Korean Journal of Chemical Engineering (v.31, #4)
Lithographically patterned micro-/nanostructures via colloidal lithography by Jin Young Park (541-547).
Colloidal lithography is an effective and facile strategy for highly ordered nanostructure arrays that is a simple, inexpensive, and high-throughput process with a broad choice of materials in manufacturing various lithographically patterned nanostructures on substrates. To develop such nanostructured systems, various nanofabrication techniques are employed on two-dimensional (2D) colloidal masks for evaporation, electrochemical deposition, etching, dewetting and mask replication. Ordered nanostructures associated with feature shapes and sizes can be diversified through a choice of methodology and a control of experimental conditions. This review presents an overview of colloidal crystals as a mask and nanostructure arrays (nanopillars, nanoring, nanopores) fabricated by colloidal lithography as well as introducing practical applications using ordered nanostructures.
Keywords: Colloidal Crystal; Colloidal Lithography; Nanostructure; Nanopillar; Nanopore
Green synthesis of silver nanoparticles using plant extracts by Mansour Ghaffari-Moghaddam; Robabeh Hadi-Dabanlou; Mostafa Khajeh; Mansoureh Rakhshanipour; Kamyar Shameli (548-557).
The strategy for design of new nanometals was developed due to their wide applications in many fields. One of the most important nanometals is silver nanoparticles (AgNPs) because of their extensive applications in biotechnology and biomedical fields. AgNPs were usually synthesized by using chemical and physical methods. In the chemical methods, various toxic chemicals are used, which are harmful to the health of living organisms. Therefore, the AgNPs were synthesized by using biological methods based on green chemistry for reducing the toxic chemicals. There are various resources for green synthesis of AgNPs, such as bacteria, fungi, enzyme and plant extracts. The green synthesis of AgNPs involves three main steps: the selection of the solvent medium, the selection of environmentally reducing agents, and the selection of non-toxic substances for the stability of AgNPs. The biosynthesis of AgNPs using plant extracts is more favorable than other biological methods because of removing the elaborate process of maintaining cell cultures. It can be also suitably scaled up for large scale production of AgNPs. This review focuses on green synthesis of AgNPs using various plant extracts.
Keywords: Nanometals; Silver Nanoparticles; Plant Extracts; Biosynthesis; Green Synthesis
Simultaneous optimization of water and heat exchange networks by Zhiyou Chen; Yanlong Hou; Xiaoduan Li; Jingtao Wang (558-567).
This paper focuses on the simultaneous optimization of the heat-integrated water allocation networks. A mathematic model is established to illustrate the modified state-space representation of this problem. An easy logical method is employed to help identify the streams of hot or cold ones. In this model, the water exchange networks (WEN), heat exchange networks (HEN), and the interactions between the WEN and HEN combine together as one unity. Thus, the whole network can be solved at one time, which enhances the possibility to get a global optimal result. Examples from the literature and a PVC plant are analyzed to illustrate the accuracy and applicability of this method.
Keywords: Optimization; Chemical Processes; Mathematical Modeling; Heat-integrated Water Allocation Networks; Statespace Representation
Polymer induced turbulent drag reduction using pressure and gravity-driven methods by Inkollu Sreedhar; Gautam Jain; Patibandla Srinivas; Kuppireddy Suresh Kumar Reddy (568-573).
Drag reduction using polymer additives has been industrially important for enhancing the flow rates and hence the power consumption. In this study, various polymers like PEG, PAM, HPMC were employed with solvents like water and lubricating oil for drag reduction using gravity and pressure driven methods. The optimum set of parameters for maximum drag reduction—polymer concentration, nature of polymer, polymer combinations, exit pipe diameter, solvent-polymer combinations, experimental methodology—were obtained and then the results validated with well known concepts like the Toms effect and Virk's maximum drag reduction asymptote.
Keywords: Drag Reduction; HPMC; PAM; PEG; Pipe Friction Apparatus; Gravity-driven Method
Gas holdup in tapered bubble column using pseudoplastic non-Newtonian liquids by Sumit Kumar Jana; Asit Baran Biswas; Sudip Kumar Das (574-581).
