نشریه علوم و فناوری رنگ
سال هفتم شماره 2 (پیاپی 24، تابستان 1392)

In this research the effects of surfactant concentration and its addition time in the synthesis procedure of kerosene based ferrofluid were investigated. Magnetite nanoparticles were prepared by co-precipitation method and were dispersed in Kerosene as carrier liquid. Oleic acid was used as surfactant. Powder X-ray diffraction was used to phase identification and crystallite size was calculated via scherrer formula. For investigating of surfactant adhesion on particles Fourrier transform infrared spectroscopy was used. Magnetic properties were studied using alternative gradient force measurement. Size and distribution of agglomerates were studied by dynamic laser scattering. Results show that addition of surfactant before reaction effectively prevents from agglomeration. If oleic acid is added about 10wt% before reaction, hydrodynamic size and particle size will be 21nm and 13nm respectively. It was revealed that the size of agglomerates and their distribution are effectively changed when the concentration and addition time of surfactant is changed. J. Color Sci. Tech. 7(2013), 85-92© Institute for Color Science and Technology.

In this research, pigment red 3 was treated using sulfonation method. The untreated organic pigments have low surface free energy. With this treating method the surface free energy of pigment increases. The aim of this study is surface modification of pigment red 3. The treated pigment showed very good dispersibility and dispersion stability in aqueous media. The dispersion of these particles in organic polar media are stable and without aggregation. After treating, the polarity of particles increased, show manifest dispersability in polar media. Parameters such as time, temperature, solvent/pigment ratio, acid/pigment ratio were considered as independent parameters at taguchi method. For obtaining standard array, for each parameter four levels were considered. The proffer array with taguchi method was L16. After the design of experiment, the treated and untreated pigments were formulated in water based flexography ink. In order to assess the inherent and application properties of treated pigments and selecting the suitable samples, examinations such as pH, fineness, rate of dispersion, gloss, tinting strength and chroma were performed. Also according to the results of analysis of variance, the effect of each independent parameter on studied properties was considered. J. Color Sci. Tech. 7(2013), 93-102©. Institute for Color Science and Technology.

In this study, the modification of multi-walled carbon nanotube (MWCNT) with a cationic surfactant (cetyl trimethyl ammonium bromide, CTAB) and its application for removal of Direct Blue 86 (DB86) was investigated. The raw and functionalized samples were characterized by Fourier Transform Infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The influence of operational parameters such as adsorbent dosage, initial dye concentration and pH were studied at 25oC. Understanding the mechanism of the adsorption, Langmuir and Freundlich models were used. The results indicate that the data for adsorption of DB86 onto raw and modified carbon nanotubes fitted well to Langmuir isotherm. The Langmuir adsorption capacities of raw and modified carbon nanotube for DB86 were established as 69.93 and 149.25 mg/g, respectively. Pseudo first and second-order models were adopted to evaluate data and elucidate the kinetic adsorption process. The rates of sorption were found to conform to pseudo-second order kinetic with good correlation. The adsorption experiments indicated that the capacity of modified carbon nanotubes is more significant than raw carbon nanotubes, thus it could be used as an effective adsorbent for removing anionic dyes from textile waste waters. J. Color Sci. Tech. 7(2013), 103-112©. Institute for Color Science and Technology

Thermal control paints are coatings with special thermo-optical properties that applied on the spacecraft outer surfaces to control the input and output heat. In this work, for evaluation of pigment to binder effect on white silicate thermal control paints properties, samples were made by ZnO pigment and potassium silicate binder in several pigment to binder ratios, then were applied on aluminum substrate. Solar absorptance and thermal emittance measurements were performed with spectroreflectometer and emissometer. Thickness, reflectance and gloss measurements were performed with their instruments. For abrasion, adhesion and bend tests, Taber, 750 sheen tape test and mandrel instruments were used. Surface evaluation was performed with scanning electron microscopy (SEM). The results indicated that increasing pigment to binder ratio led to reduction of solar absorptance, adhesion, wear, bend and impact resistance and increasing thermal emittance and reflectance. Finally, the paint with 4:1 pigment to binder ratio was introduced as the optimum sample. J. Color Sci. Tech. 7(2013), 113-121©. Institute for Color Science and Technology.

