نشریه شیمی و مهندسی شیمی ایران
سال سی و ششم شماره 2 (پیاپی 84، تابستان 1396)

Gum Tragacanth (GT) is a heterogeneous highly branched polysaccharide obtained from Asiatic species of Astragalus. Iran is the world’s largest producer of GT. This gum has been vastly used in food, pharmaceutical, cosmetic, ceramic and textile industries. In recent decades, the world market for GT has severely decreased due to a number of reasons such as the war between Iran and Iraq and the approval of xanthan gum for the food industry with the advantage of low price and constant quality. In recent years, owing to desirable properties and advantage of the use of GT in medicine, research on biomedical applications of this gum continues to grow significantly. In this study, along with a report on the properties of GT, the research on the new applications of this gum in biomedical fields are reviewed. Overall, tragacanth has excellent water adsorption capacity, biodegradability and biocompatibility, and a great potential for chemical and physical modifications. In addition, the presence of fucose and galactose in the branches of GT has improved its potential for application in tissue engineering and gene/drug delivery. So, it can be used as a promising candidate for biomedical applications in near future. To meet this expectation, further study on gum characterization and modification is necessary. However, it should be noted that the gum exudate from various species of Astragalus had different soluble/swellable ratio, chemical composition, methoxyl content and acetylation degree, so exhibit different rheological properties, ability to reduce surface tension, ability to increase viscosity, chemistry, physical and chemical interaction and other behaviors. Consequently, any try for development of biomedical applications of tragacanth without respect to the plant species will lead to misleading results.

In this study, the effects of non-covalent interactions are considered where the hydrogen cyanide act as a proton donor and different π-systems such as para-substituted (H, F, Cl, OH, SH, CH3, and NH2) benzene derivatives act as a proton acceptor. The complexes are optimized by the B3LYP method using 6-311** basis set. The intermolecular interaction energy is determined at the same level with BSSE corrections. In addition to geometrical parameters and binding energies, topological properties of electron charge density are calculated by atoms in molecules (QTAIM) method. Furthermore, the Natural Bond Orbital (NBO) analysis is applied to get a more precise insight into the nature of these interactions. Several correlations between topological, geometrical and energetic parameters are found. Finally, the effects of interactions on NMR data have been used to more investigation of the studied compounds.

Copper and alumina oxide ceramic composite nanofibers prepared via electrospinning with polyacrylonitrile, N,N-Dimethylformamide and organic precursors contain aluminum acetate, copper acetate, and nanoparticles of aluminum hydroxide (Boehmite).The composite nanofibrous ceramic with an average diameter of 90 nm and a high level of porosity obtained after passing two thermal post process; stabilization, in order to increase the thermal resistance of polyacrylonitrile and calcination in 600 ̊C to form the desired ceramic phases. Said metal ceramic nanofibers in addition to the properties of nanostructures such as high specific surface, beneficial ceramics feature like the chemical and thermal resistance that these will increase the scope of their applications. To investigate the characteristics of ceramic nanostructured optical microscopy, analysis of XRD, FT-IR, FESEM was conducted which confirms the continuity of nanofibers both before and after calcination, formation of pores on the surface of ceramic nanofibers phases of alumina, copper oxide phase and a combination of them.

In this study, the synthesis of adapalene as an active pharmaceutical ingredient on a laboratory scale is examined. Our effort was focused on catalyzing C-C coupling as a difficult step in the adapalene total synthesis, using the zinc nanoparticles as well as eliminating the magnesium reagent. The use of zinc nanoparticles in C-C coupling is associated with increased yields compared with its bulk powder form. The best results were obtained using 1- (5-bromo-2-methoxy phenyl) adamantane and methyl 6-bromo-2-naphthoate in the presence of zinc nanoparticles in dry tetrahydrofuran followed by adding NiCl2 (DPPE) as the catalyst. Replacing the magnesium with zinc nanoparticles, this reaction can scale up to higher scales.

