Iranian Journal of Chemistry and Chemical Engineering
Volume:36 Issue: 1, Jan-Feb 2017

A simple, fast and one-pot synthesis procedure based on the bioreduction ability of an algal extract solution has been developed to produce silver nanoparticles (AgNPs). We focus especially on the influencing factors of AgNPs formation. The effects of various factors like pH, temperature, the concentration of metal ions and alga, the volume ratio of silver nitrate solution to alga extract, reaction time, mixing order and the mixing rate of the silver nitrate and the alga extract on the AgNPs synthesis are evaluated. The obtained colloids have been characterized by UV–Vis spectroscopy, TEM, XRD, and FT-IR. TEM image of the silver colloids shows that the AgNPs are predominantly spherical around average particle diameters of 32±10 nm. FT-IR study indicates that the carboxyl (−C=O), hydroxyl (−OH), and amine (N–H) groups in alga extract are mainly involved in the reduction of Ag ions to AgNPs. The XRD spectrum clearly shows that the AgNPs are crystalline in nature. This work may prove to be of great value in synthesizing nanoparticles with well-controlled sizes in chemical, pharmaceutical, and materials production processes.

In the present study, some new bis-imidazole derivatives have been prepared through four-components condensation of 2,6-bis (4-aminophenyl)-4-p-tolylpyridine, benzaldehyde derivatives, benzil and ammonium acetate in presence of acetic acid. The present methodology offers several advantages such as good yields, simple procedure, milder conditions and the possibility of introducing a variety of substituents at different positions of the imidazole and pyridine rings. These new compounds were confirmed by spectral methods 1H NMR, 13C NMR, FT-IR, and elemental. Also, optimized geometries and chemical shifts have been calculated for the ýsynthesized compounds using Density Functional Theory (DFT) method. Their optimized ýgeometries are not planar.ý

Triphenyl phosphine(PPh3), an efficient and reusable catalyst, catalysed the synthesis of 2-amino-3-cyano-6-methyl-4-aryl-4H-pyran-5-ethylcarboxylate derivatives by one-pot condensation of aromatic aldehydes, malononitrile and ethyl acetoacetate in EtOH-H2O (1:1) at reflux conditions. The results show that aromatic aldehydes containing electron-donating groups or electron-withdrawing groups could react smoothly to give the corresponding products in good to excellent yields. Given the increasing levels of interest in green chemistry, the recyclability and reusability of the catalyst have been evaluated. It was also found that triphenyl phosphinecan be recycled at least four times without loss of activity. This method has the advantages of high yield,mild reaction conditions, environmentally benign methodology and short reaction time.

In this study, zirconium dodecylphosphonate was synthesized by the reported method in scientific literature. 2-Alkylbenzoxazoles were prepared from aliphatic carboxylic acids and 2-aminophenol in the presence of this catalyst under solvent-free conditions at 100°C. Their structures were recognized by IR, 1H NMR, and 13C NMR. Then, we used aromatic carboxylic acids in the similar reaction. But, the results show aromatic carboxylic acids don’t react with 2-aminophenol. So, this method introduces a selective and constructive method for synthesis of 2-alkyl benzoxazoles without salt formation. On the other hand, this research offers several advantages such as high yields, good reaction times, easy work-up and use of a safe catalyst.

KF/Al2O3 as a green and efficient catalyst has been used for the synthesis of mono and bis pyrimidine derivatives via three-component reaction of amidines, malononitrile, and aldehydes in EtOH at reflux. The great advantage of this catalyst is the ease of handling. KF/Al2O3 can be used and removed by filtration, avoid cumbersome aqueous workups and decrease solvent waste handling issues. The additional benefit is achieved by taking advantage of the strongly basic nature of KF/Al2O3, which allows replacing organic bases in the reaction. A number of advantages are with this method such as no special handing necessity of catalyst, easy monitoring of reaction process, convenient workup procedure and high yields in short reaction times.

