Korean Journal of Chemical Engineering (v.34, #6)
Recent advancements in bioreactions of cellular and cell-free systems: A study of bacterial cellulose as a model by Muhammad Wajid Ullah; Mazhar Ul Islam; Shaukat Khan; Nasrullah Shah; Joong Kon Park (1591-1599).
Conventional approaches of regulating natural biochemical and biological processes are greatly hampered by the complexity of natural systems. Therefore, current biotechnological research is focused on improving biological systems and processes using advanced technologies such as genetic and metabolic engineering. These technologies, which employ principles of synthetic and systems biology, are greatly motivated by the diversity of living organisms to improve biological processes and allow the manipulation and reprogramming of target bioreactions and cellular systems. This review describes recent developments in cell biology, as well as genetic and metabolic engineering, and their role in enhancing biological processes. In particular, we illustrate recent advancements in genetic and metabolic engineering with respect to the production of bacterial cellulose (BC) using the model systems Gluconacetobacter xylinum and Gluconacetobacter hansenii. Besides, the cell-free enzyme system, representing the latest engineering strategies, has been comprehensively described. The content covered in the current review will lead readers to get an insight into developing novel metabolic pathways and engineering novel strains for enhanced production of BC and other bioproducts formation.
Keywords: Biochemical Reactions; Biological Systems; Genetic Manipulation; Metabolic Engineering; Bacterial Cellulose
Controlled drug release in silicone adhesive utilizing particulate additives by Ji Eun Lee; Gyeong-Hyeon Gwak; Hyeon Mo Cho; Cheol Hyun Kim; Myong Euy Lee; Jae-Min Oh (1600-1603).
Polydimethylsiloxane (PDMS) based adhesives were prepared by cross-linking tetraethoxyorthosilicate (TEOS) while controlling stoichiometry with PDMS, acid catalyst, and water. Particulate additives, alginate and bentonite, were added during the cross-linking process. Cationic drug lidocaine was incorporated into the adhesive with or without additive, and the time-dependent drug release profile was evaluated in phosphate buffered saline and ethanol, respectively. According to kinetic fitting to power function and parabolic diffusion, both solvent and additive type influenced drug release. In particular, particulate additives were found to suppress or facilitate drug release in water or ethanol, respectively.
Keywords: Silicone Adhesive; Particulate Additives; Lidocaine; Release Media; Release Kinetic
Feasibility study and benefit analysis of biomass-derived energy production strategies with a MILP (mixed-integer linear programming) model: Application to Jeju Island, Korea by Minji Lee; Jiyong Kim (1604-1618).
We developed a new approach to analyze the feasibility and benefits of biomass utilization strategies for energy production. To achieve this goal, we first generated a biomass-to-energy network which consists of different conversion technologies and corresponding compounds. We then developed new optimization models using a mixed integer linear programming technique to identify the optimal and alternative strategies and point out their major cost drivers. We applied these models to the biomass-derived energy supply problem on Jeju Island, Korea, to answer a wide range questions related to biomass utilization. What is the cheapest way to produce liquid fuels from available biomass on Jeju Island? How much demand can be satisfied by biomass-derived liquid fuels? What combination of technologies and biomass resources gives the best economic benefits or productivity? Based on the case study of Jeju Island, we could provide useful guidelines to policy-makers and stakeholders in the energy business.
Keywords: Biomass; Energy Production; Optimization; MILP; Korea
Technology development for the reduction of NOx in flue gas from a burner-type vaporizer and its application by Jeongeun Son; Huicheon Yang; Geonjoong Kim; Sungwon Hwang; Hyunseok You (1619-1629).
We developed a modified process of a submerged combustion vaporizer (SMV) to remove nitric oxides (NOx) efficiently from flue gas of the SMV at liquefied natural gas (LNG) terminals. For this, excess oxygen is injected into exhaust gas that contains NOx from SMV burner. Then, the mixed gas spreads into a hydrogen peroxide solution or water bath. We initially performed experiments of the modified system to estimate the effect of various process variables (temperature, excess O2 concentration, pH of water, residence time of flue gas in water tank, and H2O2 concentration) on NOx conversion, and developed a mathematical model of the system based on the experiment results. Lastly, we confirmed higher performance of the modified system and validated the feasibility for its field application.
