Iranian Journal of Chemistry and Chemical Engineering
Volume:31 Issue: 3, May-Jun 2012

The complexation reaction between 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane (Kryptofix5) ligand with Zn2+, Ni2+, Co2+, Pb2+, Mn2+ and Cu2+ ions were studied conductometrically in different AcetoNitrile-NitroMethane (AN-NM) and AcetoNitrile-Methanol (AN-MeOH) mixtures. The formation constants of the resulting 1:1 complexes were calculated from the computer fitting of the molar conductance in various mole ratios. The enthalpy and entropy changes of the complexation reactions were derived from conductometric titrations in different AN-NM mixtures at various temperatures. The results revealed that Kryptofix5 forms very stable 1:1 complexes with mentioned cations in all AN-NM and AN-MeOH mixtures. It was found that the stability of the resulting complexes decreased with increasing nitromethane or methanol in the solvent mixture. The TΔS° vs. ΔH° plot of all thermodynamic data obtained shows a fairly good linear correlation indicating the existence of enthalpy-entropy compensation in the complexation reactions.

Diolefinic antibacterial laser dye namely 1,4-Bis[2-(4-Pyridyl) Vinyl] Benzene (4PVB) have been investigated electrochemically using cyclic voltammetry, chronoamperometry, convolution and deconvolution voltammetry combined with digital simulation techniques at a platinum electrode in 0.1 mol / L Tetra Butyl Ammonium Perchlorate (TBAP) in solvent 1,2-dichloroethane. The diolefinic species were reduced by consuming two sequential electrons to form radical anion and dianion. The second electron transfer was followed by chemical step i.e the electrode reaction proceed as EEC scheme. In scanning the potential to positive direction, the diolefinic laser dye compound was oxidized by loss of one electron, which was followed by a fast chemical process (isomerization or association). The pathway of electrode reaction and the electrochemical parameters of the investigated compound were discussed & determined using cyclic voltammetry and chronoamperometry techniques. The extracted electrochemical parameters were verified and confirmed via digital simulation and convolutive voltammetry methods.

In this work, removal of C. I. Acid Red 14 was investigated by Pumice stone as a low cost adsorbent. Various parameters such as initial dye solution, contact time and pH were studied. Removal of dye were increased by increasing of contact time and initial dye solution and deceased by increasing of pH. Three isotherm models were studied. Linear and non-linear regression analyses were used for determination of best isotherm model. In addition, Chi-square test parameter (χ2) was used for the comparison of experimental and calculated data that was obtained from equilibrium studies. The results of linear and non-linear regression analysis shows the removal of Acid Red 14 follows the Frundlich isotherm model (r2>0.987, X2=11.1). Fitting of obtained data onto kinetic models show the pseudo second order kinetic model best describe kinetic sorption of Acid Red 14 onto pumice. Mass transfer coefficient was determined at various initial dye solutions and was compared with the same work. The order of external mass transfer coefficient was 10-3-10-4. De-sorption studies demonstrate low regeneration of pumice for Acid Red 14 (9.4%

A type of novel hypercross-linked fiber adsorbent was obtained by sulfonation and cross-linking reaction of polypropylene fiber grafted styrene-divinylbenzene. The aim of the fiber sulfonation and cross-linking method was to prepare rigid three dimensional networks in the entire fiber and change the ion exchange capacity of fiber. The hypercross-linked fiber adsorbent possesses a principally different structure and could offer new possibility for adsorption, which is characterized by high adsorption capacity for aniline in this paper. A series of static adsorption tests were made. The results showed that the adsorbent has excellent adsorption capacity for aniline and the adsorption equilibrium data can be well fitted by Freundlich model. Adsorption of aniline on adsorbent was chemical adsorption and high temperature was favourable to endothermic chemisorption process. In addition, the kinetic studies were also carried out. The hypercross-linked fiber adsorbent showed faster adsorption rate than the base fiber. The quicker attainment of adsorption equilibrium (within 20 minutes) for aniline on adsorbent is advantageous for practical use. The pseudo-second-order rate model was suitable to describe the process. The pseudo-second-order model gave an excellent fit to all experimental data and adsorption capacities calculated by pseudo-second-order rate model were close to the values actually measured.