A modified literature procedure was used for synthesis [Pd(bpy)2](NO3)2, Pd(II), (where: bpy is 2,2'-bipyridine ligand) and a new zinc complex of formula K[Zn(Gly)3], Zn(II), (where: Gly is glycinato ligand). These two complexes have been characterized by elemental analysis, conductivity measurements and spectroscopic techniques such as FT-IR, 1H NMR, and UV-Vis. Pd(II) complex alone and in presence of 1, 2 and 3 molar ratio of Zn(II) complex have been tested against Chronic myelocytic leukemia K562 cell lines. They show growth suppression activity. Thus calf thymus DNA-binding studies using UV-Vis methods were carried out. The results indicate that probably the planar aromatic moiety of the Pd(II) complex cooperatively intercalate in DNA and presence of Zn(II) complexes impede the intercalation by an unknown mechanism. The impeding properties of Zn(II) complex increases by increasing the ratio of Pd(II):Zn(II) ongoing from 1:1, 1:2 to 1:3. This might be due to the decrease in positive charges of the above mixtures ongoing from 1:1, 1:2 to 1:3 ratio (f. 1). We found no such an effect in the literature. In the process of the interaction studies, several binding and thermodynamic parameters were investigated.These parameters may be used to predict DNA-binding mechanism in the series.

In this work, Dispersive Liquid-Liquid Microextraction coupled with Corona Discharge Ion Mobility Spectroscopy (DLLME-CD-IMS) was applied for the extraction and determination of diazinon in apple juice and underground water samples. For the extraction, an appropriate mixture of methanol as dispersive solvent and CCl4 as extraction solvent was injected rapidly into a glass tube with conical bottom containing an aqueous solution of diazinon. This injection led to a cloudy water solution, caused by the fine droplets dispersion of the immiscible extraction solvent (CCl4) in the aqueous sample. The result of this phenomenon was the generation of a high contact area between the aqueous phase and the extraction solvent. The final step of the microextraction procedure was centrifugation (5 min at 3000 rpm) to collect the dispersed tinny CCl4 droplets in the bottom of the test tube. Afterward, 5.0 µL of the solution was directly injected into the IMS, for analysis of the analyte. In order to obtain an optimum condition of the extraction, several parameters affecting on the extraction such as extraction solvent type, dispersive solvent type, extraction and dispersive solvent volume, salt addition, and pH were studied. Under optimum condition (pH 7, 60 µL extraction solvent, 1 mL dispersive solvent and without salt addition), enrichment factor 60 and the limit of detection of 0.2 µg/L was obtained. The good dynamic range was obtained in the range of 0.5 – 100.0 µg/L for extraction of diazinon. The relative standard deviations for analysis of 20 µg/L of diazinon in standard solutions, was 7% (n=3). The obtained recovery for spiked samples was above 89%, indicating the capability of DLLME as a rapid and convenient method for real sample analysis.

A Molecularly Imprinted Solid-Phase Extraction (MISPE) coupled with High-Performance Liquid Chromatography with UV detection (HPLC/UV) described for preconcentration and trace determination of celecoxib in human urine samples. The synthesis of the Molecularly Imprinted Polymer (MIP) was performed by a non-covalent approach using methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker monomer, chloroform as the solvent, 2,2′-azobisisobutyronitrile (AIBN) as the initiator and celecoxib template as the target drug. Non-molecularly Imprinted Polymer (NIP) was also synthesized for comparison. Scanning Electron Microscopy (SEM) and FT-IR spectroscopy were used for characterizing the synthesized polymers. Also, a Central Composite Design (CCD) under Response Surface Methodology (RSM) and chemometrics applied to investigate and optimize the MISPE procedure parameters such as pH, loading and eluent solvent flow-rate, eluent solvent volume and sorbent mass, that probably influence the extraction process, to achieve the highest celecoxib extraction efficiency. Batch rebinding capacity of celecoxib was determined from the derived Langmuir isotherm and was found to be 15.06 mg/g. The Limit of Detection (LOD) and Limit of Quantification (LOQ) of this proposed method were 8 ng/mL and 26.7 ng/mL, respectively. The recoveries were 92.60-102% and the Relative Standard Deviation (RSD %) was lower than 4.65% in spiked urine samples. Accordingly, the proposed MISPE-HPLC/UV method can be used for the separation of trace amounts of celecoxib in human urine samples.

