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Saberi R.,NSTRI | Hassani A.H.,Islamic Azad University at Tehran | Abedi M.S.,Islamic Azad University at Tehran | Ardeshir A.T.,NSTRI | Mozaffari A.,University of Tehran
Desalination and Water Treatment | Year: 2017

In this study, ozone as an advanced oxidation process was used to increase the efficiency of linear alkylbenzene sulfonate (LAS) detergent removal in the treatment of wastewater. The first part of this research contains the study of LAS removal from the wastewater by the Moving Bed Biofilm Reactors (MBBR) biological reactor. For this purpose, the LAS removal efficiency was determined at different levels of LAS (low, medium and high concentrations) for different hydraulic retention times. The results show that increasing the hydraulic retention time had a positive effect on the MBBR reactor, efficiency, but Increasing- LAS Concentration had negative impact on system performance and decreased LAS removal rate. The second part of this research contains a study on LAS removal from the wastewater by using a combination system of MBBR and post-ozonation process. The results show that this combination system can remove LAS completely at the low concentration of LAS and dramatically improving the removal efficiency of LAS in medium and high concentrations. © 2017 Desalination Publications. All rights reserved.

Shokati Poursani A.,Islamic Azad University at Tehran | Nilchi A.,NSTRI | Hassani A.H.,Islamic Azad University at Tehran | Shariat M.,Islamic Azad University at Tehran | Nouri J.,Islamic Azad University at Tehran
International Journal of Environmental Science and Technology | Year: 2015

Nano-γ-Al2O3 adsorbent was synthesized by the novel sol–gel method. The adsorbent was characterized by transmission electron microscope, Fourier transform infrared and X-ray powder diffraction. The effects of several variables such as, adsorbent weight, pH and contact time on adsorption of chromium (Cr6+), nickel (Ni2+), cadmium (Cd2+) and lead (Pb2+) ions were studied in batch experiments. The results showed that the synthesized nano-γ-Al2O3 had a good capacity to adsorb Cr and Pb. The kinetic data were described with pseudo-first- and pseudo-second-order models. Three isotherm models, namely Freundlich, Langmuir and Tempkin, were used for analysis of equilibrium data, and results showed that Langmuir and Freundlich models were suitable for describing the equilibrium data of Cr6+, Cd2+, Ni2+ and Pb2+. Using Langmuir isotherm, the maximum sorption capacities of Cr6+, Pb2+, Cd2+ and Ni2+ were estimated to be 13.3, 6, 1.1 and 0.33 (mg/g) at 25 °C, respectively. The sorption capacity did not change remarkably after reuse of sorbent for sorption–desorption cycle. The selectivity order of Cr6+, Pb2+, Cd2+ and Ni2+ sorption onto the adsorbent was Cr6+ > Pb2+ > Cd2+ > Ni2+. © 2015, Islamic Azad University (IAU).

Salahinejad M.,Environmental Laboratory | Zolfonoun E.,NSTRI
Journal of Nanoparticle Research | Year: 2013

Artificial neural network (ANN) and multiple linear regression (MLR) approaches were successfully applied to construct quantitative structure-activity relationship models of the dispersibility of single-walled carbon nanotubes (SWNTs) in different organic solvents. A subset of the calculated descriptors selected by enhanced replacement method (ERM) was used in the QSPR models development. The predictive abilities of ERM-MLR and ERM-ANN models were determined using a test set of six organic solvents affording predictive correlation coefficients of 0.924 and 0.963, respectively, showing good predictive power of the models obtained. The final models satisfied a set of rigorous validation criteria and performed well in predicting of the external test set. The results obtained in this study, confirm the importance of steric and electrostatic interactions, molecular flexibility, polarizability and hydrogen bonding ability of organic solvents in SWNTs dispersibility. This information could be useful for identification of some key molecular features of solvent molecules and to find the proper solvent for SWNTs dispersion. © Springer Science+Business Media 2013.

