Iranian Journal of Chemistry and Chemical Engineering
Volume:37 Issue: 6, Novr-Dec 2018

This paper presents a novel microwave-assisted hydrothermal technique for synthesizing tin(II) oxide nanoparticles. This technique can be used for producing large quantities of homogeneous nanoparticles in a short time. The effect of the solution molarity, final pH, hydrothermal processing time and microwave power were studied. The tin(II) oxide structure verified from XRD and the mean crystallite size was evaluated to be about 5 nm using the Debye-Scherrer formula on the most intense peak. The particle size was measured from STM pictures in the range between 4-5 nm. For different samples, UV-Vis spectroscopy showed the absorption peak due to tin(II) oxide at about 240 nm and an exitonian peak at about 280 nm that shifted with respect to solution molarity, final pH, hydrothermal processing time and microwave power. The photoluminescence spectroscopy (PL) results showed the emission peaks in the visible spectrum range. The results showed that synthesized SnO nanoparticles have a direct bandgap equal to about 2.5 eV, an Urbach energy of about 2.7 eV and activation energy of 47.75kJ/mol.

We have successfully prepared Fe3O4/MWCNT nanohybrid with a very simple and economical method. Multi-Walled Carbon NanoTubes (MWCNT) encapsulated with Fe3O4 nanoparticles were synthesized via pyrolyzing of ferrocene. The sample was characterized with XRD, TEM and Vibrating Sample Magnetometer (VSM). Also, Permeability (µ) and Permittivity (ε) were measured. The reflection-loss was measured at 2-18 GHz with a HP8722ES vector network analyzer. In 2-18 GHz frequency range (microwave frequency), the dielectric loss (tan δE=ε″ / ε′ with an amount between 0.5-0.6) effectively improves via the addition of Fe3O4/MWCNT nanohybrid in the desired composite with paraffin matrix. Therefore, it can be concluded that Fe3O4/MWCNT nanohybrid has good potential to improve microwave absorption and can be used as Radar Absorbing Material (RAM).

Single crystals of poly(ethylene glycol) (PEG)-b-polystyrene (PS), PEG-b-poly(methyl methacrylate) (PMMA), PEG-b-polycaprolactone (PCL), and polyaniline (PANI)-b-PEG-b-PANI were developed from dilute solutions and thin molten films using self-seeding methodology. The PS and PMMA grafted chains were categorized in disordered nano-brushes; however, the PCL and PANI ones were grouped in ordered nano-brushes. The characteristics of grown single crystals such as surface morphology, growth planes, and thicknesses were investigated using Atomic Force Microscopy (AFM), Electron Diffraction (ED) in Transmission Electron Microscopy (TEM), and Small Angle X-ray Scattering (SAXS). The thickness of PEG substrates, as well as polymer nano-brushes, were in the nanoscale (2-150 nm). Furthermore, the special morphologies of polymer mixed-brushes developed through the growth of single crystals of PEG-b-PS and PEG-b-PMMA diblock copolymers were introduced and characterized. Regardless of different morphologies, the total, substrate and amorphous thicknesses, tethering density as well as ED patterns were compatible in the phase regions covered by similar nano-brushes.

A new tetradentate N2O2 Schiff base ligand (MeO-bph)2bn = N,N¢-bis(2-hydroxy-4-methoxybenzophenone)-1,4-butanediamine was prepared from the condensation of butane-1,4-diamine with 4-methoxy-2-hydroxybenzophenone and characterized by 1H-NMR spectroscopy and single-crystal X-ray diffraction. Its nickel(II) and copper(II) complexes characterized using elemental analyses (CHN) and IR spectroscopy. Thermogravimetric analysis of the Schiff base ligand and its Ni(II) and Cu(II) complexes revealed their thermal stability and decomposition pattern. Finally, the complexes were used for the preparation of NiO and CuO nanoparticles by solid-state thermal decomposition. The nanoparticles were characterized by FT-IR, XRD, and SEM. FT-IR and XRD confirmed the purity of the formed products NiO and CuO.

