نشریه علوم و فناوری رنگ
سال پنجم شماره 4 (پیاپی 18، زمستان 1390)

This study was designed to compare the effect of various opacifiers of zircon and andalusite on color parameters and gloss of tile samples. Although zircon is one of the most important opacifying agents that applied to make the engobe opaque, it is interesting to find a cost-effective alternative for that in ceramic industry. At the present work, the whiteness degree was applied to determine the degree of opacification. The effect of used opacifiers on color appearance of glaze was studied by calculating the color parameters CIEL*a*b*color space. Besides, the parameters of specular gloss, reflection haze and distinctness of image were determined to show the effect of used opacifiers on geometric appearance of glaze. The results showed that the nature and particle size distribution of opacifier as well as the grinding of engobe before the andalusite application play important role. In addition, it was illustrated that using andalusite instead of zircon as opacifying agent is caused the color appearance of glaze to shift from white shade to yellowish one. The results of gloss, reflection haze and distinctness of image pointed out that the geometric appearance properties of glaze are mainly affected by its nature than the applied opacifier. The confirmation of the obtained results was checked with the optical microscopic images.

In this investigation, attempts were made to predict the effect of variations in composition of modified polypropylene (PP) with polyethylene terephthalate (PET) and a maleic anhydride grafted polypropylene (PP-g-MA) as a compatibilizer on blend’s disperse dyeability by means of a special cubic experimental design. The results showed that there seems to be a critical PET content, above which the blend’s dye uptake stays constant and the mechanical properties of the blend begin to decrease. In addition, further analysis of the results indicated that PP/PET/PP-g-MA blends with 10-15 wt% PET and 4-5 wt% PP-g-MA gave maximal dye uptake as well as desirable mechanical properties.

In this paper various derivative spectrophotometric methods including zero-crossing, peak to peak, peak to zero, and ratio derivative are used to determine dye concentration in colored fabric, which is dyed with ternary mixture of dyes. The experimental and theoretical comparisons of methods are done by using relative error of dye concentrations prediction. The relative error in normal kubelka-munk, peak to peak, peak to zero, and ratio derivative methods are 0.288, 0.257, 0.29, 0.22, 0.143, respectively. As obtained results indicated, the performance and accuracy of ratio derivative method is better than other derivative techniques and normal kubelka-munk method.

The Acid 4092 dye solution toxicity after UV/ZnO mediated nanophotocatalysis process using Daphnia magna bioassay was investigated. Daphnia magna has been evaluated as suitable indicator to test effluent toxicity in dyes wastewater. In this study, the parameters such as ZnO nanoparticles load, pH and contact time were analyzed. This study showed that toxicity increases during the UV/ZnO nano-photocatalysis process. Besides, toxicity increases with time. LC50-24 hr, LC50-72 hr, and LC50-96 hr values were 124.9, 111.6, and 91.55 mg/l, respectively.

Organic-inorganic hybrid coatings were prepared to increase abrasion and solvent resistance of polycarbonate sheets. To this end, sol-gel method was used to generate in situ nano silica network as inorganic part and UV curable urethane acrylate oligomer and acrylate monomers with different functionality as organic part. Different factors including water to alkoxide ratio, molar ratio of precursors and the ratio of inorganic to organic were studied. The effect of these parameters on transparency and mechanical properties was investigated. High amount of water to alkoxide ratio causes incompatibility between organic and inorganic part. Using moderate amount of precursors and inorganic to organic ratio, optimum transparency and abrasion resistance could be obtained.

In this research ceramic nano pigments including CoAl2O4 (cyan), Au (magenta), (Ti,Cr,Sb)O2 (yellow) and CoFe2O4 (black) which were applied by ink-jet printers for decoration of ceramic tiles, were combined by the Colors software. The target was to examine the possibility of obtaining different colors spectra using CMYK system. For comparison, equivalent micro pigments namely CoAl2O4, Cd(S,Se):ZrSiO4, (Ti,Cr,Sb)O2 and CoFe2O4 were also examined. The compositions of the magenta micro and nano pigments used in this research were totally different. The red micro pigment was a cadmium sulfide pigment, while the nano one was mainly constituted of gold nano particles. It was observed that using the present nano pigments, it was possible to cover the fourth quarter close to a+ in CIELAB system. It also was revealed that reaching the colors of gray, brown and beige shades was possible by both nano and micro sets of pigments, while making orange and yellow colors was difficult.

Concrete is one of the most frequently used construction material that is used in civil engineering industry for two centuries. Production of colored concrete is also has become a new research topic in recent decades. In the production of the colored concrete, the use of mineral pigments is a method by which fully colored concrete can be obtained because by using mineral pigments it is possible to produce vast variety of colored concrete with desirable strength and durability. The aim of this paper is to study the effects of the pigments on the compressive strength of concretes produced by mineral pigments and to predict the results by Fuzzy inference system. To do so, ordinary and colored concrete specimens were made by adding different percentages of different pigments and were tested using standard compression testing and the effects of pigments on the compressive strength and the optimum percentage of the pigments were obtained. Then having tested the specimens, Fuzzy inference system as well as linear and non-linear regression analysis were used to predict these effectcs and the results were compared with the laboratory results. The obtained results show that in comparison with linear and non-linear regression models, the Fuzzy inference system predicts results more similar to the laboratory results.

In this research, the Date Seed (DS) was investigated to remove the anionic dyes from textile effluent as a biosorbent. Direct Blue 78 (DB78) and Acid yellow 36 (AY36) were used as anionic dyes. The surface characteristics of DS were investigated using Fourier Transform Infra-Red and Scanning electron microscope. The influence of process variables such as adsorbent dosage, initial dye concentration and pH were studied. The isotherm and kinetic of dye adsorption onto DS were studied. The results indicated that the data for adsorption of DB78 and AY36 onto DS fitted well with Langmuir isotherms. The rates of sorption were found to conform to pseudo-second order kinetic with good correlation. Results indicated that DS could be used as a biosorbent to remove the anionic direct and acid dyes from contaminated watercourses.

This research deals with the application of polyaniline coated on wood sawdust (PANi/SD) for the removal of anionic dye congo red (CR) from aqueous solutions. The influence of process variables such as adsorbent dose, initial dye concentration, pH of test solution, contact time and breakthrough curves were studied. In order to find out the possibility of reuse, desorption study was also carried out in this investigation. Surface characteristics of PANi/SD were investigated using Fourier transform infrared (FTIR) technique. Among the different parameters affecting the removal of dye, it was found that pH of the solution has the most pronounced effect. Sorption/desorption of dyes can be simply controlled via pH adjustment. The experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir. It was found that the adsorption of CR on PANi/SD followed the pseudo-second order equation which indicates that the adsorption process is chemisorption controlled.

The aim of this research is to evaluate the efficiency of combustion synthesis method for production of nano CoAl2O4 and study the influence of pH (2.5, 7, and 10.5) on the characteristics of CoAl2O4 nano pigments. Gel formation, morphologies, specific surface area, and color of the powder were characterized using TG/DTA, XRD, SEM, TEM, BET, and UV-Vis techniques. The results indicate that spinel CoAl2O4 was formed independently of the different variables studied. According to the TEM figures, most particles calcined have average particle sizes less than 75 nm. Results show that pH has a strong effect on the procedure and characteristics of CoAl2O4. The best value of b* is seen at pH 2.5. In line with BET and Scherrer’s equation results, maximum specific surface area and minimum average particle size are at pH 7.