Iranian Journal of Chemistry and Chemical Engineering
Volume:33 Issue: 4, Jul-Aug 2014

Copper complexes of [Cu(phen)(tda)].2H2O(1) and [(phen)2Cu(µ-tda) C (phen)](ClO4)2.1.5H2O (2) (where phen is 1,10-phenanthroline and tda2- is thiodiacetate) have been synthesized. Both complexes were characterized by elemental analysis, IR, UV Vis spectroscopy and cyclic voltammetry. Their solid state structures were determined by the single crystal X-Ray Diffraction method. Complex 1 is mononuclear and copper has accepted a five-coordinated square-based pyramidal structure with the tda2- anion facially coordinated to copper(II). Complex 2 has accepted an unsymmetrical square pyramidal coordination of two distinct copper complexes, one containing two phenanthroline and the other containing one phenanthroline and one tda2-, bridged by a carboxylate oxygen. The strong biological activity of these compounds against six reference bacterial included Bacillus subtilis (ATCC 465), Enterococcus faecalis (ATCC 29737), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 10031), and Pseudomonas aeruginosa (ATCC 85327) were investigated.

Spinel-type of MnO2 nanoparticles which successfully synthesized by a hydrothermal process, have a required capacity for lithium uptake from liquid resources. The most lithium adsorption capacity of 6.6 mmol/g of up to now was found to be an important limiting parameter for industrial applications. Therefore, increasing uptake capacity of these ion sieves by studding the effect of six effective parameters, involving lithium compounds, manganese compounds, oxidizing reagents, calcination temperatures, heating times and Li/Mn mol ratios was investigated. To this end, Taguchi L9(34) orthogonal array was employed as a predominate method to evaluate these parameters and the results optimized by using analysis of variance (ANOVA) and analysis of mean (ANOM) in two separate stages. Although, all mentioned parameters had significant effect on lithium uptake capacity, but oxidizing reagents were the most effective factors. Hence, a new ion sieve with more than 9 mmol/g lithium adsorption capacity was synthesized for the first time, by applying this method.

MIL-53-Cu has been synthesized hydrothermally and has been used for the first time for gas separation. MIL-53-Cu shows adsorption capacities of 8.1, 0.7 and 0.5 m.mol/g, respectively, for CH4, CO2 and H2 at 30 bar and 298 K. The high CH4 adsorption capacity of MIL-53-Cu maybe attributed to the high pore volume and large number of open metal sites. The high selectivity for CH4 over CO2 (11.5) and H2 (16.2), suggests that MIL-53 Cu is a effective adsorbent material for the separation of CH4 from gas mixtures.

In this paper, the possibility of using a new ordered nanoporous carbon as a new fiber in headspace solid phase microextraction (HS-SPME) to determine of mononitrotoluenes (MNTs) in waste water is demonstrated. The structural order and textural properties of the ordered nanoporous carbon were studied by X Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) images and nitrogen adsorption isotherms. The analysis was done on a gas chromatograph equipped with flame ionization detector and capillary column. The main factors affecting the MNT compounds extraction such as rate of stirring sample solution, sample solution volume, ion strength of sample solution, extraction time and temperature have been investigated and established. Optimization of these parameters was done by Taguchi method and Orthogonal Array Design (OAD). The effects of these parameters were investigated using the analysis of variance (ANOVA). Under the optimum conditions, recovery values were between 87.1% and 106.2%, Limit Of Detections (LODs) ranged from 0.01 g/L to 0.16 g/L and Linear Dynamic Range (LDR) of 0.5–400 g/L was obtained. Relative standard deviation of single fiber and fiber-to-fiber (n=4) was in the range of 3.7-4.2% and 7.3-8.9%. Performance of the present method was evaluated for extraction and determination of nitroaromatic compounds in wastewater samples in the range of microgram per liter and satisfactory results were obtained.