Experimental studies on the gas holdup in two tapered bubble columns using non-Newtonian pseudoplastic liquid have been reported. The effects of different variables such as gas flow rate, liquid viscosity, bed height, and orifice diameter of sieve plate on gas holdup have been investigated. An empirical correlation has been developed for the prediction of the gas holdup as a function of various measurable parameters of the system. The correlation is statistically acceptable.
Keywords: Bubble Columns; Non-Newtonian Liquid; Pseudoplastic Liquid; Gas Hold-up
Characterization and activity of V2O5/CeO2-MgO catalyst in the dehydrogenation of ethylbenzene to styrene by Van-Khoa Nguyen; Jung-Hyun Park; Chae-Ho Shin (582-586).
Supported vanadia catalyst was impregnated on CeO2-MgO and characterized by N2 adsorption, XRD, XPS, TPR and solid NMR. The vanadia species dispersed well on the support surface with vanadia content up to 10 wt%. At higher vanadia content, the non-active Mg3(VO4)2 was formed. Vanadium oxides existing on the support surface as tetrahedral vanadium were observed. An ethylbenzene conversion of 43% and styrene selectivity of 91% were obtained with the 10V2O5/CeO2-MgO catalyst.
Keywords: Ethylbenzene; Dehydrogenation; Vanadia; Ceria; Magnesia
Photocatalytic degradation of dye by Ag/ZnO prepared by reduction of Tollen’s reagent and the ecotoxicity of degraded products by Boonya Thongrom; Pongsaton Amornpitoksuk; Sumetha Suwanboon; Jonas Baltrusaitis (587-592).
A heterostructure of Ag/ZnO powder was prepared by a reduction of Ag(NH3) 2 + ions in a basic solution or Tollen’s reagent. From this method, the existence of a metallic Ag coating on the ZnO surface was confirmed by transmission electron microscope and x-ray photoelectron spectroscopy. The photocatalytic activity of the Ag/ZnO powders was investigated by analyzing the degradation of an aqueous methylene blue solution under a blacklight irradiation. Furthermore, the parameters, including Ag content, catalyst loading, initial dye concentration and pH, were also studied. After the methylene blue solution was irradiated for 30min under a blacklight illumination, total mineralization was not observed as the presence of some carbon compound species was indicated in a mass spectrum. Furthermore, the toxicity of the treated methylene blue solution produced by the Ag/ZnO powders was also investigated by a test for the inhibition of the growth of Chlorella vulgaris.
Keywords: Ag/ZnO; Photocatalyst; Tollen’s Reagent; Chlorella vulgaris
Selective hydrogenation of furfural to cyclopentanone over Cu-Ni-Al hydrotalcite-based catalysts by Hongyan Zhu; Minghao Zhou; Zuo Zeng; Guomin Xiao; Rui Xiao (593-597).
A series of Cu-Ni-Al hydrotalcites derived oxides with a (Cu+Ni)/Al mole ratio of 3 with varied Cu/Ni mole ratio (from 0.017 to 0.5, with a Cu ratio of 0.0125 to 0.25) were prepared by co-precipitation method, then applied to the hydrogenation of furfural in aqueous. Their catalytic performance for liquid phase hydrogenation of furfural to prepare cyclopentanone was described in detail, considering reaction temperature, catalyst composition, reaction time and so on. The yield of cyclopentanone was influenced by the mole ratio of Cu-Ni-Al based heterogeneous catalyst and depended on the reaction conditions. The yield of cyclopentanone was up to 95.8% when the reaction was carried out under 413 K with H2 pressure of 40 bar for 8 h. The catalysts were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and H2 temperature-programmed reduction (H2-TPR).
Keywords: Hydrotalcite-based Catalyst; Furfural; Cyclopentanone; Hydrogenation
Water droplet dynamic behavior during removal from a proton exchange membrane fuel cell gas diffusion layer by Lattice-Boltzmann method by Golamreza Molaeimanesh; Mohammad Hadi Akbari (598-610).
