Iranian Journal of Chemistry and Chemical Engineering
Year:2018 | Volume:37 | Issue:3|Papers Count:22

Nano-structure of Co– Mn spinel oxide was prepared by the thermal decomposition method using [Co(NH3)4CO3]MnO4 as the precursor. The properties of the synthesized material were characterized by X-Ray Diffraction (XRD), Brunauer-Emmett-Teller (BET), Transmission Electron Microscopy (TEM), surface area measurements, Energy-Dispersive X-ray (EDX) spectroscopy analysis, UV-Vis spectrophotometer (UV-Vis), Fourier Transform InfraRed (FT-IR), Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) analyses. The results show that Co– Mn spinel oxide is spherical in shape and possess crystallite size is about 12 nm. The catalytic activity and product selectivity were also investigated, in a micro-reactor (Fischer– Tropsch Synthesis (FTS) reaction) and the results compared with conventional Co-Mn oxide catalyst. The catalyst performance increased as the particle size of the catalyst decreased. Moreover, the olefin to paraffin ratios was increased, compared to the conventional catalyst.

The present study focuses on the synthesis of Kaolin loaded Silver (Ag-KNC) and Nickel (Ni-KNC) nanocomposites by co-precipitation method. The surface morphology of them was determined by SEM technique while chemical composition was determined by FT-IR technique. The removal of Malachite Green Oxalate (MGO) was preceded by the adsorption method using (Ag-KNC) and (Ni-KNC). The adsorption models like Freundlich, Langmuir, and D-R (Dubinin-Radushkevich) was utilized to figure out the applicability of the tactic. Moreover, the pH at the point of zero charge (pHpzc) was determined to find surface neutrality. The effect of electrolyte (KCl) on the removal efficacy of MGO was additionally investigated. Furthermore, the ionic strength and thickness of Electrical Double Layer (EDL) were also determined. Thermodynamic parameters like free energy (Δ Go), entropy (Δ So) and enthalpy (Δ Ho), of the system, was also investigated. The adsorption Kinetic was resolute by Intra Particle Diffusion (IPD) and Boyd’ s models. Moreover, the adsorption efficacy was effectuality was ascertained to be 88% for (Kaolin), 97% for (Ag-KNC) and 95% for (Ni-KNC) systems.

Pd and Co nanoparticles were deposited on cellulose for use as a heterogeneous catalyst in the bimetallic catalytic reduction reaction. The catalyst was characterized with Energy Dispersive X-Ray Spectroscopy, X-Ray Diffraction pattern, Thermal Gravimetric Analysis, Flame Atomic Absorption Spectroscopy, and Transmission Electron Microscopy, and applied in the reduction reaction of nitroaromatics using NaBH4 at room temperature. Aromatic amines were obtained as the sole product of the reduction reaction during 2h. This reaction has some advantages such as mild reaction conditions, high yield, green solvent, and recyclable catalyst. Also, the recovered catalyst is applicable in the reduction reaction for 4 times without a significant decrease in the activity.

Various antibacterial fluoroquinolone compounds were prepared by the direct amination of 7-halo-6-fluoroquinolone-3-carboxylic acids with a variety of piperazine derivatives and (4aR, 7aR)-octahydro-1H-pyrrolo[3, 4-b] pyridine using Zirconia Sulfuric Acid (ZrSA) nanoparticle, as a catalyst in the presence of ordinary or magnetized water upon reflux condition. The results showed that ZrSA exhibited high catalytic activity towards the synthesis of fluoroquinolone derivatives in two forms of water. However, the magnetized water showed better results. Furthermore, the catalyst was recyclable and could be reused at least three times without any discernible loss in its catalytic activity. Overall, this new catalytic method for the synthesis of fluoroquinolone derivatives provides rapid access to the desired compounds in refluxing water following a simple work‐ up procedure, and avoids the use of harmful organic solvents. This method, therefore, represents a significant improvement over the methods currently available for the synthesis of fluoroquinolone derivatives.

