Korean Journal of Chemical Engineering (v.33, #2)
Efficient thermal desalination technologies with renewable energy systems: A state-of-the-art review by Iman Janghorban Esfahani; Jouan Rashidi; Pouya Ifaei; ChangKyoo Yoo (351-387).
Due to the current fossil fuel crisis and associated adverse environmental impacts, renewable energy sources (RES) have drawn interest as alternatives to fossil fuels for powering water desalination systems. Over the last few decades the utility of renewable energy sources such as solar, geothermal, and wind to run desalination processes has been explored. However, the expansion of these technologies to larger scales is hampered by techno-economic and thermo-economic challenges. This paper reviews the state-of-the-art in the field of renewable energy-powered thermal desalination systems (RE-PTD) to compare their productivity and efficiency through thermodynamic, economic, and environmental analyses. We performed a comparative study using published data to classify RE-PTD systems technologies on the basis of the energy collection systems that they use. Among RE-PTD systems, solar energy powered-thermal desalination systems demonstrate high thermo-environ-economic efficiency to produce fresh water to meet various scales of demand.
Keywords: Renewable Energy; Desalination; Thermo-economic; Energy; Exergy
Recent trends in environmentally friendly water-borne polyurethane coatings: A review by Aqdas Noreen; Khalid Mahmood Zia; Mohammad Zuber; Shazia Tabasum; Muhammad Jawwad Saif (388-400).
Environmentally friendly waterborne polyurethane (WPU) coatings are used extensively due to their low VOCs emission than solvent based PU coatings. Additionally, WPU coatings have low temperature flexibility, pH stability, water resistance, superior solvent resistance, outstanding weathering resistance and desirable chemical and mechanical properties. This review provides an overview on the recent developments of WPU coatings and their value added applications in the coatings and paint industry. UV-cured WPU coatings provide an important class of green and ecofriendly coatings with outstanding mechanical properties and rapid curing system. Hyper-branched polyurethanes (PUs) show interesting properties, such as high solubility, reactivity and good rheological behavior owing to multiple end groups, compact molecular structure and diminishing chain entanglement. Inherently, WPU coatings have reduced stiffness and mechanical strength that can be increased by the addition of nanoparticles, like Ag, Cu, TiO2, SiO2 and many more. Fire retardants, commonly phosphorous, are incorporated in the WPU structure to increase the flame retardancy of WPU coatings.
Keywords: WPU; Eco-friendly Coatings; UV-WPU; Hyperbranched; Flame Retardant
Facile route to multi-walled carbon nanotubes under ambient conditions by Hyunchul Ha; Soo-Hwan Jeong (401-404).
A facile and practical route is demonstrated to prepare multi-walled carbon nanotubes (MWCNTs) by a sonochemical method. By applying ultrasonic irradiation to the mixture of ferrocene and xylene with small amount of water, crystalline MWCNTs were selectively synthesized under ambient conditions, allowing MWCNTs with diameter of 25-40 nm to be obtained. A control experiment revealed that a small amount of water was essential for producing MWCNTs. The analysis of Raman spectra of MWCNTs showed that the intensity of the D-band relative to the G-band was 0.98, indicating relatively good crystallinity of these MWCNTs. This result was consistent with that of TEM observation.
Keywords: Sonochemical; Multi-walled Carbon Nanotubes; Ferrocene; Ambient Conditions; Carbon-based Nanomaterials
A design procedure for heat-integrated distillation column sequencing of natural gas liquid fractionation processes by Hanareum Yoo; Michael Binns; Mun-Gi Jang; Habin Cho; Jin-Kuk Kim (405-415).
The separation of NGL (natural gas liquids) in gas processing is energy-intensive, requiring systematic process design and optimization to reduce energy consumption and to identify cost-effective solutions for the recovery valuable hydrocarbons. As NGL fractionation processes require a sequence of distillation columns to separate multi-component mixtures the determination of optimal energy-efficient distillation sequences and operating conditions is not a simple task. A design methodology is proposed in this study in which the process simulator Aspen HYSYS® is linked with an optimization algorithm available in MATLAB®. The proposed methodology involves a procedure where in the first step possible distillation sequences are screened using a short-cut distillation column model. In the second step a few selected and promising candidate distillation sequences are further simulated and optimized, again using the same short-cut model. Finally, rigorous simulations are used to validate and confirm the feasibility of the optimal designs. A case study is presented to demonstrate the applicability of the proposed design framework for the design and optimization of NGL fractionation processes in practice.
Keywords: Distillation Sequencing; Optimization; Energy Recovery; Natural Gas Separation
Globally stable control systems for processes with input multiplicities by Jietae Lee; Thomas F. Edgar (416-422).
A nonlinear process with input multiplicity has two or more input values for a given output at the steady state, and the process steady state gain changes its sign as the operating point changes. A control system with integral action will be unstable when both signs of the process gain and the controller integral gain are different, and its stability region will be limited to the boundary where the process steady state gain is zero. Unlike processes with output multiplicities, feedback controllers cannot be used to correct the sign changes of process gain. To remove such stability limitation, a simple control system with parallel compensator is proposed. The parallel compensator can be easily designed based on the process steady state gain information and tuned in the field. Using the two time scale method, the stability of proposed control systems for processes with input multiplicities can be checked.
Keywords: Input Multiplicity; PI Control; Parallel Compensator; Two Time Scale Analysis; Global Stability
Simultaneous multi-objective optimization of a new promoted ethylene dimerization catalyst using grey relational analysis and entropy measurement by Seyed Hamed Mahdaviani; Matin Parvari; Davood Soudbar (423-437).
A hybrid approach between the Taguchi method and grey relational analysis (GRA) with entropy measurement was applied to determine a single optimum setting for reaction factors of the proposed ethylene dimerization catalyst having overall selectivity to 1-butene (S1-btn (%)) and turnover frequency (TOF (h-1)) as multiple quality characteristics. Titanium tetrabutoxide (Ti(OC4H9)4) catalyst precursor in combination with triethyl aluminum (TEA) activator, 1,4-dioxane as a suitable modifier, and ethylene dichloride (EDC) as a novel promoter were used in the catalysis. Control factors of temperature, pressure, Al/Ti, 1,4-dioxane/Ti, and EDC/Ti mol ratios were investigated on three levels and their main effects were discussed. The effect of the binary interaction between temperature, pressure, and Al/Ti mol ratio was also examined. Weight of the responses was determined using entropy. Analysis of variance (ANOVA) for data obtained from GRA indicated that EDC/Ti mol ratio with 27.64% contribution had the most profound effect on the multiple quality characteristics. Development of the weighted Grey-Taguchi method used the Taguchi method as its basic structure, adopted GRA to deal with multiple responses, and entropy to enhance the reasonability of the comprehensive index produced by GRA to make the results more objective and accurate. Overall, these combined mathematical techniques improved catalytic performance for 1-butene production.
Keywords: Multi-objective Optimization; Grey Relational Analysis; Entropy Measurement; Ethylene Dimerization; EDC
Dynamic modeling of fixed-bed adsorption of flue gas using a variable mass transfer model by Jehun Park; Jae W. Lee (438-447).