A major challenge in the application of proton exchange membrane fuel cells (PEMFCs) is water management, with the flooding of electrodes as the main issue. The Lattice-Boltzmann method (LBM) is a relatively new technique that is superior in modeling the dynamic interface of multiphase fluid flow in complex microstructures such as non-homogeneous and anisotropic porous media of PEMFC electrodes. In this study, the dynamic behavior of a water droplet during removal from gas diffusion layer (GDL) of a PEMFC electrode with interdigitated flow field is simulated using LBM. The effects of GDL wettability and its spanwise and transverse gradients on the removal process are investigated. The results demonstrate great influence of wettability and its spanwise and transverse gradients on the dynamic behavior of droplets during the removal process. Although increasing the hydrophobicity of GDL results in better droplet removal, its increase beyond a critical value does not show a significant effect.
Keywords: Multiphase Flow; Water Droplet; Proton Exchange Membrane Fuel Cell; Lattice-Boltzmann Method; GDL Microstructure
Performance evaluation of a full-scale advanced phase isolation ditch process by using real-time control strategies by Hyosoo Kim; Yejin Kim; Minsoo Kim; Wenhua Piao; Jeasung Gee; Changwon Kim (611-618).
This paper proposes real-time control strategies that can be applied in a full-scale advanced phase isolation ditch (APID) process. Real-time operation mode control (OMC) and aeration section control (ASC) strategies were developed to cope more stably with fluctuations in the influent loading and to increase the nitrification and denitrification reactions within the entire volume. The real-time OMC and ASC strategies were evaluated using mathematical models. When the NH4-N in the reactor was maintained at a high level, appropriate control actions, such as continuing the aeration state, stopping the influent inflow and increasing the aeration section, were applied in the APID process. In contrast, when the NO X -N in the reactor was maintained at a high level, the non-aeration state, influent inflow, and decreased aeration section were continued. It was concluded that stable operation in the APID process could be achieved by applying real-time OMC and ASC strategies developed in this study.
Keywords: APID Process; Real-time Operation Mode Control; Real-time Aeration Section Control; Setpoint Graph; Mathematical Model
Enhanced anaerobic digestion of livestock waste by ultrasonication: A tool for ammonia removal and solubilization by Si-Kyung Cho; Mo-Kwon Lee; Dong-Hoon Kim; Yeo-Myeong Yun; Kyung-Won Jung; Hang-Sik Shin; Sae-Eun Oh (619-623).
Ultrasonication was applied to lower the ammonia level in livestock waste to enhance the anaerobic digestion performance. In simulated waste tests, in spite of an identical temperature increase, a higher ammonia removal rate was observed at lower frequency. This could be explained by the existence of athermal effects, accounting for 64% of the total ammonia removal rate. These effects originated from various convections (micro-streaming, micro-convection, shock-waves, and micro-jets), possibly caused by stable bubbles, and this indigenous mixing ability led to a negligible effect of aeration in the ultrasound assisted ammonia stripping process. In actual waste tests, an ammonia removal rate of up to 55% was achieved with a 0.77 h−1 mass transfer rate coefficient. After ultrasonication (28 kHz, pH 11, 15 min) of livestock waste, 58% higher CH4 yield was achieved due to the decrease of ammonia concentration (28%) and enhanced solubilization (51%).
Keywords: Ammonia Inhibition; Ultrasonication; Stable Bubble; Livestock Wastewater; Anaerobic Digestion
Characteristics of pellet-type adsorbents prepared from water treatment sludge and their effect on trimethylamine removal by Junghyun Bae; Nayoung Park; Goun Kim; Choul Ho Lee; Young-Kwon Park; Jong-Ki Jeon (624-629).
We optimized the preparation method of pellet-type adsorbents based on alum sludge with the aim of developing a high-performance material for the adsorption of gaseous trimethylamine. Effects of calcination temperature on physical and chemical properties of pellet-type adsorbents were investigated. The porous structure and surface characteristics of the adsorbents were studied using N2 adsorption and desorption isotherms, scanning electron microscope, X-ray diffraction, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The adsorbents obtained from the water treatment sludge are microporous materials with well-developed mesoporosity. The pellet-type adsorbent calcined at 500 °C had the highest percentage of micropore volume and the smallest average pore diameter. The highest adsorption capacity in trimethylamine removal attained over the pellet-type adsorbent calcined at 500 °C can be attributed to the highest number of acid sites as well as the well-developed microporosity.