The surface of magnetite nanoparticles as nano-sized solid support was modified with a molybdenum-Schiff base complex to prepare an easily separable heterogeneous catalyst for the epoxidation of olefins. Characterization techniques such as Fourier transform infrared and inductively coupled plasma optical emission spectroscopies, X-ray diffraction, vibrating sample magnetometry, scanning, and transmission electron microscopies indicated the presence of molybdenum-Schiff base complex and a magnetite core in the catalyst. The magnetite nanoparticles supported Mo catalyst exhibited high catalytic activity and selectivity toward the epoxidation of olefins and was easily recovered from the reaction mixture by magnetic separation to be utilized for subsequent reactions. The catalyst showed reusability for three times without significant loss of activity.

This paper highlights the experimental and theoretical studies on the Melamine treated Active Carbon (MAC) support for an Au-Cu bimetallic catalyst in acetylene hydrochlorination reaction. Compared to the original Active Carbon (AC) loaded with the same amount of 0.1wt% Au and 1.0wt% Cu,  MAC supported catalyst(MACH), wherein Carbon/C6H6N6 mass ratio was 5:3, exhibited excellent catalytic activity. The initial conversion of acetylene increased from 77.5% to 82.7% at 150℃ and atmospheric pressure. The gas hourly space velocity (GHSV) was 120h-1 under a feed volume ratio VHCl/VC2H2 of 1.05. As polymerization of acetylene on the catalyst was the main cause of deactivation, accelerated deactivation test was carried out. The result indicated MACH performed good anti-coking capacity. Based on the characterization by using BET, XRD, SEM, TGA, TPD and XPS techniques, the variation of O1s XPS spectra of the synthesized catalysts was observed that was in line with DFT results. It is postulated that the better stability and the better dispersion of gold actions were ascribed to the additional metal and the modified substrate. The electron transmission from the auxiliary and the elevated groups on the catalyst surface partially inhibited the reduction of the Au3+ active species. Meanwhile, the stronger adsorption energy of HCl was also beneficial to catalytic activity and stability.

Some new Schiff-base compounds based on pyrrole were synthesized by the reaction of 2-amino-1-methyl-4,5-diphenyl-1H-pyrrole-3-carbonitrile (1)with aromatic aldehydes (2a-2e) in ethanol/acetic acid at room temperature. The structures of the Schiff bases were characterized by full spectral data. The fluorescence emission intensity of the Schiff bases has been measured in different polar solvents (protic and aprotic) at different temperatures and also pHs. Among the products of this reaction, 2-[(2-hydroxy-benzylidene)-amino]-1-methyl-4,5-diphenyl-1H-3-carbonitrile(3a) exhibited good results. The molecular docking studies on all Schiff bases revealed that the compound 3a forms a stable complex with polo-like kinase1 as a target and gives a binding affinity value of -8.9 kcal/mol. According to the obtained results, the DFT calculations carried out on 3a by using B3LYP/6-31+G(d,p) level of theory which the theoretical data were in good agreement with the experimental data. Furthermore, the NBO analysis showed the electron transfers correctly.

A simple, sensitive, and non-extractive spectrophotometric method was developed for the determination of copper (II) using a newly synthesized chromogenic reagent, 6-(phenanthrene-3-yl)-1,2,4,-triazine-3-thione(PhDTT), in Tween 80 neutral surfactant. To synthesize the reagent (PhDDT), amyl nitrite was added to 3-acethylphenanthrene and refluxed for 26 hours to produce 2-oxo-2-(phenanthren-3-yl) acetaldehyde oxime (I). The reaction of compound (I) with thiosemicarbazide yielded the reagent (PhDDT). Copper (II) forms a red colored complex with 6-(phenanthrene-3-yl)-1,2,4,-triazine-3-tion which shows maximum absorbance at 460 nm in the pH range 9.0-11.0. Beer’s law was obeyed over the concentration range of 1.4-10 µg/mL Cu2+ with r2 = 0.999.  The limit of detection was 0.48 μg/mL of copper (II). The within-day and between-day precision values were in the range of 0.38-3.3%. The method was tested by analyzing the amalgam samples. The results were in good agreement with the atomic absorption.

A new type of unsaturated poly ester-amide was prepared by melt polycondensation and characterized completely. Influence of heat treatment conditions and cross-linking content on mechanical and degradation properties of unsaturated polyester-amide were studied. Results suggested that the newly synthesized unsaturated poly(ester-amide) possessed good heat stabilization properties. Mechanical and degradation properties of cross-linked poly (ester-amide) were determined by heat treatment conditions and cross-linker content. Different initiation-accelerating agent systems and their content differences have an insignificant influence on the cross-linking time at Room Temperature (RT). Increasing heat treatment time increased the retention rate of mechanical properties during the degradation process and decreased hydrolysis rate in alkaline solution.