In this study, aniline-formaldehyde polymer was synthesized and then modified with extra aniline as cross-linker in the presence and absence of Ni(II) as the template to produce Ion Imprinted Poly(Aniline-Formaldehyde) (IIPAF) and Non Imprinted Poly(Aniline-Formaldehyde) (NIPAF). The IIPAF was subjected to adsorption, preconcentration and determination of Ni(II) ion in environmental samples. The effect of pH, contact time, interfering ions and other parameters on adsorption of Ni(II) was investigated. The optimum pH was found to be 8.0 with a recovery of 97.5%. Elution was performed with 0.5 M nitric acid. The sorption polymer capacity was found to be 59.4 mg.g-1. The concentration of the metal ion was detected with flame atomic adsorption spectrometry. The prepared ion imprinted sorbent showed high adsorption capacity, significant selectivity, good site accessibility and fast binding kinetics for Ni(II) ion. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The equilibrium adsorption data of Ni (II) on synthetic polymer were analyzed by Langmuir, Freundlich and Temkin models. The method was successfully applied for determination of Ni(II) ions in environmental water sample.

The aim of the present work was to investigate the ability of Cocopeat to remove of lead (II) from aqueous solutions. The effects of different parameters such as particle size, adsorbent dosage, pH, contact time, agitation speed and concentration on the removal process has been investigated. The maximum removal of lead ion (92.5%) took place in the pH range of 4 contact time in 30 minutes and initial concentration of 30 mg.L-1. Results indicated that the Langmuir model gave a better fit to the experimental data in comparison with the Freundlich equation. The process followed pseudo-second-order kinetics.

The potential of Near Infrared Reflectance Spectroscopy (NIRS) as a fast method to predict the Crude Protein (CP) and Moisture (M) content in fishmeal by scanning spectra between 1000 and 2500 nm using multivariate regression technique based on Partial Least Squares (PLS) was evaluated. The coefficient of determination in calibration (R2C) and Standard Error of Calibration (SEC) were 0.95 and 14.03 g / kg Dry Matter (DM) and 0.80 and 3.52 g / kg, for CP and M content, respectively. This study proved that the application of NIRS using PLS is well fitted to evaluate the protein and moisture content of fishmeal.

In this contribution, linearized dynamic model of Cumulative Mass Fraction (CMF) of Potassium Nitrate-Water Seeded Continues Mixed Suspension Mixed Product Removal (CMSMPR) crystallizer is approximated by a simplified model in frequency domain. Frequency domain model simplification is performed heuristically using the frequency response of the derived linearized models data. However, the CMF frequency response of the original model is obtained versus three input variables encompass seeding mass flow rate, inlet liquid volumetric flow rate and jacket temperature with emphasis on minimum model simplification assumptions. Results show that the simplified CMF frequency response predicts system dynamics and covers all system characteristics as well as the main complex model.

In this work, based on experimental observations and exact theoretical predictions, the kinetic scheme of RAFT polymerization is extended to a wider range of reactions such as irreversible intermediate radical terminations and reversible transfer reactions. The reactions which have been labeled as kinetic scheme are the more probable existing reactions as the theoretical point of view. The detailed kinetic scheme is applied to three kinds of RAFT polymerization system by utilizing the Monte Carlo simulation Method. To do this, a new approach of simulation method was used. In this approach, a multi-reaction step was used in each time step. Unknown kinetic rate constants have obtained by curve fitting of the simulation results and theoretical data, applying the least square method; or estimated by considering theoretical facts and experimental findings. The origin of the rate retardation and induction period has been understood by studying the main and pre-equilibrium stages of dithiobenzoate-mediated RAFT homo polymerization. A copolymerization system in the presence of RAFT agent has also been examined to confirm the capability of introduced simulation method in different monomer/RAFT agent systems. The simulation results were in excellent agreement with experimental data, which proves the validity and applicability of the Monte Carlo algorithm.

The effect of oleic acid (5 and 10% v/v) and xanthan gum (0.5 and 1% wt) on partitioning and retention of ethyl acetate and diacetyl from two matrices with a different composition was investigated by applying static head space gas chromatography. Two matrices with different composition have been developed: one containing carbohydrates (xanthan gum) and in the second one, called complex matrix, lipid (oleic acid) was added. The roles of Xanthan Gum (XG) and lipid (oleic acid) on the retention of aroma compounds were pointed out. Changes in the composition of matrices exhibited a considerable effect on the air/liquid partition coefficient (Ka/l) values at equilibrium. The kinetic study of the release from both matrices had shown a decrease of the initial rate of release (Ri) by reference with water. The rheological properties of all matrices were investigated and the flow behavior of all matrices was successfully modeled with power law and cross models. Power law model was found as the better model to describe the flow behavior of dispersions. KEY WORDS:

This paper introduces an effective parameter for optimum design of integrated cryogenic NGL recovery plants. The process fluid pressure is an important factor which can affect the plant characteristics. A cryogenic liquid recovery plant was selected as a case study. The influence of different values of pressure drop in various equipments on the quality and quantity of the process outputs were analyzed. The results show that the product specification, quantity and operating costs of the plant are important parameters which a balance between them will determine the optimum pressure distribution in the process. The plant wide net profit can be used as an objective for obtaining the optimum pressure distribution. The products’ price and operating costs change due to economical and political situations. So the optimum pressure distribution in a process can be changed based on the plant wide net profit in various situations.