Assessment of the total appearance of an automotive coating using standard methods would have a great impact in the automotive industry. These methods should have a good correlation with visual assessments. In this research, the correlation between visual assessments and the wave scan DOI results were investigated for white, metallic grey and metallic black automotive samples. The visual assessments were carried out by a panel of 14 observers, including 6 males and 8 females under a light source simulating D65 in a light cabinet with a viewing geometry of 45/0. The visual assessment method used was one of paired comparison. Such quality rankings were then converted to quantitative equivalents by the aid of the Thurston scale and the results were compared with each of the wave scan output parameters. Statistical and error estimation parameters (i.e. R 2 and stress) illustrated that amongst all wave scan parameters, only Wd, Wc, LW and in that order strongly correlated with human evaluations of geometric attributes for these achromatic paint samples. Investigation of structure spectrum showed that Wb is another important parameter indirectly influencing on the surface appearance and in fact the value of Wb is greater than Wd and Wc in the acceptable region. Therefore, there seems to be a complex relationship between these parameters which represent the short and the long waves which is of utmost importance in assessing perceived total appearance. J. Color Sci. Tech. 7(2013), 123-131©. Institute for Color Science and Technology

In this study, application of immobilized Horsradish Peroxidase (HRP) on calcium alginate to removal of acid blue 25 and acid orange 7 from waste water was studied. Experimental study of optimum condition for immobilization of HRP on calcium alginate and then, removal efficiency of acid blue 25 and acid orange 7 by immobilized HRP and also toxicity of by-products with bioassay were studied. Results show that immobilized HRP at optimum condition have 80% color removal efficiency from polluted wastewater. Results show alginate beads after 10 replicate usages without change in activity were reusable. Bioassay of by-products by D.Magna show that this method of treatment lead to decrease significantly in toxicity of dye from treated wastewater. J. Color Sci. Tech. 7(2013), 133-142©. Institute for Color Science and Technology.

In this work, silver-doped zinc sulfide (ZnS:Ag) has been coated on the indium tin oxide (ITO) glass via direct current electrophoretic deposition (DC-EPD). Experiments showed that the current density is the most important parameter during the coating process and it should be in the range of 0.11-0.22 mA/cm2 not only preventing ITO from damaging, but also achieving a high quality coating. Three different parameters most affecting the current density, i.e. the additive, storage time and the cathode to anode ratio have been investigated. Investigations showed that in comparison with the solvent and the powder, additive has the most influence on the deposition current density. The current density also initially increases with the storage time and then becomes rather stable at longer times. Decreasing the cathode to anode ratio increases the current density, hence the deposit yield. J. Color Sci. Tech. 7(2013), 143-149©. Institute for Color Science and Technology.

Inorganic-organic hybrid coatings with TiO2-SiO2 core/shell nanoparticles were prepared in order to develop the self-cleaning and corrosion resistant coatings. As proved in XRD test, the anatase TiO2 nanoparticles were prepared by sol-gel method in two different thermal conditions namely high temperature and low temperature process. The size and the shape of the particles in amorphous TiO2 sol and the thickness of SiO2 layer on the anatase nanoparticles revealed a core/shell structure by transmission electron microscopy. The photocatalytic activities of the coatings using the prepared TiO2-SiO2 nanoparticles were investigated via the decomposition of methylene blue (MB) under UV-radiation and compared with those samples prepared using commercial TiO2, i.e. P25 Degussa. It was found that the photocatalytic activity of the coatings was significantly attributed to the crystallinity and the particle size of anatase nanoparticles. To find out the effect of photocatalytic activity on the corrosion resistance, the nanocomposites coatings were exposed under UV for 1080 h. The Tafel curves of the samples showed lower corrosion resistance for the coatings of higher photocatalytic activity. J. Color Sci. Tech. 7(2013), 151-164©. Institute for Color Science and Technology.

In this investigation, dyeing kinetic of modified PP fibers produced as polypropylene polybuthylene terephthalate (PP/PBT) polyblend fibers was studied. The modified fibers were dyed with selected disperse dye (C.I. Disperse Blue 56) at different times and temperatures. The experimental data was adjusted to well-known dyeing kinetic equations, i.e. Vickerstaff, Patterson, McGregor and Cegarra-Puente to determine the rate constant of dyeing and diffusion coefficient at different temperatures. The results showed, exhaustion, constants rate of dyeing and diffusion coefficients, were increased with increasing the time and temperature of dyeing process. A significant enhancement in dye absorption was observed for dyeing in 120 oC compare with other temperatures. So that, the time of dyeing saturation was reached two times faster in this dyeing temperature compare to the other temperatures. The best adjustments with applied dyeing kinetic equations were occurred with the Vickerstaff and Cegarra-Puente kinetic equations. However, the Vickerstaff equation was determined as the best model with regard to their highest average regression coefficients and suitable trend of dyeing kinetic constants in the range of the dyeing temperatures. Diffusion coefficient value was increased significantly (9 times) by increasing the dyeing temperature. Furthermore, the highest variation of diffusion coefficient enhancement belongs to temperature variation from 100 oC to 120 oC. Also, trend of the diffusion coefficients showed a good conformity with the exhaustions trend in the different temperatures. J. Color Sci. Tech. 7(2013), 165-172©. Institute for Color Science and Technology.