Keywords: deNOx; Modeling; Optimization; Submerged Combustion Vaporizer; Kinetic
Computational fluid dynamics study on the anode feed solid polymer electrolyte water electrolysis by Shuguo Qu; Guanghui Chen; Jihai Duan; Weiwen Wang; Jianlong Li (1630-1637).
A steady-state two-dimensional model for the anode feed solid polymer electrolyte water electrolysis (SPEWE) is proposed in this paper. Finite element procedure was employed to calculate the multicomponent transfer model coupled with fluid flow in flow channels and gas diffusion layers and electrochemical kinetics in catalyst reactive surface. The performance of the anode feed SPEWE predicted by this model was compared with the published experimental results and reasonable agreement was reached. The results show that oxygen mass fraction increases because of the water oxidation when water flows from the import to the export on the anode side. On the cathode side, hydrogen mass fraction varies little since hydrogen and water mix well. The flux of water across the electrolyte increased almost linearly with the increase of the applied current density. Since the ohmic overpotential loss increasing as the solid polymer electrolytes’ thickness increasing, the performance of the anode feed SPEWE with Nafion 112, 115, 117 decreases at the same applied current density.
Keywords: Computational Fluid Dynamics; Anode Feed Solid Polymer Electrolyte Water Electrolysis; Finite Element Method
Performance of fly ash based polymer gels for water reduction in enhanced oil recovery: Gelation kinetics and dynamic rheological studies by Ahmad Akanbi Adewunmi; Suzylawati Ismail; Abdullah Saad Sultan; Zulkifli Ahmad (1638-1650).
The complexity of well and reservoir conditions demands frequent redesigning of water plugging polymer gels during enhanced oil recovery (EOR). In the present study, we developed coal fly ash (CFA) based gels from polyacrylamide (PAM) polymer and polyethyleneimine (PEI) crosslinker for water control in mature oil fields. The CFA acts as an inorganic additive to fine-tune gelation performance and rheological properties of PAM/PEI gel system. Hence, effects of various CFA (0.5 to 2 wt%), PAM (2 to 8.47 wt%) and PEI (0.3 to 1.04 wt%) concentrations on gelation kinetics and dynamic rheology of pure PAM/PEI gel and PAM/PEI-CFA composite gels were studied at a representative reservoir temperature of 90 oC. Experimental results reveal that gelation time of pure PAM/PEI gel increases with increasing CFA addition. Further observation demonstrates that increasing PAM and PEI concentrations decreases the gelation times of PAM/PEI-CFA composite gels. Gelation time was found to be within 3-120 hours. Understanding the property of reaction order enables better prediction of gelation time. Dynamic rheological data show that viscoelastic moduli (G′ and G″) of various PAM/PEI-CFA composite gels improved better as compared to the pure PAM/PEI gel across the strain-sweep and frequency-sweep tests. SEM analysis of selected samples at 72 hours and 720 hours of gelation activity consolidated gelation kinetics and dynamic rheological results. These polymer gels are excellent candidates for sealing water thief zones in oil and gas reservoirs.
Keywords: Fly Ash; Polymers; Reaction Order; Water Shutoff; Gelation; Oil Recovery
Perovskite-type LaFe1− x Mn x O3 (x=0, 0.3, 0.5, 0.7, 1.0) oxygen carriers for chemical-looping steam methane reforming: Oxidation activity and resistance to carbon formation by Kun Zhao; Fang He; Zhen Huang; Guoqiang Wei; Anqing Zheng; Haibin Li; Zengli Zhao (1651-1660).
The effects of Mn substitution of LaMn x Fe1−x O3 (x=0, 0.3, 0.5, 0.7, 1.0) on the oxidation activity and resistance to carbon formation for chemical-looping steam methane reforming (CL-SMR) were investigated. The desired crystalline perovskite phases were formed by transferring from the orthorhombic structure of LaFeO3 to rhombohedral lattice of LaMnO3 as the degree of Mn-doping increased. Manganese ions have a mixed state of Mn3+ and Mn4+ in the LaFe1−x Mn x O3, meanwhile inducing the states of highly mixed character of Fe2+, Fe3+ and Fe4+ in iron ions. Substitution of Mn for Fe with proper value not only increases the lattice oxygen, which is conducive to the partial oxidation of CH4 to produce syngas, but also enhances the lattice oxygen mobility from the bulk to the surface of the oxygen carrier particles. Judging from the points of the redox reactivity, resistance to carbon formation and hydrogen generation capacity, the optimal range of the degree of Mn substitution is x=0.3–0.5.