In the present study, the volatile compounds of the cinnamon extract were separated using solid phase microextraction. Polyamide nanofibers prepared by electrospun technique was used in the separation procedure. The scanning electron microscope image from polyamide nanofibers shows adequate porosity with 50-100 nm. Chemometrics methods such as experimental design and multivariate curve resolution were used to obtain optimum results and to resolve the overlapped peak clusters. Experimental design with central composite design approach was used to optimize the extraction conditions in solid phase microextraction. The extracted samples were separated and analyzed using gas chromatography-mass spectrometry technique. Even in the optimum conditions of extraction and separation, there are overlaps in some parts of the obtained chromatogram. In order to overcome this problem, the multivariate curve resolution-alternating least squares method was implemented to resolve the overlapped peak clusters into concentration and spectral profiles. Using explained methods in the optimum condition, 30 compounds have been identified in the cinnamon extract. The most important volatile compounds in the extract are trans-cinnamaldehyde (51.23%), Eugenol (26.45%), Cinnamic acid (4.72%), Gurjunene (1.81%) and Copaene (1.44%). In the present study, the chemical composition in the cinnamon extract can be determined at low temperature without any side reaction.The present procedure can be used for separation and identification of volatile compounds in complex mixtures like medicinal plants in optimum condition as a fast and inexpensive routine.

Toxicities of water sources due to the discharge of industrial effluents is a worldwide environmental problem. Industrial wastewater often contains a considerable amount of heavy metal ions and organic pollutants, which would endanger public health and the environment.Cadmium Cd(II) is a toxic heavy metal, normally found in industrial wastewater, especially from metal plating industries, Cd–Ni batteries, phosphate fertilizer, mining, pigments, stabilizers, and alloys. Cd(II) adversely effects human health because of serious damage to the kidney, renal disturbances, and bones lesions. In this work, heavy metal ions were removed using biodegradable polymer based on chitosan and functionalized graphene with amine groups. Nanocomposite Samples containing 0.5, 1, 2, 5 wt.% of functionalized graphene were obtained via solution method. At first, graphene was oxidized with sulphuric and nitric acid then triethylenetetramine was grafted on the graphene surface. Functionalized graphene was characterized by Fourier Transform Infra-Red (FT-IR) spectroscopy, Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). Results showed functionalization of graphene was successfully accomplished. The morphology of nanocomposite was monitored by SEM. Adsorbing heavy metal ions (Cadmium) was investigated with Flame Atomic Absorption Spectrometry (FAAS) and results revealed that the nanocomposite samples have a higher potential for ion metals adsorption than that of neat chitosan. The adsorption of nano samples for cadmium was increased around 20% in comparing to neat chitosan. The effect of sorbent concentration, pH, mixing time and heavy metal ion concentration was studied on the adsorption behavior and it was found that the optimum adsorption occurs at pH=7, 50 ppm ion metal concentration, 2h contact time and 25 mg of sorbent.

The utilization of polymer-clay composites as adsorbents in the remediation of polluted water has been the subject of many recent research studies. In the present work, poly(acrylic acid) –bentonite (PAA-Bentonite), was synthesized and its chromium ion adsorption performance was investigated. The adsorption behavior of the composite towards chromium from aqueous solution was studied under varying conditions such as initial concentration of chromium (5–500 mg/L) and contact time (30–1440 min). Experimental equilibrium data were fitted to Langmuir and Freundlich isotherm models by non-linear regression method, however, the adsorption equilibrium data were well interpreted by the Langmuir model. The maximum capacity of PAA-Bentonite toward chromium was 29.55 mg/g at 25 °C, which was much higher than that of the Bentonite (1.3 mg/g). The maximum chromium removal efficiency of 85 % was achieved by the composite at 25°C with 30 min contact time for an initial metal concentration of 50 mg/L. The adsorption kinetics followed both pseudo first-order and pseudo second-order models.The results showed the high potential of PAA-Bentonite composite for the removal of chromium ions from aqueous solution.