Ethylbenzene (EB) dehydrogenation to styrene (SM) on an industrial scale is generally performed using classic and SMART (Styrene Monomer Advanced Reheat Technology) technologies. In the current study, spent catalysts structural changes through classic and SMART technologies were investigated and compared with the fresh catalyst. For this purpose, XRF, XRD, SEM-EDX, FT-IR, BET and crushing strength analysis were employed. It was found that styrene production via SMART technology with 40% potassium loss is led to more catalyst deactivation than the classic ones (26%). Due to pore mouth blocking by coke formation, the average pore radius in both classic and SMART spent catalysts is reduced about 33% and 53% compared to the fresh ones, respectively. SEM analysis showed that potassium migration mechanism is related to the temperature gradient in the classic spent catalysts and chemical vapour transportation in the SMART spent catalysts. Comparative evaluation of the catalysts performance indicated that the SMART spent catalyst with about 72% activity loss is more deactivated than the classic ones (61%).The large drop of styrene yield (72-74%) of SMART spent catalyst revealed that the activity is more depending on the pore mouth size, rather than the specific surface area. However, in situ steam injection redistributed migrated potassium and increased the selectivity of the classic spent catalyst, but it was led to more potassium migration and catalyst deactivation in the SMART spent ones. According to this study, styrene production and industrial unit design based on SMART technology not recommended strongly.

In this work, poly (o-Anisidine) (POA) was prepared by consecutive potential cycling in an acidic monomer solution at the surface of Carbon Paste Electrode (CPE). Nickel ions were dispersed into the polymer by immersing the electrode in NiSO4 solution. The prepared Ni/POA/CPE was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Atomic Force Microscopy (AFM) and electrochemical methods. The electrochemical oxidation of ethanol and ethylene glycol was investigated at the Ni/POA/CPE by cyclic voltammetry and chronoamperometry techniques. The results indicated that the Ni/POA/CPE in comparison with Ni/CPE exhibited excellent electrocatalytic activity towards oxidation. Then, using a chronoamperometry method, the catalytic rate constant, k, for ethanol and ethylene glycol oxidation were found to be 2.6×106 and 1.07×107 cm3/mol s, respectively. Furthermore, the effect of several parameters such as OA concentration, POA thickness, and NiSO4 concentration and accumulation times towards the ethanol oxidation as well as the long-term stability of the modified electrode has been investigated.

Accumulation of large quantity of non-biodegradable textile dyes into the environment made much attention to finding a suitable solution for the degradation of textile dyes. In this present study, decolorization efficiency of two different treatment technologies such as Photo-Assisted Chemical Oxidation (PACO – UV/H2O2) and Electrocoagulation (EC) on Reactive Blue 194 dye solution (RB194) at different operational conditions were analyzed and the competitiveness of the treatment technologies in terms of energy consumption and operational costs were discussed. Even though both the processes follow different mechanistic approach for the degradation of dye solution, both the processes achieved more than 99% of decolorization efficiency. In terms of material/chemical consumption for the decolorization of dye solution PACO (US$ 0.016) competes with the EC (US$ 0.5937). But in terms of electrical energy consumption as well as the overall operating cost EC process compete (US$ 0.0481 & US$ 0.6418) with the PACO process (US$ 1.0267 & US$ 1.04337).

The effect of acid-alkaline treatment of lignocellulosic material (wild carob forest wastes) on Ethyl violet adsorption was investigated. It was found that surface chemistry plays an important role in Ethyl Violet (EV) adsorption. HCl treatment produces more active acidic surface groups such as carboxylic and lactone, resulting in an increase in the adsorption of EV dye. The adsorption efficiency was higher for treated lignocellulosic material with HCl (WCHCl) compared to that treated with KOH (WCKOH); maximum biosorption capacities were 170 and 130 mg/g for WCHCl and WCKOH at pH 6, respectively.It was also found that for both treated materials less than 150 min was needed to reach equilibrium.The adsorption of a basic dye (i.e. ethyl violet or basic violet 4) was carried out by varying some process parameters, such as the initial concentration and pH. The adsorption process can be well described by means of a pseudo-second-order reaction model and experimental data were accurately expressed by the Sips and Langmuir models for both WCHCl and WCKOH.

