جستجوی مقالات مرتبط با کلیدواژه "عامل دار کردن" در نشریات گروه "مهندسی شیمی، نفت و پلیمر"

In this study, a magnetic metal-organic framework functionalized with 8-aminoquinoline was synthesized to monitor and measure arsenic in rice and tuna samples consumed in the Iranian market. After identifying the nanoadsorbent by FT-IR, SEM, TEM, VSM, XRD, CHN, DLS, Zeta potential and BET methods, parameters affecting adsorption and desorption were optimized. Optimization of the extraction process was performed by the experimental design method based on a three levels Box-Behnken design. Then the desired method was validated and finally, the synthesized adsorbent was used to monitor and measure arsenic in rice and tuna samples consumed in the Iranian market. The optimal extraction conditions were: pH of the sample solution, 3.6; adsorption time, 12 minutes; nanoadsorbent dose, 16 mg; type and concentration of elution solvent, 0.06 M nitric acid; elution time, 8.5 minutes; eluent volume, 0.8 ml. Under the optimal conditions, the detection limit of the method was equal to 0.01 μg/l, and the method exhibited good accuracy in the analysis of the sample with the confirmed concentration. Under the optimal conditions, the desired method was evaluated in order to monitor and measure arsenic in rice and tuna samples available in the Iranian market, and very good results were obtained.The most important advantages of the present method are its simplicity, easiness, time saving and high accuracy.

Adsorption of lead metal ion [Pb(II)] from aqueous samples was investigated using polyethersulfone (PES)/amine-functionalized carbon nanotubes (NCNTs) via changes of pH, stirring speed, contact time, adsorbent content and initial metal ion concentration. The FTIR and EDX results for the modified sample showed that the first type amine groups (N-H2) and the second type amine groups (N-H) were located on the CNT surface. The SEM images also showed CNTs structure change, their breaking down followed by providing more order. The rate of ion adsorption by the nanocomposite sample showed that the kinetic equilibrium of adsorption occurred within the first 10 min of contact time. To maximize the metal ion removal, the amounts of nano-adsorbent, pH and initial ion concentration were determined 0.1 g/100 mL aqueous sample, 7, and 95 ppm, respectively. Also, the Freundlich isotherm model and the pseudo-second order kinetic model had the best correspondence with the experimental data.

Poly (dimethyl siloxane) (PDMS) has received special attention due to its unique properties such as high surface tension، high gas permeability، high hydrophobicity، high chain flexibility at room temperature، good biocompatibility and very low glass transition temperature. One of the simplest methods to impart these properties in copolymers is to use PDMS as a macroinitiator in the controlled radical polymerization. In the present study، hydroxyl-ω PDMS was characterized by FTIR، 1H NMR and GPC analyses. The results showed that there is an impurity present in the commercial hydroxyl-ω PDMS. Functionalization reactions were used to investigate the reactivity of the impurities. Hydroxyl-terminated PDMS was brominated via 2-bromopropionyl bromide and α-bromoisobutyryl bromide. Brominated PDMS، used as a macroinitiator in the atom transfer radical polymerization، was then iodinated by sodium iodide in anhydrous acetone as a solvent to prepare iodinated PDMS. Bromination and iodination were verified by FTIR، 1H NMR and GPC analyses. GPC results showed that a high molecular weight impurity present in the sample can be removed after functionalization and purification of PDMS though there may be still impurities remain in the purified product. 1H NMR spectrum of the brominated and iodinated PDMS showed that the peaks related to the impurity do not show any change in intensity and chemical shift in comparison with those appeared in the 1H NMR spectrum of the hydroxyl-ω PDMS، indicating that impure species are not reactive in chemical modifications. In other words، these impurity species do not have any hydroxyl reactive functional group.

Since the last decade, researcher activities in the field of nano-materials have been considerably increased.Carbon nanotubes has exploited as efficient adsorbent for removal of heavy metals, macromoleculars and microorganism due to high length to diameter ratio, large accessible external surface area, and favorite reactivity. These materials are used in membrane processes in order to achieve high flux and selectivity. Adding CNT to photocatalysts increases the removal efficiency of pollutants. By functionalization of carbon nanotubes, their aggregations have suppressed in solutions. This leads efficiency improvement and uniform dispersion.