In the present research, the selective oxidation of lauryl alcohol to lauraldehyde was studied under liquid-liquid phase transfer conditions using potassium chromate (K2CrO4) as an oxidizing agent and tetrabutyl ammonium bromide (TBAB) as the phase transfer catalyst. Chromium (VI) reagents are used in these oxidations since the alcohols are selectively oxidized to the aldehydes without any over-oxidation. In non-aqueous solutions the oxidation by chromium (VI) does not go to completion as the intermediate partially oxidized material containing chromium must be hydrolysed for oxidation to continue. Liquid-Liquid Phase Transfer Catalysis (LL-PTC) involves the transfer of one reactant from the aqueous phase to the organic phase with the help of small quantities of a phase transfer catalyst which is usually quaternary ammonium or phosphonium salt. It was observed that no over-oxidation products such as lauric acid and high molecular weight esters of lauryl alcohol were formed under the reaction conditions used. The effect of various reaction parameters such as the speed of agitation, temperature, the concentration of lauryl alcohol, the concentration of potassium chromateand phase transfer catalyst loading were studied. A reaction mechanism involving the formation of chromate ester in the organic phase has been proposed and a kinetic model has been developed based on the experimental results obtained.

This paper describes the performance of Granular Activated Carbon (GAC) to adsorb and separate glucose and maltose solutes from the industrial effluents by adsorption process. In this study, the capability of Granular Activated Carbon (GAC) to adsorb glucose and maltose were experimentally examined. Commercial GAC (mesh 12-20), supplied by Sigma Aldrich company in the UK was used in this work. The parameters affecting the sorbate adsorption such as the pH of the solution, initial solution concentration, shaking time and speed, sorbent dose and temperature were tested. Additionally, the adsorption equilibrium isotherm was also tested using the common isotherm modules; Langmuir and Freundlich. GAC exhibited a capability to adsorb glucose and maltose from the industrial effluent. Also, the glucose adsorption process was physical and in good agreement with the Freundlich isotherm model, while, the maltose adsorption process was a physical and the adsorption data can be adequately described by the Freundlich and Langmuir models.

Adsorption of Chromium ions (VI) and (III) in aqueous solution was investigated using activated carbon prepared from olive wastes, by one step physical activation with steam. After adsorbent material characterization using adsorption capacity of methylene blue, iodine and phenol, BET surface area, Fourier Transform InfraRed (FT-IR) spectroscopy, pHpzc, surface functions based on the Boehm method and, Scanning Electron Microscopy (SEM), the effect of different parameters (initial pH, absorbent dosage, initial concentration of solutes, time) on the adsorption of chromium ions were carried out in a batch system. The obtained activated carbon has a large specific surface area of 1050,9 m2/g and good adsorption capacity for iodine (1017 mg/g) and methylene blue MB (349 mg/g), which confirm that its structure is essentially composed of micropores (61 % of the surface) and mesopores. It has a basic chemical nature. Experimental results showed that the adsorption capacity of the prepared activated carbon was strongly dependent on solution pH. It was found that the initial pH of 2.0 was most favorable for Cr(VI) adsorption, and basic pH was best for Cr(III) removal. The adsorption process was studied using two kinetic models (pseudo-first order and pseudo-second order) and three functions isotherms (Langmuir, Freundlich, Temkin). The results showed that the adsorption process follows the pseudo-second order kinetics and the adsorption data were found to agree with the Langmuir isotherm model. Maximum adsorption capacity for Cr (VI) was 74,9 mg/g at pH 2, and 14,3 mg/g at pH 9 for Cr (III), and was comparable to results reported by other researchers working on activated carbon prepared from various solid wastes. Temperature effect was determined using the thermodynamic parameters. Negative values of ΔH0 and ΔG0 proved the feasibility of the adsorption process with its spontaneous and exothermic natures. Tests of desorption were performed in three different media: neutral (distilled water), acidic (2N hydrochloric and acetic acid solutions) and alkaline (2N NaOH solution). The magnitudes of desorption efficiency in the acetic acid medium were 94% and 71% for Cr(VI) and Cr(III) respectively.

