نشریه علوم و فناوری رنگ
سال هفدهم شماره 1 (پیاپی 63، بهار 1402)

In the art of tiling, turquoise and green colors have been the colors considered by traditional architects. Their beauty depends on the coloring materials as one of the important glaze materials. This study aims to obtain technical information about the historical glazes of the Green Dome of Kerman. Written sources and field surveys were conducted to obtain samples to achieve this goal, and the color components of the glazes were measured using the CIE L*a* b* system. The X-ray energy diffraction (EDX) spectroscopy method was used to determine the constituent elements in the existing glazes. The results analysis show that the color tonality of the green glazes is due to chromium oxide, copper, vanadium, nickel, and iron in the glaze. The results of the examination of samples of turquoise glaze demonstrate that copper oxide served as the color generator in the glazes and that potassium and sodium oxide also contributed to the strength of the turquoise color.

Plant dyes have been used in the dyeing process of persian carpets for many years. In this study, jujube fruit, a new source of plant dye, was introduced, and its dyeability on wool yarn was investigated. The results showed that jujube is a vast source of bioactive compounds and can be considered as a good candidate for wool dying without any mordants. Response surface methodology was applied to optimize the natural dying process and investigate the simple and simultaneous effects of the main parameters. Results also showed that the value of the correlation coefficient of the model was high (97.60 %), and there was a low difference between the experimental color strength value and the predicted value (0.64 %). So, the RSM method could predict and optimize the wool dyeing process with few experiments. Jujube was found to have agronomic potential as a natural dye in wool dying, producing good fastness properties without any mordants.

Simultaneous removal of methylene blue and crystal violet was investigated. Adsorbents made of clinoptilolite/Fe3O4 (Clin/Fe3O4) nanocomposites and alginate/clinoptilolite/Fe3O4 (Alg/Clin/Fe3O4) nanocomposite beads were used. The effects of effective environmental parameters such as pH, adsorbent amount, temperature, contact time, and dye concentration were examined in the adsorption process. The results showed that the highest amount of dye adsorption using both adsorbents was obtained under pH = 8, adsorbent dose of 2 g/l, contact time of 60 minutes, temperature of 25 ºC, and dye concentration of 10 ppm. Under optimal conditions, the adsorption percentage of methylene blue dye was obtained as 80.36 and 74.51 %, and the adsorption percentage of crystal violet dye was obtained as 75.83 and 70.19 %, using Clin/Fe3O4 and Alg/Clin/Fe3O4 adsorbents, respectively. Investigating isothermal models showed that both dyes' adsorption process was mainly physical and desirable. Experimental data on dye adsorption using both adsorbents was most consistent with the Langmuir isotherm and the pseudo-second-order kinetic models. The thermodynamic study showed that the adsorption process was exothermic and spontaneous.

Concrete is one of the most significant and widely utilized materials in road and building construction. The usage of colored concrete in urban development projects can play a valuable role in improving urban aesthetics metrics. This research aims to investigate the effect of Limonite pigment (a yellow mineral pigment native to Iran) on concrete's compressive, tensile, and abrasion resistance, with emphasis on the decoration of contemporary cities. In this regard, samples of colored concrete replaced cement in concrete using limonite pigment in different weight ratios of 5, 10, 15, and 20 %. The newly colored concrete was subjected to compressive, tensile, and abrasion resistance tests. The compressive strength test results showed that iron oxide in Limonite pigment could increase the compressive strength of concrete. However, the results of concrete tensile and abrasion resistance tests show that adding 5, 10, 15, and 20 percent of pigment can reduce tensile strength by 4, 8, 19, and 29 % and abrasion resistance by 9, 19, 28, and 38 %. Therefore, colored concrete with a 15 % Limonite pigment rate or more; should be used to optimize urban decoration or ornamentation like flooring, urban elements, and urban passages. In this case, other pozzolanic additives such as micro silica, fly ash, steel fibers, and polypropylene should be utilized to increase concrete's abrasion resistance.

The waste of tea factories is a good source for extracting food colorants that can be replaced with synthetic colors in the food industry. The present study was designed and implemented at a semi-industrial scale to complete the results obtained from research that was previously conducted to determine the best extraction method with the highest performance and color stability from black tea wastes on a laboratory scale. Extracting color from the wastes of the tea factory was done using a reverse condensation system with water: ethanol solvent for 30 minutes and at the solvent boiling temperature. After purification and pasteurization, the extract was concentrated, and a part of it was converted into dried extract in a spray dryer. Quality assessments, including microbial, physicochemical, and marketability tests, were performed on the sample. The results demonstrated that the number of microorganisms and heavy metal elements in tea color did not exceed the standard limit. The amount of antioxidant activity, total polyphenol, and caffeine were 94.5 %, 18.3 and 4.7 % in solid color and 49.7, 2.8 and 0.4 % in liquid color, respectively. In the sensory test, applying a solid and liquid color mixture in Gummy candy obtained a higher score (p≤0.05) from the evaluators. In their opinion, there was no significant difference between vinegar with tea color and vinegar with color available in the market. The extracted color can be prepared in liquid and solid form, increasing its usability in various food products.

By varying the level of graphene's surface oxidation in this paper, the thickness of the interphase region was altered, and its influence on the conductivity was investigated. Due to the similarity of water-based epoxy chemical groups with graphene oxide oxygen groups, the interphase region was reinforced. Infrared spectroscopy and thermal gravimetry were performed to evaluate the graphene oxide synthesis, and Raman spectroscopy was also performed to investigate the structural defects on graphene sheets. At first glance, based on the interphase region theory, it is expected that by increasing the oxidation rate of graphene nanosheets, the electrical conductivity of polymeric coatings will increase, and the percolation threshold will decrease. On the other hand, due to increased oxidation, the structural defect on graphene nanosheets increases, and the conductivity of the coatings is expected to decrease. Due to the opposite effect of the two factors mentioned above, the effectiveness of nanocomposite samples was studied, and the impressment of each factor was investigated in this project.