Korean Journal of Chemical Engineering (v.33, #7)
Phase behavior of gas hydrates in nanoporous materials: Review by Daeok Kim; Huen Lee (1977-1988).
A precise understanding of phase behavior for a variety of both artificial and natural processes is essential to achieving scientific and technological goals. There has been growing research interest in gas hydrates confined in nanoporous media aiming to simulate and analyze the unique behavior of natural gas hydrates in sediments. Moreover, the appearance of peculiar properties due to the confinement effect stimulates research on gas hydrate technology for gas separation, such as CO2 capture from versatile pre/post combustion emissions. In spite of their importance, reliable phase equilibrium data on gas hydrates confined at a nanoscale are scattered throughout the literature, while those in bulk state are abundant. Accordingly, we surveyed the previous studies on the phase behavior of gas hydrates in various nanoporous materials to include and provide valuable information and knowledge for start-up researchers in various gas hydrate fields.
Keywords: Gas Hydrate; Nanoporous Material; Phase Equilibria; Water; Confinement Effect
Developments in photocatalytic antibacterial activity of nano TiO2: A review by Hemraj Mahipati Yadav; Jung-Sik Kim; Shivaji Hariba Pawar (1989-1998).
TiO2, which is one of the most explored materials, has emerged as an excellent photocatalyst material for environmental and energy fields, including air and water purification, self-cleaning surfaces, antibacterial and water splitting. This review summarizes recent research developments of TiO2-based photocatalyst used for photocatalytic antibacterial applications. Several strategies to enhance the efficiency of TiO2 photocatalyst are discussed, including doping with metal ions, noble metals, non-metals, and coupling with other materials. The mechanism of photocatalytic antibacterial activity in the presence of nano-sized TiO2 is also discussed. The modified TiO2 photocatalyst significantly inhibits the growth of bacterial cells in response to visible light illumination. TiO2 photocatalysis appears to be promising as a route of advanced oxidation process for environmental remediation.
Keywords: Antibacterial; TiO2 ; Photocatalysis; Bacteria; Photocatalytic Disinfection
Kriging models for forecasting crude unit overhead corrosion by Kyungjae Tak; Junghwan Kim; Hweeung Kwon; Jae Hyun Cho; Il Moon (1999-2006).
Crude unit overhead corrosion is a major issue in the refinery field. However, the corrosion models in the literature are difficult to apply to real refinery processes due to the characteristics of corrosion. We propose a Kriging model, an advanced statistical tool for geostatistics, to forecast the corrosion rate in a real refinery plant. Instead of spatial coordinates, the proposed model employs the non-spatial coordinates of six key corrosion variables: H2S, Cl−, Fe2+, NH3, pH, and flowrate. The Kriging model is compared with two well-known forecasting models, multiple linear regression and an artificial neural network. To overcome the insufficiency of the number of data sets measured in the plant to use the six non-spatial coordinates, the significance probability is applied to reduce the dimensions from six to four. Among all the developed models in this paper, the Kriging model with four corrosion variables showed the best forecasting performance.
Keywords: Refinery Process; Corrosion Rate; Forecasting Model; Multiple Linear Regression; Artificial Neural Network; Kriging Model
Numerical simulation of flow field characteristics in a gas-liquid-solid agitated tank by Liangchao Li; Bin Xu (2007-2017).
Computational fluid dynamics simulation was carried out to investigate flow field characteristics in a gas-liquid-solid agitated tank. The Eulerian multifluid model along with standard k-ε turbulence model was employed in the simulation. A multiple reference frame approach was used to treat the impeller rotation. Liquid velocity, gas holdup and solid holdup distributions in the agitated tank were obtained. The effect of operating conditions on gas and solid distributions was investigated. The predicted flow pattern was compared with results in literature. The simulation results indicate that local hydrodynamic behaviors such as velocity, gas and solid holdup distribution, are strongly influenced by operating conditions. Within the scope of our study, increasing gas inlet rate caused liquid circulation to be weakened and was not in favor of gas dispersion. Solid holdup in the upper part of the tank, especially near the wall region decreased. Adding solid loadings resulted in liquid mean velocity near the surface region decreased, gas dispersion and solid suspension becoming worse.
Keywords: Agitated Tank; Gas-liquid-solid; Three Phase Flow; Multiple Reference Frame Approach; Numerical Simulation
Highly efficient Al-doped ZnO : Ag catalyst for RB19 photocatalytic degradation: Microwave-assisted synthesis and characterization by Mohamad Reza Khodadadi; Mohamad Ebrahim Olya; Alireza Naeimi (2018-2026).