Keywords: Pellet-type Adsorbent; Water Treatment Sludge; Microporous Material; Acidity; Trimethylamine
Reductive removal of hexavalent chromium from aqueous solution using sepiolite-stabilized zero-valent iron nanoparticles: Process optimization and kinetic studies by Amirhosein Ramazanpour Esfahani; Saeid Hojati; Amin Azimi; Leila Alidokht; Alireza Khataee; Meysam Farzadian (630-638).
We studied the optimization of hexavalent chromium (Cr(VI)) removal from aqueous solution using the synthesized zero-valent iron nanoparticles stabilized with sepiolite clay (S-ZVIN), under various parameters such as reaction time (min), initial solution pH and concentration of S-ZVIN (g·L−1) using response surface methodology (RSM). The kinetic study of Cr(VI) was conducted using three types of the most commonly used kinetic models including pseudo zero-order, pseudo first-order, and pseudo second-order models. The rate of reduction reaction showed the best fit with the pseudo first-order kinetic model. The process optimization results revealed a high agreement between the experimental and the predicted data (R2=0.945, Adj-R2=0.890). The results of statistical analyses showed that reaction time was the most impressive factor influencing the efficiency of removal process. The optimum conditions for maximum response (98.15%) were achieved at the initial pH of 4.7, S-ZVIN concentration of 1.3 g·L−1 and the reaction time of 75 min.
Keywords: Zero-valent Iron; Sepiolite; Hexavalent Chromium; Response Surface Methodology; Central Composite Design
Synthesis and characterization of Co and Mn doped NiO nanoparticles by Kaliyan Vallalperuman; Mathivanan Parthibavarman; Sekar Sathishkumar; Manickam Durairaj; Kuppusamy Thavamani (639-643).
Diluted magnetic semiconductors (DMS) are intensively studied for their potential spintronics applications, especially those with Curie temperature above the room temperature. Ni1−x Mn x O and Ni1−x Co x O (x=1% & 2%), nanoparticles with size around 40–50 nm, were prepared by co-precipitation method. An NiO single phase structure was confirmed by powder X-ray diffraction measurements. Also, diffraction peaks show a systematic shift towards higher angle with an increase in Mn concentration, which is associated with the lattice variation. The samples were pelleted and examined for its magnetic property using a vibrating sample magnetometer (VSM); it indicates paramagnetic-like behavior at room temperature. The increase in a.c conductivity with increasing temperature is attributed to the increase in drift mobility of the charge carriers.
Keywords: Diluted Magnetic Semiconductors; Nanocrystalline; Crystal Structure; Vibrating Sample Magnetometer
Synthesis and characterization of polyurethane/bentonite nanoclay based nanocomposites using toluene diisocyanate by Muhammad Fiayyaz; Khalid Mahmood Zia; Mohammad Zuber; Tahir Jamil; Muhammad Kaleem Khosa; Muhammad Asghar Jamal (644-649).
Polyurethanes (PUs) prepolymers blended with bentonite nanoclay and without bentonite nanoclay were prepared by the reaction of toluene-2,4-diisocyanate (TDI) and hydroxyl terminated polybutadiene (HTPB), and the chain was further extended with 1,4-butane diol (1,4-BDO) to get final polyurethane nanocomposites (PUNC). A mixture of polymer and bentonite clay enriched in montmorillonite (MMT) was formed in solution polymerization, in which MMT dispersed depending on interaction of MMT with polymer chains. The molecular structure of the monomers and the prepared PU nanocomposites was confirmed by FTIR. A series of PUNCs were prepared by varying the percent compositions of bentonite nanoclay into the PU matrix. The existence of the clay in to the PU was confirmed by scanning electron microscope (SEM). SEM images verified the good dispersion of the bentonite nanoclay in PU matrix.
Keywords: Polyurethane; Nanocomposites; Bentonite Clay; FTIR; SEM
Oxygen transfer to cassava starch solutions in an aerated, well-mixed bioreactor: Experimental and mass transfer studies by Agus Saptoro; Morgan Ting Hock Herng; Emily Liew Wan Teng (650-658).