This study introduces a dynamic mass transfer model for the fixed-bed adsorption of a flue gas. The derivation of the variable mass transfer coefficient is based on pore diffusion theory and it is a function of effective porosity, temperature, and pressure as well as the adsorbate composition. Adsorption experiments were done at four different pressures (1.8, 5, 10 and 20 bars) and three different temperatures (30, 50 and 70 °C) with zeolite 13X as the adsorbent. To explain the equilibrium adsorption capacity, the Langmuir-Freundlich isotherm model was adopted, and the parameters of the isotherm equation were fitted to the experimental data for a wide range of pressures and temperatures. Then, dynamic simulations were performed using the system equations for material and energy balance with the equilibrium adsorption isotherm data. The optimal mass transfer and heat transfer coefficients were determined after iterative calculations. As a result, the dynamic variable mass transfer model can estimate the adsorption rate for a wide range of concentrations and precisely simulate the fixed-bed adsorption process of a flue gas mixture of carbon dioxide and nitrogen.
Keywords: CO2 Capture; Dynamic Modeling; Fixed Bed Adsorption; Flue Gas; Variable Mass Transfer Coefficient
Flocculation and viscoelastic behavior of industrial papermaking suspensions by Mustafa S. Nasser; Mohammed J. Al-Marri; Abdelbaki Benamor; Sagheer A. Onaizi; Majeda Khraisheh; Mohammed A. Saad (448-455).
The effects of the surface charge type and density C496, C492 and A130LMW polyacrylamides (PAMs) on the rheological behavior of real industrial papermaking suspensions were quantitatively related to the degree of flocculation for the same industrial papermaking suspensions. The floc sizes were larger but less dense when anionic PAM was used, and this due to the repulsive forces between the anionic PAM and colloidal particles, leading to the development of open structure flocs of less density. On the other hand, rheological measurements showed that the papermaking suspension is thixotropic with a measurable yield stress. The results showed that the magnitude of the critical stress, τ c , complex viscosity, η*, elastic modulus, G′, and viscous modulus, G″, depend on the number of interactions between the PAM chains and particle surface and the strength of those interactions. Cationic PAM showed higher values of η*, G′, G″ and τ c compared to anionic PAM. This behavior is in good agreement with Bingham yield stress, τ B , adsorption and effective floc density results. Similar to oscillatory measurements, creep measurements also showed that the deformation was much lower for the cationic PAM based suspensions than for the anionic PAM based suspensions. Furthermore, the results revealed that increasing the cationic PAM surface charge decreases the floc size but increases the adsorption rate, elasticity and effective floc density proposing differences in the floc structures, which are not revealed clearly in the Bingham yield stress measurements.
Keywords: Papermaking Suspensions; Flocculation; Floc Size; Effective Floc Density; Rheology
Graphene-ZnO nanocomposite for highly efficient photocatalytic degradation of methyl orange dye under solar light irradiation by Venkata Ramana Posa; Viswadevarayalu Annavaram; Janardhan Reddy Koduru; Varada Reddy Ammireddy; Adinarayana Reddy Somala (456-464).
A facile synthesis of graphene oxide-zinc oxide nanocomposite (GO-ZnO) was performed by using wet chemical method of graphene oxide and zinc acetate precursors. The nanocomposite was characterized and intercalated with Raman spectroscopy, FE-SEM, TEM, SAED and EDAX. The crystalline nature was studied from P-XRD, and surface area of the sample was analyzed by BET. The chemical composition was explained in the light of XPS phenomenon. The photo electron-excitation (PL) studies were conducted for understanding the photocatalytic mechanism, and photocatalytic degradation of methyl orange was studied by using UV-VIS spectrophotometer. We investigated the photocatalytic activity involving GO-ZnO nanocomposite besides checking the re-stability of the composite. Significant high-performance photocatalytic activity of GO-ZnO nanocomposite was exhibited on methyl orange degradation under solar light.
Keywords: Nanocomposite; ZnO Cubic Voids; Photo Degradation; Methyl Orange Dye; Solar Light Irradiation
Catalytic application of metallic iron from the dyeing sludge ash for benzene steam reforming reaction in tar emitted from biomass gasification by Sung-Bang Nam; Yeong-Su Park; Yong-Sik Yun; Jae-Hoi Gu; Ho-Jin Sung; Masayuki Horio (465-472).
Because it is the most promising method for reforming tar in a gasification system, a catalytic steam reforming reaction of tar using a dyeing sludge ash catalyst that contains mostly iron oxide has been modeled using benzene to investigate whether a steam reforming catalyst produced from waste is viable. The catalytic activity of the ash catalyst is similar to that of the commercially available iron-chrome-based catalyst for the same equivalent total amount of Fe2O3. The activity over the ash catalyst has been examined in terms of the weight hour space velocity (WHSV) and the reaction temperature to develop a model for the reaction kinetics. Using a power law model, the reaction order coefficients of the benzene and steam were estimated to be 0.43 and 0, respectively. The activation energy required for the ash catalyst was approximately 187.6 kJ mol−1. In addition, the reductive properties of the iron oxide in the ash catalyst were also examined via XRD and H2-TPR analyses.
Keywords: Biomass Gasification; Steam Reforming; Catalytic Tar Reduction; Iron Oxide Catalyst; Benzene
High temperature water gas shift reaction over Fe-Cr-Cu nanocatalyst fabricated by a novel method by Seyed Mahdi Latifi; Alireza Salehirad (473-480).
Fe-Cr-Cu nanocatalyst was synthesized through an inorganic-precursor thermolysis approach and exploited for high temperature water gas shift reaction. The results demonstrated that the method used for the nanocatalyst fabrication led to smaller crystallite size (32.9 nm) and higher BET surface area (127.3 m2/g) compared to those of a reference sample (65.5 nm, 78.6 m2/g) prepared by co-precipitation conventional method. Furthermore, the obtained data for catalytic activity showed that the catalyst prepared via inorganic precursor has better activity than the reference sample in all studied temperatures (350-500 °C) and also exhibited higher catalytic activity than a commercial Fe-Cr-Cu catalyst in higher temperatures (more than 450 °C).
Keywords: Water Gas Shift Reaction; Nanocatalyst; Inorganic Precursor; Synthesis; Catalytic Activity
Adsorption and photocatalytic degradation of organic dyes onto crystalline and amorphous hydroxyapatite: Optimization, kinetic and isotherm studies by Solmaz Valizadeh; Mohammad Hossein Rasoulifard; Mir Saeed Seyed Dorraji (481-489).
We evaluated the adsorptive/photodegradation properties of hydroxyapatite. Hydroxyapatite was synthesized by two different precipitation methods and examined for the removal of two kinds of textile dye. The physicochemical properties of the products were characterized using Fourier transform infrared, X-ray diffraction, inductively coupled plasma atomic emission spectroscopy and scanning electron microscopy. The effects of different parameters, including hydroxyapatite synthesis method and removal process type, pH, reaction time, temperature and amount of hydroxyapatite, were investigated and optimized by Taguchi design. The kinetics of adsorption and isotherm studies showed that the pseudo-second-order model and the Freundlich isotherm were the best choices to describe the adsorptive behavior of hydroxyapatite. Photocatalytic degradation of dye followed Langmuir-Hinshelwood mechanism, illustrated a pseudo-first-order kinetic model with the adsorption equilibrium constant and kinetic rate constant of surface reaction equal to 0.011 (l mg-1) and 1.3 (mg l -1 min-1), respectively.