Keywords: Perovskite; CL-SMR; Manganese; Carbon Formation; Hydrogen
Esterification of acrylic acid with ethanol using pervaporation membrane reactor by Ghoshna Jyoti; Amit Keshav; Jayapal Anandkumar (1661-1668).
Esterification of acrylic acid with ethanol was carried out using an in-situ reactor with an integrated pervaporation assembly (IPAE) made of polyvinyl alcohol (PVA) membrane and was compared with a non-integrated (NIE) system. Effect of reaction temperature (T r ), catalyst loading (C C ), molar ratios of reactants (MR) and ratio of effective membrane area to unit volume of reaction mixture (S/V o ) on kinetics of esterification reaction were studied. Conversions achieved in IPAE were found to be distinctly higher than the NIE. The highest conversion of acrylic acid was obtained as 83.3% at T r =60 °C, M R =3 : 1, C C =2% and S/V o =14.1 m−1. Equilibrium conversion of acrylic acid in NIE was obtained as 55.1% at 60 °C, 1 : 1 in 7 h, while using IPAE conversion enhances to 67.6%. Esterification of acrylic acid and ethanol with presently studied operating parameters provides a new approach to existing literature reported esterification-pervaporation system.
Keywords: Pervaporation; Acrylic Acid; Esterification; Kinetics; Equilibrium
Effective photoconversion of CO2 into CH4 over Ti30Si70MCM-41 nanoporous catalyst photosensitized by a ruthenium dye by Younghwan Im; Jae Hyung Lee; Misook Kang (1669-1677).
Nanoporous Ti30Si70MCM-41 was applied as a photocatalyst for effective reduction of CO2 to CH4. A ruthenium dye (N719) was also introduced onto the surface of Ti30Si70MCM-41 as a photosensitizer to improve its photoabsorption in the visible range. The catalytic performance of N719-photosensitized Ti30Si70MCM-41 was superior to that of the non-photosensitized Ti30Si70MCM-41 and N719-photosensitized Ti30Si70O200 nanomaterials. The photoreduction of CO2 to CH4 was remarkably improved on N719-(5 h)-photosensitized Ti30Si70MCM-41, with a production of 1,900 μmol g cat −1 L−1 after an 8 h reaction. The results were attributed to the effective charge separation and the inhibited recombination of photogenerated electron-hole pairs on N719-photosensitized Ti30Si70MCM-41. Lastly, a model for the enhanced photoactivity over N719-photosensitized Ti30Si70MCM-41 was proposed.
Keywords: Ruthenium dye; N719-photosensitized-Ti30Si70MCM-41; CO2 Photoreduction; CH4 Production; Nanoporous; Recombination of Electron-hole Pairs
Determination of thermal decomposition kinetics of low grade coal employing thermogravimetric analysis by Prakash Parthasarathy; Hang Seok Choi; Jae Gyu Hwang; Hoon Chae Park (1678-1692).
The decomposition kinetics of low grade coals was studied and compared with the kinetics of higher grade coals using thermogravimetric analysis. The effect of atmospheres (air, O2 and N2) on coal decomposition kinetics was also investigated. Experiments were carried out under non-isothermal conditions from room temperature to 950 °C at a heating rate of 10 °C/min. Three kinetic models—multiple linear regression equation, unreacted shrinking core and continuous reaction—were used to determine the kinetic parameters of coal decomposition. From the kinetic parameters determined through the multiple linear regression equation, coal type and the atmosphere had an effect on coal decomposition kinetics. Also, there was some variation in the kinetic parameters of coal decomposition determined by the chosen kinetic models. However, the model employing multiple linear regressions yielded consistent results with respect to theoretical background. Under air, the order of the secondary decomposition of coal samples was found to be 0.88, 1.33, 1.69 and 1.52 for samples A, B, C and D, respectively. The order of the secondary decomposition of coal samples when operated under O2 was 1.09, 1.45, 2.36 and 1.81 for samples A, B, C and D, respectively. Under N2, the order of the secondary decomposition of coal samples was 0.72, 0.79, 1.15 and 1.02 for samples A, B, C and D, respectively.