In this work, the effects of preparation methods such as CE oven, microwave irradiation and ultrasound on the morphology, particle size and crystallinity of MIL-53(Fe) are firstly investigated. Furthermore, the methods are utilized to prepare Pt NPs@MIL-53(Fe). As a result, well-defined Pt NPs@MIL-53(Fe) prepared by microwave irradiation exhibits uniformed morphology, high crystallinity, and high-disperse Pt NPs, which has been confirmed by FT-IR, TG, N2 adsorption at 77K, TEM and PXRD. Pt NPs@MIL-53(Fe) composite can selectively catalyze the thiophene hydrogenation over nitrobenzene and benzothiophene hydrogenation. The result shows that the sulfur amount can rapidly be reduced to less than 10 ppm and the crystallinity of reacted Pt NPs@MIL-53(Fe) is unchangeable.

Efficient and environmentally friendly syntheses of xanthenes derivatives by using γ-Fe2O3@HAP-Fe2+ NPs as a catalyst has been carried out. The catalyst can be readily isolated by using an external magnet and no obvious loss of activity was observed when the catalyst was reused in eight consecutive runs. The procedure has several advantages, such as economic availability of catalyst, simple procedure, ease of product isolation, no harmful byproducts, less reaction time and high yields.

The mixture of Synthetic Petroleum Acids (SPA) and oxyacids (OSPA) have been synthesized on the basis of naphthenic-paraffinic hydrocarbons separated from 217-349° C fractions of Azerbaijan oils in the presence of the salts of Natural Petroleum Acids (NPA). The acid number of the obtained (SPA+OSPA) was 165 mgKOH/g, the yield was 40%. Imidazoline derivatives have been synthesized based on the mixture of SPA+OSPA and polyethylene polyamine (PEPA) and their complexes were prepared with CH3COOH and HCOOH. The inhibition action of these complexes on steel corrosion in 1% NaCl solution saturated with CO2 has been studied at 50° C. The results showed that all compounds are good inhibitors and the inhibition efficiencies in the presence of imidazoline derivatives based on SPA+OSPA were 93% and 97% at 25 and 50 ppm, respectively. The activation parameter study suggests the chemisorption for all inhibitors. The obtained values for Gibbs free energy show that the compounds are spontaneously adsorbed on the metal surface by chemisorptions. The image of the steel surface proved that the formed protective film on the electrode surface was stable. The adsorption of the studied compounds on steel surface follows the Langmuir adsorption isotherm.

Reaction of gas-phase oxidation of 4-methylpyridine on individual V2O5, binary and ternary vanadium-oxide catalysts was studied. These catalysts were modified by additives of SnO2 and TiO2. It was found that modifying V2O5 leads to increase in the activity of binary contacts. Upon transition from binary V2O5-SnO2 and V2O5-TiO2 catalysts to the ternary system of V2O5-TiO2-SnO2, a higher increase in activity is observed. This extension in activity leads to increase conversion of initial substance and shifting the maximum yield of intermediate pyridine-4-carbaldehyde and isonicotinic acid to the low-temperature area. To research the mechanism of promotion, we used the quantum chemical method of Density Functional Theory. It was found that the promoting effect of SnO2 and TiO2 was caused by increasing a proton affinity of vanadyl oxygen (PAV=O). Upon transition from binary clusters to the ternary system of V2O5-TiO2-SnO2 the synergism effect is observed. It is shown that by transfer of a proton to vanadyl oxygen and formation of a new O− H bond the energy is emitted. This energy compensates a heterolytic C− H bond cleavage. It was found that the promoting effect of SnO2 and TiO2 causes the decrease of deprotonation enthalpy of the methyl substituent of the chemisorbed substrate. The results of the calculations agree with the experimental data on the influence of oxide modifiers on activity and selectivity of the studied catalysts in 4-methylpyridine oxidation.

Nano-powders of diluted magnetic semiconductor Zn1-xFexO (0. 0≤ x ≤ 0. 1) were prepared via the sol-gel auto-combustion method. Crystal structure and phase identification carried out by X-Ray Diffraction (XRD) analysis. Mean crystallite size of the powders was estimated by Scherrer's formula. As M-H loops of the Fe substituted ZnO showed ferromagnetic behavior. The results of X-Ray Photoelectron Spectroscopy (XPS) showed that there is a mixture of Fe3+ and Fe2+ ions in all Fe substituted samples. Antiferromagnetic interaction between neighboring Fe3+-Fe2+ ions suppressed the ferromagnetic behavior of the samples at higher doping concentrations of Fe.