Keywords: Hydroxyapatite; Crystalline; Amorphous; Dye; Adsorption; Photodegradation
CO x -free hydrogen and carbon nanofibers production by methane decomposition over nickel-alumina catalysts by Nima Bayat; Mehran Rezaei; Fereshteh Meshkani (490-499).
Nickel catalysts supported on mesoporous nanocrystalline gamma alumina with various nickel loadings were prepared and employed for thermocatalytic decomposition of methane into CO x -free hydrogen and carbon nanofibers. The prepared catalysts with different nickel contents exhibited mesoporous structure with high surface area in the range of 121.3 to 66.2m2g−1. Increasing in nickel content decreased the pore volume and increased the crystallite size. The catalytic results revealed that the nickel content and operating temperature both play important roles on the catalytic performance of the prepared catalysts. The results showed that increasing in reaction temperature increased the initial conversion of catalysts and significantly decreased the catalyst lifetime. Scanning electron microscopy (SEM) analysis of the spent catalysts evaluated at different temperatures revealed the formation of intertwined carbon filaments. The results showed that increasing in reaction temperature decreased the diameters of nanofibers and increased the formation of encapsulating carbon.
Keywords: Methane Decomposition; Hydrogen; CO x -free; Carbon Nanofibers; Nickel; Alumina
CO hydrogenation to higher alcohols over Ni- and Mo-modified Cu/CeO2 catalyst by Jun Chen; Wei Li; Rongchun Shen (500-506).
Ni-Mo promoted Cu/CeO2 catalyst was synthesized by co-precipitation method using 28%wt NH3·H2O as the precipitant. The catalysts were characterized by BET, XRD, TPR and XPS. The results showed that Ni and Mo could promote the reducibility of Cu, and the interaction between Ni and Mo may be needed for catalytic activity and higher alcohols synthesis. Therefore, CuNiMo/CeO2 catalyst showed a higher activity for higher alcohols synthesis than Cu/CeO2. In the meantime, the effect of pyrogallol used in preparing the CuNiMo/CeO2 catalyst was investigated. Pyrogallol had a significant influence on lowering the methanol selectivity and improving the C2+-OH selectivity. The methanol selectivity decreased from 52.99% to 44.81% and S C2+OH /S MeOH (MeOH denoted as methanol) ratio increased from 0.27 to 0.35. The XPS results gave evidence that pyrogallol can form complexes with Cu+ on the CeO2 support, which causes methanol decrease. In addition, pyrogallol could serve as a “temperature addictive agent” to save power.
Keywords: Co-precipitation; NH3·H2O; Higher Alcohol; Pyrogallol; Temperature Addictive Agent
Oxidation of ash-free coal from sub-bituminous and bituminous coals in a direct carbon fuel cell by Duc-Luong Vu; Choong-Gon Lee (507-513).
The present study proposes the production of ash-free coal (AFC) and its oxidation as a primary fuel in direct carbon fuel cells (DCFCs). The AFC was produced by the extraction of Arutmin sub-bituminous coal (AFC1) and Berau bituminous coal (AFC2) using polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). It was carried out at a temperature of around 202 °C under atmospheric conditions and using a microwave irradiation method. Using NMP as the solvent showed the highest extraction yield, and the values of 23.53% for Arutmin coal and 33.80% for Berau coal were obtained. When NMP was added to DMSO, DMA and DMF, the extraction yield in the solvents was greatly increased. The yield of AFC from a sub-bituminous coal was slightly lower than that from a bituminous coal. The AFC was evaluated in a coin-type DCFC with a mixture of AFC and carbonate electrolyte (3 g/3 g) at 850 °C. The AFC and gaseous H2 fuels were compared using the electrochemical methods of steady-state polarisation and step chronopotentiometry. The DCFC ran successfully with the AFCs at 850 °C. The open-circuit voltages were about 1.35 V (AFC1) and 1.27 V (AFC2), and the voltages at 150 mA cm−2 were 0.61 V (AFC1) and 0.74 V (AFC2).
Keywords: Ash-free Coal; Solvent Extraction; Sub-bituminous Coal; Bituminous Coal; Molten Carbonate; Direct Carbon Fuel Cell
Properties of LiNi0.8Co0.1Mn0.1O2 as a high energy cathode material for lithium-ion batteries by Duc-Luong Vu; Jae-won Lee (514-526).
Nickel-rich layered materials are prospective cathode materials for use in lithium-ion batteries due to their higher capacity and lower cost relative to LiCoO2. In this work, spherical Ni0.8Co0.1Mn0.1(OH)2 precursors are successfully synthesized through a co-precipitation method. The synthetic conditions of the precursors - including the pH, stirring speed, molar ratio of NH4OH to transition metals and reaction temperature - are investigated in detail, and their variations have significant effects on the morphology, microstructure and tap-density of the prepared Ni0.8Co0.1Mn0.1 (OH)2 precursors. LiNi0.8Co0.1Mn0.1O2 is then prepared from these precursors through a reaction with 5% excess LiOH· H2O at various temperatures. The crystal structure, morphology and electrochemical properties of the Ni0.8Co0.1Mn0.1 (OH)2 precursors and LiNi0.8Co0.1Mn0.1O2 were investigated. In the voltage range from 3.0 to 4.3 V, LiNi0.8Co0.1Mn0.1O2 exhibits an initial discharge capacity of 193.0mAh g-1 at a 0.1 C-rate. The cathode delivers an initial capacity of 170.4 mAh g-1 at a 1 C-rate, and it retains 90.4% of its capacity after 100 cycles.
Keywords: Lithium-ion Battery; Cathode Material; LiNi0.8Co0.1Mn0.1O2 ; Co-precipitation; Electrochemical Properties
Energy efficiency of a scaled-up microwave-assisted transesterification for biodiesel production by Daeho Kim; Seung Kwon Seol; Won Suk Chang (527-531).
We propose a scalable and energy-efficient microwave-assisted chemical reactor for biodiesel production, which is composed of a partially modified conventional 10-L stainless steel vessel and a microwave coupler to enable an optimized microwave injection of 99% power efficiency. The microwave power applied via a waveguide can be directly injected into the reaction vessel using a coupling rod clamped to a pressured microwave window, giving convenience of scale-up of the reactor volume because a conventional microwave transparent vessel like glass is not need. Microwave-assisted transesterification of triglycerides with potassium hydroxide catalyst achieved an accelerated conversion of 95% in 5 min. The precisely measured microwave energy consumption was only 87% of the calculated heat requirement for both the reactant and the vessel. Computer simulation studies indicated that the cause of the energy efficiency for microwave heating was the relatively low temperature of the vessel due to a reverse temperature gradient, in contrast to those done with conventional hot wall heating.
Keywords: Microwave; Scale-up; Energy Efficiency; Transesterification; Microwave Coupler
Degradation of azo dye C.I. Acid Red 18 using an eco-friendly and continuous electrochemical process by Ali Reza Rahmani; Kazem Godini; Davood Nematollahi; Ghasem Azarian; Sima Maleki (532-538).
