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

Optical sensors and biosensors have the great potential to detect metal cations, anions, organic dyes, drugs, pesticides and other contaminants. These sensors are considered for their easy preparation, fast sensing, high sensitivity and selectivity, as well as naked eye detection. Optical sensors are divided into two categories of colorimetric and fluorescent sensors. In this regard, molecularly imprinted polymers, indicators, nanomaterials (metal nanoparticles, metal oxides, quantum dots) and etc. are used for the designation of optical sensors. The fabrication of MIP-based optical sensors is one of the considerable methods for the preparation of optical sensors. This method, known as the molecular lock-key method, for creating molecularly imprinted polymers (MIPs) which are complement to template molecules in shape, size, and functional groups. These materials are similar to biological systems in structure and application that result from the copolymerization of functional monomers and crosslinkers in the presence of the target molecule. These polymers are used for the detection, separation and removal of trace amount of various contaminants in complex substrates. For the preparation of MIP-based sensors, fluorescent functional monomers and dyes including coumarins, xanthenes, naphthalimides, carbazoles, boron dipyrromethenes, azo dyes, schiff bases and etc. are used. Therefore, in this study, various applications of MIPs including environmental, pharmaceutical and medical usage through separation, biomimetic assays, sustained delivery and release, new application areas and specially, optical sensors (synthesis process and its mechanism), will be expressed. In addition, recent developments and commercialization of MIPs and MIP based sensors, will be discussed as well as the introduction of some active companies in this field.

With the strong global increase in transportation technology and daily increase of cars, the interest in recycling of waste tires have been increased due to energy resources and environmental protection. One of the recycling methods for waste tires is pyrolysis and converting them into liquid fuels. In this study the effect of final reaction temperature and residence time on pyrolysis process and obtained liquid fuels were investigated. Among the pyrolysis products which are solids, liquids and gases, the liquids were selected for further investigation. These pyrolysis liquids were characterized by FTIR spectroscopy, and the results showed that liquids contain linear hydrocarbon more than 4 carbon moves toward aromatic component with increasing pyrolysis temperature. These findings were also confirmed by Detailed Hydrocarbon Analysis(DHA). The components of pyrolysis liquids consisted mainly of 2,3-dimethylbutene, 2-Methylbutene, t-Isobutyl-4-ethyl-benzene, and 1-m-4Isopropyl-benzene. The results also showed that the percentages of gases and liquids were increased and decreased respectively with increasing of temperature but there is no change in char percentage yields above 500°C. It is Obviouse that the maximum amount of solids is equal to the percentage of carbon black and other minerals in the rubber formulation that remain in pyrolysis. Measuring of calorific value of pyrolysis liquids showed good compatibility with commercial heating fuels.

Adsorptive desulfurization using mesoporous carbons are of the preeminent methods to meet serious international standards in case of sulfur. In this research, the absorbent CMK-3 containing nickel nanoparticles was synthesized and characterization using XRD, BET, SEM and FT-IR. The results showed that the nanostructure was formed and the despite high nickel loading, structural order is still preserved and specific surface of the synthesized samples is maintained at an acceptable level. Then, in the next step, the capability of synthesized adsorbent was carried out in various conditions, which shows the significant yield of them in both low and high temperature. In addition, the absorption yield of these nano-adsorbents was preserved after several reduction, indicating the high potential of these adsorbents in desulphurization.

Generally, polymer surface engineering has vast applications in biotechnology,membranes, self-cleaning and electronic devices. These applications are based oncontrollable changing in some properties such as surface energy, surface topography, andbiocompatibility of polymer. For choosing a proper method for the surface modificationof polymer, three parameters should be considered carefully. These parameters include:chemical structure of polymer which is focused on strengths and weaknesses of demandedpolymer, the surface properties that we need to achieve after treatment and finally surfacegeometry which is related to the presence or absence of porosity and or chemical andphysical heterogeneity of polymer surface. This research investigates the popular surfacemodification methods like wet chemistry, flame, plasma, UV radiation, laser and grafting.Furthermore, for accurate understanding of quantitative and qualitative changes of surfaceproperties of polymers, the general characteristics of used methods (depth analyzed,resolution, and analytical sensitivity) were briefly mentioned. Some of the popularmethods for include contact angle measurement, Fourier-transform infrared spectroscopy(FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-rayphotoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), Augerelectron spectroscopy (AES) and scanning tunnelling microscopy (STM).