ZnO: Ag.Al nano-catalyst was synthesized by microwave technique. The characterization and evaluation of this semiconductor catalyst was examined in contrast with ZnO and ZnO:Ag by X-ray diffraction (XRD), scanning electron microscopy (SEM), tunneling electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Thermodynamic study of combustion synthesis showed the reaction temperature for ZnO: Ag·Al samples decreased to 481.48 oC compared to ZnO that is 1141 oC. Tauc’s plot was used to calculate the band gap of samples and the location of absorption edge was found at 380 nm. Different molar ratios of Ag and Al were examined to find the best activity of catalyst. In this study, reactive blue 19 (RB19) as a water pollution was used to find the efficiency of catalyst, and the effect of pH on the reaction was studied in a batch reactor under UV radiation. Also, the recyclability experiments confirm that the synthesized ZnO: Ag·Al (7mole% Ag and 3% mole Al) has responsible photocatalytic activity as compared to ZnO at a similar operating condition.
Keywords: Nano-catalyst; Doping; Band Gap; Recyclability; Reactive Blue 19
Ni2+ reduction under solar irradiation over CuFe2O4/TiO2 catalysts by Maamar Fedailaine; Sabrina Berkani; Mohamed Trari (2027-2033).
The photo-electrochemical characterization of the hetero-system CoFe2O4/TiO2 was undertaken for the Ni2+ reduction under solar light. The spinel CoFe2O4 was prepared by nitrate route at 940 °C and the optical gap (1.66 eV) was well matched to the sun spectrum. The flat band potential (-0.21 VSCE) is more cathodic than the potential of Ni2+/Ni couple (-0.6 VSCE), thus leading to a feasible nickel photoreduction. TiO2 with a gap of 3.2 eV is used to mediate the electrons transfer. The reaction is achieved in batch configuration and is optimized with respect to Ni2+ concentration (30 ppm); a reduction percentage of 72% is obtained under sunlight, the Ni2+ reduction is strongly enhanced and follows a first order kinetic with a rate constant of 4.6×10-2 min-1 according to the Langmuir-Hinshelwood model.
Keywords: Photocatalysis; Spinel CuFe2O4 ; Nickel; Sunlight
The catalytic performance of methylation of naphthalene with methanol over SAPO-11 zeolites synthesized with different Si content by Xiaoxiao Wang; Fang Guo; Xianxian Wei; Zhenmin Liu; Wei Zhang; Shaoqing Guo; Liangfu Zhao (2034-2041).
A series of SAPO-11 zeolites with different Si contents were prepared by hydrothermally synthesized method. They were characterized by ICP, XRD, SEM, FT-IR, N2 adsorption-desorption, NH3-TPD and 29Si MAS NMR, and evaluated by the methylation of naphthalene with methanol to 2,6-dimethylnaphthalene (2,6-DMN). According to XRD and SEM results, the crystallinity of SAPO-11 sample increased with increase of the Si content until the SiO2/Al2O3 ratio was up to 0.2. However, a reduction in the crystallinity was observed with further increase of the Si content of the synthesis. N2 adsorption-desorption results showed that all the samples possessed micropores and secondary mesopores. SAPO-11 sample with SiO2/Al2O3 ratio of 0.2 exhibited the largest secondary mesopores size distributions. NH3-TPD and 29Si MAS NMR showed that the Si content was incorporated into the framework affecting not only the acid sites but also the acid strength of SAPO-11. SAPO-11 with SiO2/Al2O3 ratio of 0.2 presented the high catalytic performances for the methylation of naphthalene, which was mainly attributed to the amount of secondary mesopores in the SAPO-11 zeolite.
Keywords: SAPO-11; Si Content; Pore Structure; Methylation of Naphthalene
Prediction of biodiesel properties and its characterization using fatty acid profiles by Mahdieh Samavi; Barat Ghobadian; Mehdi Ardjmand; Aliakbar Seyfkordi (2042-2049).
Biodiesel, the mono-alkyl esters of vegetable oils or animal fats, is an eco-friendly alternative to petrodiesel. The molecular structures of biodiesels, fatty acid methyl esters were applied to predict the characteristics of biodiesel fuels. Based on the structural similarity of biodiesel and petroleum fractions, molecular weight of biodiesel was correlated with other characteristics including boiling point, viscosity and specific-gravity in the form of three equations. For 24 different kinds of biodiesel, the minimum average relative deviation (ARD) of these correlations was calculated to be 0.68%. Moreover, two correlations were developed to predict viscosity and flash point of biodiesel as a function of weighted-average number of carbon atoms (N C ) and weighted-average number of double bonds (N DB ) with ARD 3.72% and 4.24% respectively. Also, a high degree of correlation was shown by the logarithmic function with ARD 0.30% between specific gravity and viscosity of biodiesel. Proposed predictive models were verified by experimental data.
Keywords: Biodiesel; Characterization; Prediction; Biodiesel Property; Fatty Acid Profile
Mechanism of methane hydrate formation in the presence of hollow silica by Hari Prakash Veluswamy; Pinnelli Seetha Rama Prasad; Praveen Linga (2050-2062).