Considering the environmental pollution by the colored waste, the need for nanostructured materials is self-evident. Hence, in this research, the decolorization property of the ZnO/SnO2 nanocomposite was investigated. To produce the desired nanocomposite, the co-precipitation method was used. The desired nanocomposite characterization was performed by PSA, FT-IR, XRD, and SEM, where the nanocomposite size was about 15 nm. The effect of several parameters such as the initial wastewater concentration and the amount of catalyst and time were examined. The nanocomposite particles size reduction due to an increase in the nanocomposites surface area increased the amount of decolorization. In all the experiments the dye removal rate was 100% and the difference pertained to the complete removal time of the dye. It is noteworthy that a decrease in the methylene-blue concentration in the range of the tested concentrations reduced the decolorization and by increasing the amount of nanocomposite tested in the range of the values, a decline was observed in decolorization.

In this work, the electrocatalytic performance of nitrogen-doped graphene (NG)-based catalyst for Oxygen Reduction Reaction (ORR) has been compared with its counterpart while supported on MultiWall Carbon NanoTubes (MWCNTs).Nanoflower-like NG with designed nitrogen types is directly synthesized using a low-temperature solvothermal process Fe and Co nanoparticles were precipitated on NG and for comparison on MWCNTs using a modified polyol method.
The morphology of the NG is studied using scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The synthesized electrocatalysts are characterized using transmission electron microscopy and energy-dispersive X-ray spectroscopy.The electrocatalytic properties of NG, Fe-Co/NG, and Fe-Co/MWNT catalysts are investigated for ORR in 0.1 M KOH. Cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy are used to measure electrocatalytic activity. The Fe-Co/NG catalyst exhibited higher ORR activity than NG and Fe-Co/MWNT catalysts.

The removal of ethylbenzene from a contaminated air stream was studied in a lab scale biotrickling filter. Plastic pall rings were used as packing for immobilization of microorganisms and the biofilter was inoculated with a mixture of compost extract and ethylbenzene-contaminated water from Assaluyeh region. The active volume of biofilter was 4.7 liter and empty bed resistance time was considered 1 min. Operating phase lasted 95 days, during which inlet air flow rate was constant at 4.7 L/min and ethylbenzene concentration in inlet flow was increased from 0.5 to 2.5 g /m3. At the end of this phase, maximum elimination capacity of 133 g/m3h was obtained with removal efficiency of 93%. The results showed good performance of the biotrickling filter to remove ethylbenzene from the gas phase and promise operational applications of these bioreactors in various industries.

In this study, a graft copolymer of Methyl MethAcrylate (MMA), on Corn Starch (CS) backbone, by slurry polymerization was carried out in order to the preparation of a bioplastic. The effect of temperature, MMA/ Starch weight ratio and amount of the initiator on the percentage of grafting was investigated. A maximum grafting (34%) was obtained using the weight ratio of MMA/starch (80%), initiator/starch (2.5%) and temperature (75˚C). Results showed that increase in polymerization temperature up to optimum temperature (75˚C) causes to increase in the percentage of grafting, percentage of homopolymer and the total monomer conversion and after that just the percentage of homopolymer increases. Results showed that by increasing monomer weight percent up to optimal percent (80%), the percentage of grafting increased. Beyond the optimal weight ratio of the monomer, percentage of grafting was decreased, amount of the homopolymer increased and the total conversion almost remained constant. Effect of the weight ratio of the initiator on the percentage of the grafting and amount of homopolymer was similar to the effect of the weight ratio of the monomer, with the difference that the total conversion of the monomer was increased with the weight ratio of the initiator beyond the optimal amount (2.5%). FT-IR spectra of extracted samples showed a peak at 1730 cm-1 as evidence on the grafting of PMMA on starch. SEM micrographs illustrated the presence of patches of PMMA on the surface of bulk starch. The Melt Flow Index (MFI) measurements were carried out in order to evaluate the processability of the copolymer and the results showed that by increasing the percentage of grafting, MFI of the copolymer was increased and the processing properties of samples were improved, consequently.