Continuous anodic oxidation of azo dye C.I. Acid Red 18 by using PbO2 electrode in aqueous solution was studied. To reach the best conditions of the process, the influence of various operating parameters such as pH, current density, hydraulic retention time (HRT) and dye concentration on the removal rate of chemical oxygen demand (COD) and color, as indexes showing the amount of efficiency, was investigated. The findings showed that, respectively, 99.9% and 80.0% of the dye and COD were removed (at optimized conditions). Mineralization current efficiency results indicated that at the beginning of the reaction mineralization occurred quickly at a low current density, whereas at high amounts the rate of mineralization the efficiency decreased. At the optimum conditions, the majority of COD was removed only with 38.2 kWh/kg COD of energy consumption in 120 min. By controlling HO•/dye concentration ratio via the parameters adjustment, particularly HRT and current density, this system can treat Acid Red 18 well even at high concentrations. Furthermore, the voltammetry study illustrated that electroactive intermediates created during the process were mineralized at current density of 8.6mA/cm2.
Keywords: Azo dye Acid Red 18; Anodic Oxidation; Constant Current Electrolysis; Wastewater Treatment
Photocatalytic degradation of azo dye using nano-ZrO2/UV/Persulfate: Response surface modeling and optimization by Mahsa Moradi; Farshid Ghanbari; Mohammad Manshouri; Kambiz Ahmadi Angali (539-546).
Dyes have always been considered in the context of recalcitrant organic pollutants in water. The present research has focused on the decolorization of Direct Blue 71 (DB71) using photocatalysis process of nano-ZrO2/UV/ Persulfate. Response surface method with central composite design was applied to determine the effects of four main factors (time, ZrO2 dosage, persulfate dosage and pH) on decolorization of DB71. The results indicated that the obtained quadratic model had a high R-squared coefficient based on the analysis of variance (ANOVA). Time had the highest effect (45.5%) on decolorization of DB71. The optimum condition predicted for complete decolorization was pH=7, 0.4 g ZrO2, 0.75 mM persulfate and 40 min reaction time. Verification experiments confirmed that there was good agreement between the experimental and predicted responses. The studied photocatalytic process could oxidize and destruct the structure of the DB71, and average oxidation state (AOS) significantly increased from −1.5 to +1.33, indicating the presence of more oxidized by-products and, consequently, improvement of biodegradability. The quenching tests showed that sulfate radical was the major agent in DB71 decolorization. It can be concluded that nano-ZrO2/ UV/Persulfate is a very effective process for decolorization of colored wastewater.
Keywords: Nano-ZrO2 ; Synthetic Dye; Sulfate Radical; Response Surface Method
Enhanced electrokinetic remediation of fluorine-contaminated soil by applying an ammonia continuous circulation system by Shufa Zhu; Ming Zhou; Shuangyan Zhang (547-552).
The objective of this research was to investigate the effects of ammonia continuous circulation enhanced electrokinetic remediation of fluorine contaminated soil and to analyze its influence on soil pH after remediation. An experimental study was carried out in self-made electrokinetic apparatus. The voltage gradient was set at 1.0V/cm and ammonia water with different concentrations was used as electrolyte which circulated in series. Comparative studies were made by using deionized water as electrolyte which circulated separately in one experiment and continuously in another. According to the experiment the continuous circulation of ammonia water increased the current value during the remediation process and maintained current through the soil cell stabler, which not only increased fluorine migration but also reduced energy consumption. Among the given ammonia concentrations (0, 0.01, 0.1 and 0.2mol/L) the removal rate increased with ammonia concentration. 0.2mol/L had the highest current (26.8mA), and the removal rate amounted up to 57.3%. By using ammonia circulation enhanced electrokinetic technology, the difference between pH values of cathode soil and anode soil became smaller. Ammonia continuous circulation enhanced electrokinetics can effectively remediate fluorine contaminated soil and the residual ammonia in the soil can also improve soil fertility.
Keywords: Ammonia Water; Electrokinetic Remediation; Fluorine; Circulation Method
Adsorption properties of Friedel’s salt for the nitrate in the landfill by Jun Yao; Qingna Kong; Huayue Zhu; Dongsheng Shen; Zhen Zhang (553-558).
Adsorption characteristics of nitrate on Friedel’s salt under the landfill circumstance were investigated to explore the effect of Friedel’s salt on the migration of nitrate in the landfill. Friedel’s salt was synthesized by a coprecipitation method and characterized by XRD and FTIR spectroscopy. The kinetics and isotherm of the adsorption were studied. The effect of the variation of landfill circumstance on the adsorption was also discussed. The result showed that the adsorption capacity of Friedel’s salt for nitrate was 2.494mg g-1. The adsorption process was exothermic and could be well described by pseudo-second-order kinetics and Langmuir-Freundlich equation. Cl- could enhance the adsorption, while SO 4 2- , PO 4 3- and organic matter could restrict the adsorption. The results suggested that the migration of nitrate in the landfill could be altered by Friedel’s salt, which was related to the variation of the landfill circumstance.
Keywords: Adsorption; Friedel’s Salt; Landfill; Migration; Nitrate
Simultaneous removal of Cr(VI) and phenol from synthetic binary solution using consortium culture of Bacillus sp. and E. coli immobilized on tea waste biomass in packed bed reactor by Ankur Gupta; Chandrajit Balomajumder (559-566).
A continuous bio column reactor was designed for the simultaneous bioaccumulation of Cr(VI) and biodegradation of phenol from their binary synthetic solution with the ratio of (2: 1). Consortium culture of Bacillus sp. and Escherichia coli was immobilized onto tea waste biomass in the packed bed column. The metabolites formed during the biodegradation of phenol by Bacillus sp. were utilized by Escherichia coli for the bioaccumulation of Cr(VI). The considerable effect of empty bed contact time (EBCT), bed height (cm) and flow rate (mL/min) was investigated onto the simultaneous removal of Cr(VI) and phenol in the column reactor. However, after 3-4 days of continuous treatment of Cr(VI) and phenol the effect of these process parameters was not significant. Dissolved oxygen (DO) of effluent has been found to decrease with run time of packed bed column. The pH of the effluent decreased initially for 2 days but after that it became the same as the influent. A mass transfer study was carried out to calculate the pseudofirst-order rate constant for Cr(VI) and phenol, which was in good agreement with experimental results.
Keywords: Consortium Culture; Bio Column; Escherichia coli ; Bacillus sp.; Mass Transfer
Characterization, isotherm and kinetic study of Phaseolus vulgaris husk as an innovative adsorbent for Cr(VI) removal by Shalini Srivastava; Shashi Bhushan Agrawal; Monoj Kumar Mondal (567-575).
Phaseolus vulgaris husk as a novel, very common milling agro waste, showed good performance for mutagenic Cr(VI) removal from chromium enriched aqueous solution. The study involves batch experiments to investigate the effects of influencing parameters, such as pH, temperature, contact time, initial Cr(VI) concentration, and adsorbent dose, on the adsorption process. Results showed a maximum of 99.88% removal of Cr(VI) at pH 1.16, temperature 20 °C and adsorbent dose of 6 g L−1. The adsorption equilibrium data followed the Freundlich model, suggesting a heterogeneous nature of the adsorbent surface and the correlation coefficient for pseudo-second-order kinetic model was found to be very high, showing its applicability during the adsorption process. The maximum Cr(VI) uptake capacity was 3.4317mg g−1. Thermodynamic parameters like standard free energy change (−7.175 kJ mol−1), enthalpy change (−8.29 kJ mol−1) and entropy change (0.005 kJ mol−1 K−1) revealed the spontaneous and exothermic nature of adsorption of Cr(VI) onto P. vulgaris husk. Desorption with 1mol L−1 NaOH followed by 1mol L−1 HCl was effective (92.76%) and, hence, it exhibited the possibility of recycling of used husk.