Methane hydrates are studied extensively as a prospective medium for storing and transporting natural gas due to their inherent advantages, including high volumetric energy storage density, being environmentally benign and extremely safe method compared to conventional compression and liquefaction methods. Enhanced formation kinetics of methane hydrates has been reported in hollow silica due to the increased gas/liquid contact surface area available for efficient conversion of water to hydrates. This work elucidates the mechanism of methane hydrate formation in light weight hollow silica. Hollow silica-to-water ratio was varied and its effect on the methane hydrate formation/dissociation morphology was observed. There exists a critical hollow silica-to-water ratio (1 : 6) beyond which the hydrates preferentially crystallize on the top of the bed by drawing water from the interstitial pores, whereas below this ratio the hydrate formation occurs within the bed between inter-particular spaces of hollow silica. Due to the very low bulk density, a small fraction of hollow silica was observed to be displaced from the bed during the hydrate formation above the critical hollow silica to water ratio.
Keywords: Gas Hydrates; Methane Hydrate; Morphology; Hollow Silica; Gas Storage
Transesterification of soybean oil to biodiesel by tin-based Brønsted-Lewis acidic ionic liquid catalysts by Xiaoxiang Han; Wei Yan; Chin-Te Hung; Yanfei He; Pei-Hao Wu; Li-Li Liu; Shing-Jong Huang; Shang-Bin Liu (2063-2072).
A series of Brønsted-Lewis acidic ionic liquid (BLAIL) catalysts consisting of sulfonated ionic liquid [SO3H-pmim]Cl and Sn(II) chloride have been synthesized and exploited for catalytic transesterification of soybean oil with methanol to biodiesel. The structural and chemical properties of these [SO3H-pmim]Cl-xSnCl2 (x=0-0.8) catalysts were characterized by different analytical and spectroscopic techniques, such as FT-IR, TGA, and NMR. In particular, their acid properties were studied by solid-state 31P NMR using trimethylphosphine oxide as the probe molecule. The BLAIL catalysts were found highly efficient for transesterification reaction due to the introduction of Lewis acidity by SnCl2 in the initially Brønsted acidic [SO3H-pmim]Cl catalyst. The effects of three independent process variables on biodiesel yield were optimized by response surface methodology (RSM). Consequently, an excellent biodiesel yield of 98.6% was achieved under optimized reaction conditions over the BLAIL catalyst with SnCl2 loading (x) of 0.7.
Keywords: Brønsted-Lewis Acidic Ionic Liquid; Biomass; Transesterification; Biodiesel; Optimization; Response Surface Methodology
Investigation of synergistic adsorption between methyl orange and Cd(II) from binary mixtures on magnesium hydroxide modified clinoptilolite by Weihua Zou; Lie Liu; Hongping Li; Xiuli Han (2073-2083).
The simultaneous removal of Methyl orange (MO) and Cd2+ (mainly from organo-metallic dyes) onto magnesium hydroxide modified clinoptilolite (MHMC) was described and compared to a single adsorbate situation. The adsorption performance was studied by batch experiments. The adsorption mechanism of MO and Cd2+ on MHMC was investigated. Langmuir and Dubinin-Raduskevich (D-R) isotherm successfully predicted the adsorption of MO and Cd2+ in single and binary systems. Maximum adsorption capacity calculated from Langmuir isotherm equation in single solution for MO and Cd2+ was 0.305 and 0.282mmol/g, respectively. In a binary system of MO/Cd2+, the adsorption capacity for both MO and Cd2+ was higher than in single solutions. The results indicated that the adsorption system of MO/Cd2+ presented a synergistic effect, not competitive adsorption, which suggested that MHMC can be used as an adsorbent for removal of dyes and heavy metal in the multi-solute system.
Keywords: Magnesium Hydroxide Modified Clinoptilolite (MHMC); Adsorption; Isotherms; Kinetics; Methyl Orange; Cd2+
Effects of oxidized biodiesel on formation of particulate matter and NO x from diesel engine by Hyungkyu Kang; Hoyoung Song; Jonghan Ha; Byung-Ki Na (2084-2089).
A test was conducted to investigate the effect of pure biodiesel without additives on formation of particulate matter (PM) and nitrogen oxide (NOx) in the exhaust gas of a diesel engine. Pure biodiesel from waste cooking oil without adding any additive was used. The biodiesel was oxidized at 110 °C for 10 days and blended with commercial automobile diesel oil distributed in the market as a testing fuel. Blended fuels were produced by adding 10% of oxidized biodiesel and un-oxidized biodiesel to automobile diesel oil, respectively. Material properties such as density, kinematic viscosity, oxidation stability, and cetane number were tested. Emission tests were conducted using a large diesel engine of direct injection type, inline six-cylinder, 4 stroke, turbocharger and intercooler. The oxidized and unoxidized biodiesel blends did not show any difference in density and kinematic viscosity. The oxidation stability of the oxidized biodiesel blends was lower than that of the unoxidized biodiesel blends. In the emission test, the two blends showed almost no difference in the total number of concentration of the micro-particles, and also showed almost no difference in particle size distribution such as nucleation mode and accumulation mode. On the other hand, the oxidized biodiesel blends showed less PM and NOx emission than the unoxidized biodiesel blends.
