نشریه علوم و فناوری رنگ
سال پانزدهم شماره 2 (پیاپی 56، تابستان 1400)

Today, attention is paid to clean solar energy to reduce fossil fuel pollution. Dye-sensitized solar cells (DSSCs) convert light energy into electrical energy. One of the important components of DSSCs is the dye. Natural dyes are very convenient because of their low cost and ease of access. For this end, 9 natural dyes based on anthocyanin were selected and employed in DSSCs structure. For the first time, the reflection diagrams, CIELAB and CIELCH color spaces were achieved to study the color behavior of natural dyes applied in DSSCs. According to the results, the natural dyes applied in DSSCs structure have different color and lightness. Besides, the color gamut volume of anthocyanin based natural dyes applied in DSSCs was computed about 2.67 ×104 using well-known algorithm.

Today, many researches have been done in the field of textile dyeing using natural dyes for environmental protection by reducing the use of co- agent and synthetic dyes. Different herbal dyes are used in dyeing. Due to the widespread use of madder and weld dyes and the different chemical structure of these two dyes, madder and weld dyes were used to dye wool yarn and eucalyptus and pomegranate peel, which are tannins, were used as mordants. Aloe vera, which has a polyphenolic structure, was also used to improve dyeing fastness and preserve the original hue. Based on the results of experiments, it was found that the use of 10% eucalyptus and pomegranate peel reduces the amount of alum mordant to about 1%. They changed the hue of weld in the light color. The use of aloe vera as an herbal mordant had no effect on the final hue of dyes and significantly reduced the use of alum mordant.

In this study, a magnetic nanocomposite of metal-organic framework (NiFe2O4@SiO2@HKUST-1) with the weight ratio of nickel ferrite to silica matrix (10:90) was synthesized and characterized via the in-situ self-assemble method. Phase formation, type of formed bonds, morphology, crystal size, magnetic property and special surface area size werre characterized and investigated by X-Ray diffraction analysis (XRD), scanning electron microscopy (SEM) analysis, vibrating-sample magnetometer analysis (VSM) and Brunauer–Emmett–Teller analysis (BET). Finally, the removal of methylene blue cationic dye and the effect of pH on the removal rate were investigated. According to the obtained results in acidic environments, contact time of 60 minutes and 0.1 g of the synthesized magnetic nanocomposite of metal-organic framework, the highest adsorption capacity of the methylene blue cationic dye was observed. Experimental data were well-fitted with the Longmuir absorption isotherm. The kinetic studies showed that the process of adsorption of methylene blue dye at different pHs, was best described by a pseudo-second-order model.

The paper coating process has a special place in the paper industry in order to reduce production costs and improving quality. In this study, kaolin was first extracted from waste paper and XRD, FTIR, SEM/EDX analysis are used to investigate the microstructural properties of kaolin recycled from waste paper. Then, the coating solution of Recycled kaolin was coated on paper at four levels of thickness 30, 60, 90, and 120 micrometers. Based on the study of permeability properties and mechanical properties, the superior treatment was related to coated paper with 120 micrometers thickness.

Nowadays, Azolla become a problem in aquatic habitats. Also, the existence of colors in the water and the effluent of industries cause water contamination. In this research, the application of surface modified Azolla with nanoparticles of magnetite (Fe3O4) as a natural sorbent has been studied in removal of brilliant blue dye. The size and structure of the nanoparticles were examined by SEM and FT-IR, and particle size was less than 40 nm. Dye removal parameters including solution pH, ionic strength, absorbent weight, stirring time and solution volume have been optimized. The kinetic of brilliant blue adsorption on surface modified Azolla by magnetic nanoparticles showed that it is followed pseudo-second-order kinetic which indicate the chemical absorption of the dye on magnetite nanoparticle. Based on adsorption isotherms the process is coherent with Freundlich model. By using Azolla powder surface modified with magnetite nanoparticles, color removal is done in a very short time with high efficiency, which has the advantage of the application of these particles in treatment of wastewaters containing colored compounds .

This study was aimed to investigate the effect of wood extractivesclearing up of Aspen (Populus spp) and Oak (Quercus spp) wood species on the adhesion strength of nitrocellulose (clear) and acid-catalyzed transparent finishes. In order towood extractives clearing up, industrial acetone and hot water (45°C) solvents were used. Specimens’ surfaces were sanded with 120 and 180 grate sizes sandpaper, respectively, and covered with the transparent finish in two separate processes with clear and acid-catalyzed coatings. The wettability of the specimens’ surfaces was evaluated by using the contact angle method. The adhesion strength of the transparent coating was determined according to Pull off method. The results showed that wood extractives clearing up had a significant effect on surface wettability and adhesion strength of coating so that these samples showed higher wettability and adhesion strength than that of control samples. The highest wettability and adhesion strength were found in the wood samples cleared up with industrial acetone solvent. In general, the highest adhesion (8.14 MPa) of coating observed in the oak specimens cleared up with industrial acetone solvent and covered with acid-catalyzed coating. The lowest adhesion (2.01 MPa) also was obtained in control specimens’ of Aspen coated with clear finish.

The ZnFeAl-LDH was synthesized via the well-known co-precipitation method. The obtained solid was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). Taguchi orthogonal design with five factors, namely adsorbent type and dosage, pH, dye concentration, and time was performed to optimize and model the dye removal efficiency and the percentage by LDH and derived MMO. The proposed model was in accordance with the experimental results with a correlation coefficient of 95.2% and 98.7% for removal efficiency and percentage, respectively. The desirability approach was adopted in order to maximize the adsorption capacity (q) and adsorption percentage (R %). Under optimum conditions, the maximum adsorption capacity of 151.48 mg/g and the removal percentage of 99.7% were obtained. Isotherm modeling and kinetic investigations showed that Langmuir and pseudo-second-order models describe both the adsorption equilibrium and kinetic behavior well.