주제어: Polyvinyl chloride 막; Bis-(2-ethylhexyl)phthalate; Malachite green; 고상추출 ABSTRACT. A new sensitive and selective spectrophotometric method for determination of trace amounts of cadmium using a polyvinyl chloride membrane containing bis-(2-ethylhexyl)phthalate as a solid phase extraction medium was investigated. Bis-(2-ethylhexyl)phthalate has used as a plasticizer. Cd(II) in an aqueous solution was trapped on the membrane in the form of colorful Cd (II)-I --MG complexes (which MG is malachite green) and the cadmium complex was concentrated in the membrane. The absorbance of the green membrane was measured at 629 nm using a spectrophotometer, and then, the concentration of the cadmium was calculated using a calibration curve, which expressed the relationship between the Cd(II) concentration and the membrane absorbance after coloring for 25 min. The calibration curve was linear in the range of 10-760 µgL and the relative standard deviations (RSD) were less than 4 % (n=5). The proposed method has been successfully applied to the determination of trace amounts of cadmium in the Tadjan River water sample (Sari-Iran), and the mean value of 28.7 µgL -1 was obtained.
CNTsare one of the most significant achievements of nano-technology with important applications in the design of electronic nano-devices. Nano-tubes with small size, physical stability and sensitivity of their electric properties to adsorption of N2and O2make them ideal materials for use in gas sensors. In this investigation the (DFT) method is utilized to study the adsorption of oxygen, nitrogen molecules on the surface of (5,0) CNT. The electronic structure, NMR spectrum, dipole moment of nitrogen, oxygen and carbon nuclei's are thoroughly studied. The computational results indicate that rich adsorption patterns may result from the interaction of oxygen and nitrogen with the CNTs. Sometimes, C-O bounds are formed via breaking C-C bounds and sometimes a carbon atom in the nanotube is replaced with an oxygen atom. Sometimes oxygen and nitrogen molecular are attracted to a C-C bound. In summary, the optimized adsorption rates are calculated. The nitrogen molecules adsorb with a comparatively lower rate and almost never a chemical binding is formed with the CNT. Gaussian 98 software has been used to carry out quantum chemistry calculations.
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