Iranian Journal of Chemistry and Chemical Engineering
Year:2018 | Volume:37 | Issue:1|Papers Count:24

In this research, spherical a-Fe2O3 nanoparticles (NPs) were supported on the surface of 12-tungstosilicic acid (12-TSA.7H2O) as a catalyst support, using two different Forced Hydrolysis and Reflux Condensation (FHRC) and Solid-State Dispersion (SSD) methods. a-Fe2O3 and 12-TSA.7H2O were synthesized due to previous reports. All products were characterized by using FT-IR, SEM, EDX, elemental map, XRD and BET surface area. The results indicated that the supported catalyst (a-Fe2O3 /12-TSA.7H2O) successfully was prepared and no change was found on the chemical structures of 12-TSA.7H2O and a-Fe2O3. By using XRD analysis average sizes of spherical a-Fe2O3 NPs supported by SSD and FHRC methods were measured 50.5 and 70.82 nm, respectively. The catalyst presented in this study can be applied in the different areas such as nano photo catalytic reactions.

in the recent years, laser ablation in liquid has become an increasingly important technique for the fabrication of NPs. this paper reports our recent studies on the generation of ZnO NPs by ablation of metal targets in aqueous environments using Q-switch Nd-YAG laser (l=532nm) immersed in NaOH (0.1M). The Surface topography studied by atomic force microscopy revealed wider size distributions, with particle sizes (80.76 nm to 102.54nm) and shape were measured by using SEM shows spherical shape while the composing of the prepared nanoparticle were determined by X-ray, UV-Visible spectroscopy has been employed for the optical properties, the UV-VIS spectrum of the produced solution shows red shifted in the peak position with the laser ablation energy. The produced collide was a good stable.

In this work, a Fe3O4@polydopamine core-shell nanocomposite (Fe3O4/PDA) was synthesized through an in situ self-polymerization methods and was applied as a sorbent for Rhodamine B (RhB) removal. The synthetic procedure is simple and involves no organic solvents.The as-prepared Fe3O4/PDA nanocomposite was characterized by transmission electron microscope, Fourier transforms infrared spectra, and X-ray photoelectron spectroscopy. Due to the catechol and amine groups, the polydopamine (PDA) polymer provided multiple interactions in combination with RhB. The removal ratios of the RhB by Fe3O4/PDA were all above 98% at the optimum experimental conditions, suggesting that the Fe3O4/PDA nanocomposite was an excellent sorbent for acid dyes removal from aqueous solution. The kinetic studies revealed that sorption follows a pseudo-second order kinetic model which indicates chemisorption between sorbent and adsorbate molecules. The Langmuir adsorption models were applied to describe the equilibrium isotherms, and the isotherm constants were also determined. The maximum adsorption capacity derived from the Langmuir model was 195.3 mg/g.

Toxic leadions removed efficiently from water by a newly fabricated, magnetically recyclable, antibacterial nano-Ag/g-Fe2O3@GOadsorbent, at ambient and the physiological pH=7. The adsorption depends on the adsorbent dosage, initial Pb (II) concentration, pH and the contact time. The optimumremoval efficiency of the leadion is found to be 93.1% with a dosage rateof 20 mg/L, in 40 minutes, at pH 5 (to 14). Equilibrium data fits well with the Langmuir and Freundlichmodels with a maximum adsorption capacity of 90.91 mg/g of Pb (II) per 20 mg/L of Ag/g-Fe2O3@GO. The removal/uptake mechanism involves interaction between Pb (II) and the oxide/hydroxyl layer around Ag/g-Fe2O3@rGO, in the contaminated water medium.

Electrical sensitivity of a boron nitride nanosheet (BNNS) to phosphine (PH3) molecule is studied using Density Functional Theory (DFT) calculations at the B3LYP/6-31G (d) level of theory. The adsorption energy (Ead) of phosphine on the surface of pristine nanosheet is about -678.96×1019eV. Pristine BNNS is a suitable adsorbent for phosphine and can be used in separation processes or adsorption of phosphine toxic gas from environmental systems. Consequently, BNNS is doped by Al atom and results show that the adsorption energy range is about - 28882.18×1019 to -52097.61×1019eV which means an increase in adsorption energy. Moreover, the HOMO/LUMO energy gap (Eg) reduces significantly. This reduction shows that the doped BNNS in the presence of phosphine is a suitable semiconductor and generates an electrical signal. Therefore it can be used potentially as phosphine toxic gas detection sensors in environmental systems.