Experimental and mass transfer studies of oxygen transfer to cassava starch solution in an aerated, well-mixed bioreactor of 2 L have been carried out. The volumetric mass transfer coefficient was estimated and parametric studies were performed to study the effect of process variables of stirring rate, aeration rate, concentration of starch and temperature on the volumetric mass transfer coefficient. From the experimental results, it is evident that the first two and the last variables are directly proportional to the volumetric mass transfer coefficient. However, the volumetric mass transfer coefficient is inversely proportional to the concentration of the starch. Also, the saturation dissolved oxygen concentration is greatly affected by temperature and starch solution concentration. Whereas, stirring and aeration rates have neutral impacts on saturation dissolved oxygen concentration. Simulated data generated from obtained volumetric mass transfer coefficient agrees well with the experimental data, which indicates the accuracy of the coefficient.
Keywords: Bioreactor; Cassava Starch; Mass Transfer Studies; Volumetric Mass Transfer Coefficient
Synthesis, characterization and evaluation of antioxidant and anticancer activities of novel benzisoxazole-substituted-allyl derivatives by Mohanam Anand; Vaithialingam Selvaraj; Muthukaruppan Alagar (659-663).
A novel series of various 2-allylbenzo[d]isoxazol-3(2H)-ones were synthesized using benzo[d]isoxazol-3(2H)-one treated with different allyl bromides/chlorides in the presence of water-mediated cesium carbonate as a new catalyst 3(a-h). The structures of the newly synthesized Benzisoxazole-substituted-allyl derivatives were characterized by spectroscopic methods and mass spectrometry. These synthesized compounds were evaluated for their in vitro antioxidant and anticancer activity. Compounds 3b, d, f, h were identified as the best hit against HT-29 Human colon cancer cells. Similarly, compounds like 3b, d, f, h showed significant antioxidant activity compared to the standard drug butylated hydroxy toluene (BHT).
Keywords: 2-Allylbenzo[d]isoxazol-3(2H)-ones ; Antioxidant Activity; Anticancer Activity
Polyelectrolyte complexes of chitosan self-assembled with fucoidan: An optimum condition to prepare their nanoparticles and their characteristics by Eun Ju Lee; Kwang-Hee Lim (664-675).
The preparation conditions for both a high yield without aggregation and a small mean-size of chitosanfucoidan nanoparticles were sought by a screening method, i.e., discarding the ones satisfying neither of both to prepare them by polyelectrolyte complexation with chitosan and fucoidan. The effect of the pH level of chitosan solution and the chitosan-fucoidan mass ratio was investigated on the following aspects: the turbidity and aggregation pattern of suspension, the yield of dried mass, electrostatic interaction, fucoidan loading efficiency, the particle size distribution and the morphology of the polyelectrolyte complex prepared by polyelectrolyte complexation between chitosan and fucoidan. The mean size of prepared nanoparticle ranges between 365-900 nm. The nanoparticles tended to grow as the pH of chitosan was increased up to 3.69, after which they became smaller. This pattern of growth is prominent as the mass ratio of chitosan and fucoidan decrease. The conditions of pH 5 and 1: 1 chitosan-fucoidan mass ratio were suggested as ad hoc optimum conditions by the screening method to prepare chitosan-fucoidan nanoparticles for high yield, small size and good suspension stability. They were almost consistent with the optimum conditions for the maximum value of chitosan-fucoidan nanoparticles prepared per unit input mass, which were analyzed by response surface methodology (RSM).
Keywords: Nanoparticle; Optimum Condition; Polyelectrolyte Complexation; Chitosan; Fucoidan
Comparison between conventional and ultrasound-assisted extractions of natural antioxidants from walnut green husk by Reza Tabaraki; Shahrbanoo Rastgoo (676-683).
Agricultural industries produce substantial quantities of phenolic-rich by-products, which have gained much attention due to their antioxidant properties. Ultrasonic technology was applied for extraction of antioxidants from the walnut green husk using ethanol as a food grade solvent. Response surface methodology (RSM) was used to optimize experimental conditions. The responses were total phenolic content (TPC), ferric reducing antioxidant power (FRAP), scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and yield. TPC varied from 6.28 to 7.23mg GA g−1 dry sample. FRAP and DPPH values varied from 0.33 to 0.46 mmol Fe2+ g−1 of dry sample and 33.98% to 56.31% inhibition, respectively. Extraction yields ranged from 33.04% to 38.72%. The optimal conditions were 60% ethanolwater mixture as solvent, temperature of 60 °C and extraction time of 30 min. Comparison of ultrasonic-assisted extraction (UAE) and conventional extraction was shown that TPC, FRAP, DPPH and yield obtained by UAE during 30 min were significantly higher than by conventional extraction during 16 hours. The extract can be used as substitute of synthetic antioxidants for food products, color and oxidative stabilization.