Salahinejad M.,Environmental Laboratory | Zolfonoun E.,NSTRI
Solvent Extraction and Ion Exchange | Year: 2014

Three-dimensional quantitative structure activity relationships (3D-QSAR) methods of comparative molecular field analysis (CoMFA), CoMFA region focusing (CoMFA-RF), and comparative molecular similarity indices analysis (CoMSIA) were successfully employed to predict and model of the separation factors of N-donor heterocyclic extractants in the separation of americium(III) from europium(III) ions from acidic aqueous solutions. An all-orientation search (AOS) strategy was used to acquire the best orientation and minimize the effect of the initial orientation of aligned compounds. The obtained 3D-QSAR models showed R2 > 0.97 and an absolute error of > 0.1 in log unit of the separation factors. Validation, reliability, and robustness of 3D-QSAR models were evaluated by the prediction of external test sets, leave-one-out, leave-four-out, bootstrapping, and progressive scrambling approaches. The results confirmed that steric hindrance and electrostatic interactions besides hydrophobic effects of N-donor extractants play an important role in Am(III)/Eu(III) separation processes. The obtained information could be very useful in designing the most efficient ligands and finding new extractants for lanthanide and actinide separation. © 2014 Taylor and Francis Group, LLC.

Heidary S.,University of Tehran | Setayeshi S.,University of Tehran | Ghannadi-Maragheh M.,NSTRI | Negarestani A.,ICST
Radiation Measurements | Year: 2011

A new radon calibration chamber has been designed, constructed and tested to set various desired environmental parameters. The chamber is cubic with two trapezoid sides with a total volume size of 0.498 m3. The three parameters, temperature, humidity and flow are controlled in the range of 20-45 °C (±2 °C), 10-70% (±2.5%) and 0.2-10 m3/min (±0.1 m3/min) respectively. The chamber is equipped with a controllable speed centrifugal fan to achieve a desirably uniform radon flow rate. Many parts of this system are controlled and monitored with a PLC (Programmable Logic Control) and HMI (Human Monitoring Interface) software (Citect Scada). Finally a radon detector (Alpha-Guard) registers the activity parameter. © 2011 Elsevier Ltd. All rights reserved.

Nilchi A.,NSTRI | Saberi R.,NSTRI | Moradi M.,University of Tehran | Azizpour H.,University of Tehran | Zarghami R.,University of Tehran
Chemical Engineering Journal | Year: 2011

In this study, copper hexacyanoferrate-polyacrylonitrile composite (CHCF-PAN) was prepared and used as an ion exchanger for the separation of cesium from aqueous solution. Various characterization methods including XRD, FT-IR, TG-DSC, SEM, BET and XRF were utilized for the evaluation of the synthesized ion exchanger. In order to obtain the optimum conditions for the adsorption, the influence of pH of initial aqueous solution, contact time, solution temperature and presence of the interfering cations on the distribution coefficient of cesium onto CHCF-PAN sorbent were studied. Furthermore, adsorption thermodynamic parameters namely the standard enthalpy, entropy, and Gibbs free energy were calculated and it was found that the ion exchange reaction is an endothermic and spontaneous process. Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherm models were fitted to the obtained experimental sorption data and it was observed that the sorption of cesium on the synthesized sorbent was better represented by the Freundlich model. Finally, in order to calculate the dynamic adsorption capacity of the synthesized ion exchanger, the column experiments were also investigated. © 2011 Elsevier B.V.

Nilchi A.,NSTRI | Saberi R.,NSTRI | Azizpour H.,University of Tehran | Moradi M.,University of Tehran | And 2 more authors.
Chemistry and Ecology | Year: 2012

In this study, a cerium molybdate-polyacrylonitrile (CM-PAN) composite ion exchanger was synthesised and its characteristics were determined by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetry (TGA), specific area measurement (BET), X-ray fluorescence and CHN elemental analyses. The adsorption of caesium from aqueous solutions by CM-PAN composite was investigated under batch and continuous conditions. The distribution coefficient of caesium on the composite sorbent was studied as a function of pH, solution temperature and the presence of interfering cations, and the optimum conditions for a batch system were determined. Pseudo-first- and second-order sorption kinetic models were used to investigate the kinetics of adsorption and the results pointed to the pseudo-second-order model for caesium sorption kinetics. The intraparticle diffusion model was used to the predict rate-limiting step of the ion exchange process in order to specify the sorption mechanism. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models were fitted to the experimental sorption data, where the Freundlich model showed a good agreement. The adsorption thermodynamic parameters, standard enthalpy, entropy and Gibbs' free energy were calculated and the reaction was found to be endothermic and spontaneous. Finally, the dynamic sorption capacities of the sorbent at two breakthroughs were calculated from the continuous system. © 2012 Copyright Taylor and Francis Group, LLC.

