JOURNAL OF COLOR SCIENCE AND TECHNOLOGY
Year:2008 | Volume:2 | Issue:2|Papers Count:7

In this work, decolorization of a reactive dye (C.I. Reactive Black 5) by ozonation method was evaluated by UV-Vis spectrophotometry. The effective operational parameters such as ozonation dosages, stirring, pH, temperature, dye concentration, wastewater volume and the electrolytes were studied.  Results showed that the ozonation was a very effective method for reactive dye decolorization. Complete decolorization was achived in different dye concentrations, wastewater volume and electrolytes. These parameters just had some effect on rate of decolorization and not the yield.  The concentration of ozone stream and mixing rate were two important factors among all other factors.

In this study, a new red pigment with good thermal and chemical resistance has been synthesized by solution combustion method. By substituting choromium ions in aluminium ion sites in YAlO3 perovskite structure and synthesis the YAl1-yCryO3 (y=0.01-0.1) solid solution, can provide red color. In the first step, effect of various mineralizers on YAlO3 formation has been investigated. Then effect of the doped choromium amount on the pigment color was studied. Latter, thermal stability and chemical resistance of synthesized pigment were investigated. Results showed that the most appropriate mineralizer system for the formation of YAlO3 perovskite was NaF:MgF2:Li2CO3 (3:2:1 by weight). Calcination at 1400oC for 4 hr is the best condition for preparation of pigments with suitable color. The highest redness (a*) has been obtained when y was 0.03 (YAl0.97Cr0.03O3). Application of the prepared red pigment in low and high temperature glazes, demonstrated high chemical and thermal stability.

This study aims to investigate the performance of polyaluminum chloride (PAC) as a coagulant to remove Acid blue 292 (AB292), which is used widely in textile industry in Iran. The effect of pH, coagulant dosage, kaolinite (as a natural coagulant aid), and initial dye concentration were examined in the coagulation process with PAC. Results showed that the optimum pH range to remove AB292 was 6-8. In such conditions, the dye removal using 40mg/L of PAC was more than 83%. This dosage (40mg/L) was considered as the optimum dosage of PAC to remove AB292. Addition of kaolinite as a coagulant aid increased the efficiency of the process. With the aid of 40 mg/L kaolinite, dye removal efficiency increased by 30% when the coagulant dosage was 30mg/L. As the initial dye concentration increased, the dye removal efficiency decreased, so that the efficiency for dye concentrations of 25 and 250 mg/L was 95% and 21%, respectively.

In this research for the first time in Iran, the anatase crystallographic structure of titanium dioxide was produced from the ilmenite concentrate from the Kahnooj mine by the sulphate method .The raw material contained 47.9 w% of titanium dioxide. By several experiments including grinding and drying, digestion, dissolution and reduction, crystallization, hydrolysis, purification of the hydrolyzate and calcination stages, titanium dioxide was produced. In these experiments, the calcination temperature of 650± 5oC was found suitable for producing anatase crystallographic structure. The samples obtained from performing the experiments for three times were analysed by XRD and XRF. According to the results, three products have anatase crystallographic structure of TiO2 and the purity of 97.95, 96.03 and 96.39 w%. Regarding the high purity of them and low percentages of undesirable impurities, the final products obtained from the ilmenite concentrate from the Kahnooj mine by the sulphate method, could be applicable as a coloring agent and opacifier for glazes.

Blends of vacuum bottom residue with wastes of polyethylene and styrene-butadiene rubber were prepared and their morphology and rheological properties were studied. Since the applied stresses on bitumen in asphaltic pavements are dynamic, the dynamic mechanical behavior of bitumen is of a prime importance. Thus the ratio of G*/sind at 10rad/s was used to estimate the resistance of bitumen to rutting. It was found that the values of this ratio and other rheological functions such as loss, storage and complex module are in such a magnitude that cracking at low temperatures and rutting at high temperatures are avoided. The morphological studies showed that the wastes particles had homogeneous dispersion in vacuum residue. Concerning these rheological properties of bitumen it is concluded that a proper application is found for recycling the considered wastes.

Two types of bituminous coating, bitumen and coal tar pitch, were investigated using cathodic delamination and adhesion measurements. The bituminous coatings were applied on shot blasted steel with 100 µm thickness and then were subjected to cathodic delamination and wet adhesion tests during immersion in %3.5 NaCl w/w solution. The wet adhesion test results showed good agreement with cathodic delamination resistance. It could be indicate that the mechanism of cation diffusion to the interface in cathodic delamination process is similar to immersion condition without applied voltage. The mechanism of cation diffusion for bitumen based coating was through the intact coating and for coal tar pitch based coating was through defects in coating. The results showed that the cathodic delamination process is a criterion for estimating of the wet adhesion failure during immersion time.

Alkyd resins which are used in the organic coating industry have various properties with different applications which include flexibility, resistance to stroke, high adhesion property and resistance to breakage. Nevertheless, it has some shortcomings as well, which should be removed by combination of other resins and polymers. One of the properties which need correction is weak thermal properties that can be removed by combining with silicon resins. In the present study manner of preparing silicon - alkyd copolymer, its properties, specifications and it’s thermal application range have been explained. Thermal resistance of alkyd based coating is improved with silicone effect in resin and flexibility of ethyl silicate primer increased by alkyd effect in silicon modified resin. Silicone-alkyd based of primer is comparable with ethyl silicate primer in mechanical properties and has lower price.