Keywords: Particulate Matter; Total Particle Number; NO x ; Hydroperoxide; Fatty Acid Methyl Ester; Lower Heating Value
Treatment of biodiesel wastewater by indirect electrooxidation: Effect of additives and process kinetics by Pattaraluk Jaruwat; Wipawan Pitakpoolsil; Mali Hunsom (2090-2096).
Due to the presence of growth inhibitor and high impurity concentration in biodiesel wastewater, both biologicaln and chemical processes are ineffective for treating such wastewater. In this work, biodiesel wastewater was treated by electrooxidation via Ti/RuO2 electrodes in batch and continuous modes. Effects of the additive type, hydrogen peroxide (H2O2) and sodium chloride (NaCl), and concentration on the treatment efficiency, monitored in terms of the reduction in the biological oxygen demand (BOD), chemical oxygen demand (COD) and oil and grease level, were explored. The addition of NaCl gave higher treatment efficiency than H2O2, and both were higher than no addition, due to the continuous generation of the oxidizing chloride species. The removal of almost all the COD and oil and grease and ~95% BOD was obtained in the presence of 0.061 M NaCl at an applied current density of 4.28 mA/cm2 for 7h. In continuous operation mode, the steady state condition was reached within 11 h and the treatment efficiency decreased as the wastewater feed rate increased. By using wastewater feed rate of 2mL/min, approximately 83.56, 61.43 and 91.72% of BOD, COD and oil and grease levels were respectively removed. The rate of pollutant removal fitted a first order reaction for both the batch and continuous operation modes.
Keywords: Biodiesel Wastewater; Indirect Electrooxidation; NaCl
Coupling conversion of methanol and 1-butylene to propylene on HZSM-5 molecular sieve catalysts prepared by different methods by Ting Bai; Xin Zhang; Xiling Liu; Tengfei Chen; Wentao Fan (2097-2106).
A series of HZSM-5 catalysts were synthesized by different methods. The physicochemical properties of the HZSM-5 catalysts were characterized by XRD, SEM, N2 isothermal adsorption-desorption, NH3-TPD, Py-IR and TGA, respectively. The results indicated that different preparation conditions lead to different morphologies, textures and the distribution of acid sites. The nanosized HZSM-5 catalysts exhibited better catalytic reactivity and coke capacity than the micro-sized HZSM-5 because nanosized HZSM-5 had larger specific surface area, higher pore volume, more exposed channels and more accessible acid sites. The large particles of NZ-3 in a reasonable range and the smooth surface were conducive to product diffusion; therefore, NZ-3 exhibited higher specific propylene yield and stability than the other nanosized catalysts. The moderate density and distribution of acid sites on NZ-3 also favored the formation of propylene.
Keywords: Methanol; 1-Butylene, Propylene; HZSM-5 Zeolite; Morphology; Acidity
Recovery and reuse of TiO2 photocatalyst from aqueous suspension using plant based coagulant - A green approach by Arunkumar Patchaiyappan; Sarangapany Saran; Suja Purushothaman Devipriya (2107-2113).
Separation of TiO2 from aqueous suspension is a major constraint in heterogeneous photocatalytic water treatment. As an alternative for existing less effective immobilization techniques, the application of plant based coagulant for the recovery and reuse of TiO2 was investigated for the first time. Aqueous extract derived from seeds of Strychnos potatorum was found to be an effective coagulant for the sedimentation of TiO2. Further, the potential for recovery and reuse of the sedimented photocatalysts TiO2, was investigated by photocatalytic degradation of rhodamine B and terephthalic acid tests. The photocatalytic degradation experiments with recovered catalyst obey pseudo first-order kinetics with enhanced photocatalytic activity than that of the pure TiO2. The investigation of recovered catalysts with XRD, BET, SEM etc., suggests that there is no change in surface and morphological properties when compared with pure TiO2 and the recovered catalysts are highly suitable for recycle and reuse.
Keywords: Titanium Dioxide; Flocculation and Coagulation; Plant Coagulants; Reuse of Photocatalyst; Strychnos potatorum
Adsorptive removal of nickel(II) ions from aqueous environments using gum based and clay based polyaniline/chitosan nanobiocomposite beads and microspheres: Equilibrium, kinetic, thermodynamics and ex-situ studies by Lina Rose Varghese; Devlina Das; Nilanjana Das (2114-2126).