Nilchi A.,NSTRI | Zarghami R.,University of Tehran | Saberi R.,NSTRI | Moradi M.,University of Tehran | Azizpour H.,University of Tehran
Journal of Radioanalytical and Nuclear Chemistry | Year: 2012

Ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) as an organic-inorganic composite ion exchanger was synthesized and investigated for adsorption of cesium from aqueous solutions. The synthesized composite was characterized by various techniques including X-ray powder diffraction, Fourier Transform Infrared Spectroscopy, thermogravimetry-differential scanning calorimetry, specific surface analysis, scanning election microscopy, X-ray fluorescence spectroscopy and CHN elemental analysis. The cesium adsorption on composite adsorbent was studied as a function of contact time, pH, temperature, and presence of various cations. In addition, adsorption thermodynamic parameters were determined and it was observed that the adsorption of cesium on the adsorbent is an endothermic and spontaneous process. The Langmuir and Freundlich adsorption isotherms were fitted to the adsorption data and the results showed that the Langmuir model best predicates the cesium adsorption on the adsorbent. The dynamic behavior of cesium adsorption on AMP-PAN ion exchanger was also investigated for a fixed bed column and desorption was carried out. © 2012 Akadémiai Kiadó, Budapest, Hungary.

AL-Othman Z.A.,King Saud University | Naushad M.,King Saud University | Nilchi A.,NSTRI
Journal of Inorganic and Organometallic Polymers and Materials | Year: 2011

A new crystalline organic-inorganic composite cation exchanger polyaniline Sn(IV) molybdate was developed by mixing polyaniline into the inorganic precipitate of Sn(IV) molybdate. This material was characterized using Fourier transform infrared spectroscopy (FTIR), simultaneous thermogravimetry-differential thermogravimetry (TGA-DTA), X-ray, scanning electron microscopy (SEM) and elemental analysis studies. Ion-exchange capacity, effect of calcinations (100-500 °C) on ion exchange capacity, pH-titrations, chemical stability, elution and distribution behavior were also carried on this material. On the basis of distribution studies, the material was found to be highly selective for Pb 2+ ion and its selectivity was tested by achieving some important binary and ternary separations. In order to demonstrate the practical utility of the material, quantitative separations of Pb 2+ from a standard reference material (Rompin Hematite) of lead have been achieved. Thermodynamic parameters viz- entropy change (ΔS), enthalpy change (ΔH) and Gibb's free energy change (ΔG) were also calculated. © 2011 Springer Science+Business Media, LLC.

Arabieh M.,NSTRI | Platas-Iglesias C.,University of La Coruña
Computational and Theoretical Chemistry | Year: 2016

The most feasible complexes formed between dipicolinic acid and hydrated Fe2+ cation (namely, [FeL(H2O)3] and [FeL2]) have been modeled using density functional theory. A comparison among several computational levels of theory and available X-ray data showed that the B3LYP/6-311G(d) computational level provides accurate geometrical parameters for geometry optimization of complexes. The energetics and thermochemistry of complexation reactions in the gas phase and solvated medium (PCM) were evaluated at the B3LYP/6-311G(d) and B3LYP/6-311++G(2df,pd)//B3LYP/6-311G(d) levels of theory. The calculated thermochemistry data exhibited high complexation energies for both complexes and decreasing in the exothermicity of complexation reactions when PCM model was included in the calculations. The calculated free energy changes of complexation reactions pointed to spontaneous procedures. Detailed analysis of energy levels and major composition of selected frontier orbitals were performed and the results suggested the higher stability for the [FeL(H2O)3] system than for [FeL2]. Based on QTAIM, several bond-indexes such as electron density at the bond critical points, the Laplacian of the electron density, ellipticity and the total energy density were utilized to analyze chemical bonding in these complexes. Natural bond orbital (NBO) analysis was carried out to provide more precise insight on the interactions and nature of the bonds established between the ligand and the metal ion. © 2016 Elsevier B.V.

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