The current study focuses on the development of the modified surface of the alumina by anionic surfactant sodium dodecyl sulfate. The synthesized Surfactant Modified Alumina (SMA) effectively associated with dye molecules and amended their properties. The triphenylmethane (CBB) and thiazine dyes (MB) were selected as a simulated dye wastewater system. The removal was carried out by adsorption method under the optimized amount of adsorbent dosage, the concentration of adsorbate, contact time and temperature. The adsorption isotherm models like Langmuir, Freundlich and Dubinin Radushkevish were employed. The mechanism of the interaction represents the decolorized leuco dye molecules were formed after adsorption. Moreover, the thermodynamic parameters like (DS°), (DH°) and (DG°) were calculated represents the endothermic and spontaneous nature of the adsorption process. The pH at the point of zero charges (pHPZC) was determined. The photocatalytic degradation of respective dye systems was also observed. The surface morphology of (SMA) was determined by FT-IR and SEM techniques. Whereas the pseudo second order kinetics model was followed in the present system. The Pearson correlation Coefficient was conjointly applied. The removal efficiency was ascertained to be 99.50% for CBB (R-250) and 95.70% for (MB).

The reaction of fly ash with a KOH solution was used to synthesize Linde F (K) zeolite, following which Fourier transform infrared spectroscopy were used to characterize the crystalline material. The competitive adsorption of Cu, Ni, Pb, and Cd onto this zeolite was subsequently studied in quaternary solution systems. The results show that the metal removal rates gradually increase with increases in the pH of the adsorption solution until reaching an asymptotic value. During the early stages of adsorption, the metal removal rate is very rapid, after which it gradually decreases. The overall adsorption efficiency order is Pb>Cd>Cu>Ni. The adsorption process is best represented by pseudo-second-order kinetics and an internal surface diffusion model. The primary adsorption process, which takes place between approximately 1 to 2 min and 40 min, appears to be controlled by internal surface diffusion.

This study assesses the potential of activated carbon prepared from sewage sludge for nickel ions adsorption from aqueous solutions. Activated carbon physicochemical properties were determined. Batch adsorption experiments were performed as a function of pH solution, adsorbent dose, initial metal ions concentration, contact time and temperature. The experimental data were analyzed by the Langmuir, Freundlich, and Temkin isotherm models. The Freundlich model showed a better representation of equilibrium data (R2>0.99) and the Langmuir monolayer adsorption capacity of activated carbon was found to be 11.52 mg/g. The kinetics of nickel ions was discussed using different kinetic models and the adsorption experiments indicated that the pseudo-second-order model well fitted the kinetic data (R2=0.999). Thermodynamic parameters have also been evaluated. It was found that the adsorption process was feasible, spontaneous and endothermic. Desorption experiment and recovery of Ni (II) ions from activated carbon was found to be 100 % using hydrochloric acid. The results suggest that the activated carbon prepared from sewage sludge could be used beneficially for nickel adsorption from aqueous solutions for environmental cleaning purpose.

In this paper, a simple dispersive liquid-liquid microextraction for the extraction and pre-concentration of formaldehyde in seawater samples followed with spectrophotometric is proposed. Formaldehyde was derivatized in situ with acetyl acetone in the presence of ammonium acetate in a single step. Then it was collected into a mixture of ethanol (disperser solvent) and chloroform (extracting solvent). Experimental parameters which have an influence on the extraction, including type and volume of extracting and disperser solvent, pH of sample solution, the concentration of acetyl acetone and ammonium acetate, reaction time and temperature were evaluated and optimized. Under optimal experimental conditions, good linearity was observed in the range of 1-500 mg/L for the analyte with a limit of detection of 0.29 mg/L. The proposed method was applied to the analysis of real seawater samples. For spiked samples, good recoveries in the range of 97.7-101.5% were obtained. The relative standard deviations were below 2.1%. Using this method, formaldehyde content in seawater from several locations in Chabahar Bay (southeast Iran) were determined in the range of 1.4 to 4.8 mg/L.