Some key factors such as high growth rate, low demand for arable land and fresh water and high carbohydrate content causes microalgae to introduce a new sourceof bioethanol.In this study,mixed microalgae culture was cultivated in the plate photo-reactors. Afterwards, nitrogen starvation strategy was used to accumulate storage carbohydrates. After harvesting of microalgae, enzymatic hydrolysis was applied to extract the sugars in biomass. The concentrations of extracted reducing sugar using hydrolysis process were investigated at four different substrate concentrations and three different temperatures over time. The process simulation by neural networks was performed using MATLAB software program. The networkinput consisted of substrate concentration, temperature, hydrolysis time and the networkoutput consisted of reducing sugar concentration. Artificial neural network with one hidden layer of 8 neurons in conditions (70-15-15) has minimum Mean Square Error (MSE).

One of demanding issues that engineers encounter in the production of highly viscous oils is the high-pressure drop of oil moving across the pipeline. A wide range of methods have been introduced to overcome this problem, and among them, the chemical injection is considered to have a dramatic effect on viscosity and hence the pressure drop reduction. In this study, the role of nanoparticles in oil production is simulated using Pipesim software, and the level of pressure drop in the pipeline is estimated. In addition, the pressure drop was investigated with changing the type and concentration of particles, temperature, the inner diameter of the pipe, oil’s flow rate and the flow type in order to detect the effect of each parameter. Results suggested that microparticles of copper with 0.1 wt% concentration prompt the lowest pressure drop per unit length. At lower temperatures, the concentration of microparticles dictates the level of pressure drop while at a higher temperature, the effect of temperature is dominant. Moreover, we founded that in higher flow rates, the presence of particles desirably reduces the pressure drop, regardless of their amount. The pressure drop in laminar and turbulent flow demonstrated to have a direct relation with viscosity, while in the transient flow the viscosity reduction was followed by an increase in pressure drop.

In this research, investigation of ethylene hydrate formation kinetics was carried out in the presence of nanosilver suspension. The hydrate formation induction time was measured at 4˚C and initial pressures of 14 and 16 bar. According to the results, ethylene hydrate formation induction time decreased at all concentrations of nanosilver suspension in comparison to pure water. Also, the minimum induction time at the pressure of 14 bar was 21 minutes and at the pressure of 16 bar was 17 minutes which compared to pure water, 93% and 87% decrease was observed, respectively. Hydrate formation tests were also performed at 1.5˚C and 30 bar. Based on the results, in the presence of this suspension, hydrate storage capacity increased compared to pure water. The maximum storage capacity of 151.85 was achieved for 5 ppm of nanosilver suspension suggesting 261.3% increase compared to pure water.

In this study, thermal, exergetic analysis and performance evaluation of seawater and fresh wet cooling tower and the effect of parameters on its performance is investigated. Base on the definition of an economic model for capital and variable costs, an optimized efficiency of a cooling tower has been evaluated. With modeling of a cooling tower and using of experimental results and a developed code in EES, this study has been performed. Due to lack of fresh water, seawater cooling is an interesting choice for future of cooling, so the effect of seawater in the range of 1 g/kg to 60 g/kg for salinity on the performance has been studied. Effect of changing the salinity of the water on performance and parameters which are related to exergy has been compared with a cooling tower which used fresh water. Results showed that decreasing of air efficiency about 3%, increasing water efficiency about 1.5% are some of these effects. Moreover with the formation of fouling the performance of cooling tower decreased about 15% which this phenomenon and its effects like increase in output water temperature and tower excess volume have been shown.