The present study was carried out using gum (Ga) based and clay (MMT) based nanobiocomposite beads and microspheres composed of polyaniline NPs (PANI) and chitosan (Ch) as adsorbent for the removal of Ni(II) ions from aqueous environments. Under optimized conditions maximum Ni(II) removal 98.12% was exhibited by clay based nanobiocomposite (PANI-Ch-MMT) beads followed by gum based nanobiocomposite (PANI-Ch-Ga) beads (95.02%), PANI-Ch-MMT microspheres (85.12%) and PANI-Ch-Ga microspheres (75.23%). Equilibrium studies suggested a homogeneous mode of Ni(II) adsorption. Better applicability of pseudo-first order kinetic model suggested physisorption as the underlying phenomenon. Thermodynamic studies showed that adsorption was endothermic and spontaneous. The mechanism of adsorption by PANI-Ch-MMT and PANI-Ch-Ga beads was elucidated using SEM, EDX and FT-IR analyses. Ex-situ studies showed a maximum Ni(II) removal of 80.55% from mining wastewater using PANI-Ch-MMT beads in column mode. Regeneration studies suggested that PANI-Ch-MMT beads could be consistently reused up to five cycles.
Keywords: Adsorption; Chitosan (Ch); Polyaniline NPs (PANI); Nickel(II); Wastewater
Tuning surface-active properties of bio-surfactant sophorolipids by varying fatty-acid chain lengths by Changha Ahn; Vivek Kumar Morya; Eun-Ki Kim (2127-2133).
Sophorolipids are a kind of glycolipid-based bio-surfactant, and some known yeasts can produce them by utilizing plant oil at elevated glucose. In spite of a high production yield, sophorolipids have a limited industrial application, due to their narrow range of HLB (hydrophile - lipophile balance) value. These molecules have regained the attention of researchers and industrialists due to their surface properties and versatile applicability in herbal medicine and cosmetics. The bioactivity and surface properties of sophorolipids are mainly governed by chain length and type of the fatty acid. Therefore, the present study was designed to produce and characterize sophorolipids with varying fatty acid chain lengths. Surface-properties like critical micelle concentration of produced sophorolipids were varying from 43 to 62 (dyne/cm). Foamability, dispersion power, and detergence were found to be higher for short chained fatty acids than the longer ones. Cleaning ability of sophorolipid for FLUX coated PCB was found to be better than the chemical surfactants. Biodegradation rates of the sophorolipids were found to be higher than of the linear alkylbenzene sulfonate (LAS) at room temperature as well as 4 oC. These results showed that the properties of sophorolipids can be tuned by varying the chain’s properties of fatty acids, and it may be possible to customize the properties of sophorolipids for specific industrial applications.
Keywords: Sophorolipids; Candida bombicola ; Foamability; Dispersion Power; Detergency
Effects of ball milling on structural changes and hydrolysis of lignocellulosic biomass in liquid hot-water compressed carbon dioxide by Xiaoliang Yuan; Shijie Liu; Guangrong Feng; Yingying Liu; Yongdan Li; Houfang Lu; Bin Liang (2134-2141).
Mechanical activation is an effective method for destroying the crystalline structure. Biomass, especially its hemicellulose, can be degraded in the green solvent of liquid hot-water compressed carbon dioxide. To improve the degradation of crystalline cellulose in liquid hot-water compressed carbon dioxide, pretreatment of camphorwood sawdust by mechanical activation with a stirring ball mill was studied. Ball milling parameters and their effects on structure were determined by SEM, XRD and FT-IR. The influence of milling parameters on cellulose conversion can be ranked as follows: ball milling speed>activation time>the mass ratio of ball to biomass. The optimum milling condition was obtained at ball milling speed of 450 rpm and mass ratio of 30: 1 of ball to biomass for 2 h. In this condition, cellulose crystallinity of sawdust decreased from 60.93% to 21.40%. The cellulose conversion was 37.8%, which was nearly four times of raw material (10.2%). The glucose yield in the hydrolysate was 1.49 g·L−1, which was nearly three times of that of raw material. It showed mechanical activation can destroy the crystalline structure of cellulose to promote degradation and the damage of lignocellulosic internal structure caused by ball milling is irreversible.
Keywords: Mechanical Activation; Biomass Pretreatment; Cellulose; Crystalline Structure; Carbon Dioxide Hydrolysis
Coal and solvent properties and their correlation with extraction yield under mild conditions by Kihong Kim; Heechan Cho; Sihyun Lee; Myoungwook Mun; Deayang Lee (2142-2159).
Coal solvent extraction is a clean coal technology that involves the extraction of organic matter from coal using solvents. In this study, the effects of various coal and solvent properties on extraction yield were studied and their correlations were observed. Solvent extraction was performed for fifteen coal samples of different ranks with eight solvents under mild conditions. Statistical analyses were then conducted to find correlations between the extraction yields and the coal and solvent characteristics. The extraction yield was strongly correlated with the atomic H/C ratio or volatile matter content. Among the solvent properties, the correlation between the electron donor, acceptor number (DN-AN) and yield was confirmed to be high. The results of multiple regression showed that positive correlations were found with the content of volatile matter of coal and polar force, DN-AN of solvent. Whereas negative correlations were found with the Ca/Mg content of coal and dispersion force, hydrogen bonding force of solvent. The regressionequation- calculated value was similar to the experimental value.