The main objectives of this study were to remove surface-active agents and to predict the adsorption rejection models.  The effects of surfactant concentration and PAC amount on the adsorption were determined. For both surfactants, It was found that the adsorption values also increased when PAC amount increased. It was observed that the rejection values are different for the adsorption of CTAB and LABS. In addition, new rejection models are proposed to be able to estimate the rejection of surfactants depending on surfactant concentration and PAC amount. The results indicated that model predictions were in accordance with the experimental data.

In this research, cerium recycling was studied by Adsorbing Colloid Flotation (ACF). Ten important parameters including collector type and dosage, cerium and colloid concentrations, frother type, activator type, preparation and frothing time, air flowrate and pH, each in two levels, were investigated. Statistical design of experiment was implemented for process modelling and analysis of variance showed that factors pH, collector type, collector and cerium dosage and colloid concentration were the most significant factors which effecting Ce recovery and grade. Results showed that the cerium maximum recovery was 99.84 %. The feed initial concentration was 500 ppm in each test and the final concentrate grade was enhanced to 25.1 % by Adsorbing colloid flotation. The SEM (Scanning Electron Microscope) analysis before and after adsorbing flotation showed that ACF was a great method for cerium extracting from solutions and waste waters. Finally, results showed an economical optimum point to achieve maximum recovery and grade simultaneously under minimum consumption of flotation reagents.

Coal is a major source of energy. The available Indian coal quality is very poor having very high ash content and low calorific value. Indian coal generates a large quantity of ash as a by-product of combustion. The objectives of the present study were to reduce the ash content of coal to produce ultra-clean coal. The coal was treated with a dual chemical leaching process consisting of NaOH followed by HCl.During experiments, the concentration of NaOH was varied from 2.5 to 10 M with 1.4 N HCl. Effect of shaking speed and time was analysed at 0, 50, 100, 150 and 200 rpm and 1, 2, 3 and 4 hours respectively. After chemical leaching, the ash content was reduced from 35.33 to 0.98% in the ultra-clean coal. The concentration of alkali, shaking speed and time of duration were found as highly influencing parameters for the reduction of ash content in the coal. Moreover, the current study should result in a better option for the removal of ash content from low-rank Indian coals.

Fluid Catalytic Cracking (FCC) process is a vital unit to produce gasoline. In this research, a feed forward ANN model was developed and trained with industrial data to investigate the effect of operating variables containing reactor temperature feed flow rate, the temperature of the top of the main column and the temperature of the bottom of the debutanizer tower on quality and quantity of gasoline, LPG flow rate and process conversion. Eventually, validated ANN model and firefly algorithm which is an evolutionary optimization algorithm were applied to optimize the operating conditions. Three different optimization cases including maximization of RON (as the parameter which demonstrates the quality of the gasoline), gasoline flow rate and conversion were investigated. In order to obtain the maximum level of targeted output variables, inlet reactor temperature, temperature of the top of the main column, temperature of the bottom of debutanizer column and feed flow rate should respectively set at 525,138, 169ºC and 43000 bbl/day. Also, sensitivity analysis between the input and output variables were carried out to derive some effective rule-of- thumb to facilitate the operation of the process under unsteady state conditions. The result introduces a methodology to compensate for the negative effect of undesirable variation in some operating variables by manipulating the others.

Intermolecular interactions of different configurations in the HOClO3···CO and HOClO3···H2O dyad and CO···HOClO3···H2O triad systems have been studied at MP2/6-311++G(2d,2p) computational level. Molecular geometries, binding energies, cooperative energies, many-body interaction energies, and Energy Decomposition Analysis (EDA) were evaluated. The results reveal that the stability of cyclic triads is more than linear ones and in the order IV > III > II > I configurations. All of the triads have diminutive energy. Red shifts of H-O stretching frequency for complexes involving HClO4 as HB-donor are predicted. The electronic properties of the complexes are analysed using parameters derived from the Quantum Theory of Atoms in Molecules (QTAIM) methodology.