Keywords: Low Grade Coal; Decomposition; Thermogravimetric Analysis; Kinetics; Kinetic Parameters
Comparative evaluation of purity of green energetic material (ammonium dinitramide) depending on refining method by Wooram Kim; Younja Kwon; Seong Yun Hwang; Youngmin Jo (1693-1698).
Although the solid propellant, ammonium dinitramide (ADN, NH4N(NO2)2) is safe and thermally stable, it requires high purity for practical commercial applications. Even a small amount of impurities in ADN can create negative effects, including catalyst poisoning and thruster nozzle cloggings when it is used as a liquid propellant. Thus, we explored several purification processes for the precipitated ADN particles, such as repetition extraction, adsorption by activated carbons, and low-temperature extraction. These purifying methods help to improve the chemical purity as evaluated by FTIR, UV-vis, DSC, and IC analyses. Among the purification processes, adsorption was found to be the best method, showing a final purity of 99.768% based on relative quantification by ion chromatography.
Keywords: Green Propellant; Ammonium Dinitramide; Purification; Adsorption
Removal of methylene blue dye from aqueous solutions by a new chitosan/zeolite composite from shrimp waste: Kinetic and equilibrium study by Mohammad Hadi Dehghani; Aliakbar Dehghan; Hossein Alidadi; Maryam Dolatabadi; Marjan Mehrabpour; Attilio Converti (1699-1707).
The adsorption of methylene blue dye (MBD) from aqueous solutions was investigated using a new composite made up of shrimp waste chitosan and zeolite as adsorbent. Response surface methodology (RSM) was used to optimize the effects of process variables, such as contact time, pH, adsorbent dose and initial MBD concentration on dye removal. The results showed that optimum conditions for removal of MBD were adsorbent dose of 2.5 g/L and pH of 9.0, and initial MBD concentration of 43.75 mg/L and contact time of 138.65 min. The initial concentration of dye had the greatest influence on MBD adsorption among other variables. The experimental data were well fitted by the pseudo-second order kinetic model, while the Freundlich isotherm model indicated a good ability for describing equilibrium data. According to this isotherm model, maximum adsorption capacity of the composite was 24.5 mg/g. Desorption studies showed that the desorption process is favored at low pH under acidic conditions.
Keywords: Methylene Blue Dye; Shrimp Wastes; Chitosan; Zeolite
Insight into adsorption mechanism of cationic dye onto agricultural residues-derived hydrochars: Negligible role of π-π interaction by Hai Nguyen Tran; Sheng-Jie You; Huan-Ping Chao (1708-1720).
Hydrochars derived from golden shower pod (GSH), coconut shell (CCH), and orange peel (OPH) were synthesized and applied to remove methylene green (MG5). The results indicated that the hydrochars possessed low specific surface areas (6.65-14.7m2/g), but abundant oxygen functionalities (1.69-2.12mmol/g). The hydrochars exhibited cellular and spherical morphologies. Adsorption was strongly dependent on the solution pH (2-10) and ionic strength (0-0.5M NaCl). Equilibrium can be quickly established in the kinetic study (60-120 min). The maximum Langmuir adsorption capacities at 30 °C followed the order GSH (59.6mg/g)>CCH (32.7mg/g)>OPH (15.6mg/g)> commercial glucose-prepared hydrochar (12.6mg/g). The dye adsorption efficiency was determined by the concentrations of oxygen-containing functionalities on the hydrochar surface. The adsorption process occurred spontaneously (− ΔGo) and exothermically (−ΔHo). Desorption studies confirmed the reversible adsorption process. Oxygenation of the hydrochar surface through a hydrothermal process with acrylic acid contributed to increasing MG5 adsorption and identifying the negligible role of π-π interaction to the adsorption process. The analysis of Fourier transform infrared spectrometry demonstrated that the aromatic C=C peak did not significantly decrease in intensity or shift toward higher/lower wavenumbers after adsorption, which further confirms the insignificant contribution of π-π interaction. Electrostatic attraction played a major role in adsorption mechanisms, while minor contributions were accounted for hydrogen bonding and n-π interactions. The primary adsorption mechanisms of MG5 onto hydrochar were similar to biosorbent, but dissimilar to biochar and activated carbon (i.e., π-π interaction and pore filling).
