Optimization of Cu(II)-ion imprinted nanoparticles for trace monitoring of copper in water and fish samples using a Box–Behnken design

We describe a nanoparticles ion-imprinted polymer (IIP) for the selective preconcentration of copper (II) ions. It was obtained by precipitation polymerization from 2-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the initiator), 2,9-dimethyl-1,10-phenanthroline (the copper-binding ligand) and nickel nitrate (the template ion) in acetonitrile solution. The IIP particles were characterized by Fourier Transformed Infra Red Spectroscopy (FTIR), thermogravimetric and differential thermal analysis, and by scanning electron microscopy. The optimization process was carried out using the Box–Behnken design (BBD). Effects of several factors such as solution pH for adsorption, amount of polymer, type, concentration and volume of eluent for extraction, as well as adsorption and desorption times were investigated. Under the optimum conditions (type and concentration of eluent, HCl 1.6 mol L^?1; volume of eluent, 6 mL; adsorption solution pH, 6.0; amount of polymer, 30 mg; adsorption time, 25 min; desorption time, 25 min), preconcentration factor of the proposed method was approximately 100. Under the optimized conditions, the detection limit was found to be 0.1 μg L^?1, while the relative standard deviation (RSD) for six replicate measurements was calculated to be <4%.     

Spherical Pseudo‐Inverse Opal Silica with Pomegranate‐Like Polymer Microparticles as Templates

Spherical silica particles with pseudo‐inverse opal structure are synthesized by using pomegranate‐like polymer microparticles as templates. A micro‐dispersion polymerization occurring in the suspended monomer droplets in the presence of a silica precursor leads to the formation of nearly monodisperse polymer sub‐particles of about 1 µm size, randomly‐packed within a 30–100 µm polymer particle. The polymerization is followed by an acid‐catalyzed reaction that induces formation of silica in the interstices between the sub‐particles within a polymer particle. Spherical PIOS particles are eventually produced by selectively removing the polymer template by pyrolysis. The PIOS particles show large specific surface areas with unique pore geometry and pore size distribution.

     

Evolutionary design of optimum distillation column sequence

Synthesis of the optimum distillation column sequence (DCS), which incorporates a huge search space composed of both conventional and complex arrangements, is a highly complicated combinatorial problem in the field of chemical process design and optimisation. In this study, a novel procedure for the synthesis of optimum DCS proposed by Boozarjomehry et al. [Boozarjomehry et al., Can. J. Chem. Eng. 87, 477–492 (2009)] is expanded to include the complex distillation arrangements. The method is based on evolutionary algorithms, and the total annual cost (TAC) is the main criterion used to screen alternatives. Efficient procedure has been proposed for encoding mechanism to include and classify various complex arrangements together with conventional distillation columns. All columns existing in each DCS alternative are designed using the most recommended short‐cut methods to estimate the TAC of the DCS. Four standard benchmark case studies are carried out to clearly demonstrate the excellent performance of the proposed method. The produced results for these problems indicate that the proposed method outperforms the other existing approaches in terms of flexibility, accuracy and comprehensiveness. © 2011 Canadian Society for Chemical Engineering     

气相分配比对隔板精馏塔性能和操作影响的模拟研究(英文)

Operability problem of dividing wall column (DWC) raised by vapor split was investigated by numerically analyzing four cases defined by different compositions of a three-component mixture. DWCs were firstly designed for each case by optimizing the vapor split to the two sides of the dividing wall, and then their feasibilities and total annual costs in operation were evaluated against different vapor split ratios. The analysis on the operability of the DWC for four cases was made based on two scenarios: (1) vapor split is shifted by the vapor resistance difference between the column sections in the two sides of the dividing wall and (2) the feed composition is changed. It was demonstrated that the positioning of the dividing wall and the decision on the vapor split may affect significantly the operability of a DWC.     

Growth of polyaniline on rGO-Co3S4 nanocomposite for high-performance supercapacitor energy storage

Recently, since the supercapacitors have drawn considerable attention, a vast study have been triggered in order to develop efficient electrodes for responding to the increasing demand of supercapacitors. In this report, a possible approach have been used to prepare a ternary nanocomposite, polyaniline/reduced graphene oxide-cobalt sulfide (PANI/rGO-Co₃S₄). At first, a simple and inexpensive hydrothermal route has been used for the preparation of cobalt sulfide (Co₃S₄) on the surface of graphene oxide sheets (rGO-Co₃S₄). Then, the polyaniline nanorods have been flourished on the surface of rGO-Co₃S₄ sheets via in situ chemical polymerization of aniline which was synergistically adjoined to the graphene surface. Polyaniline has uniformly covered the surface of the rGO-Co₃S₄ due to the rational combination of two components. Combining of PANI with rGO-Co₃S₄ electrode material amplify its electrochemical efficiency in terms of a high specific capacitance of 767 F g^?1 at 1 A g^?1 and 81.7% of specific capacitance maintenance after 5000 cycles due to the creation of synergistic effect. Therefore, the ternary nanocomposite of PANI/rGO-Co₃S₄ provides a new promising pathway for the expanding of high-performance electrode materials for supercapacitors.     

Economic optimization of shell and tube heat exchanger based on constructal theory

In this paper, the new approach of constructal theory has been employed to design shell and tube heat exchangers. Constructal theory is a new method for optimal design in engineering applications. The purpose of this paper is optimization of shell and tube heat exchangers by reduction of total cost of the exchanger using the constructal theory. The total cost of the heat exchanger is the sum of operational costs and capital costs. The overall heat transfer coefficient of the shell and tube heat exchanger is increased by the use of constructal theory. Therefore, the capital cost required for making the heat transfer surface is reduced. Moreover, the operational energy costs involving pumping in order to overcome frictional pressure loss are minimized in this method. Genetic algorithm is used to optimize the objective function which is a mathematical model for the cost of the shell and tube heat exchanger and is based on constructal theory. The results of this research represent more than 50% reduction in costs of the heat exchanger.     

Purification of water from heavy metal of lead by nanocomposite of Ce-TZP/Al2O3

In this study, nanocomposites of Ce-TZP/Al₂O₃ with four different mole percent of alumina from 20% to 80% were prepared by aqueous combustion synthesis method and effects of alumina mole fraction on the adsorption of lead ions were investigated. Lead (Pb²⁺) ion adsorption process was performed at the temperature of 25°C, contact time of 100 minutes for all the samples. The results showed that as the alumina content increases in the nanocomposite, the adsorption capacity of lead increases which was 63.72% for the nanocomposite containing 80% alumina. X-ray diffractometry and scanning electron microscopy were applied to characterize the powders and the samples after the adsorption reaction.