نشریه علوم و فناوری رنگ
سال شانزدهم شماره 1 (پیاپی 59، بهار 1401)

"Kaman Oil" is one of the essential protective coatings of artworks in Iran, based on the old texts. It is made from diterpenoid resin and linseed oil at boiling point. This product's making method and temperature have always been discussed in various sources. Accordingly, this article aims to investigate temperature and chemical changes occurring in its production to obtain a standard product for use in traditional art. Therefore, according to the literature, three resins of Moroccan Sandarac, Colophony and Manilla Copal, and linseed oil were selected to produce "Kaman Oil." Thermal analysis of DSC and TG/DTA was used to examine changes in product properties during the heat treatment for different amounts of resin and oil. Finally, the chemical changes were studied with Fourier transform infrared spectroscopy. The result shows that the making temperature mostly depends on the oil changes and occurs between 380-390°C. Also, demethylation, aromatization, and decarboxylation reaction appeared at these temperatures to form the final product.</em>

Studies have proved that the appearance of yellow and red colors in autumn leaves results from carotenoid and anthocyanin pigments, respectively. Anthocyanins are synthesized in certain plants, depending on species composition and phenology, during leaf senescence, in the autumn season at enough sunshine but decreased temperature and day length. In this study, the accumulation of red anthocyanin pigment in Nadina domestica (berberidaceae) shrub autumn leaves was investigated. Leaves of the mentioned shrub were collected from Tehran environment, fully dried, and ground. The anthocyanins and carotenoid content of the powder were extracted using ethanol as a solvent. These pigments were separated by n-hexane solvent. Anthocyanin components were characterized by the following methods UV-visible spectrophotometry, thin-layer chromatography (TLC), colorimetry parameters (CIE LAB), and high-performance liquid chromatography (HPLC). The results showed that anthocyanin compounds, including Cyanidin, Delphinidin, Petunidin, Plargonidin, and Malvinidin, are the major and attractive red color anthocyanins of the leaves extract.

This study investigates the effects of the thermal cycles on changes in impact resistance and hardness of some coatings used in the wood and furniture industries. Platanus wood species and three types of acrylic, polyurethane, and alkyd coatings made by the Reef factory were used. Also, scratch hardness, pendulum hardness, impact, and roughness tests were used to evaluate the surface properties of the samples before and after coating and thermal stresses. The results showed that the highest resistance to scratch hardness and pendulum hardness among the coatings were related to alkyd coatings. However, in the impact and surface roughness tests, it was found that Acrylic coating has more resistance than other polyurethane and alkyd coatings. Due to thermal stresses, the resistance generally decreased in all coatings, and the best performance was obtained with Acrylic coating. Also, the statistical analysis results showed a significant difference between Acrylic and alkyd coatings.

In this research, the following three adsorbents were synthesized and characterized to investigate the role of nanoparticles in the removal of the cationic dye safranin: a nanocomposite of graphene oxide-activated carbon (GO-AC) as a blank sample, graphene oxide-activated carbon-aluminum hydroxide nanoparticle (GO-AC-Al(OH)3 NPS) and graphene oxide-activated carbon-cerium oxide nanoparticles (GO-AC-CeO2 NPS). The synthesized nanomaterials were identified and characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and energy-dispersive X-ray spectroscopy (EDX). The effect of various parameters such as pH, initial dye concentration, adsorbent amount, contact time, and temperature in the safranin dye adsorption process was investigated. The used nanoparticles have a high surface area, good mechanical strength, and different functional groups. Graphene oxide, activated carbon, nanoparticles of cerium oxide, and aluminum hydroxide can be effective in the adsorption of safranin dye by forming various electrostatic interactions, π-π, and hydrogen bonds due to their different cavities and functional groups. Mechanisms affecting the removal of contaminants were studied with the Freundlich and Langmuir isotherm models. The results showed that the removal of safranin dye followed the Freundlich isotherm, and the value of the R2 correlation coefficient for oxide graphene /activated carbon, oxide graphene/activated carbon/cerium oxide, and oxide graphene /activated carbon/aluminum hydroxide were obtained 0.973, 0.986 and 0.9994, respectively. The synthesized nanocomposites from cerium oxide and aluminum hydroxide nanoparticles showed good performance in removing safranin dye as compared to the blank sample (GO-AC).

Thermal decomposition of copper (II) acetate monohydrate and polyvinyl alcohol results in CuO/Cu2O nanocomposite synthesis. It was characterized by FT-IR, XRD, and TEM techniques. The peaks appeared in the FT-IR spectrum and the XRD pattern, confirming the CuO/Cu2O nanocomposite preparation. The TEM image shows that the particles are agglomerated. The CuO/Cu2O nanocomposite was used as a new adsorbent to remove methyl orange dye from the aqueous solution. The results of the dye removal study show that initial dye concentration has no effect on the removal percentage, and the dye removal percentage was constant at about 97%. However, dye removal increased with an increase in pH from 2 to 8, with the highest yield occurring at pH equal to 8. After increasing the pH and reaching 12, the removal percentage has been reduced. The dye removal efficiency increases to 99.5% by increasing the amount of adsorbent from 5 to 20 mg and by increasing the contact time from 5 to 30 minutes.

In this research, BFO/g-C3N4 nanocomposite was prepared via the hydrothermal method and was analyzed by FTIR, XRD, FESEM, Dot mapping, and EDS. BET and BJH techniques were used to determine the specific surface area and pore size of BFO/g-C3N4 nanocomposite. The efficiency of BFO/g-C3N4 nanocomposite as a photocatalyst was evaluated on photocatalytic degradation of Congo Red dye under visible light irradiation. The effect of key factors, i.e., time, pH of the solution, initial Congo Red concentration, and BFO/g-C3N4 dosage, was studied on photocatalytic degradation of Congo Red dye. Results revealed that degradation of Congo red is increased by increasing time and BFO/g-C3N4 dosage and is decreased by increasing Congo Red concentration and pH. The maximum removal percentage of Congo red reached 74.66% at 40 min, pH=2, initial dye concentration of 10 mg/L, photocatalyst dosage of 0.05 g/100mL under 30 w visible light. It can be deduced that BFO/g-C3N4 nanocomposite act as an effective photocatalyst for removing Congo red from aqueous solutions when exposed to visible light.

In the civil engineering industry, concrete is a material that is widely used and highly significant. </em>The production of colored concrete has also been considered in recent decades as one of the emergent research projects in the desired industry. Using colored concretes in prominent urban structures, besides adding the desired resistance to usual concrete and other materials, play an important role in improving the urban`s color palette and the visual richness of urban environments. This study aims to investigate the effect of mineral pigments on the compressive strength of colored concrete by focusing on the role of the improved color palette in current cities of Iran. For this purpose, the samples of colored concrete with 2, 4, and 6% pigments compared to ordinary concrete were tested. The research results showed that the percentage increase in the strength of colored pigmentation of concrete samples compared to the usual concrete was 2.3%, 4.9%, and 8%, respectively, which emphasizes the strength and rigidity of colored concrete to be used in urban structures.</em>