Keywords: Mutagenic Cr(VI); Phaseolus vulgaris Husk; Freundlich Isotherm; Correlation Coefficients; Pseudo Second Order; Exothermic
Effective removal of anilines using porous activated carbon based on ureaformaldehyde resin by Fu-Qiang An; Dong Zhang; Xiao-Xia Yue; Guo-Li Ou; Jian-Feng Gao; Tuo-Ping Hu (576-581).
The effective removal of aniline and its derivatives from wastewater is very important due to the high toxicity. Adsorption with a high-performance adsorbent is an efficient pathway. A novel activated carbon, ACUF-700, was synthesized using homemade ureaformaldehyde resin as the major carbon source carbonized at 700 °C. ACUF-700 is characterized by surface area analyzer, FTIR, elemental analyzer, and SEM. The adsorption properties of ACUF-700 towards anilines are also investigated by using batch methods. The test results showed that the ACUF-700 possesses higher specific surface area and narrower pore size distribution. In virtue of its developed pore structure and nitrogencontaining chemical groups, the adsorption capacities towards aniline, p-toluidine and p-chloroaniline could reach 95.6, 108.1 and 128.9mg/g, respectively. The adsorption process could be well described by the intra-particle mass transfer diffusion model and Sips model. Besides, ACUF700 was regenerated easily using diluted hydrochloric acid solution as eluent and ACUF700 possesses better reusability.
Keywords: Activated Carbon; Nitrogen-containing; Adsorption; Anilines; Ureaformaldehyde Resin
Esterification of acetic and oleic acids within the Amberlyst 15 packed catalytic column by Jamshed Ali Khan; Yousuf Jamal; Afeeq Shahid; Bryan O’Neil Boulanger (582-586).
A packed column system was used to study the esterification of acetic and oleic acids by the macro-porous acidic resin, Amberlyst 15. All reactions were at a constant temperature (75 oC) and catalyst mass (3 g). The impact of column flow rate conditions and the molar fatty acid to ethanol feedstock ratio on ester production is reported. The maximum ester production was noted at a flow rate of 0.25mL/min. The maximum observed ester yield for acetic acid (95.2±0.5%) and oleic acid (43.8±1.3%) was observed at an acid:ethanol molar ratio of 1: 3 and 1: 1, respectively. The difference in yield indicates the importance of the fatty acid chain length to the reaction.
Keywords: Heterogeneous Column; Fatty Acid; Esterification; Amberlyst 15; Percent Conversion
CO2 fixation and lipid production by microalgal species by Pavani Parupudi; Chandrika Kethineni; Pradip Babanrao Dhamole; Sandeep Vemula; Prasada Rao Allu; Mahendran Botlagunta; Sujana Kokilagadda; Srinivasa Reddy Ronda (587-593).
Microalgal species Nannochloropsis limnetica, Botryococcus braunii, and Stichococcus bacillaris were compared for their ability to grow, remove CO2, and accumulate lipids in their biomass under CO2-enriched atmosphere. Overall, N. limnetica outperformed the other two cultures and distinctly exhibited higher specific growth rate (0.999 d−1) and CO2 fixation rate (0.129 gL−1 d−1) with a high specific lipid yield (40% w/w). The volumetric CO2 fixation rate for all three species was validated with biomass productivity and mass transfer methods (P<0.005 and R2=0. 98). At 10% CO2, N. limnetica showed one-and-a-half times more carbon fixation efficiency over B. braunii, and S. bacillaris. On the other hand, total fatty acids of N. limnetica dispalyed an apparent increase in oleic acid. Whereas, under similar conditions, N. limnetica exhibited reduced eicosapentaenoic acid. These findings suggest that at high CO2 conditions, N. limnetica proved to be an efficient CO2 capture algal system and can be considered for biofuel applications.
Keywords: Microalgae; Lipid; Biofuel; CO2 Fixation Rate; Fatty Acid
Preparation of polyphenol fine particles potent antioxidants by a supercritical antisolvent process using different extracts of Olea europaea leaves by Chandrasekar Chinnarasu; Antonio Montes; Clara Pereyra; Lourdes Casas; María Teresa Fernández-Ponce; Casimiro Mantell; Sangma Pattabhi; Enrique Martínez de la Ossa (594-602).
Various extracts from olive leaves have been precipitated by a supercritical antisolvent (SAS) process to evaluate the possibility of producing polyphenol fine particles with controlled size and size distribution. Olive leaves were initially extracted with subcritical fluids using mixtures of CO2+ethanol at 10% and 50%, by pressurized liquid extraction (PLE) with water, ethanol and a hydroalcoholic mixture (50: 50) (v/v), and also by conventional ethanol extraction (CE). PLE gave the extract with the highest yield and the best antioxidant activity. SAS precipitation was unsuccessful for the extracts obtained with pressurized water and with the hydroalcoholic mixture (50: 50) (v/v). The SAS precipitates with the smallest particle sizes were produced from extracts obtained with subcritical fluids. The SAS precipitates obtained after the conventional ethanol extraction of olive leaves showed the best antioxidant activity.
Keywords: Olive Leaves; Supercritical CO2 ; Ethanol; Polyphenol Particles; Antioxidant Activity
Synergetic effect of biomass mixture on pyrolysis kinetics and biocrude-oil characteristics by Ramesh Soysa; Yeon Seok Choi; Sang Kyu Choi; Seock Joon Kim; So Young Han (603-609).
Biocrude-oil characteristics were investigated from fast pyrolysis of a mixture of Douglas fir and coffee ground. The mixture was prepared on a 1: 1 weight basis and pyrolyzed in a bubbling fluidized bed reactor. Characteristics of biocrude-oil were compared at various reaction temperatures ranging from 673-873K. The mixture resulted in a more improved quality biocrude-oil than each biomass feedstock at the reaction temperature of 823 K with significantly low atomic ratio of 0.43 O/C. The kinetic parameters for biomass decomposition were investigated through Friedman, KAS, FWO and CC isoconversional models. In mixture pyrolytic conversion range of 0.1-0.8, the average activation energy was found to be 135 kJ/mol. The results showed that pyrolysis of coffee ground with Douglas fir has more synergetic effect than individual biomass, which leads to a potentially higher quality fuel with lower activation energy to that of biomass.
Keywords: Biocrude-oil; Fast Pyrolysis; Biomass Mixture; Kinetic Models; Atomic Ratio
A facile technique to prepare cross-linked enzyme aggregates of bovine pancreatic lipase using bovine serum albumin as an additive by Jian Dong Cui; Rong Lin Liu; Lin Bo Li (610-615).
Cross-linked enzyme aggregates from bovine pancreatic lipase were prepared by co-aggregation of lipase and BSA (Lipase-BSA-CLEAs). The main factors in the preparation of lipase-BSA-CLEAs were optimized. The highest activity recovery was around 75% under the condition of using 1% (v/v) glutaraldehyde as cross-linker and 0.05 g/L bovine serum albumin as feeder for 2 h cross linking. The optimum temperature for both lipase-CLEAs and lipase- BSA-CLEAs was measured as 60 °C, which is 10 °C higher than that of free lipase. Moreover, the lipase-BSA-CLEAs evidenced higher thermal stability and excellent reusability in comparison with the lipase-CLEAs. Lipase-BSA-CLEAs retained more than 75% of the initial activity after eight cycles of reuse, while lipase-CLEAs only retained 20% of its initial activity. Additionally, lipase-BSA-CLEAs showed more storage stability than free lipase and lipase-CLEAs. The high stability and recyclability of lipase-BSA-CLEAs make it efficient for different industrial applications.