Keywords: Coal; Solvent Extraction; Extraction Yield; Extraction Factor; Multiple Regression
Vacuum enhanced membrane distillation for trace contaminant removal of heavy metals from water by electrospun PVDF/TiO2 hybrid membranes by Rasoul Moradi; Saeed Mahruz Monfared; Younes Amini; Abolfazl Dastbaz (2160-2168).
Electrospun hybrid membranes were synthesized using electrospinning of Poly (vinylidenefluoride) - titanium tetraisopropoxide (PVDF-TTIP) sol. Asymmetric post-treatment of membrane conducted for deprotonation of titanate and making hydrophilic/hydrophobic dual characteristics. The membranes were characterized by various methods such as wettability, scanning electron microscopy, infrared spectroscopy, X-ray diffraction and liquid entry pressure tests. For evaluating the separation performance, these membranes were applied in the VMD process to treat water heavy metal contaminants. The effects of operating parameters such as flow rate, temperature and membrane properties as porosity, on contaminant removal and producing ultra-pure water have been studied.
Keywords: Vacuum Membrane Distillation; PVDF/TiO2 ; Hydrophobic Membrane; Permeability Measurement; Electrospinning; Metal Removal
Computational fluid dynamics simulation and particle image velocimetry experimentation of hydrodynamic performance of flat-sheet membrane bioreactor equipped with micro-channel turbulence promoters with micro-pores by Fang Xie; Jinrong Liu; Jianmin Wang; Weiwei Chen (2169-2178).
We propose a new type of micro-channel turbulence promoter with micro-pores (MCTP-MPs) which is configured on the flat-sheet membrane surface to decrease membrane fouling and reduce energy consumption. The computational fluid dynamics (CFD) simulation and particle image velocimetry (PIV) experiment are employed to predict turbulent flow in a flat-sheet membrane channel equipped with MCTP-MPs. Velocity profiles and wall shear stresses on membrane surface obtained from PIV were compared with the simulated data to validate the reliability of the CFD simulation. The CFD simulation results and PIV experiment results showed that the corrugated MCTP of 300 μm micro-pores crosswise placed on the membrane surface could increase velocity and wall shear stress on the flat-sheet membrane surface, which improved the filtration flux, reduced concentration polarization and mitigated membrane fouling in the meantime.
Keywords: CFD; Flat-sheet Membrane Bioreactor; Micro-channel Turbulence Promoters with Micro-pores; Membrane Fouling; PIV
Liquid-liquid equilibrium data for water-ethanol-entrainer ternary system with entrainers: Cyclohexane, n-pentane, DEE (diethyl ether), DIPE (di-isopropyl ether), ETBE (ethyl tert-butyl ether) by Faraz Qasim; Hyeung Chul Choi; Jae Sun Shin; Sang Jin Park (2179-2185).
The water-ethanol system was studied experimentally to find the liquid-liquid equilibrium (LLE) data at various temperature values by using five different entrainers: cyclohexane, n-pentane, DEE (diethyl ether), DIPE (diisopropyl ether), and ETBE (ethyl tert-butyl ether). Ternary LLE data for water-ethanol-entrainer system was determined based on an experimental procedure. Exact liquid activity coefficient parameters were found by experimental data and LLE data was predicted. For this purpose, two thermodynamic models, NRTL and UNIQUAC, were compared and contrasted with experimental data to probe into the better thermodynamic model for the azeotropic processes of ethanol system. The most promising entrainer was found through root mean square and average absolute deviations.
Keywords: Liquid-liquid Equilibrium (LLE) Data; NRTL; UNIQUAC; Entrainer; Average Absolute Deviation; Root Mean Square Deviation
13C NMR analysis of C2H6+C2H4+THF mixed hydrate for an application to separation of C2H4 and C2H6 by Jeasung Park; Seong-Pil Kang; Jong-Won Lee (2186-2190).
Mixed hydrates (C2H4+5.56mol% THF, and C2H4+C2H6+5.56mol% THF) were analyzed using 13C MAS NMR spectroscopy. The hydrates were formed using a variety of feed gas compositions (100% C2H4; 20% C2H4+80% C2H6; 40% C2H4+60% C2H6; 60% C2H4+40% C2H6; and 80% C2H4+20% C2H6). According to the peak identification results, C2H4 molecules can occupy both the small and large cavities in the sI and sII hydrate structures, while C2H6 molecules can occupy only the large cavities of sI. Moreover, the mole fraction of C2H4 in the hydrate matrix was found to increase with increasing feed ratio of C2H4. On the basis of the NMR analysis, a hydrate-based process for separating C2H4 and C2H6 by repeated hydrate formation and dissociation was proposed. For cases with a feed-gas mixture with 20% C2H4 and 80% C2H6, a recovery of more than 88% C2H4 in the gas mixture could be achieved after five cycles of hydrate-based separation.