In this work, an environmentally friendly sample pre-treatment method, Ultrasound Assisted Surfactant Enhanced Emulsification Microextraction (UASEME) followed with spectrofluorimetry was performed for determination of oxadiazon residues in water samples. After the determination of the most suitable extraction solvent and its volume, other parameters such as type and concentration of surfactant, pH, extraction time and ionic strength were optimized. Under the best conditions for extraction recovery, 50µL of chlorobenzene was chosen as extraction solvent and Tween 20 in concentration of 0.06 mmol/L as emulsifier and 2 min was the required time for quantitative analysis, without ionic strength and pH adjustment. Limit of detection and relative standard deviation were calculated as 0.05µg/L and 3.2% respectively. The procedure was applied successfully for assessing matrix effect in real water samples with relative recovery 96-104% with the precision in the range of 2.9-3.4%. The results demonstrate that UASEME procedure as reported is reliable, rapid and easy to use for analysis of oxadiazon in water samples.

In this study, we combined Ionic Liquid-based Dispersive Liquid Liquid Micro Extraction (IL-DLLME) with FAAS for determining the palladium in different real samples at the trace level. 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6] ionic liquid and 1-(2-pyridylazo) 2-naphthol (PAN), were chosen as the extraction solvent and the chelating agent, respectively. The hydrophobic Pd–PAN complex was extracted into the [Hmim][PF6] and separated from the aqueous phase. Then, the concentration of the enriched palladium in the sediment phase was determined by FAAS. Some effective parameters that would influence the FAAS signals and the microextraction efficiency, such as concentration of the chelating agent, pH, amount of the ionic liquid, type of disperser solvent and diluting agent, ionic strength, extraction and centrifugation times were investigated and optimized. Under optimum experimental conditions, the detection limit (3 s) and enhancement factor were 3.2 μg/L and 16.2, respectively. The Relative Standard Deviation (RSD) was 1.2% at a concentration of 50 μg/L. The developed method was successfully applied for determining trace amounts of the palladium in the water, soil and vegetable samples.

A new Fourier Transform-Infra Red (FT-IR) spectrometric method was developed for assaying hydrochlorothiazide (HCT) and enalapril maleate (ENM) in binary solid pharmaceutical formulations. Multivariate Partial Least Squares (PLS) method was used for calibration of derivative spectral data. Acetonitrile was used as solvent due to its spectral transparency and adequate solubility of analytes in it. A 4- levels full factorial design of binary standard solutions of HCT and ENM were prepared and used for calibration in the spectral range of 1550-1800 cm-1. Statistical parameters such as correlation coefficien (R), Standard Error of Estimation (SEE), Standard Error of Prediction (SEP), and Standard Error of Cross Validation (SECV) have been evaluated and used for selecting of optimizing of parameters. Correlation coefficients were 0.9990 and 0.9995 and Relative Standard Deviation (RSD) were 1.97% and 1.35% (n=5) for HCT and ENM, respectively. Detection limits of ENM and HCT were obtained 0.54 and 0.99 mg/mL respectively. The proposed methods were successfully applied to the determination of the over mentioned drugs in laboratory-prepared mixtures and in commercial tablets. This method has suitable accuracy, precision, repeatability and is comparable with reference standard methods.

To observe the feasibility of the removal of carmine, peanut husk, an agriculture by-product, was crosslinked with epichlorohydrin in alkaline medium and used for adsorption of carmine from aqueous solution. Batch experiments were carried out to study the effects of various parameters such as initial pH, contact time, adsorbent dosage and initial carmine concentration as well as temperature on carmine adsorption. The results indicated that adsorption equilibrium data could be more effectively described by Langmuir isotherm equation than by Freundlich equation. The maximum monolayer adsorption capacity of peanut husk from the Langmuir model was 6.68 mg/g at 323 K. The pseudo second-order model provided a better fit to experimental data in the kinetic studies. The mass transfer model such as the intraparticle diffusion was applied to the experimental data to examine the mechanisms of the rate-controlling step. It was found that the intraparticle diffusion is the significant controlling step under the experimental conditions but it was not the unique one. The thermodynamic parameters of the adsorption process were also calculated by using constants derived from Langmuir equations, which propose an endothermic physical spontaneous adsorption process.