In this work, two approaches based on Dispersive Liquid-Liquid MicroExtraction (DLLME) and Dispersive Liquid-Liquid MicroExtraction based on Solidification of Floating Organic Drop (DLLME-SFO) were compared for the extraction and preconcentration of crocin from saffron and biological samples. Different DLLME and DLLME-SFO parameters influencing the extraction efficiency were studied and optimized. The results showed that both extraction methods exhibited good linearity, precision, enrichment factor, and detection limit. Under optimal conditions, the limits of detection were 0.008 and 0.005 ng/mL for DLLME and DLLME-SFO, respectively. The preconcentration factors were 88 and 95 for DLLME and DLLME-SFO, respectively. The applicability of the proposed methods was examined by analyzing crocin in saffron, urine and milk samples and good results were obtained. The percentage recovery values for spiked samples were between 96.4 and 99.1.

The ultrasound-assisted magnetic stirrer was used as an effective extraction technique for the evaluation of total phenolic contents (TPC) and antioxidant potential of ten Pakistani brown rice cultivars. For this purpose, ultrasonic (240W frequency 50/60 Hertz) assisted magnetic stirrer coupled with three solvents methanol, ethanol, and isopropanol in pure and aqueous fractions (80: 20) were used for the extraction of brown rice material. The extract yields of brown rice were obtained from 1.62 g/100g to 3.67 g/100g for all the varieties. Aqueous isopropanol preferably and methanol (80: 20) showed best extraction yields on the dry mass basis of brown rice. The contents of total phenolics were determined as highest (496.9 mg GAE/kg) in Basmati Pak while lowest (137.7 mg GAE /kg) in non-basmati Irri-6 variety. For antioxidant activity, brown rice extracts of Basmati Pak showed the best potential at IC50 2.19 mg/mL against DPPH radical scavenging. Reducing the power of Basmati Pak was found highest at 0.85. Brown rice extract of Basmati 515 showed best ferrous ion metal chelation at 5.78 Eq. EDTA mg/100g.

This study aims to extract Glycyrrhizic Acid (GA) from Glycyrrhiza glabra L. (licorice) using a novel, high efficiency, and low-cost extraction method. Water was chosen as the proper solvent for the extraction process to eliminate the requirement of harmful and toxic solvents, prepare an environmentally friendly process, and reduce the costs. The effect of different process variables (extraction time, feed to solvent ratio, pH of extraction medium, and temperature) on the extraction, yield was investigated experimentally and statistical analysis using the RSM method was performed to analyze the effect of variables and obtain a proper model correlating the yield of extraction to variables. The obtained model was found successful in fitting the experimental results. It was found that all the four variables affect the yield of extraction significantly, and only the interaction between pH and extraction time was found important in increasing the GA% in the precipitate. The highest yield was achieved experimentally 54.9%, for the case with the extraction time of 17 h, feed to solvent ratio of 10 g/ml, pH of 10, and temperature of 60 ºC. On the other hand, the optimum condition obtained by the model was found at extraction time of 10.12 h, feed to solvent ratio of 10.71 g/ml, pH of 9.8, and temperature of 119.7 ºC.

The aim of this work is to provide insight intoalcohol-kerosene fuels and their promising use as an alternative in commercial aviation. A detailed chemical and physical experimental analysis is drawn, with a focus on the advantage of the isopropanol-kerosene blend. Despite reported beneficial isopropanol effects on retarding fuel combustion, knocking prevention, and much lower emissions, few investigations managed to offer clear prospects for such an alternative commercial aviation fuel. The ease of mixing with kerosene and the advantage of improved freezing points overcome negative effects of volatility and corrosion for low isopropanol percentage and makes it a strong candidate for alternative jet fuels.

Today seafood plays a significant role in feeding people worldwide. Identification nutritional value of these products over other protein intake is increasing day by day. In parallel with the increase in fish consumption, assessment of hygiene and health of these products is important. In this study, Heavy metals (Pb, Cr, and Cd) were investigated in white fish (Rutilus frissi kutum) from the Caspian Sea in Mazandaran province. Different food treatments were used (frying, salting, grilling, microwaving, boiling and steaming). The results obtained were statistically compared with those of raw fish. An ANOVA test was used to compare the mean metal concentrations between and within groups. The results indicated that the heavy metal content in white fish decreased on various cooking methods. Concentrations of grilled, microwaved and boiled fish were considerably decreased.

