نشریه علوم و فناوری رنگ
سال شانزدهم شماره 2 (پیاپی 60، تابستان 1401)

Paper turns yellow over time. Bleaching with oxidizing agents is one of the most common methods, which creates a colorless result by breaking down the light-absorbing chromophores. In this research, the changes in the properties of paper by applying oxidizing agents are studied. The paper samples were characterized by colorimetric, infrared spectroscopy, tensile, acidity, and SEM microscopes. Four oxidizing solutions were deployed for whitening the samples of Whatman paper using the Immersion method, including Hydrogen Peroxide (2 % V/V), Sodium Peroxide (2 % W/V), Potassium Periodate (2 % W/V), and Potassium Persulphate (2 % W/V) all solved in distilled water. The samples were treated within 48 hours, and characterizing tests were deployed. The results show that hydrogen peroxide with the highest tensile strength (17.75 Nm/g) and the lowest color difference (∆E= 1.48) after accelerated aging has the best performance among other samples. Also, hydrogen peroxide can be improved tensile strength, increase brightness, reduce yellowing, cause fibers stability, and keep the paper at an almost neutral acidity.

With the growing awareness about cleaner surroundings, using natural materials in textile dyeing has been developed recently. In this way, in this research, one of the galls of the oak tree named Sichka was selected as a sample of cultural waste, and the optimal conditions of wool dyeing were investigated for the first time. The results show that sichka is a vast source of polyphenolic and tannins compounds and then can be considered an excellent candidate for wool dyeing and produced outstanding antibacterial properties. Results indicate that for the conditions used in our experiments, the optimum dyeing conditions are dye concentration of 45 % at the temperature of 80 ºC, time of 60 min, and pH of 4.5. The results also show that the wheat barn and citric acid were used as the bio- mordants to increase the affinity of wool yarns to the dye extract and improve dye fastness properties. It provides an excellent way to protect the ecosystem as much as possible and a space for new businesses with value-added.

In the present study, the performance of a scanner for measuring the fabric's color in a small color space of CIELAB space was evaluated using the complete factorial design. In this regard, the effect of two critical factors in the setup of the scanner, namely resolution and bit depth at different levels, on the color difference of the paired samples was investigated using analysis of variance. The evaluations showed that these two factors did not significantly affect measuring the color difference of the paired samples located in the small color space of CIELAB space. Also, the effect of the hue of the samples on the results of the scanner was investigated. It was found that the scanned samples' hue significantly affected the scanner's results. The evaluations carried out in the present research are essential in various applications, such as shade sorting.

Trace amounts of Cu (II) and Pb (II) in the wastewater sample were removed with a new nano biosorbent based on cross-linked chitosan magnetic beads modified with methionine-glutaraldehyde Schiff's base (MG-Chi/Fe3O4) in wastewater samples. Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) analysis, and scanning electron microscope (SEM) have been applied to characterize nano biosorbent. Various parameters affecting the uptake behavior of the metal ions were examined and optimized, including pH, adsorbent dose, contact time, and initial concentration. Freundlich and Langmuir isotherm models were applied to estimate adsorption mode. The equilibrium data were well fitted with the Langmuir isotherm model. The maximum adsorption capacities for Cu (II) and Pb (II) were 172.4 and 175.4 mg g-1, respectively. The adsorption kinetics are better consistent with the pseudo-second-order model. It was concluded that this method was successfully applied for the simultaneous removal of Cu (II) and Pb (II) in industrial wastewater samples.

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 %.

This research aimed to study sonophotocatalytic degradation of Reactive Orange 16 dye (RO16) by MgO/g-C3N4@Zeolite nanocomposite. MgO/g-C3N4/Zeolite nanocomposite was synthesized and characterized using the following

X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and dot mapping. The synthesized nanocomposite was used as a photocatalyst to degrade RO16 dye aqueous solution. The tests were performed under UV light and ultrasound irradiation. The effect of main factors on the removal of the dye, such as reaction time, solution pH, initial dye concentration, and nanocomposite dosage, were investigated. Results demonstrated that the percentage of dye removal was increased by raising the reaction time, the solution pH, and nanocomposite dosage and decreased by increasing the initial dye concentration. The maximum removal percentage reached 72.36 % at a reaction time of 50 min., pH of 10, initial dye concentration of 10 mg/L, and nanocomposite dosage of 0.25 g/500mL.

Notwithstanding the indefatigable endeavor to explore antibacterial drugs and agents, achieving improved antibacterial properties and minimizing hazardous matters has always been challenging. Garlic extract was utilized to reduce and dope graphene oxide simultaneously, considering the astonishing antibacterial characteristics of garlic extract instead of using dangerous reducing agents. A hydrothermal method was used to reduce/ dope graphene oxide. Copper cations were also loaded on the graphene oxide nanosheets doped with garlic extract. The successful synthesis of the products was confirmed by Fourier transform infrared spectroscopy. X-ray photoelectron spectroscopy was used to affirm the doping of graphene oxide using garlic extract. Furthermore, according to the results obtained from X-ray photoelectron spectroscopy, the atomic percentage of S and N elements was 1.4 % and 1 %, respectively. The result revealed that double-doped graphene oxide in water base acrylic coating on PVC panels showed a 100 percent decrease in the growth of bacteria after 6 hours.