Keywords: Clathrate Hydrate; Ethane; Ethylene; Tetrahydrofuran; Separation; 13C NMR
Volumetric properties of binary mixtures of 1-butyl-3-methylimidazolium halides with water, methanol or ethanol at 293.15 to 318.15 K by Byung Heung Park (2191-2204).
Densities of nine binary solutions made of one of three 1-butyl-3-methylimidazolium ([bmim]) halides with water, methanol, or ethanol were measured at atmospheric pressure. The compositions of an ionic liquid ([bmim]Cl, [bmim]Br, or [bmim]I) were increased up to 0.4 as a mole fraction at a given temperature within a range of 293.15 to 318.15 K. The measured values were correlated by a quadratic equation to obtain a temperature dependency of the respective systems. Furthermore, the equation was used to obtain the volume expansivity, which would be used for a pressure-volume-temperature behavior of a condensed phase. The apparent molar volumes were also calculated from the experimental data. The remarkable distinction of the volumetric property behavior between aqueous and nonaqueous solutions was found and attributed to strong ion–solvent interactions in the aqueous systems.
Keywords: 1-Butyl-3-methylimidazolium Halides; Ionic Liquid Mixtures; Densities; Volume Expansivity
Continuous biosorption of U(VI) and Fe(II) using Cystoseira indica biomass packed bed column: Breakthrough curves studies in single, binary and multi-component systems by Ali Talebian; Ali Reza Keshtkar; Mohammad Ali Moosavian (2205-2214).
Ca-pretreated Cystoseira indica algae was used as a biosorbent for the biosorption of U(VI) and Fe(II) ions in single, binary and multi-component systems by using a packed bed column. Experiments were conducted to study the effect of important design parameters such as bed height and flow rate. FTIR and XRF analyses and pH and Ca2+ ion concentration recordings showed that the biosorption of U(VI) and Fe(II) proceeded through ion-exchange mechanism. BDST, Thomas and Modified dose-response models were used for predicting breakthrough curves and for estimations of the parameters necessary for the design of a large-scale packed bed column.
Keywords: Biosorption Mechanism; U(VI); Fe(II); Packed Bed Column; Cystoseira indica Algae
Effect of pyrolytic temperature on the adsorptive removal of p-benzoquinone, tetracycline, and polyvinyl alcohol by the biochars from sugarcane bagasse by Guoting Li; Weiyong Zhu; Lingfeng Zhu; Xiaoqi Chai (2215-2221).
Sugarcane bagasse was pyrolyzed under oxygen-limited conditions from 100 to 600 °C and used for the adsorptive removal of oxidation intermediate p-benzoquinone, tetracycline, and polyvinyl alcohol. The three organic pollutants have different polarities and solubilities. The carbon content increased from 57.7% of the raw bagasse to 75.3% of the biochar pyrolyzed at 600 °C, while the O content decreased from 13.2% to 6.1%. Accordingly, the biochar surface became more hydrophobic with increasing pyrolytic temperature. Interestingly, the adsorption affinity of biochars towards the three pollutants improved with an increase in the pyrolytic temperature. The adsorption of tetracycline molecules was almost unaffected by its being negatively charged with increasing solution pH. A mechanism of π-π electron-donor-acceptor interaction might contribute to the adsorption of tetracycline and p-benzoquinone, while H-bond interaction between polyvinyl alcohol and the biochar might be dominant during adsorption. The Elovich model fitted the kinetic model well, indicating that the diffusional rate-determining step was more pronounced. An isotherm study indicated that the contribution of partitioning was also dominant in the adsorption processes. Wide application of the prepared biochars is expected for the efficient adsorptive removal of organic pollutants.
Keywords: Biochar; Sugarcane Bagasse; Pyrolytic Temperature; Adsorption; Micropollutants
Biocompatibility of cobalt iron oxide magnetic nanoparticles in male rabbits by Tanveer Ahmad Tabish; Muhammad Naeem Ashiq; Muhammad Azeem Ullah; Shahid Iqbal; Muhammad Latif; Muhammad Ali; Muhammad Fahad Ehsan; Furhan Iqbal (2222-2227).