The oxidation of Mandelic Acids (MA) to the corresponding oxoacids with tripropylammonium fluorochromate (TriPAFC) in aqueous acetic acid has been studied. The reaction is first order with respect to [TriPAFC], [MA] and [H+]. The oxidation of α-deuteriomandelic acid shows the presence of a primary kinetic isotope effect (kH/kD = 5. 54 at 303 K). The reaction has been found to be catalyzed by H+ ions. The various thermodynamic parameters for the oxidation have been reported and discussed along with the validity of the isokinetic relationship. The Exner plot showed that all the selected mandelic acids are oxidized by the same mechanism.

Residue curve maps are a powerful tool for the preliminary design of Reactive Distillation (RD). In this study, residue curve maps of the n-butyl acetate synthesis reaction were calculated based on the Langmuir– Hinshelwood– Hougen– Watson kinetic and UNIQUAC models to calculate the physical properties of the system. The results showed that the unstable node branch emerged from the n-butyl acetate/water edge, moved toward the chemical equilibrium surface with increasing Damkö hler number, and no ternary reactive azeotropic point appeared when the reaction was added. Conceptual design of n-butyl acetate synthesis by reactive distillation based on residue curve maps is presented. Based on the simulation results, both the energy consumption and the total annual cost were lower than previously reported values.

The study of the interaction between DNA and small molecules such as drugs is one of the current general interest and importance. In this paper, the electrochemical investigation of the interaction between some flavonoids such as rutin, quercetin, and hesperidin with dsDNA on the surface of Supramolecular Ionic Liquid grafted on the Graphene Oxide Modified Glassy Carbon Electrode (SIL-GO/GCE) is reported for the first time. The apparent binding constant (K) of the interaction between flavonoids and dsDNA was calculated using the current titrations. The apparent binding constants (K) of rutin, quercetin and hesperidin were calculated to be 4. 3×105, 2. 1×105 and 9. 2×1-6 M-1, respectively. Furthermore, the electrochemical behavior of rutin on the surface of SIL-GO/GCE was studied in details using cyclic voltammetry and linear sweep voltammetry. The mechanism of the electrochemical redox reaction of rutin was proposed. When DNA was added into flavonoid solutions, their cathodic peak currents were decreased with few changes in the peak potentials. Furthermore, the interaction between rutin and bovine serum albumin was studied using differential pulse voltammetry. In conclusion, the SIL-GO/GCE provides a promising platform for the study of the interaction between DNA and small molecules.

Partial least square and principal component regression methods were applied to various mixtures of Allura Red and Brilliant Blue to determine the concentrations. Colorants, at the same time, were analyzed with UV-spectrophotometry in chemical separation. The obtained experimental data have been evaluated by chemometric methods as Partial Least Squares (PLS) and Principle Component Regression (PCR). In the first step, the synthetic mixtures containing three-color materials were examined, and the obtained results were applied to the PCR and PLS. In the next step, using PLS and PCR methods, the quantities of Allura Red and Brilliant Blue in commercial beverage, samples were measured at the same time. The results were compared statistically.

The corrosion inhibition effect of N, N′-bis(n-Hydroxybenzaldehyde)-1, 3-Propandiimine on mild steel has been investigated in 1 M HCl using electrochemical impedance spectroscopy. A predictive model was presented for Nyquist plots using an artificial neural network. The proposed model predicted the imaginary impedance based on the real part of the impedance as a function of time. The model took into account the variations of the real impedance and immersion time of steel in a corrosive environment, considering constant corrosion inhibitor concentrations. The best-fit training data set was obtained with eleven neurons in the hidden layer for Schiff base inhibitor, which made it possible to predict the efficiency. On the validation data set, simulations and experimental data test were in good agreement. The developed model can be used for the prediction of the real and imaginary parts of the impedance as a function of time.

Polypyrrole magnetic graphene oxide (PPy/MGO) composites have been synthesized from a natural source (water hyacinth roots) using polymerization technique for Th(IV) ions pre-concentration from aqueous solutions. The effects of controlling factor have been studied using the batch technique. The obtained results show that the maximum Th(IV) adsorption capacity by PPy/MGO composite is 277. 8 mg/g at pH 4, which is higher than traditional adsorbents. PPy/MGO composite also presents excellent regeneration/reuse property. The PPy/MGO was thoroughly characterized by a number of techniques namely, Fourier transforms infrared, Raman, as well as X-ray diffraction, thermogravimetric and Energy-Dispersive X-ray (EDX). Due to the high adsorption capacity of Th (IV), PPy/MGO composite can be used in nuclear fuel achievement and for Th(IV) environmental pollution cleanup.