Keywords: Ultrasonic; Antioxidants; Walnut Green Husk; Response Surface Methodology
Modeling and simulation of breakthrough curves during purification of two chitosanases from Metarhizium anisopliae using ion-exchange with expanded bed adsorption chromatography by Sergio Carvalho de Santana; Raimundo Cosme da Silva Filho; Jorge dos Santos Cavalcanti; Jackson Araujo de Oliveira; Gorete Ribeiro de Macedo; Francine Ferreira Padilha; Everaldo Silvino dos Santos (684-691).
A mathematical model was developed to predict breakthrough curves during purification of the two chitosanases from Metarhizium anisopliae by expanded bed adsorption, taking into account the axial dispersion of liquid and using Streamline DEAE and SP XL adsorbents, anion and cation exchange resins, respectively. All the experiments were performed without clarification (with cells) aiming at the reduction of unit operations in future projects of separation processes, thereby reducing capital and operating costs. Chitosanases are enzymes that hydrolyze the carbohydrate chitosan, resulting in oligosaccharides that have many remarkable biological activities, such as anti-cancer, anti-HIV and antioxidant activities. The two adsorbents had similar performance in relation to hydrodynamics and mass transfer. The results of the parametric sensitivity analysis agree with the literature, and the model was validated with an average high degree of fit (94.68%) between simulated and experimental data obtained in this work.
Keywords: Modeling; Expanded Bed Adsorption; Purification; Chitosanase; Metarhizium anisopliae
Optimization of parameters for competitive adsorption of heavy metal ions (Pb+2, Ni+2, Cd+2) onto activated carbon by Mohammad Kavand; Tahereh Kaghazchi; Mansooreh Soleimani (692-700).
This study investigates optimization of various competitive adsorption parameters for removal of Cd(II), Ni(II) and Pb(II) from aqueous solutions by commercial activated carbon (AC) using the Taguchi method. Adsorption parameters such as initial metal concentration of each metal ion (C0,i ), initial pH (pH0), adsorbent dosage (m) and contact time (t) in batch technique were studied to observe their effects on the total adsorption capacity of metals onto activated carbon (q tot ). The adsorbent dosage has been found to be the most significant parameter. Interactions between C0,Cd ×C0,Ni , C0,Cd ×C0,Pb and C0,Ni ×C0,Pb have been considered for simultaneous metal ions adsorption. The optimum condition for adsorption of metal ions were obtained with C0,i =100 mg L−1, pH0=7, m=2 g L−1 and t=80 min. Finally, experimental results showed that a multi-staged adsorptive treatment would be necessary to reach the minimal discharge standards of metal ions in the effluent.
Keywords: Heavy Metals; Competitive Adsorption; Activated Carbon; Multi-component
CO2 absorption characteristics of a jet loop reactor with a two-fluid swirl nozzle in an alkaline solution by Go-Eun Cha; Ho-Jin Sung; Jun-Heok Lim; Tae-Yoon Lee; Jea-Keun Lee (701-705).
To investigate the performance of a jet loop reactor with the two-fluid swirl nozzle (TSN), CO2 absorption experiments in an alkaline solution were performed. The experimental results obtained in the reactor were compared with those in a jet loop reactor with the two-fluid conventional nozzle (TCN). The neutralization time of alkaline solution and the CO2 removal efficiency were used as the indices for a comparison of the reactor performance. Due to the swirling flow, the neutralization times of alkaline solutions by CO2 in the reactor with the TSN were shortened compared with those in the reactor with the TCN. Also, the instantaneous and/or overall CO2 removal efficiencies in the reactor with the TSN were higher than those in the reactor with the TCN at the same liquid circulation flow rate.