In order to comply with stringent pollutant emissions regulations, a detailed analysis of the engine combustion and emission is required. In this field, computational tools like CFD and engine cycle simulation play a fundamental role. Therefore, the goal of the present work is to simulate a high speed DI diesel engine and study the combustion and major diesel engine emissions with more details, by using the AVL-FIRE commercial CFD code. The predicted values of the in cylinder pressure, heat release rate, emissions, spray penetration and in-cylinder isothermal contour plots by this code are compared with the corresponding experimental data in the literature and is derived good agreement. This agreement makes the model a reliable tool that can use for exploring new engine concepts.

In this research, feasibility study of integrating thermal desalination unit with Gas Turbine (GT) has been investigated using retrofit and grass root design techniques for Lavan Island Oil Refinery which is located in Persian Gulf. According to computed parameters on developed code for the power generation unit No.1 using EES (Engineering Equation Solver) software, thermal efficiency of the GT unit No.1 and thermal energy recovered by HRSG (Heat Recovery Steam Generator) are equal to 22.79% and 4847 kW, respectively. Therefore, it shows a considerable potential on heat recovery and motive steam production. Effect of variations on different quantitative and qualitative parameters has been reviewed on the next step of this research. Finally, effect of engineering and economical parameters has been compared based on the following scenarios:● Integrating available Thermal Desalination Unit (TDU) with available steam boiler,● Retrofitting available TDU with HRSG,● Integrating GT unit No.1 with novel simulated TDU based of grass root design.As a result, based on economical model, which has been developed using GAMS (Generalized Algebraic Modelling System) software, the selected scenario is the third scenario.

In this paper, the MagnetoHydroDynamic (MHD) boundary layer flow over a nonlinear porous stretching sheet is investigated by employing the Homotopy Perturbation Transform Method (HPTM) and the Pade´ approximation. The numerical solution of the governing non-linear problem is developed. Comparison of the present solution is made with the existing solution and excellent agreement is noted. Graphical results have been presented and discussed for the pertinent parameters. The results attained in this paper confirm the idea that HPTM is powerful mathematical tool and it can be applied to a large class of linear and nonlinear problems arising in different fields of science and engineering.

A Fault-Tolerant Control (FTC) methodology has been presented for nonlinear processes being imposed by control input constraints. The proposed methodology uses a combination of Feedback Linearization and Model Predictive Control (FLMPC) schemes. The resulting constraints in the transformed process will be dependent on the actual evolving states, making their incorporation in the design context a non-trivial task. A feasible direction method has been integrated in the design procedure based on active set technique to resolve the challenging constraint–based FLMPC problem. The formulated FLMPC design method is utilized to develop a FTC scheme by providing a set of backup control configurations for a CSTR benchmark process. The successful performance of the proposed FTC methodology has been demonstrated via a category of common fault scenarios by exercising an arbitrary replacement of control configurations through a supervisor to maintain the CSTR operation at an unstable desired steady-state point.

This paper presents an optimal integrated instrumentation sensor network design methodology for complex nonlinear chemical process plants using a Combinatorial Particle Swarm Optimiazation (CPSO) engine. No comprehensive sensor network design approach has been addressed yet in the literature to simultaneously incorporate cost, precision and reliability requirements for nonlinear plants. The presented approach attempts to accomplish this objective via enhancement of the estimation accuracy of the aimed instrumentation sensor network subject to desired cost, reliability and redundancy constraints. An Unscented Kalman Filter (UKF)-based data reconciliation algorithm has been developed to present evaluating measures through comparisions of the estimated and real variables in terms of Modified Root Mean Squared of Error (MRMSE), while CPSO maintains the provisions of the Network Fault Tolerence (NFT) including sensor netowrk reilability (R), strong and weak redundancy degrees (i.e., SRD and WRD). The developed CPSO engine searches in a diverse variety of possible sensor networks to adopt the most fitted one based on the imposed NFT and cost design constraints. The effective capabilities of the proposed design methodology has been illustrated in a simulated nonlinear Continuous Stirred Tank Reactor (CSTR) as a complex process plant benchmark.