In this study, Saccharum bengalense(SB) was used as biosorbent for the removal of Mn (II) ions from aqueous solution. The influence of biosorbent dose, time, pH and temperature was investigated in the biosorption process. Studies showed that by increasing pH of the solution, metal removing efficiency of Saccharum bengalensefrom the aqueous environment was enhanced but to a specific extent, pH 5.0, at time 50minutes and dose 0.1g/50mL. Langmuir, Freundlich, Harkin Jura and Halsey adsorption isotherm were used to studying adsorption efficiency of Saccharum bengalense. Langmuir and Harkin Jura adsorption isotherms well explained the adsorption process as compared to other isotherms with correlation coefficient 0.943 and 0.968 respectively. At 313K temperature, adsorption capacity (qe) of Saccharum bengalense for removal of Mn (II) ions from aqueous solution was 21.72mg/g. Kinetic study showed that pseudo second order was best followed by the adsorption process with correlation coefficient 0.997.

Determination of changes in physicochemical properties of different vegetable oils (sunflower, corn, hazelnut, palm, and olive oils)  was aimed after the frying process with different frying material used (potato and pepper). The increase in free fatty acid content, peroxide value, viscosity and polar compound formation of oils was observed, while the reduction of the polyunsaturated fatty acid content of oils was detected with the increase of frying time. The minimum increase of free fatty acid content was determined in sunflower oil (for fried pepper %0.23; for fried potato %0.22), while the best result of peroxide values for both of frying samples was found in olive oil (for fried pepper 2.49 meq O2/kg; for fried potato 4.11 meq O2/kg oil). The highest increase of total polar compound was also ascertained in sunflower oil (for fried pepper%4.50; for fried potato %5.00). The increase of frying time caused a decrease of L* and a* values of oils except for olive oil and increase of b* values. The effect of frying oil or material and frying process time on physicochemical properties of oils was found statistically significant (p<0.01).

Alzheimer’s Disease (AD) is a progressive neurological disorder associated with cognitive and memory deficits. Accumulation of amyloid beta (Aβ) plaques is one of the major causes of AD. Therefore, inhibition of the plaque formation has been aimed to play a preventive role in the disease. Lavender, through some neuroprotective roles such as antioxidant effects, is known to be an effective candidate in the treatment of neurodegenerative disorders. In this study using Thioflavin T Measurement and Atomic Force Microscope (AFM) Imaging, we evaluated the effect of essential oil of lavender on Aβ polymerization. Thioflavin T Method showed that essential oil enhances the Aβ aggregation. The results of the AFM method also confirmed it. Our data antagonizes previous results indicating the clearing effect of aqueous extract of lavender on Aβ plaque. It seems that the different combination of essential oil and aqueous extract considerably determines if or not the aggregation occurs.

Antioxidant activities of Satureja boissieri extracts were detected by using specific in vitro techniques. Standard antioxidant compounds such as ascorbic acid, BHA (Butylated Hydroxyanisole) and BHT (Butylated Hydroxytoluene) were used to compare with the results obtained from ethanol and water extracts of the plant samples. Both extracts presented high antioxidant actions on ABTS cation radical and DPPH free radical scavenging methods. Furthermore, the antimicrobial activity of S. boissieri was defined by using three fungi species, three Gram-positive and four Gram-negative bacteria species. The reducing power antioxidant activities of samples were measured by CUPRAC and FRAP techniques. Also, phenolic compounds of S. boissieri leaves were identified by UHPLC-ESI-MS/MS. The high concentration of hesperidin (5051 ± 247 ppb) and rosmarinic acid (4364 ± 214 ppb) was characterized quantitatively. According to the results, high phenolic content can be thought of as one of the responsible parameters for effective biological activity. Also, its flavonoid and phenolic contents are good natural sources for using in the food industry and pharmacological process.