Keywords: Bovine Pancreatic Lipase; Cross-linked Enzyme Aggregates; Immobilization Enzyme; BSA
Preparation of nanoporous activated carbon and its application as nano adsorbent for CO2 storage by Ali Morad Rashidi; Davood Kazemi; Nosrat Izadi; Mahnaz Pourkhalil; Abbas Jorsaraei; Enseyeh Ganji; Roghayeh Lotfi (616-622).
Nanoporous activated carbons, as adsorbent for CO2 storage, were prepared from walnut shells via two chemical processes including phosphoric acid treatment and KOH activation at high temperature. Specific surface area and porosities were controlled by KOH concentration and activation temperature. The obtained adsorbents were characterized by N2 adsorption at 77.3 K. Their carbon dioxide adsorption capacities were measured at different pressures at 290 K by using volumetric adsorption equipment. The KOH-treated nanoporous carbons typically led to the production of high specific surface areas and high micropore volumes and showed better performance for CO2 adsorptions. The maximum experimental value for adsorption capacity happened when pressure increased from 5 to 10 bar (1.861-2.873mmol·g−1). It was found that in order to improve the highest capacity of CO2 adsorption for KOH-modified carbon (9.830-18.208mmol·g−1), a KOH: C weight ratio of 3.5 and activation temperature of 973 K were more suitable for pore development and micro-mesopore volume enhancement.
Keywords: Nanoporous Activated Carbon; KOH Treatment; CO2 Storage; Adsorption
Impact of seed loading ratio on the growth kinetics of mono-ammonium phosphate under isothermal batch crystallization by Bingwen Long; Haotian Yang; Yigang Ding (623-628).
The effect of seed load ratio on the growth kinetics of Mono-ammonium phosphate (MAP) under isothermal batch crystallization was investigated quantitatively. A direct parameter estimation method was proposed and applied to extract the growth kinetic parameters from a simple crystallization model using our experimental solution concentration decline data. The method assured the globally best parameters to be obtained and was found less sensitive to experimental errors. The linear growth constants k g and the growth order g were found to be in the range of 1,000-2,600 μm·min−1 and 0.93-1.12, respectively, for MAP crystallized at 40 °C. Both parameters decreased significantly with increase of seed load ratio and k g even showed a strong linear decline trend. The effective crystallization time also decreased with the seed mass. The proposed methodology could be extended to study the effect of other operation variables such as temperature and initial supersaturation on the crystal growth rate.
Keywords: Mono-ammonium Phosphate; Crystallization Kinetics; Seeding Effect; Parameter Estimation; Optimization
Fabrication of poly(ether sulfone) based mixed matrix membranes modified by TiO2 nanoparticles for purification of biodiesel produced from waste cooking oils by Farah Sadat Halek; Samaneh Koudzari Farahani; Sayed Mohsen Hosseini (629-637).
Biodiesel produced from waste cooking oils was purified by use of polyethersulfone-co-TiO2 nanocomposite membranes. The membranes were prepared by solution casting technique through phase inversion method. Titanium dioxide nanoparticles were used as inorganic filler additive in membrane fabricating. The effect of nanoparticle concentration in the casting solution on the physico-chemical characteristics, morphology and performance of prepared membranes was studied. SEM, AFM and XRD analyses were carried out for the characterization of membrane. The results showed uniform nanoparticle distribution in the membranes matrix. XRD results also indicated a crystalline structure for the membranes. Membrane surface roughness was decreased sharply by increase of nanoparticle concentration up to 0.05%wt in membrane matrix and then increased slightly. Membrane flux, rejection, water content, porosity and membrane mechanical strength were enhanced initially by increase of nanoparticles concentration up to 0.05%wt and then decreased by more increase of nanoparticles content ratio. The nanocomposite membrane containing 0.05 wt% TiO2 showed more appropriate performance compared to others.
Keywords: Nanocomposite Membrane; TiO2 Nanoparticles; Fabrication/Characterization; Biodiesel Purification; Transesterification
Sorption of Cr(VI) by MgAl-NO3 hydrotalcite in fixed-bed column: Experiments and prediction of breakthrough curves by Mohamed Khitous; Zineb Salem; Djamila Halliche (638-648).
This study describes the sorption of Cr(VI) by MgAl-NO3 hydrotalcite in a fixed-bed column. The sorbent was prepared via coprecipitation method and characterized by XRD, FTIR, BET surface area and pH zpc . The effects of operating parameters such as bed height, flow rate and inlet concentration were investigated in continuous mode. As a result, the exhaustion time increased with the increase of bed height, decrease of flow rate and inlet concentration. A mathematical model based on the constant pattern theory and the Freundlich isotherm was applied to predict the experimental data, and to evaluate the model parameters of the fixed-bed column. The developed model describes well the breakthrough curves at various operating conditions. The calculated volumetric mass transfer coefficient K L a depends directly on these conditions. K L a increased with increasing flow rate and inlet concentration, while remained almost constant with varying bed height.
Keywords: Fixed-bed Column; Cr(VI); Breakthrough Curve; Model; Sorption
Kinetic model for sorption of divalent heavy metal ions on low cost minerals by Aseem Chawla; Murari Prasad; Rishta Goswami; Shweta Ranshore; Ankita Kulshreshtha; Akhouri Sudhir Kumar Sinha (649-656).
A mathematical model is proposed that could predict the kinetic parameters for adsorption of divalent heavy metal ions (lead, copper and zinc) onto low-cost adsorbents such as pyrophyllite and rock phosphate using experimental data. The experiments were conducted with the initial concentrations of metal ions ranging from 10mg/L to 100mg/L. The mathematical model is based on the application of the Redlich-Peterson isotherm to mass transfer across the film surrounding the adsorbent. The developed non-linear sorption kinetic (NSK) mathematical model was solved using numerical integration by the trapezoidal method in Microsoft Excel along with the SOLVER function to obtain the best simulated values of the Redlich-Peterson constants A, B, r, the order of reaction n, and the film transfer coefficient α. Dissolution followed by precipitation was found to be the most probable mechanism responsible for heavy metal ion uptake by rock phosphate, while for pyrophyllite physical adsorption was governing mechanism at low concentrations (<100mg/L). The values of parameters A, B, r and α lie in the ranges of 0.015-23.2, 0.00003-3.09, 0.072-1, and 0.000057-52.8 [(L/mg)(n−1)/min], respectively, under different experimental conditions.
Keywords: Adsorption; Divalent Heavy Metal Ions; Rock Phosphate; Pyrophyllite; Sorption Kinetic Model; Redlich-Peterson Isotherm
CO2/CH4 separation with poly(4-methyl-1-pentyne) (TPX) based mixed matrix membrane filled with Al2O3 nanoparticles by Mohammad Hadi Nematollahi; Amir Hossein Saeedi Dehaghani; Reza Abedini (657-665).
