, these electro- and photo-sensitive dyes have provided wide range of applications. This article presents the latest report on the development of small to medium sized phenothiazine-based dyes for dye sensitized solar cells, organic light emitting diodes, nonlinear optical materials, hole transporting components and sensors. For this end, an attempt structure properties and molecular design to improve these application and to test landscape perspective.

The aim of this research was study and comparison of FT-IR and TLC results for characterization of kermes dyes in archaeological and historical fibers and assessment of their advantages and disadvantages. Samples were prepared from silk and wool fibers. The samples were artificially aged according to Feller (1994). After aging, color change and pH were measured. Fourie Transform Infrared Spectroscopy-Attenuated Total Reflectance (ATR-FTIR) was applied for assessment and comparison of aged and unaged samples. Moreover, Thin Layer Chromatography was used before and after aging by choosing appropriate solvent. Results showed after aging, pH content of dyed silk with kermes was increased and Rf in TLC indicated minor change. The ATR-FTIR spectometer results showed that there are no differences between raw and dyed fibers, therefore, the color should be extracted in order to specify the sepctrum of color ingredients. After extarcting the samples, they do not differ much with the aged ones.

In this research, manganese hydrogen sulfate as a novel green catalyst was used to synthetize diazo dyes. Manganese hydrogen sulfate was used as a hydrogen source to produce diazonium salt and then, the obtained anion formed a stable gel with diazonium salt at room temperature which was stable until 70 °C.  Moreover, in order to produce diazonium salts, synthetic heterocyclic amines were utilized. The proposed heterogeneous acidic catalyst, manganese hydrogen sulfate, can be applied in industrial scale due to the advantages such as environmentally friendly features and easy catalyst transfer. This method provides several advantages such as, high-efficiency catalyst, mild operational conditions, room temperature conditions, low cost, availability, easy catalyst preparation, and a simple workup procedure.

Dyes are used in a number of industries such as printing, textile, paper, leather, and plastic manufacturing. Large amounts of dyes are discharged from industries as wastewater. The toxicity of dye effluents threatens human beings and other living organisms. In general, dye containing wastewaters are treated by a number of different physical, chemical, and biological methods. Physical treatments are classified into membrane separation, conventional coagulation/flocculation and adsorption. In various industries, water and chemicals including inorganic salts (NaCl, Na2SO4) are used in dying process that generate large volumes of strongly colored wastewaters with high load of toxic organic and inorganic compounds. Therefore, the recovery of dye and salt from industrial wastewater has a great significance. Membrane processes can separate and recycle both dyes and inorganic salts with considerably high efficiencies, while in other techniques; primary resources are not sufficiently recycled from industrial wastewater. Ceramic membranes are comparable to polymer membranes based on their characteristics such as easy control of the pore size, higher durability, thermal and chemical resistance, mechanical strength, extended lifetime. Nanofilteration (NF) is applied to remove dyes that are usually in the form of composites and composed of one or more several layers with different ceramic materials. Ceramic membranes generally have a macroporous support, one or two mesoporous intermediate layers and a microporous top layer. Ceramic supports are formed by shaping a powder and then consolidating by sintering. There exist a number of methods for fabrication of ceramic supports such as extrusion, tape casting, slip casting and press. The sol-gel process is the most appropriate methods for the preparation of intermediate and top layer. The process of separating salt from dye solution by NF needs a high dye rejection and a low salt rejection. The purpose of this paper is to review the fabrication techniques of ceramic membranes and their applications in treatment of dye-containing wastewaters.

In nanostructured solar cells, sensitizers are responsible for light absorption. A quarter century after the birth of this kind of solar cells, different types of sensitizers, containing dyes, quantum dots and perovskites have been introduced and used in solar cells. One of the most important features of a sensitizer is its band gap, optical properties and ability of light absorption. In each kinds of sensitizers, molecular structure determinds optical properties. In this paper the relation between structure and optical properties of different sensitizers were discussed.