Present study was conducted to study the in vivo biocompatibility of cobalt iron oxide magnetic nano-particles (CoFe2O4 MNPs) in rabbits. CoFe2O4 MNPs were synthesized by the conventional micro emulsion technique in crystallite size range of 30 to 50 nm. The lattice constant (a) and cell volume were found to be 8.386 Å and 589.75 Å3, respectively, revealed by XRD. Subject animals were divided in three groups—low dose, high dose and control group without nanoparticles implantation for biocompatibility evaluation. CoFe2O4 was intraperitoneally implanted in rabbits: low dose (1mg CoFe2O4/Kg body weight) and high dose (10mg CoFe2O4/Kg body weight). Blood, serum and histological study of vital organs (liver, heart, kidney and spleen) were carried out in seven days of time protocol after sacrificing of animals. Results indicated that CoFe2O4 had drastically affected the blood chemistry in a dose-dependent manner as RDWa (P=0.01), Platelet (P<0.001) and Plateletcrit (P<0.001) concentrations reduced significantly in low dose and high dose CoFe2O4 treatments as compared to sham treated control group. Histological analysis revealed that CoFe2O4 exposure resulted in disordered and abnormal histology of liver, kidney and that of muscles at surgical site. It is concluded that CoFe2O4 has low biocompatibility and higher toxicity levels in living system at the applied doses.
Keywords: CoFe2O4 ; Micro Emulsion Synthesis; Male Rabbit; Hematology; Serum Biochemistry; Histology
Hierarchically nanostructured carbon-supported manganese oxide for high-performance pseudo-capacitors by Xinhua Huang; Miri Kim; Hongsuk Suh; Il Kim (2228-2234).
We developed 3-D network carbon materials by directly pyrolyzing as-prepared polynaphthalene (PNT). The PNT-based materials were synthesized from chloromethylated naphthalene and were self-polymerized using anhydrous aluminum chloride as the Friedel-Crafts catalyst and chloromethyl methyl ether as a crosslinker. The micro-, meso-, and macroporous 3-D carbon materials showed large specific surface areas, large electrolyte-electrode interface areas, and continuous electron transport paths. MnO2/carbon composites were then synthesized by chemically depositing MnO2 onto the carbon substrate surfaces through a self-limiting redox reaction between KMnO4 solution and carbon substrates, producing high-performance pseudo-capacitor electrodes. The unique electrode architecture demonstrated high capacitance up to 286.8 F g-1, and good cycling stability up to 1000 cycles without losing its capacitance. The electrode shows potential applications for the development of high-performance supercapacitors for a variety of power-demanding devices.
Keywords: Capacitor; Carbon Materials; Composite; Metal Oxide; Network Structure; Polynaphthalene
Electrolytic reduction rate of porous UO2 pellets by Min Ku Jeon; Eun-Young Choi; Sung-Wook Kim; Sang-Kwon Lee; Hyun Woo Kang; Sun Seok Hong; Jeong Lee; Jin-Mok Hur; Sang-Chae Jeon; Ju Ho Lee; Yung-Zun Cho; Do-Hee Ahn (2235-2239).
The electrolytic reduction rate of porous UO2 pellets in a LiCl salt was investigated for various applied charges. The degree of reduction (α) value was evaluated from the ratios of cross-sectional areas of the reduced and oxide parts. An analysis of the experimental results revealed that the first-order reaction model is the best geometry function to describe the reduction reaction. An electrolytic reduction rate equation was proposed using the first-order model, although it was available in a limited region of (0≤α≤0.56). A power law based reaction rate equation was also suggested for the whole range of α, and the reaction time for a complete reduction, estimated using the power law equation, was confirmed through the experimental results. Changes in the Li-Li2O concentration around the reduced pellets for various applied charges were also measured, which increased up to 23 wt% with increasing α.
Keywords: Electrolytic Reduction; Reaction Rate; Pyroprocessing; Uranium Dioxide; Reaction Model
Detection of gas-solid flow faults of a circulating fluidized bed using pressure fluctuations in wind caps by Hua-wei Jiang; Jian-qiang Gao; Hong-wei Che; Jun-fu Lu; Fu-mao Wang; Yang Wang; Zhen-xin Wu (2240-2251).
Wind cap partial blockages and agglomeration are two of the most common gas-solid flow faults that occur under the actual operations of circulating fluidized bed boilers. Using the method of measuring pressure fluctuations, for the characterization of fluid dynamics in fluidized beds, has a great advantage, due to its flexible adaptation to any operating conditions to monitor fluidization. This paper presents research into the use of measuring and analyzing pressure fluctuations in wind caps, for the analysis of the gas-solid fluidization characteristics in a fluidized bed with wind cap partial blockages or agglomeration fault. Partial blockages in a wind cap near feeding side and partial blockages in another wind cap near recycling side as well as agglomeration of different extents were simulated in a cold circulating fluidized bed. Pressure fluctuations in the inlets of several wind caps were measured at different primary air velocities under different fault conditions. They were then analyzed with the methods of statistical average, standard deviation, wavelet analysis and homogeneous index. Based on the calculated characteristic parameters, the effects of gas-solid flow faults on the gas-solid fluidization characteristics were analyzed. Results showed that variations of characteristic parameters of pressure fluctuations were related to variations of the gas-solid flow condition, which were caused by wind cap partial blockages or agglomerations. It is shown that the proposed method is practical.
Keywords: Gas-solid Flow; Circulating Fluidized Bed; Wind Cap Partial Blockages; Agglomeration; Pressure Fluctuation