Poly (N- vinylpyrrolidone -co- maleic anhydride) @ eggshell @ Fe3O4 (PNVPMA@ES@Fe3O4) eco-friendly nanocomposite was synthesized by a two-step method. In the first step, the PNVPMA copolymer was synthesized via radical polymerization method. In the second step, the PNVPMA@ES@Fe3O4 nanocomposite was synthesized through an in-situ co-precipitation technique. The PNVPMA@ES@Fe3O4 nanocomposite was used as high performance eco-friendly adsorbent to remove Congo red (CR) dye from aqueous solutions at various conditions, such as pH effect, contact time, adsorbent dosage and dye concentration. Results showed that the percentage removal of CR by synthesized magnetic nanocomposite was more than 95% at pH=6 and contact time 30 min. The results showed that the interactions between CR and the PNVPMA@ES@Fe3O4 nanocomposite were in agreement with the Langmuir isotherm and pseudo second order kinetic model. Also, thermodynamic model showed that the CR adsorption on the synthesized nanocomposite was spontaneous.

In this research, modified zinc ferrite nanoparticle by 3-amino propyl triethoxysilane was synthesized and its dye removal ability was studied. The synthesized adsorbent was characterized using Fourier Transform Infrared and Scanning Electron Microscopy. Acid bule 25 (AB25), Direct green 6 (DG6) and Direct red 23 (DR23), were used as model compounds. The effect of operational parameter such as adsorbent dosage, pH, dye concentration and salt was evaluated. The isotherm and kinetic of dye adsorption were studied. The maximum dye adsorption capacity (Q0) of adsorbent for AB25, DG6 and DR23 was 333 mg/g, 53 mg/g and 167 mg/g, respectively. It was found that dye adsorption onto adsorbent followed with Langmuir isotherm. Adsorption kinetic of dyes was found to conform to pseudo-second order kinetics. The results showed that the modified zinc ferrite nanoparticle being a high dye adsorption capacity might be a suitable adsorbent.

Chemical reactions on the structure of polymers، especially natural polymers result in production of new properties. One of these cases is chitin deacetylation reaction for production of chitosan. Property and application of chitosan with extensive uses in food، cosmetic، healing and drug industries depend on the degree and percent of acetyl groups or in other words the degree deacetylation (DDA). Proton nuclear magnetic resonance spectroscopy (1HNMR) is the simplest، most accurate and fastest method for quantitative determination of the degree of deacetylation in chitosan and its salts. In this method، the degree of deacetylation، ranging from 50 to 100%، with acceptable accuracy and repeatability is determined by a small amount of material without undergoing degradation and simple calculation. In addition، if the molecular weight of polymer is low، this test method can determine the number average degree of polymerization (DPn) in chitosan and chitosan salts for use in biomedical and pharmaceutical applications.

The «enterprise resource planning» (ERP) and business process integration through organizations have many benefits، including increased productivity، improved quality and lower costs. However، ERP implementations are complex and expensive and the processes of ERP implementation projects often fail. In this research، the most influential elements، verified by appropriate publications and discussions with the experts، in breaking down of ERP systems has been categorized in four groups of: managerial، human resources، processing and technological factors. To determine the level of importance of each element and ranking of statistical companies، based on their readiness in implementing a successful ERP، some questionnairs were handed out. The identified elements، found by the experts، were evaluated through Shanon entropy technique to assess their degree of significance. According to the weight of every element، we ranked companies through TOPSIS technique (Excel software) and linear assignment (Lingo software and answers like Global optimal). Because of the incompatibility of some results of these two techniques، we used the combinatory mean arithmetic to reach unanimous consent. The results showed that the companies which were ready to implement ERP successfully were specifically fulfilled by their managerial and human resource preparedness.

Lower diamondoids, methyl and ethyl derivatives are commonly present in gas condensation reactions. In this study, all samples were collected from Gonbadly, Shourijeh, Mozdooran (North-East) gas fields. Column  chromatography and urea adduction techniques were applied for clean up. Also a precise GC/MS instrument was used for separation and identificaton of lower diamondoids. The identified lower diamondoids and their  derivates were compared in terms of mass spectra, retention times and mass chromatograms. The concentration of lower diamondoids was quantified and calculated within the range of 0.07-4.85 mg/l.