Keywords: Jet Loop Reactor; Two-fluid Swirl Nozzle; CO2 Absorption; Neutralization Time; CO2 Removal Efficiency
Leaching kinetics of neodymium in sulfuric acid from E-scrap of NdFeB permanent magnet by Ho-Sung Yoon; Chul-Joo Kim; Kyeong Woo Chung; Su-Jeong Lee; A-Ram Joe; Yang-Ho Shin; Se-Il Lee; Seung-Joon Yoo; Jin-Geol Kim (706-711).
The leaching kinetics of neodymium in NdFeB permanent magnet powder was analyzed for the purpose of recovery of neodymium in sulfuric acid (H2SO4) from E-scrap (electric scrap) of NdFeB permanent magnet powder treated by oxidation roasting to form a reactant. The reaction was conducted with H2SO4 concentrations ranging from 2.5 to 3.5M, a pulp density of 110.8 g/L, an agitation speed of 750 rpm, and a temperature range of 30 to 70 °C. After 4 h of leaching, the neodymium content in the E-scrap powders was completely converted into a neodymium sulfate (Nd2(SO4)3) solution phase in H2SO4 in the condition of 70 °C and 3.0M H2SO4. Based on a shrinking core model with sphere shape, the leaching mechanism of neodymium was determined by the rate-determining step of the ash layer diffusion. Generally, the solubility of pure rare earth elements in H2SO4 is decreased with an increase in leaching temperatures. However, the leaching rate of the neodymium in E-scrap powders increased with the leaching temperatures in this study because the ash layer included in the E-scrap powder provided resistance against the leaching. Using the Arrhenius expression, the apparent activation energy values were determined to be 2.26 kJmol−1 in 2.5M H2SO4 and 2.77 kJmol−1 in 3.0 M H2SO4.
Keywords: NdFeB Permanent Magnet; Leaching; E-scrap; Neodymium Sulfate; Ash Layer Diffusion
Supercapacitive behavior of mesoporous carbon CMK-3 in calcium nitrate aqueous electrolyte by Heming Luo; Liwen Zheng; Longyan Lei; Deyi Zhang; Jingxiang Wu; Jian Yang (712-718).
Calcium nitrate Ca(NO3)2 aqueous solution was found to be an effective aqueous electrolyte for a supercapacitor using ordered mesoporous carbon as the electrode materials. The supercapacitive behavior of ordered mesoporous carbon CMK-3 electrode in Ca(NO3)2 aqueous electrolyte was investigated utilizing cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge measurements. CMK-3 electrode shows excellent supercapacitive behavior with wide voltage window, high specific gravimetric capacitance and satisfactory electrochemical stability in Ca(NO3)2 aqueous electrolyte. The specific gravimetric capacitance of CMK-3 electrode in Ca(NO3)2 aqueous electrolyte reaches 210 F g−1 at a current density of 1 A g−1, which is higher than that in conventional aqueous electrolytes NaNO3 and KOH solution about 40% and 54%, respectively. The high charge density of the electric double layer formed at the interface of the CMK-3 electrode and Ca(NO3)2 aqueous electrolyte and the pseudo-capacitive effect originating from the oxygen groups on the surface of CMK-3 were believed to respond for the excellent supercapacitive behavior of CMK-3 electrode in Ca(NO3)2 aqueous electrolyte.
Keywords: Mesoporous Carbon; Ca(NO3)2 ; Aqueous Electrolytes; Supercapacitive Behavior
Effects of solvent properties on cationic dyeing process of acrylic yarn by Zhengyu Zhang; Ailing Yuan; Haibo Wang; Ling Zhu; Hong Xu; Chunling Zheng (719-723).
Cationic dye is a special dye for acrylics, but it is very difficult in dyeing through the core. In practice, the price of a special leveling agent for acrylic fiber is high, and uniform staining is poor. By mixing a number of organic solvents in the dye bath, we can improve the structure of fibers and their deep-dyeing. We used n-propanol, isopropanol and benzyl alcohol as organic solvents, by adjusting the pH value and the appropriate temperature, and with special depth and leveling agent for dyeing soaping fastness contrast, to find economically viable process conditions.
Keywords: Acrylic; Soaping Fastness; pH Value