An adsorbent Modified Biochar (MB) made from sewage sludge was characterized by FT-IR spectra and SEM image. The effects of contact time, solution temperature, pH and initial concentration on the adsorption performance Pb(II) onto MB was investigated in a batch adsorption experiment. Results showed that MB had great adsorption capacity, due to the existence of hydroxyl, carboxyl, ether, alcohol and amino groups. As the contact time prolonged, the adsorption quantity of MB increased sharply first and then tended to the balance. The adsorption capacity increased slightly with the temperature increase. The effect of pH on the absorbability of MB was non-linear, and the maximum adsorption capacity was obtained when the pH was approximately 6. The adsorption capacity increased abruptly first and then become slowly with the initial concentration increase. Compared with the pseudo-first-order, the pseudo-second-order kinetic models were more suitable to test the kinetic experimental data. Equilibrium data were analyzed using the Langmuir and Freundlich isotherm models and it was found to correspond to the Langmuir isotherm model better.

The potential of Bread Fruit (artocarpus altilis) Seed Husk (BFSH) as low-cost biosorbent for the removal of Pb (II), Zn (II) and Co (II) ions from aqueous solution was investigated. The adsorbent was characterized by the Fourier Transform InfraRed (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The batch methodology was utilized to determine the effect of pH, metal ion concentration, adsorbent dose, contact time and temperature on biosorption. Data generated were fitted into appropriate isotherm, kinetic and thermodynamic models. The effect of pH showed an increase in adsorption of metals with an increase in pH and an optimum pH of 5. 0 was obtained for Pb (II), while 6. 0 were obtained for Co (II) and Zn (II) ions biosorption. An equilibrium sorption contact time of 30, 40 and 60 min was obtained for Co (II), Zn (II) and Pb (II) ions respectively. The biosorption of metal ions was in the order Co (II) > Pb (II) > Zn (II). In general, the Freundlich model provided a better fit than the Langmuir, Tempkin, and Dubinin-Radushkevich isotherm models with R2 values greater than 0. 9. The pseudo-firstorder kinetic model was applicable in the adsorption of Pb (II) and Zn (II) ions while the pseudo-second-order model provided the best fit for Co (II) ion adsorption. The adsorption mechanism was found to be controlled by the liquid film diffusion model (R2>0. 9) rather than the intraparticle diffusion model (R2<0. 9). Thermodynamics revealed a spontaneous, feasible, exothermic physisorption process and over 60% of the metal ions were desorbed using 0. 1M HCl and 0. 1M NaOH as eluent. The results showed that BFSH could be utilized as low-cost adsorbent for the removal of toxic heavy metals from solution.

Micro Encapsulated Phase Change Materials (MEPCM) are green materials which could be used for thermal energy saving applications in buildings as a non-pollutant method for environmental. PCMs could passively reduce peak cooling loads in hot seasons because of their high energy storage capacities at a constant temperature. Purpose of this paper is manufacturing Microencapsulated PCM (MPCM) products for use in gypsum wall applications, with the aim of expanding in use from butyl palmitate in polystyrene-co-methyl methacrylate shells. This type of micro-encapsules synthesis had not been previously described in the literature, nor patented. PCM (butyl palmitate) can be encapsulated by these processes and in the form of core-shell structure with the use of different stirring rates and hybridized suspension agents. SEM micrographs of microencapsulated MPCMs show that spherical microcapsules were obtained with a narrow PSD (0-150 μ m) with a stirring rate of 800 rpm and hybridized suspension agent (TCP). About, 65 % (wt. ) of MPCMs was butyl palmitate with 70. 6 J/g of latent heat energy which indicates the applicability of this synthesis MPCMs for thermal energy storage in gypsum walls. Our synthesis results on the basis of suspension like polymerization process show good encapsulation efficiency with proper thermal energy storage capacity in gypsum walls.