A facile and efficient one-pot, multicomponent synthesis of4 H - chromenes is reported, through the reaction of arylglyoxal monohydrates with 1, 3-diketones and malononitrile in ethanol in the presence of L-proline as a catalyst.

5-acetyl-6-methyl-4-aryl-3, 4-dihydropyrimidin-2 (1H) -ones were synthesized in good to excellent by one-pot three-component Biginelli condensation in the presence of ammoniumsalt [Et3NH] [HSO4] as an inexpensive and green catalyst under solvent-free conditions. High yields, short reaction time, easy work-up, a green environment which requires no toxic organic solvents and reusability of the catalyst are the advantages of this procedure. A broad range of structurally diverse aldehydes (aromatic aldehydes bearing electron withdrawing and electron releasing groups) was applied successfully, and corresponding products were obtained in good to excellent yields without any by-product. In addition, this catalyst was stable during the reaction process and could also be reused several times with consistent activity.

As the basis and preliminary work of future experimental study on PAHs formation under high temperature, theoretical computations on the intramolecular rearrangement reactions of sylvestrene (1-methyl-3-vinylcyclohexene) and 1, 4-dimethyl-4-vinylcyclohexene are conducted and reveal that they may be transformed to themselves. The conversion between Dipentene and 2, 4-dimethyl-4-vinylcyclohexene is also predicted. All the reactions proceed along concerted paths through a single cis-endo transition state with relatively high energy barrier (~200 kJ/mol) and presumably occur when alkenes burn. These possible Cope rearrangement reactions have some characters of stepwise Diels-Alder cycloadditions during which diene and dienophile are replaced by each other and may suggest the complexity of cyclic hydrocarbons formation.

Polyethylene’s application for insulating is highly advanced but due to thermoplastic properties, its application confronts constraints such as the limited 70°C temperature of the conductor. Polyethylene thermosetting procedure in which molecules are knotted and a 3D-molecular-network formed is developed to conquer the mentioned problem and to raise the applicable temperature of the insulation. This paper reports the cross-linking of two cable grades of LLDPE by using DCP (Dicumyl Peroxide). DCP was chosen for its prevalence among various cross-linking agents. Structural parameters like molecular weight, melt flow index, viscosity and number of branches were obtained using relative tests as Gel Permeation Chromatography (GPC), Rheometry and Fourier Transform-InfraRed (FT-IR) spectrometer. After calculating the percentage of gel content, properties of the pure and cross-linked samples were compared by thermal and mechanical analysis with DSC, TGA, and DMTA. The effects of cross-linking like melting and decomposition temperatures, crystal formation, viscous and elastic modulus were discussed by using various structural parameters such as MFI, molecular weight, short chain branches. Studies declared that cross-linked polymer, unlike the pure one, had a solid state with thermal mechanical properties in the range of 110 to 120°C, so this assist overcomes the problem of using polyethylene in temperatures around the melting point.

In current work, halogenated sunflower oil was reacted with Na2S3 to produce sunflower oil-based polysulfide polymer. Cloisite 30B as organomodified nanoclay was used in different contents to investigate its effect on the properties of the synthesized polymer. All nanocomposites were prepared via in situ polymerization method in aqueous media. Fourier Transform-InfraRed (FT-IR) spectroscopy revealed the inclusion of nanoclay in a polymeric matrix. X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) were used to study the degree of intercalation/exfoliation of nanoplatelets in matrices. Proton Nuclear Magnetic Resonance (1H NMR) was utilized to study the molecular weight of synthesized polymers. Thermal stability of nanocomposites was determined by means of Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) was used to investigate thermophysical properties. According to results, nanocomposite with 1 wt. % of Cloisite 30B showed an exfoliated morphology whereas the higher amount of nanoclay resulted in intercalated nanoplatelets with different degrees of intercalation. Also, adding more Cloisite 30B nanoplatelets led to more decrease in molecular weight. After the introduction of nanoclay into nanocomposites structure and increasing its content, the thermal stability of nanocomposites was improved whereas no significant improvement of thermal stability was observed by increasing clay content from 3 to 5 wt. %. Also, all samples showed only the glass transition temperature (Tg) and no distinct peak related to melting was observed. Adding more nanoclay resulted in higher Tg value due to the confinement effect of nanoplatelets.