In this study, Cynara scolymus L. leaves aqueous extract powder was produced using a novel spray drying approach by incorporation of ongoing ultrasonic atomization and vacuumed drying chamber. A Response Surface Methodology (RSM)-based central composite face-centered design was employed for optimization of the operating conditions of the ultrasonic vacuum spray dryer. The independent variables of the prepared mode include inlet temperature, the vacuum pressure in the drying chamber and concentration of extract solution. Drying experiments were carried out with an inlet temperature range of 55–75 °C, a vacuum pressure range of 20–40kPa and extract solution concentration of 2–3%. The responses were Moisture Content (MC), Solubility Index (SI), the bulk density of extract powder, Total Phenolic Content (TPC) and DPPH scavenging capacity. Optimum operating conditions were found to be an inlet temperature of 70.58℃, a vacuum pressure of 20kPa, and an extract solution concentration of 3%. In this optimum condition, Moisture Content (MC), Solubility Index (SI), bulk density of extract powder, Total Phenolic Content (TPC) and DPPH scavenging activity were found to be 6.73%, 58.5%, 0.5838 g/cm3, 13.53 mg of GAE/g of spray dying extract powder and 18.43%, respectively. The morphology of microstructures analyzed with Scanning Electron Microscopy (SEM) also showed spherical and smooth particles in optimum condition.

Dill (Anethum graveolens L.) and parsley (Petroselinum crispum Mill.) were dried by using sun and oven (50oC) drying methods. Oven drying decreased the drying time approximately 50% when compared to the sun drying method for both herbs. K, Ca, P, Mg and Na were the most abundant elements in dill and parsley samples. Oven-dried samples had higher mineral values than that of the sun-dried samples. Page, Modified Page, Midilli and Küçük and Diffusion approach were shown to give a good fit to the sun drying of parsley. The Midilli and Küçük and Verma models have shown a better fit to the experimental sun drying data of dill. Wang-Singh and Midilli and Küçük models gave the highest r2 values for oven drying of parsley and dill, respectively.

In the present study, two-phase nanofluid flow in a three-dimensional system is modeled over a stretching infinite solar plate and the heat transfer analysis is performed for this problem. The governing equations are presented based on previous studies and the suitable solution method is recommended due to infinite boundary condition in the problem. Keller Box Method (KBM) using the Maple 15.0 mathematical software is applied as the solution method for the governing equation of the problem. The effect of some parameters existed in the equations (Pr (Prandtl number), Sc (Schmidt number), Nb (Brownian motion parameter), Nt (Thermophoresis parameter), λ=b/a (ratio of the stretching rate along y to x directions) and n (power-law index)), are discussed on the velocities, temperature, and nanoparticles concentration functions. As an important outcome, increasing both n and λ parameters, makes a reduction in shear stress, while it increase the Nusselt number function of heat transfer.

Dividing Wall Column(DWC) offers the large potential for operating and capital cost saving in compared with conventional distillation sequence. In the studied DWC in this study, the aid of Vmin diagrams, it is shown that without a suitable value for vapor split fraction bellow the dividing wall in different operating conditions, the energy requirement increases from optimal value and it will lead to the suboptimal operation. Accordingly, a control structure based on the self-optimizing concept is designed using vapor split fraction as the control degree of freedom (active vapor split). To find the best self-optimizing Controlled Variables (CV) the exact local method is used. It is shown that the value of loss with the aid of active vapor split is lower than 0.7 percent of nominal value with using the conventional single measurement self-optimizing CV, which is a reasonably small value, and using a more complex combination of measurement as a self-optimizing CV provides a little enhancement in reducing the loss. So, including vapor split fraction in the self-optimizing control structure of the DWC can save energy and in the meantime avoid the complexity of combination of measurement. Moreover, the dynamic simulation studies show that the proposed control structure with the simple decentralized control loops can conveniently stabilize the plant and reject the effects of disturbances.

Nowadays, UnderBalanced Drilling (UBD) technology is widely applicable in the petroleum industry due to its advantages to an overbalanced drilling operation. UBD success depends on maintaining the drilling fluid circulating pressure below the reservoir pore pressure during operations. One of the main prerequisites of a successful UBD operation is the correct estimation of the pressure profile. In this investigation, the pressure profile was obtained with consideration of the influx to the wellbore. A spreadsheet was developed to obtain the pressure profile using an analytical solution for aerated mud in UBD operation. Moreover, a numerical simulation was employed to simulate the three-phase flow in annulus through the UBD operation and the transient Eulerian model flow via the turbulence k-ε model. The effects of solid particle size and rotation of the inner pipe were considered on the pressure drop. It was observed that pressure drop was significantly increased with increasing solid particle size while it remained almost constant with increasing of the inner pipe rotation. The analytical and numerical results were compared with published experimental results and showed a good agreement.