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

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.

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.

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.

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.