Keywords: Hydrothermal Treatment; Hydrochar; Adsorption Mechanism; Cationic Dye; Oxygenation Method; π-π Interaction
Effects of co-ion initial concentration ratio on removal of Pb2+ from aqueous solution by modified sugarcane bagasse by Jing Zhu; Jun-xia Yu; Jia-dong Chen; Jie-sen Zhang; Jia-qi Tang; Yuan-lai Xu; Yue-fei Zhang; Ru-an Chi (1721-1727).
A modified sugarcane bagasse (SCB) fixed bed column was used to remove Pb2+ from aqueous solution. To determine the optimal condition for Pb2+ separation, Ca2+ was chosen as the model interfering ion, and effects of Ca2+ and Pb2+ initial concentration ratio (C 0 Ca : C 0 Pb ) on the adsorption of Pb2+ were investigated. Results showed that adsorption amount ratio of Ca2+ and Pb2+ (q e Ca : q e Pb ) had a good linear relationship with C 0 Ca : C 0 Pb . Mass ratio of Pb2+ absorbed on the modified SCB was higher than 95% at C 0 Ca : C 0 Pb <1.95, illustrating that Pb2+ could be selectively removed from aqueous solution. To verify that, simulated waste water containing co-ions of K+, Na+, Cd2+ and Ca2+ was treated, and results showed that the equilibrium amount of Pb2+, K+, Na+, Cd2+ and Ca2+ adsorbed was 134.14, 0.083, 0.058, 1.28, and 1.28mg g−1, respectively, demonstrating that the modified SCB could be used to remove Pb2+ from aqueous solution in the investigated range.
Keywords: Sugarcane Bagasse; Fixed Bed Column; Adsorption; Pb2+ ; Ca2+
Development of Cre-lox based multiple knockout system in Deinococcus radiodurans R1 by Sun-Wook Jeong; Jung Eun Yang; Seonghun Im; Yong Jun Choi (1728-1733).
The extremophilic bacterium Deinococcus radiodurans R1 has been considered as an attractive microorganism due to its remarkable tolerance to various external stresses. Considering the nature of D. radiodurans R1, it has potential as a platform microorganism for industrial applications, including biorefinery and bioremediation process. However, D. radiodurans R1 is well known for its hard genetic manipulation. Thus, much effort has been made to develop efficient genetic engineering tools for making D. radiodurans R1 suitable for industrial platform microorganism. Although a plasmid-based single gene knockout method has been reported, development of multiple gene knockout system has not yet been reported. Here we report, for the first time, Cre-lox based rapid and efficient multiple knockout method for metabolic engineering of D. radiodurans R1. Also, deletion of dr0053 gene was successfully achieved within seven days to make biofilm overproducing strain.
Keywords: Deinococcus radiodurans R1; Cre-lox ; Multiple Knockout Method; Genetic Engineering; Biofilm Production
Construction of methanol sensing Escherichia coli by the introduction of novel chimeric MxcQZ/OmpR two-component system from Methylobacterium organophilum XX by Vidhya Selvamani; Murali Kannan Maruthamuthu; Kulandaisamy Arulsamy; Gyeong Tae Eom; Soon Ho Hong (1734-1739).
Methylobacterium organophilum XX is a type II facultative methylotroph that can grow on methanol. In M. organophilum XX, the MxcQ/MxcE two-component system (TCS) is involved in methanol metabolism. EnvZ/OmpR in E. coli TCS was exploited to develop a methanol biosensor by engaging the MxcQ/MxcE TCS system. The MxcQZ/OmpR methanol sensing chimeric TCS was constructed by integrating the sensing domain of M. organophilum MxcQ with the transmitter domain of E. coli EnvZ. The response regulator of the chimeric TCS system is OmpR, which regulates the expression of the ompC and gfp. The expression of ompC was monitored by real-time quantitative PCR analysis. The expression of gfp also confirmed the expression of the ompC. The maximum expression of ompC and gfp occurred with 0.05% of methanol, and the expression started to decline with further increases in methanol concentration. This system delivers rapid detection of methanol in the environment.