In this study, the diffusivity and volumetric mass transfer coefficients for the extraction of β-carotene from crude palm oil using CO2 solvent in supercritical fluid were determined in the pressure range of 7.5-17.5 MPa and temperature range of 80 120 ºC. For this purpose, a statistical method was applied in order to minimize the number of experiments required. The volumetric mass transfer coefficient for the extraction of β carotene was then correlated as a function of pressure, temperature and extraction time in order to study the effect of each of these variables on the coefficient. The experimental results showed that the maximum volumetric mass transfer coefficient was around 2.486 × 10-2 s-1 at pressure of 7.5 MPa, temperature of 100 ºC and extraction time of 1 hour. The minimum volumetric mass transfer coefficient was 0.046 × 10-2 s-1 at pressure of 17.5 MPa, temperature of 120 ºC and extraction time of 5 hours. The optimum volumetric mass transfer coefficient was statistically obtained around 6.700 × 10-3 s-1 at pressure of 17.7 MPa, temperature of 100.5 ºC and extraction time of 3.9 hours.

In this paper, a reaction system consisting of two parallel, non-isothermal autocatalytic reactions in a Continuous Stirred Tank Reactor (CSTR) has been considered. Reactor chaotic behavior is possible for a certain values of system parameters. Two types of controllers are designed and compared in order to control both the reactor temperature and the product concentration. The first controller is a linear state feedback type, designed based on the linearized model of the process and the second one is designed based on the Global Linearizing Control (GLC) strategy. Since the system states are not measured completely, a nonlinear observer has been used to estimate the system states. Finally, computer simulation is performed to show the effectiveness of the proposed schemes. Simulation results indicate that the GLC-based control scheme is more effective for set point tracking, while the control scheme obtained using the linearized model of the process is more efficient for load rejection purposes.

Oxygen delignified kraft pulp from eucalyptus (E. urophylla × E. grandis) was catalytically pretreated in aerobic condition using ammonium persulfate in present of catalists like cupric acetate and/or cobalt acetate in acetic acid-water solution, i. e. S2O8 --Cu2+, S2O82--Co2+ and S2O82--(Cu2++Co2+). Final bleached pulp after pretreatment with the three catalytic systems showed higher delignification (23.45%, 21.85% and 19.63% respectively), better optical properties (82.93, 82.18 and 81.92% ISO brightness respectively) and pulp viscosity (787, 791 and 762 mL/g respectively; mL/g: intrinsic viscosity unit of pulp) than the control pulp (14.12% delignification, 77.33% ISO brightness and 746 mL/g viscosity). S2O82--Cu2+ and S2O82--Co2+ showed similar reduction in hydrogen peroxide consumption (61.91%, 62.48%), and S2O82--(Cu2++Co +) showed a greater reduction in hydrogen peroxide consumption than the two treatments 83.05%). Some improvements in tensile and tear strength of the resulting pulp were observed. The new sequence also yields composite effluents with larger percentage of lignin aromatic compounds compared to the control.

The wheat straw as abundant lignocellulosic resource was successfully undergone in a benzylation reaction and plasticized with different contents (2.5, 3, 5 and 7 wt. %) of glycerol and stearic acid. The effect of type and concentration of plasticizers on the mechanical, thermomechanical, morphological and water absorption properties of Benzylated Wheat Straw (BWS) was investigated by tensile, Dynamic Mechanical Thermal Analysis (DMTA) measurements and Scanning Electron Microscopy (SEM), respectively. The experimental results show that addition of plasticizer may increase the elongation at break, and may decrease the tensile strength for the sheet plasticized with 5% or 7% stearic acid and 3% or 5% glycerol. The addition of 7% glycerol or 3% stearic acid make increase both tensile strength and elongation at break. These films are stronger but less tough compared to unplasticized BWS film. The porosity at the surfaces of samples from the SEM micrographs showed good correlation with the mechanical properties of the blends. On addition of plasticizer, it is observed that there is a decrease in the size of micro-pores and for higher concentration, it no longer exists. Compared with glycerol, the water absorption of the BWS films plasticized with stearic acid was significantly lower. Glycerol is soluble in water and removed from films after floating in water. The film plasticized with 2.5% both glycerol and stearic acid had better water resistance than others. As usual, glass transition temperatures of samples were decreased by addition of plasticizers according to DMTA results.