Rigorous analysis of the determinants of volumetric mass transfer coefficient (kLa) and its accurate forecasting are of vital importance for effectively designing and operating stirred reactors. Majority of the available literature is limited to systems with low solids concentration, while there has always been a need to investigate the gas-liquid hydrodynamics in tanks handling high solid loadings. Several models have been proposed for predicting kLa values, but the application of neuro-fuzzy logic for modeling kLa based on combined operational and geometrical conditions is still unexplored. In this paper, an ANFIS (adaptive neuro-fuzzy inference system) model was designed to map three operational parameters (agitation speed (RPS), solid concentration, superficial gas velocity (cm/s)) and one geometrical parameter (number of curved blades) as input data, to kLa as output data. Excellent performance of ANFIS’ s model in predicting kLa values was demonstrated by various performance indicators with a correlation coefficient of 0. 9941.

In this research, Effect of thermal treatment on beneficiation of low-grade laterite nickel by calcination-magnetic separation method was studied. In order to determine the components and elements of the sample, to recognize the main and minor minerals and their bond, and phase transformation caused by thermal treatment, Chemical analysis (XRF and ICP), microscopic studies and XRD analysis were done, respectively. SEM analysis was done to study the content of nickel and other minerals. In order to determine the phase transformation of the sample because of calcination treatment, thermal analysis of DTA/TG and XRD analysis, before and after of calcination were done. Wet magnetic separation tests with two methods of calcination-magnetic separation and only magnetic separation were done on the sample and the results in grade and recovery of nickel concentrate were compared. According to results, nickel content in the sample was0. 94%. Main minerals of laterite sample were Hematite, Goethite, Quartz, and dolomite and minor minerals were Magnetite and minerals of serpentine group. Furthermore, there is no independent nickel mineral in the sample. SEM studies declared that nickel was substituted in ironcontaining minerals (Hematite and Goethite). XRD and thermal analysis (DTA/TG) showed that at 350 ° C, Goethite transformed to Hematite and at 750 ° C, Hematite transformed widely to Magnetite. Calcination of feed at 750° C followed by wet magnetic separation with the magnetic field of 6000 Gauss in comparison with alone magnetic separation caused an increase in recovery and grade of magnetic concentrate to 12. 7% and 0. 41%, respectively. Results showed that an increase in temperature of more than 750 ° C, caused a decrease in recovery and grade of nickel in magnetic concentrate.

The aim of this study is to characterize and find the location of geological boundaries in different wells across a reservoir. Automatic detection of the geological boundaries can facilitate the matching of the stratigraphic layers in a reservoir and finally can lead to a correct reservoir rock characterization. Nowadays, the well-to-well correlation with the aim of finding the geological layers in different wells is usually done manually. For a rather moderate-size field with a large number of wells (e. g., 150 wells), the construction of such a correlation by hand is a quite complex, labor-intensive, and time-consuming. In this research, the wavelet transform as well as the fractal analysis, with the aid of the pattern recognition techniques, are used to find the geological boundaries automatically. In this study, we manage to use the wavelet transforms approach to calculate the fractal dimension of different geological layers. In this process, two main features, the statistical characteristics as well as the fractal dimensions of a moving window, are calculated to find a specific geological boundary from a witness well through different observation wells. To validate the proposed technique, it is implemented in seven wells of one of the Iranian onshore fields in the south-west of Iran. The results show the capability of the introduced automatic method in detection of the geological boundaries in well-to-well correlations.

One of the most significant tasks for proteomic research and industrial applications, is the preparation of recyclable enzyme reactor. Herein, a novel recyclable enzyme reactor has been developed based on monodispersed spherical poly(quaternary ammonium ionic liquid)s particles immobilized trypsin. A new quaternary ammonium ionic liquids functional monomer was first synthesized. The ionic liquids functional monomer was then copolymerized with ethylene glycol dimethacrylate by precipitation polymerization. The resultant monodispersed spherical particle showed a large surface area (231 m2/g) and high binding capacity for trypsin (200 mg/g) due to the large surface area and strong interaction. The polymer microsphere loaded trypsin was used as an enzyme reactor for the digestion of standard protein, semi-complex samples and skim milk, respectively. The results indicated that the enzyme reactor exhibited highly efficient protein digestion and excellent stability. The digestion time of the present ionic liquids enzyme reactor for the digestion of protein, the solution could be reduced to even 5 min. The ionic liquids enzyme reactor showed excellent reusability and could be reused for more than four times. When it was kept at 4 ° C for 12 d, and used for skim milk digestion, the obtained MALDI-TOF score could also reach 88 with 29 matched peptides.