Batch Adsorption of Acid Red 37 (AR37) and Basic Orange 2 (BO2) on amino ethyl-functionalized SBA-15 have been studied. SBA-15 was synthesized and functionalized according to the procedure in the literature. Amino ethyl-functionalized SBA-15 showed the BET surface area 520 m2/g and pore diameter 7.02 nm, based on adsorption-desorption of N2. SEM image shows lengthy fiber-like morphology for the title material. The presence of organic groups in the silica framework was demonstrated by thermogravimetric analysis. The effects of pH, contact time and dye concentration on adsorption were investigated in order to find the optimum adsorption conditions. The results have indicated that modification of adsorbent with a functional group of amino ethyl will remarkably increase the elimination of these two dyes but amino ethyl-functionalized SBA-15 has higher affinity to AR37. The experimental data were analyzed using the Langmuir and Freundlich adsorption models. The data fitted well to the Langmuir model with maximum adsorption capacities 333.3 for Acid Red 37 and 250.0 for Basic Orange 2. Finally, this methodology was applied for the removal of the pollutant dyes from textile wastewater. The results were shown that amino ethyl-functionalized nanoporousSBA-15 acts as an effective sorbent for the removal of both anionic and cationic dyes from aqueous solution.

A novel, magnetic silica sorbent with polyelectrolyte multilayers (PEMs) on its surface was prepared, and was used for Magnetic Solid Phase Extraction (MSPE) of trace A via Flame Atomic Absorption Spectrometry (FAAS). The experimental parameters for the MSPE procedure, such as the pH, type, and concentration of eluent, ultrasonic time and effects of co-existing ions were investigated. The detection limit of the developed method was 0.17 ng/mL for Ag with an enrichment factor of 35. This method was also successfully applied to the determination of trace Ag in the leaching solution of different antibacterial products with satisfactory results.

An open-label, single-dose, randomized, 2-way crossover study was conducted in fasted healthy Iranian male volunteers. Eligible participants randomly assigned in a 1:1 ratio to be given one tablet of the test or reference formulation, followed by a 2-week washout period and administration of the exchange formulation. A quick and susceptible Liquid Chromatography–tandem Mass Spectrometry (LC-MS) method for the evaluation of amlodipine and atorvastatin in tablets.Revealing of analysts was achieved by tandem mass spectrometry with ElectroSpray Ionization (ESI) interface in positive ion mode was operated under the multiple-reaction monitoring mode. The assay results ascertain the presence and compendia quality of amlodipine and atorvastatin in all these products. The validation tests on the developed method indicated an acceptable degree of linearity, sensitivity, precision, accuracy and recovery for the method. The intra-day and inter-day precision and accuracy results were well within the acceptable limits. The method is rapid, simple, very stable and specific for the partition, assignment, evaluation of amlodipine and atorvastatin healthy Iranian adult male volunteers.

In this research, a fast colorimetric method for the detection of
4-phenylthiosemicarbazid (4-PTSC) in environmental samples, is reported for the first time. Semicarbazide compounds have been used as pesticides or fungicides in agriculture and for chemical synthesis in industrial processes. With this method, one or the total amount of Semicarbazide in real samples can be detected within 6-7 min. For this purpose, 4-PTSC was determined and can be used as a representative of the Semicarbazide family. The assay principle is based on the oxidation of 4-phenylthiosemicarbazid (as reducing agent) with Ferric ions in the presence of ferricyanide ion and triton X-100 as a stabilizer, as well as the formation of Prussian Blue NanoParticles (PBNPs). These nanoparticles exhibit a strong UV-Vis extinction band at 700 nm with high absorption coefficient (3.0× 104 M-1 cm-1 at 700 nm). A UV-Vis spectrophotometer is used to monitor changes in the absorption intensity of PBNPs. A change in the color of the solution can be easily observed by naked eyes, in the presence of sub-ppm levels of 4-PTSC, which is directly related to the 4-PTSC concentration. TEM images showed an average diameter of 30 nm. The effect of several reaction variables on the formation rate of PBNPs was studied. Beer's law was obeyed in the concentration range of 0.20-3.20 µg/mL. The detection limit was found to be 0.10 µg/mL. This method was successfully applied for the determination of 4-PTSC in different environmental samples. Interfering species with reducing properties are not commonly present in environmental samples. Hence, this optical assay is simple and has acceptable selectivity.