The effect of alumina (Al2O3) nano-particles on gas separation properties of poly(4-methyl-1-pentyne) known as TPX was evaluated. Mixed matrix membranes (MMMs) were prepared with various weight percent (5, 10, 15, 20 and 30) of alumina nano-particles through solution casting along with solvent evaporation method. TPX and consequent MMMs were characterized using FT-IR, SEM and TGA methods. The MMMs permselectivities were determined through pure CO2 and CH4 permeation measurement and CO2/CH4 selectivity calculation. SEM images demonstrated the proper dispersion of alumina nano-particles in TPX matrix. Results from gas permeation showed that the permeability of both CO2 and CH4 as well as CO2/CH4 selectivities were increased with increasing alumina content. Significant increase of CO2 permeability (from 157.43 Barrer at 8 bar and no loading of Al2O3 to 527.78 Barrer at 8 bar and 30 wt% loading of Al2O3) and conspicuous enhancement of selectivity, from 7.73 to 12.51, were obtained in TPX MMMs.
Keywords: Poly(4-methyl-1-pentyne); TPX; CO2/CH4 Separation; Alumina Nano-particles; Mixed Matrix Membranes
1-Methyl-3-octylimidazolium tetrafluoroborate/AgO nanoparticles composite membranes for facilitated gas transport by Dahye Ji; Sang Wook Kang (666-668).
AgO nanoparticles (NPs) were generated in ionic liquid 1-methyl-3-octylimidazolium tetrafluoroborate (Moim+BF 4 - ). The formation of Ag NPs was attributable to the favorable interaction between the surface of particles and counteranions of ionic liquid. The generated AgO nanoparticles in Moim+BF 4 - were confirmed by TEM, and the average size was 40 nm. Coordinative interactions of AgO NPs with Moim+BF 4 - were investigated by FT-Raman spectroscopy. The prepared Moim+BF 4 - /Ag NPs composites were utilized for CO2 separation membrane, and consequently, CO2 separation performance for composite membranes was improved compared with neat Moim+BF 4 - . The ideal selectivity for CO2/N2 was 23.4 with a CO2 permeance of 18.7GPU was observed, while the neat Moim+BF 4 - membrane showed a selectivity of 15.9 and a CO2 permeance of 12.7GPU.
Keywords: Membrane; Facilitated Transport; Composite; Ionic Liquid; AgO
Polypyrrole-polyaniline/Fe3O4 magnetic nanocomposite for the removal of Pb(II) from aqueous solution by Amirhossein Afshar; Seyed Abolfazl Seyed Sadjadi; Afsaneh Mollahosseini; Mohammad Reza Eskandarian (669-677).
Lead ion which is engaged in aqueous solution has been successfully removed. A novel technique was utilized for the separation and absorption of Pb(II) ions from aqueous solution. Magnetic Fe3O4 coated with newly investigated polypyrrole-polyaniline nanocomposite was used for the removal of extremely noxious Pb(II). Characteristic of the prepared magnetic nanocomposite was done using X-ray diffraction pattern, Field emission scanning electron microscopy (FE-SEM), Fourier transform-infra red spectroscopy (FT-IR) and energy dispersive x-ray spectroscopy (EDX). Up to 100% adsorption was found with 20mg/L Pb(II) aqueous solution in the range of pH=8-10. Adsorption results illustrated that Pb(II) removal efficiency by the nanocomposite increased with an enhance in pH. Adsorption kinetics was best expressed by the pseudo-second-order rate form. Isotherm data fitted well to the Freundlich isotherm model. Upon using HCl and HNO3, 75% PPy-PAn/Fe3O4 nanocomposite, desorption experiment showed that regenerated adsorbent can be reused successfully for two successive adsorption-desorption cycles without appreciable loss of its original capacity.
Keywords: Polypyrrole-polyaniline; Nanocomposite; Lead; Heavy Metals; Fe3O4 ; Kinetic
Controlling the morphology of the active layer by using additives and its effect on bulk hetero-junction solar cell performance by Viet Hau Thanh Pham; Nguyen Tam Nguyen Truong; Thanh Kieu Trinh; Sang Hoon Lee; Chinho Park (678-682).
-Improvement of the surface roughness and power conversion efficiency (PCE) of bulk hetero-junction (BHJ) solar cells was made by the addition of organic additives for the cells based on a low energy-gap polymer, poly [2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b'] dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT), as an electron donor and [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) as the electron acceptor. The PCPDTBT: PC61BM active layers were prepared by spin-coating process from four different organic solvents: pure chlorobenzene, chlorobenzene with 2.5 vol% 1,2-ethanedithiol (EDT) additive, chlorobenzene with 2.5 vol% 1,8-octanedithiol (ODT) additive, and chlorobenzene with a combination of 2.5 vol% EDT and 2.5 vol% ODT additives. The smoothest surface of the active layer, which was observed by AFM, was obtained in the case of PCPDTBT:PC61BM prepared with a combination of EDT and ODT additives in chlorobenzene, and a maximum PCE of 3.5% was achieved.
Keywords: Organic Solar Cells; Bulk Hetero-junction; 1,2-Ethanedithiol; 1,8-Octanedithiol; Additives
Synthesis of rare earth oxide nanoplates with single unit cell thickness using a thermal decomposition method by Euiyoung Jung; Taekyung Yu; Woo-Sik Kim (683-687).
We report the colloidal synthesis of rare earth oxide nanoplates with square and disk shapes using thermal decomposition of Ln(CH3CO2)3·xH2O in the presence of a mixture of oleylamine and oleic acid (Ln=La, Pr, Nd, Dy, Er, and Y). In this synthesis, oleylamine plays an important role in the formation of ultra-thin nanoplates with thickness of 1.1 nm, which corresponds to a single unit cell dimension of rare earth oxides, and oleic acid serves as a capping agent for the formation of nanoplates having nano-sized side dimension (around 15-40 nm). By varying the rare earth precursors, we obtained square-shaped nanoplates (La2O3, Pr2O3, and Nd2O3) and disk-shaped nanoplates (Dy2O3, Er2O3, and Y2O3), respectively, confirming that our synthesis could be extended to the synthesis of various rare earth oxide nanoplates.
Keywords: Rare Earth Oxide; Nanoplates; Single Unit Cell Thickness; Thermal Decomposition; Oleylamine; Oleic Acid
Characteristics of LiFePO4/C composite prepared by sonochemical method under multibubble sonoluminescence by Ki-Moon Kang; Hyo-Won Kim; Ho-Young Kwak (688-696).
LiFePO4/C composites with various weight percent of carbon nanotubes (CNT) were prepared through one-pot sonochemical method under the condition of multibubble sonoluminescence (MBSL). The electrical performance of the composites depends crucially on ultrasound irradiation time, the calcination temperature and duration and weight percent of CNTs. The best initial discharge capacity was obtained for a calcination temperature of 650 °C for 6 h, 30minutes ultrasound irradiation and with 2 wt% of CNTs. The electric conductivity of the LiFePO4/C composite with 2 wt% CNTs was approximately 3.4·10−4 S/cm. The coin cell made of LiFePO4/C composite whose average diameter is 683 nm exhibits an initial discharge capacity of 142mAh/g at 0.1 C, a flat and long voltage plateau and low ΔV between the initial charge and discharge plateaus of 0.03 V and small fade rate of capacity of 0.08% per cycle at 0.5 C. The first efficiency, the ratio of the initial discharge to the initial charge capacity, of the LiFePO4/C composite, is about 90%.
