نشریه علوم و فناوری رنگ
سال سیزدهم شماره 3 (پیاپی 49، پاییز 1398)

The purpose of this study is investigation of the colourfastness of saffron according to the instructions of dyeing in Persian historical treatises, and identifying the advantages and disadvantages of applying it in the restoration of manuscripts. Three types of selected papers (I, II and III) were dyed with saffron via different instructions. Ageing was done based on the ISIRI 20283 in Xenon container. Then, the color changes, fiber morphology and degree of cellulose degradation were compared before and after ageing. The experiments had shown that paper III, which was not dyed, had more stability than the other two types of paper after ageing. Comparing three types of dyeing methods, saffron had not been caused the oxidation of papers and the direct dyeing method was more appropriate for dyeing among three types of papers. Colourfastness in meta-mordanting method was more stable than pre-mordanting method. However, in the pre-mordanting method, comparing the total color difference (∆E) show that paper II was more stable than paper I. So, the type of paper can affect on the colourfastness of dye and this should be considered as an important issue in dyeing.

This work intends to study the effect of epoxy silicon resin mixture ratio with aminosilane hardener on corrosion protection properties of the coating. Coatings with different mixture ratio ranging 15-50% resin: hardener were prepared and cured for 1 h at 120 °C. To evaluate corrosion protection properties, electrochemical impedance spectroscopy (EIS) was employed after 240 h exposure of samples to salt spray. In addition, pull-off adhesion strength was measured after salt spray exposure. Results showed deterioration of protection properties and adhesion strength of the coatings below and above 20% mixture ratio. According to the tests results, the optimal mixture ratio of epoxy silicon to aminosilane was 20%.

In this research, samarium doped cadmium sulfide (Sm-CdS) nanoparticles were prepared through an ultrasound-assisted co-precipitation method. The synthesized sample was characterized by XRD, UV-Vis, ICP-OES and TEM techniques. The photocatalytic performance of the Sm-CdS was evaluated through the degradation of Rhodamine 6G (Rh-6G) under visible light irradiation. The effect of operational parameters on the degradation efficiency was modeled and optimized using response surface methodology (RSM). Under the optimal conditions ([Dye]0= 4 mg/l, [Catalyst]0= 0.6 g/l, pH= 8 and t= 70 min), more than 85% of the dye molecules were degraded. The results of the reusability of the photocatalyst showed that a negligible change in the photocatalytic activity was occurred after four reuses. Byproducts resulting from the photocatalytic degradation of Rh-6G were identified using the GC-MS technique.

Surface quality is a key point for expressing the specifications of tools that these specifications are improvable by coating methods. In this study, seed layers was deposited on Al - substrate by dip coating process and chemical bath deposition was used for tin oxide coating over deposited seed layers. Taguchi L18 was utilized for designing the experiments and preparation of required samples for studying the effective parameters (surfactant type and concentration in seed layer, seed layer deposition cycles, and seed layer nature and concentration of precursors). Furthermore, surfactant concentration showed the highest effect on surface wettability. In addition, artificial neural network (ANN) was used for modelling and optimization of process. A multilayer perceptron (MLP) ANN with 4 and 5 neurons in the first hidden layer and second hidden layer, respectively, was obtained as the best network. Optimum point prediction of 142° and 132° was calculated by Taguchi design and ANN modelling, respectively. However, prediction error of 3.5% was calculated comparing with experimental results (137°).

In this study the impacts of the electron delocalization on the structural and electronic properties and reactivity of 4-(Phenyldiazenyl) aniline in the reaction with (5, 0) zigzag open-end single wall carbon nanotubes (SWCNTs) was studied based on the Density Functional Theory (DFT) calculations. Calculation of the thermodynamic functions and the vibrational frequency in the gas and solvent phase was carried out. In order to determinate the dynamic and electron behavior of carbon nanotubes in reaction with yellow aniline, structural parameters and solvent energy of the reaction compounds and the total electronic energy, adsorption energies (EAd) were calculated. The results show that the reaction of adsorption of azo color on the surface of carbon nanotubes in the gas phase and solvent in terms of energy is desirable. The adsorption energy for the optimized structure of azo dye-CNT was calculated -3.953 and -4.612 (kcal/mol) in the gas and aqueous phase respectively, and results showed that the physical adsorption reaction was occurred.

In this work, degradation of C.I. Reactive Orange 7 dye in aqueous solutions was investigated. The electrolysis process optimized based on titanium electrode coated with SnO2 nanoparticles (nano-SnO2/Ti) as anode using response surface methodology. The nano– SnO2/Ti electrode was prepared using electrophoretic deposition (EPD) method and characterized by field emission scanning electron microscopy (FE-SEM). The initial pH, current density, reaction time and electrolyte concentration were selected as independent variables in central composite design while color removal efficiency was considered as the response function. Based on analysis of variance (ANOVA), the coefficient of determination value (R2=0.987) was high showing that the experimental values fitted well with the predicted values. In optimum conditions, maximum color removal efficiency (90.1%) was obtained after 25 minute; and the total organic carbon (TOC) was reduced to 32.2% after 60 minute.

In this study, a metal organic framework based on the Ti (MIL-125) was synthesized by the hydrothermal method and characterized using XRD, SEM and DRS. The photocatalytic activity of synthesized MIL-125 was evaluated in photocatalytic degradation of Reactive blue 19 as an organic pollutant. The degradation efficiency was more than 90% confirming photocatalytic activity of synthesized MIL-125. The kinetics of photocatalytic reactions of MIL-125 were also studied. The results of experiments showed pseudo first-order kinetics for photocatalytic process by MIL-125. Based on the first-order kinetics, the empirical kinetic model was developed to predict the rate constant and degradation efficiency. There is a good agreement between the calculated apparent rate constants and experimental ones.