The density and viscosity of carbonated aqueous 35wt% methyldiethanolamine solution were experimentally measured accompanied with the solubility of CO2 at temperatures from (303.15 to 363.15) K and pressures up to 0.8 MPa using the new setup developed in our laboratory.It was observed that both density and viscosity of mixtures decrease by increasing temperature and increase by increasing acid gas solubility (loading) in solution. Acid gas loading has an intense effect on the viscosity of solutions than on their density. The modified Seth now correlation was used to predict the density and viscosity of all solutions studied in this work.

The mass transfer performance of a pulsed disc and doughnut column for extraction of samarium and gadolinium from aqueous nitrate solution with D2EHPA was investigated. The effects of operating parameters such as pulsation intensity, continuous and dispersed phase velocities on column performance were investigated. The axial dispersion model was used to obtain the overall mass transfer coefficient. The previous models for overall mass transfer coefficient were reviewed and compared with experimental data. A new correlation was derived for prediction of the overall mass transfer coefficients. The presented model was compared with the experimental results and a good agreement between them was obtained.The mass transfer experiments revealed the feasibility of operating the separation of samarium and gadolinium in the pulsed disc and doughnut columns.

This study treats one important aspect of starch-filled rubber compounds which is their rheological behavior. Starch-based SBR1712 masterbatches resulting from various formulations were prepared using a mini two roll mill and an internal mixer (Plastograph Brabender).The content in starch was varied from 0 to 50 phr. The effect of starch content on the rheological behavior was evaluated through the flow characteristics in the temperature range (130-160 °C) which matches that used in the vulcanization process. Four experimental techniques were considered to assess the mixing and the flow behavior of the materials: 1) Brabender mixer, 2) melt flow index, 3) capillary rheometer and finally 4) dynamic rheological properties through strain sweep experiments using a plate-plate rheometer. It came out that the four techniques used in the assessment of the rheological behavior of such materials are appropriate, complementary and successful. The melt flow index and viscosity measurements indicate a resistant flow for the rubber and its starch composites. Even high temperatures do not seem to reduce the viscosity considerably. Nevertheless, small amounts of starch incorporated in the gum will ease the flow to some extent. The materials showed a pseudoplastic behavior, and storage made a slight change in their melt flow index. Morphological studies showed that the particles of starch were not destructed during the mixing and their interaction with the rubbery matrix is very poor.

The current study is an attempt to contribute for efficient and cost-effective substrates for xanthan gum production. In this context, the sugar cane molasses wastes can be used as a cheap substrate for xanthan gum production. Xanthan biopolymer production by a novel Xanthomonas campestris strain IBRC-M 10644 was optimized with statistical approaches. Based on the results of Response Surface Methodology (RSM) with Central Composite Design (CCD) technique, a second-order polynomial model was developed and evaluated the effects of variables on the maximum xanthan production. Agitation rate (X1: 200-500 rpm), sugar cane molasses concentration (X2: 30-90 g/L) and operation temperature (X3: 25-35 °C) were the factors investigated. The optimal conditions for maximum yield of xanthan production were derived from agitation rate 500 rpm, carbon source concentration 65 g/L and operation temperature 30°C. Under these conditions, xanthan and biomass production were found to be 16.03 g/L and 1.37 g/L, respectively. Our results signify that the sugar cane molasses can be used as a cheap substrate for xanthan biopolymer production.