Keywords: Biosensors; Chimeric Two-component System; Fluorescence Sensors; Methanol; Synthetic Biology
Synergistic extraction of Nd(III) with mixture of 8-hydroxyquinoline and its derivative with di-2-ethyl hexyl phosphoric acid in different diluents by Sutanuka Roy; Sukalyan Basu; Mallavarapu Anitha; Dhruva Kumar Singh (1740-1747).
Solvent extraction of neodymium (III) from chloride medium with synergistic mixture of 8-hydroxyquinoline or 2-methyl-8-hydroxyquinoline and di-2-ethyl hexyl phosphoric acid was investigated in different diluents. Effect of various experimental parameters such as pH, extractant concentration, diluents and temperature was studied. Role of diluents on extraction of neodymium is explained in terms of activity coefficient adopting Hildebrand regular solution theory. The negative value of enthalpy change suggests that the extraction of ternary system is exothermic. The IR data for the extracted species also substantiated the nature of extracted species as observed by slope analysis method.
Keywords: Neodymium; Synergistic Extraction; D2EHPA; 8-Hydroxyquinoline; Diluent; Ternary Extraction
Ultrasonic-assisted leaching kinetics in aqueous FeCl3-HCl solution for the recovery of copper by hydrometallurgy from poorly soluble chalcopyrite by Ho-Sung Yoon; Chul-Joo Kim; Kyung Woo Chung; Jin-Young Lee; Shun Myung Shin; Sung-Rae Kim; Min-Ho Jang; Jin-Ho Kim; Se-Il Lee; Seung-Joon Yoo (1748-1755).
We studied the ultrasonic effect on the leaching of copper from poorly soluble chalcopyrite (CuFeS2) mineral in aqueous FeCl3 solution. The leaching experiment employed two methods, basic leaching and ultrasonic-assisted leaching, and was conducted under the optimized experimental conditions: a slurry density of 20 g/L in 0.1M FeCl3 reactant in a solution of 0.1M HCl, with an agitation speed of 500 rpm and in the temperature range of 50 to 99 °C. The maximum yield obtained from the optimized basic leaching was 77%, and ultrasonic-assisted leaching increased the maximum copper recovery to 87% under the same conditions of basic leaching. In terms of the leaching mechanism, the overall reaction rate of basic leaching is determined by the diffusion of both the product and ash layers based on a shrinking core model with a constant spherical particle; however, in the case of ultrasonic-assisted leaching, the leaching rate is determined by diffusion of the ash layer only by the removal of sulfur adsorbed on the surface of chalcopyrite mineral.
Keywords: Leaching Kinetics; Poorly Soluble Chalcopyrite Mineral; Basic Leaching; Ultrasonic-assisted Leaching; Ferric Chloride; Shrinking Core Model; Product and Ash Layer Diffusion; Ash Layer Diffusion
Purification of Chinese herbal extract with chitosan hydrochloride: Flocculation of single impurity and flocculation mechanism by Xiaojiao An; Yong Kang; Li Qin; Yajing Tian; Guishui Li (1756-1762).
Chitosan hydrochloride (CHC) was used for flocculation of impurities (tannin and protein) in Ma-xinggan-shi solution (MSS), which is a Chinese herbal medicine solution (CHMS). To study the flocculation mechanism, simulated solutions of pure tannin and pure protein in water flocculated by CHC were investigated. For MSS flocculation by CHC, flocculation performance was assessed in terms of suspended turbidity, impurities removal rate as well as active components retention rate. CHC showed high capability of maintaining a low turbidity over a wide range of the polymer dosage. The optimum dosage of CHC was 0.6 g/L in base of different solution turbidity, and it also demonstrated the retention rate of total soluble polysaccharide (TSP) and ephedrine reached 78.4% and 92%, respectively.
Keywords: Chitosan Hydrochloride; Chinese Herbal Medicine Solution; Flocculation Mechanism; Tannin; Protein
Efficient pressure swing adsorption for improving H2 recovery in precombustion CO2 capture by Jehun Park; Rai H. Kang; Jae W. Lee (1763-1773).
