نشریه علوم و فناوری رنگ
سال پانزدهم شماره 1 (پیاپی 55، بهار 1400)

In the present research, heterogeneous electro-fenton operation was employed to remove methylene blue (MB) as a cationic dye. To reach the purpose, we used a reduced graphene oxide (rGO) modified carbon electrode. At first, GO was synthesized using modified Hummer’s method, and then rGO nanoparticles were obtained by reducing GO using reducing agents such as hydrazine and ammonia. In order to produce Fe+2 and Fe+3, magnetite nanoparticles (Fe3O4) have been synthesized. Na2SO4 salt was used as an electrolyte to enhance electrical current. And also, some effective parameters such as pH, electrical current, Fe3O4 value and pollutant concentration were studied. The dye removal results showed that the modified electrode has a high potential for cationic dye removal in acidic and alkaline pH so that it can remove MB 99 and 98% in acidic and alkaline pH, respectively. Optimum conditions for dye concentration, magnetic amount, current intensity and pH were 10 mg/L, 0.08 g, 0.06 A and 3, respectively. Furthermore, cyclic voltammetry and dye removal tests were done. The two comparative tests were carried out in order to exhibit more electron transfer capability of the modified electrode than the bare electrode.

In this study, the doping effect of TiO2 on carboxylated multi-walled carbon nanotube (FMWCNT) on adsorption of Indigo carmine dye, an acidic dye, form aqueous enviroment has been Investigated. TiO2 was doped on FMWCNT surface and it was checked by fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and scanning electron microscope (SEM). The dye adsorption experiments were carried out by using a batch procedure. The effects of contact time, pH, dye concentration, adsorbent dose and temperature on adsorption of indigo carmine by TiO2 doped and undoped adsorbents (FMWCNT /TiO2 and FMWCNT) were evaluated. Pseudo first order, pseudo second order and intra-particle kinetic models were used to describe adsorption kinetics. Furthermore, Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms were used to describe equilibrium adsorption of the indigo carmine dye on adsorbents. The obtained data were then analyzed using linear regression method. Experimental results have shown that acidic pH (3.0), favored the adsorption for both adsorbents. The dye adsorption equilibrium was attained after 90 minute of contact time. The capacity of adsorption of indigo carmine increases with doping of TiO2 on FMWCNT. Pseudo second order kinetic model is best fitted with experimental data for both adsorbents. The equilibrium data of dye adsorption on both adsorbents are best fitted with Langmuir isotherm at 25, 35 and 45 ºC. Thermodynamic study of dye adsorption on FMWCNT and Fmwcnt /TiO2 adsorbents showed that the adsorption process is exothermic and chemisorption.

In this research, firstly Bentonite was treated by Hyamine, a cationic surface active agent, and then its capacity for the adsorption of acidic dyes was investigated. Correlation coefficient of equilibrium adsorption study showed that the surfactant adsorption is predominantly described by Freundlich adsorption isotherm. The maximum adsorption capacity was calculated about 94.7 mg/g at 30 oC. This was measured for the adsorption of the dye onto the modified adsorbent around 86.3 mg/g at 30 oC which was higher than the ones obtained at room temperature and 40 oC. Kinetics of adsorption significantly fitted by pseudo second order equation for both Hyamine and acid dye adsorption onto the adsorbent. Initial adsorption rate was increased by increasing of temperature. Intraparticle diffusion study revealed that the diffusion of the cationic surface active agent and the acid dye in the related adsorption structure was concurrently done by film diffusion.

In this study, an organic emission light diode (OLED) with the ability to adjust the color was created using two organic pigments as guests at the same time. Tunable color organic light-emitting diodes (OLEDs) using two dyes as guests have been fabricated and investigated. The structure of the manufactured part was ITO /PEDOT:PSS /PVK /C6:TPP:Alq3(x nm) /BCP/ Al. First, an organic norepinephrine diode blocker was made, and then the effect of different thicknesses of the Norgecil layer on the electrical characteristics, color, and optical coordinates of the diodes made was evaluated. The green diode was made at a thickness of 10 nm. By changing the thickness, an orange diode was obtained. It was found that by reducing the thickness, in addition to direct recombination, indirect recombination also has a significant effect on diode color. This made the color adjustable diode with thickness control. For part 2, the maximum brightness was obtained at 12 volts. Finally, the experimental results were compared with the simulated results.

In recent years, synthesis of carbon dots from plant precursors has received great attention. In the present study, the green synthesis of carbon dots with two different methods and their cytotoxicity was compared. The size and morphological properties of carbon dots have been analyzed by facility of DLS, AFM, and TEM. Then cytotoxicity assay was performed. UV-Vis spectrum observed an absorption band at 250-280 nm suggesting the formation of carbon dots. Also, size and morphological properties of carbon dots were done. Despite the smaller size of the carbon dots in Teflon lined stainless-steel autoclave, both methods lacked significant cytotoxicity. Therefore, both methods have the necessary efficiency for different purposes due to their appropriate size and non-toxicity.

In this study the effect of cerium nitrate existing in the structure of plasma electrolytic oxidation (PEO) coating on the protective behavior and adhesion strength of PEO/epoxy duplex coating applied on AZ31 Mg alloy was investigated. PEO coating was considered as the pretreatment for applying the epoxy layer. The presence of Ce additive affected the morphology of the surface of the PEO coating and its corrosion resistance. Embedding Ce in the structure of the PEO layer showed that the PEO structure, in addition to its pretreatment role, acts as the container of cerium. The results of the electrochemical impedance spectroscopy (EIS) test and the pull-off adhesion test in dry and wet conditions on duplex coatings revealed that the presence of Ce improves the protective behavior of the epoxy layer and its adhesion strength. Formation of cerium hydroxide in chathodic regions leads to improvement in the protection properties of duplex coating system.

In this study, a simple method was used to prepare nickel oxide nanoparticles. The prepared nickel oxide nanoparticles were characterized using Fourier Transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) techniques. Also, the adsorption of methyl green solution at a concentration of 20 mg/L was investigated by changing the parameters of the amount of nickel oxide adsorbent, stirring time and temperature of the solution. The results show that the best condition for removing methyl green is to use 10 mg of nickel oxide adsorbent for 45 minutes at 45 °C. Therefore, this adsorbent will be able to remove similar colors.