جستجوی مقالات مرتبط با کلیدواژه « Spectrophotometer » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Optical properties of graphene oxide and poly methyl methacrylate nanocomposite was investigated in this paper. Initially, graphene oxide was prepared from the oxidation of graphite powder by a strong acid by Hummers-Offemane method. Then identification, purity determination and particle size were obtained by using infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The average size of graphene oxide nano particles was estimated about 38.4 nm using the XRD technique. So nano composites of graphene oxide based on poly methyl methacrylate were prepared by the co-precipitation method as an optical sensor element. Nano  composites were identified and characterized by FE SEM, EDX, XRD and FT IR analyzes. To investigate the optical properties of the specimens, UV-vis spectro photometry and reflective spectrometer were used. For three samples of the poly methyl methacrylate nano composite containing nano -graphene oxide, the values ​​of the color parameters b *, a * and L * were obtained that were prepared in the same conditions. Then the black index of the Westlanchr(chr('39')39chr('39'))s ratio was calculated. The average blackness index calculated was 3.7 for this nano composite. The study of UV-vis spectra in the region of 400-1100 nm for this nano composite showed that in the 400 - 700 nm regions the light transmission of UV light is approximately zero. Therefore, the results showed that the use of graphene oxide in the PMMA matrix improves the nano composite coating properties against UV waves and nano oxide graphene gives better shades of black color compared to other fillers and pigments.

In this paper, ozonation method is used to remove carbendazim from aquatic environment. In this method, the produced ozone gas passes through an injector and then is converted into little bubbles and finally is injected into the synthetic wastewater. Spectrophotometer was used to measure carbendazim concentration. The complete factorial method was used to design the experiment. This design is considered to be repeated for two times for time parameters at five different levels of 5, 10, 15, 30 and 45 per minute, pH levels of 5, 6.73 and 9, and initial concentration of carbendazim levels of 2, 6, and 10 mg/l. The results showed that the maximum removal efficiency of carbendazim was 91% for a period of 15 minutes, pH level of 9 and concentration of 10 ppm and the most effective parameters on carbendazim removal efficiency have been initial carbendazim concentration, initial wastewater pH and ozonation time, respectively.

In the present investigation four spectrophotometers from different models of the X-Rite company were compared in terms of precision and truness using BCRA standard tiles. We investigated the effect of manufacturer’s re-calibration procedure on the reduction of error for spectrophotometers in which only two of them were calibrated. The repeatability results of this research show that the precision of all spectrophotometers is acceptable and there is no significant difference between calibrated and non-calibrated devices. Moreover, the average of color difference results for a series of fourteen BCRA tiles show that only the CE7000 A as a non-calibrated spectrophotometer needs the manufacturer’s re-calibration procedure whereas the SP62 spectrophotometer which was not calibrated, shows no significant error in comparison to both other calibrated devices. Additionally for achromatic tiles, the new calibrated Ci64 device demonstrates a larger error than both SP62 and SP64 devices. Meanwhile, the average of color difference values per device for BCRA tiles are larger than acceptable values. Therefore, it seems that the acceptable value for trueness of spectrophotometers is an unreasonable expectation and needs to be revised.

Camouflage، in visual and near infrared region (NIR)، is one of the important topics developed for military purposes. In order to impart camouflage in NIR region، the reflectance profile of the object and its surrounding should be matched. So، the reflectance profile of a selected dye in NIR region is of great importance. If the fabrics are dyed with various pigments and then examined for their power of imparting camouflage in NIR region there would be much waste of human effort and cost to use a reflectance spectrophotometer. To challenge these problems، a new method is developed and reported in this study. For this purpose، a UV-Vis absorbance spectrophotometer is employed and the transmittance profiles of the selected dyes are compared with a known NIR camouflage imparting dye. The novel dye has been studied and evaluated for its potentials as camouflage substance. Since C. I. Vat Blue 13 is one of the camouflage dyes and because structural properties of the dye such as the transmittance curve or the reflectance curve are influenced by its structure، it was concluded that C. I. Vat Blue 6 dye can be used as a camouflage dye in NIR region by similarity of its transmittance curve with that of C. I. Vat Blue 13.

In this work, the behavior of leuco solutions of vat dye was studied by using their spectrophotometeric data. Initially, the leuco solutions of C.I.Vat Green 1 were prepared with different concentration of sodium hydrosulfite and soda. Then, the absorbance spectral of leuco solutions were measured by spectrophotometer. The relationship between color and absorbance of leuco solution and concentration of soda and sodium hydrosulfite was studied. The obtained result shows, that the color and absorbance of leuco solution depend on the amount of soda and sodium hydrosulfite. Beside, the reduction properties of sodium hydrosulfite depend on the concentration of soda. Subsequently, the leuco solution was simulated by using subtractive color mixing low. J. Color Sci. Tech. 1(2007), 19-24. © Institute for Colorants, Paint and Coatings.