Thermo Gravimetric Analysis (TGA) analysis was employed to investigate activation energy (Ea) for the process of degrading of poly (o-toluidine) (POT) applying Horwitz & Metzger, Coats & Redfern and Chan et al., methods. POT was synthesized by chemical oxidative polymerization method using Ammonium per Sulphate (APS) as an oxidant while Dodecylbenzene Sulphonic Acid (DBSA) and sulfuric acid as co-dopants. Different samples, synthesized by variations in the reactions parameters, were evaluated in order to choose the one with the highest activation energy of degradation. Additional characterization of the polymer was carried out through differenttechniques such as Scanning Electron Microscopy (SEM), UltraViolet Visible spectroscopy (UV-Vis)and X-Ray Diffraction (XRD) analysis.

The leaching kinetics of smithsonite ore in acetic acid solutions, an environmental friend, and natural reagent was investigated. The influence of parameters such as reaction temperature, particle size, solid-liquid ratio and acid concentration was studied in order to reveal the leaching kinetics of smithsonite ore. In this study, experimental and statistical methods were carried out in order to analyze the kinetics data to investigate a kinetics model which describes the dissolution. The results indicate that the unreacted shrinking core model for fluid-solid heterogeneous reactions was favorable for the leaching process. The apparent activation energy of the leaching process was found as 74 kJ/ mol. It was determined that the leaching rate of smithsonite was controlled by the chemical reaction below: (1-x)1/3=3.7×105e-74/RTt.

Two major concerns for cement factories are environmental aspects and production costs. The number of cement factories is increasing in Iran which from an environmental point of view is not favorable. Different pozzolans such as brick, potted clay, volcanic rocks, sedimentary rocks and rice bran were used in the cement produced by Lamerd factory in the south of Iran. Among these additives, rice bran fails to be proper pozzolan. This research shows that using pozzolansup to 10% does not have a significant effect on the quality of Lamerd cement. Almost the similar texturesof compositions for differently mixed types of cement were determined using XRD and XRF experiments. Considering these additives, volcanic and sedimentary rocks seem to be more favorable regarding both quality and price. In fact, the additives can reduce both the emission of CO2 (reduction of more than around 400 tons CO2 per day) and the production costs (the money saved is around $76000 per day) in cement factory of Lamerd.

Determination of the type of precipitated calcium sulfate in mixing two incompatible injection and formation waters was studied experimentally in this work at two temperatures of 26oC and 80oC. Here the SEM, EDX and XRD techniques have been used to inspect the temperature effects on the morphology, type, and size of the precipitated calcium sulfate crystals. The results of this work show that the precipitated scales at these temperatures are calcium sulfate dihydrate and the temperature influences the size of crystals dramatically. The crystallization mechanism is the next issue which has been studied in this work. Measuring the amount of precipitated scale in the mixing of the incompatible waters versus time depicts the scale formation controlling mechanisms. According to the obtained results in this work, three primary nucleations, crystal growth, and secondary nucleation control the calcium sulfate scale precipitation.

Determination of the type of precipitated calcium sulfate in mixing two incompatible injection and formation waters was studied experimentally in this work at two temperatures of 26oC and 80oC. Here the SEM, EDX and XRD techniques have been used to inspect the temperature effects on the morphology, type, and size of the precipitated calcium sulfate crystals. The results of this work show that the precipitated scales at these temperatures are calcium sulfate dihydrate and the temperature influences the size of crystals dramatically. The crystallization mechanism is the next issue which has been studied in this work. Measuring the amount of precipitated scale in the mixing of the incompatible waters versus time depicts the scale formation controlling mechanisms. According to the obtained results in this work, three primary nucleations, crystal growth, and secondary nucleation control the calcium sulfate scale precipitation.