نشریه علوم و فناوری رنگ
سال سیزدهم شماره 2 (پیاپی 48، تابستان 1398)

In the present work CdTe/ ZnS, ZnSe, CdS, CdSe core-shell quantum dots were synthesized via co-precipitation route. The effect of reflux intervals from 1 to 7 hours, on the CdTe cores, characteristics such as: photoluminescence properties, band gap, structure, and microstructure were studied. Results showed that synthesis with the reflux time of 1 hour led to proper CdTe core with the size of about 4nm, emission wavelength of 555 nm, and band gap of 2.25 eV. More reflux time caused to particle size enlargement, emission shift to higher wavelength values, and band gap decrease. Moreover, ZnS, ZnSe, CdS, and CdSe shells were in-situ synthesized on the CdTe cores. Formation of these shells led to emission red shift with the wavelength up to 591 nm and band gap decrease to 2.15 eV.

Using Near-infrared spectroscopy methods to create the physical and chemical properties estimation model of material has been developed and considered by the food industries in recent years. The present study was conducted to investigate the statistical effects of various pre-processing techniques such as Moving Average (MA), Multiplicative Scatter Correction(MSC), Savitzky-Golay(SG), Standard Normal Variate(SNV), First and Second derivative on the Near-Infrared spectral data of the sugar syrups on sucrose concentration estimation model.  The results showed that the SNV and the Second derivative techniques could have an effective improvement in the estimation model.

Laccase is a biocompatible compound which is able to catalyze the oxidation of polyphenolic aromatic dyes and graft them to wool. Weld (Reseda Luteolla, L.) as a natural dye, contains polyphenolic aromatics with flavonoid structure and could be a substrate for Laccase. In this research, the effect of laccase on Weld and its use to make a covalant bond between wool and polyphenols compounds of Weld was studied. For this purpose the colourant compounds of Weld were extracted and the effect of laccase on it was studied by UV-Vis spectrophotometry, Size-exclusion chromatography and measuring the changes in the dissolved concentration of the oxygen co-reactant. Kinetic of Laccase-Catalyzed Oxidation of weld was studied and the effect of laccase on weld-dyed wool was surveyed. The results showed that Weld is a suitable substrate for laccase and the use of laccase can improve the dye fixation, and dye fastness against washing.

The aim of this study was to investigate the performance of nanocomposites hydrogel as adsorbents for removal of Direct Red 31 dye from aqueous solutions. Here, these nanocompsites were prepared from polyacrylamide (PAM) and polyacrylic acid (PAA) hydrogels in the presence of sodium montmorillonite as nanofiller. The resulting nanocomposites were well characterized by FTIR, TGA, XRD and SEM analysis. The effect of various operation factors such as nanocomposite dosage, solution pH, contact time and initial dye concentration on the adsorption process was studied. The results showed that the maximum adsorption capacity (qmax) of Direct Red 31 was obtained in acidic pH, contact time 90 min and adsorbent dosage 0.05 g which was 168.63, 108.22 and 128.9 mg/g in PAM, PAA and (PAM-co-PAA) nanocomposites respectively. The experimental data were fitted into Langmuir and Freundlich adsorption isotherms and it was found that data fitted well with Freundlich model. Kinetic studies showed that dye adsorption process followed the pseudo-second-order kinetic model.

Nowadays, there is an increasing interest in finding new sources of natural dyes with easy accessibility, high color strength, low cost, and high fastness properties. In this study, harmal seed has been used as a new source of natural dye on wool fibers. Harmal (Peganum Harmala) can be found extensively in several regions of Iran as a self-growing wild plant. Dyeing pH, dyeing Temperature and alum mordant concentration were chosen as the main influencing factors of this study and 25 samples were prepared according to the experimental design. The amounts of color strength of the dyed samples were measured. The results showed that the color strength was increased with increasing the dyebath pH and dyeing temperature. Increasing the concentration of alum decreased the color strength.

Corrosion inhibitors are a simple and economic method for corrosion control of metals in acidic environments. In this regard, green corrosion inhibitors based on plant extracts have received much attention as a suitable replacement to the synthetic and environmentally unsafe inhibitors. The presence of various active compounds in the aqueous extract of Cinnamomum Verum converted it to a rich source of green inhibitors for steel corrosion control. In this study, the inhibition action of Cinnamomum Verum extract was evaluated by electrochemical and surface analysis methods. The electrochemical impedance spectroscopy (EIS) results demonstrated that after 2.5 h steel immersion in 1 M HCl solution containing 800 ppm inhibitor 88% inhibition efficiency was obtained. In addition, the potentiodynamic polarization results indicated the significant reduction of corrosion current density, anodic and cathodic reactions rates. The images of scanning electron microscopy and atomic force microscopy evidenced the lower steel surface damage, indicating formation of inhibitor film over the steel surface. Furthermore, the inhibitor adsorption obeyed the Langmuir adsorption isotherm.

In this research, we are proposing carbon-ceramic electrodes containing TiO2 nanoparticles and MWCNT for the degradation of Reactive Blue 222 dyes by sonoelectrochemistry. In addition, an electrochemical nanosensor based on glass carbon electrode modified with graphene oxide and gold nanourchins was introduced to online determination of dye. Due to the special characteristics of nanoaddetive, the proposed nanosensor has unique features such as high surface area, accelerated electron transfer and high stability. The results of determination the Reactive Blue 222 dye in a concentration range of 25-900 μM with a detection limit 8 μM depict a good performance of the sensor for determined dye. The degradation process were optimized various factors affecting including the amount of potential difference, the amount of TiO2 nanoparticles, MWCNT and the solution pH by the statistical response surface method. At optimal conditions, including pH 0.8, potential difference 0.90 V on carbon ceramic electrode containing 0.2 wt% TiO2 and 3.89 wt% multiwall carbon nanotube during 120 min applying sonoelectrochemical degradation, 96% of 1.0 mM Reactive Blue 222 was degradaed and 88% of initial TOC value (121.33 ppm) was reduced.