Keywords: Lithium Iron Phosphate; Multibubble Sonoluminescence; Carbon Nanotube; Initial Discharge Capacity; First Efficiency; Cathode Material
Oxidative conversion of anilines to azobenzenes with alkaline chloramine-T by Adalagere Somashekar Manjunatha; Shankarlingaiah Dakshayani; Nirmala Vaz; Puttaswamy (697-706).
Anilines are widely used in the manufacture of dyes, medicinals, plastics and perfumes. Anilines are readily oxidized to give products depending on reaction conditions. Conversion of anilines to azobenzene is important in organic synthesis. In the course of this research, optimum conditions for the facile oxidative conversion of anilines to azobenzenes have been established in very good yields. The kinetics of oxidation of aniline, p-methoxyaniline, p-methylaniline, p-carboxylicaniline and p-nitroaniline by chloramine-T (CAT) in NaOH medium shows identical kinetics with a first-order dependence of rate on [CAT] o , fractional-order on [Aniline] o , and an inverse-fractional order on [OH-]. Activation parameters and decomposition constants have been determined. Oxidation products were characterized by NMR spectral studies. Isokinetic temperature is 415 K indicating enthalpy as a controlling factor. The rates increased in the order: p-methoxyaniline>p-methylaniline>aniline>p-carboxylicani- line>p-nitroaniline. A Hammett linear free energy relationship is observed for the reaction with ρ=-0.52. Reaction scheme and kinetic rate law were deduced. We have developed a simple and efficient protocol for the synthesis of azobenzenes by anilines in good yields and hence we believe that this methodology will be a valuable addition to the existing methods.
Keywords: Anilines; Chloramine-T; Oxidation-kinetics; Mechanism; Structure Reactivity
Effects of composition and layer thickness of a butyl acrylate/acrylic acid copolymer on the adhesion properties by Deoukchen Ghim; Jung Hyeun Kim (707-710).
Acrylic pressure-sensitive adhesives are synthesized by solution copolymerization using n-butyl acrylate and acrylic acid (AA) in ethyl acetate anhydrous. The copolymer composition is controlled for good adhesive properties by varying AA content. The monomer conversion is measured by the gravimetric method and FTIR technique. The adhesive layer thickness is measured by scanning electron microscopy, and the adhesive properties are evaluated with loop tack, 180° peel, and holding time measurements. The peel force increases with increasing the AA content up to 3 wt% and decreases at the AA content higher than 3 wt%, but the tack force decreases with increasing the AA content. The holding time increases with increasing the AA content, and it shows a similar trend with the T g of adhesives. The increase of layer thickness improves tack and peel forces, but it weakens the holding power. A tape thickness of about 20 μm shows well-balanced properties at 3 wt% AA content in the acrylic copolymer system.
Keywords: Solution Synthesis; Adhesion; Polymers
Synthesis and characterization of a new polymeric surfactant for chemical enhanced oil recovery by Keshak Babu; Nilanjan Pal; Vinod Kumar Saxena; Ajay Mandal (711-719).
Chemical enhanced oil recovery methods are field proven techniques that improve efficiency and effectiveness of oil recovery. We have synthesized polymeric surfactant from vegetable oil (castor oil) for application in chemical enhanced oil recovery. First, an eco-friendly surfactant, sodium methyl ester sulfonate (SMES) was synthesized from castor oil, and then the polymeric surfactant (PMES) was produced by graft co-polymerization reaction using different surfactant to acrylamide ratios. The synthesized PMES was characterized by FTIR, FE-SEM, EDX, TGA, DLS analysis. The performance of PMES as a chemical agent for enhanced oil recovery was studied by measuring the interfacial tension (IFT) between crude oil and PMES solution, rheological behavior and contact angle against sandstone surface. Addition of sodium chloride in PMES solution reduced the IFT to an ultra-low value (2.0×10-3mN/m). Core flooding experiments were conducted in sandpack system, and 26.5%, 27.8% and 29.1% additional recovery of original oil in place (OOIP) was obtained for 0.5, 0.6 and 0.7mass% of PMES solutions, respectively, after conventional water flooding.
Keywords: Polymeric Ssurfactant; Synthesis; Interfacial Tension; Contact Angle; Enhanced Oil Recovery
Enhanced adsorption of fluoride from aqueous solutions by hierarchically structured Mg-Al LDHs/Al2O3 composites by Tao Zhang; Hanqiang Yu; Yuming Zhou; Jian Rong; Zhanyu Mei; Fengxian Qiu (720-725).
Hierarchically structured layered double hydroxides (LDHs)/Al2O3 composites were fabricated from waste paper fibers using a two-step method. In the first step microscaled Al2O3 fibers were prepared by template-directed synthesis employing waste paper fibers as templates; and in the second step nanoscaled LDHs platelets were fabricated into hierarchical architectures based on crystal growth on Al2O3 fibers surface. The morphology and structure of asprepared samples were characterized by scanning electron microscopy (SEM), N2 adsorption/desorption analysis and X-ray diffraction (XRD) analysis. The SEM results revealed that the inorganic fibers were covered by LDHs platelets, forming the hierarchical structures with micro- to nanoscales. The BET analysis showed that the surface area was increased from 76.66m2/g (Al2O3 fibers) to 165.0m2/g (composites) by the growth of LDHs platelets on the surfaces of Al2O3 fibers. As compared to bare LDHs particles and Al2O3 fibers, the LDHs/Al2O3 composites show a high fluoride adsorption capacity, and the maximum adsorption capacity can reach up to 58.7mg/g. The Langmuir isotherm model was found to agree well with the equilibrium data, while the pseudo-second order model provided the highest correlation of the kinetic data for fluoride adsorption. The as-prepared LDHs/Al2O3 composites and corresponding design strategies developed herein are expected to be applicable to the synthesis of other LDHs based composites for the removal of pollutants from water.
Keywords: Mg-Al LDHs/Al2O3 ; Hierarchical Structures; Waste Paper; Adsorption; Fluoride
Characteristics of pressure drop during the pulse-jet cleaning of a ceramic filter for high temperature and high pressure by Jin-Hyoung Kim; Young-Chul Kim; Joo-Hong Choi (726-734).
The operation range of the pressure drop between the peak and the base line during the pulse-jet cleaning of a ceramic filter relates closely with the grouping number of the filter elements in the filter unit, as well as the design and the operation conditions of the pulse cleaning system. A semi-empirical model was developed to predict the pressure drop of the filter unit versus the operation time according to the grouping numbers of the total filter elements in this study. The model is based on theoretical considerations and the application of the experimental data to develop a simple equation, which should be useful for preliminary design and operational inspection. The semi-empirical formula predicts the operational values of the pressure drop between the peak and the base line, which suggests the guideline for grouping of the filter elements for the pulse-jet cleaning. Peak pressure drop decreases gradually and then finally approaches a minimum stable value as the number of the cleaning group increases. Otherwise, the base line pressure drop increases gradually and then finally approaches a maximum stable value as the number of the cleaning group increases. Thus, the gaps between the peak and the base line pressure drop become narrow as the number of cleaning group increases. This phenomenon of gap reduction is desirable for the pulse cleaning of the filter element as it reduces the pulse cleaning load. Moreover, pulse cleaning becomes more effective as the number of the cleaning groups increases.
Keywords: Pulse-jet; Pressure Drop; Ceramic Filter; Group Filter; Semi-empirical Model; Dust Collection