An efficient design for pressure swing adsorption (PSA) operations is introduced for CO2 capture in the pre-combustion process to improve H2 recovery and CO2 purity at a low energy consumption. The proposed PSA sequence increases the H2 recovery by introducing a purge step which uses a recycle of CO2-rich stream and a pressure equalizing step. The H2 recovery from the syngas can be increased over 98% by providing a sufficient purge flow of 48.8% of the initial syngas feeding rate. The bed size (375m3/(kmol CO2/s)) and the energy consumption for the compression of recycled CO2-rich gas (6 kW/(mol CO2/s)) are much smaller than those of other PSA processes that have a CO2 compression system to increase the product purity and recovery.
Keywords: CO2 Capture; Pre-combustion Process; Pressure Swing Adsorption (PSA); H2 Recovery; Purge Step; Pressure Equalizing Step
Adapting the performance and physico-chemical properties of PES nanofiltration membrane by using of magnesium oxide nanoparticles by Sayed Mohsen Hosseini; Ehsan Bagheripour; Mohsen Ansari (1774-1780).
A new mixed matrix Polyethersulfone (PES)-co-Magnesium oxide nanoparticles (MGO) nanocomposite nanofiltration membrane was prepared through phase inversion method by using polyvinylpyrrolidone (PVP) as pore former and N, N dimethylacetamide (DMAc) as solvent. The influence of MGO nanoparticles concentration in the membrane matrix on the separation performance and physico-chemical characteristics of prepared membrane was studied by scanning electron microscopy, surface analysis, porosity measurement, water contact angle, permeability flux, salt rejection, antifouling property, and tensile strength. SEM images exhibited situating of MGO nanoparticles on the top surface of mixed matrix prepared membranes. SEM analysis also showed formation of a dense nanoparticle layer on the surface of prepared membrane at high additive concentration. Surface analysis results that revealed membrane surface roughness was increased initially by addition of MGO and then was decreased. Measured porosity showed reduction behavior for all prepared membranes filled with MGO nanoparticles. The membrane surface hydrophilicity was enhanced 35% by incorporating MGO nanoparticles into the membrane matrix. Results showed that membrane permeation flux was improved 32% by utilizing of MgO nanoparticles into the membrane matrix. Salt rejection was also improved 49% by using MGO nanoparticles in the membrane matrix relatively. The modified membranes filled with different concentrations of MGO nanoparticles showed higher antifouling properties and tensile strength compared to the neat PES membrane.
Keywords: Nanofiltration; Magnesium Oxide Nanoparticles; Hydrophilicity; Separation Performance; Antifouling Behavior
Phase behavior of arbutin/ethanol/supercritical CO2 at elevated pressures by Chang-Nam Han; Choon-Hyoung Kang (1781-1785).
The phase behavior of a ternary system containing arbutin, which is effective for skin lightening, in a solvent mixture of ethanol and supercritical carbon dioxide (CO2) was investigated. A high-pressure phase equilibrium apparatus equipped with a variable-volume view cell was used to measure the phase equilibrium loci of the ethanol+CO2 binary mixture from 298.2 K to 313.2 K and pressures between 2MPa and 9MPa. The solubility of arbutin in the mixed solvent comprising ethanol and CO2, which equivalently represents the critical locus of T-x, was determined as a function of temperature, pressure, and solvent composition by measuring the cloud points under various conditions. Throughout, the arbutin loading was maintained at 1.5 wt% on a CO2-free basis in the solvent mixture and the pressure and temperature were varied up to 14 MPa and 334 K, respectively. For a CO2 loading less than 34wt% on ethanol basis, the cloud point was not observed. However, the solid remained undissolved when the CO2 loading exceeded 54 wt%. Between these loadings, steep and almost pressure-insensitive solubility curves, which extended downward to the vaporization boundary, were found.
Keywords: Arbutin; Supercritical CO2 ; Cloud Point; Solubility; Mixed Solvent
V2O5-TiO2 heterostructural semiconductors: Synthesis and photocatalytic elimination of organic contaminant by Meltem Isleyen; Eda Sinirtas Ilkme; Gulin Selda Pozan Soylu (1786-1792).
V2O5-TiO2 binary oxide catalysts were successfully prepared with different wt% V2O5 loading by solid state mechanical mixing (SSDMMix), and these nanocomposites were modified with hexadecyltrimethylammonium bromide (HTAB) and cetyl trimethylammonium bromide (CTAB) and polyvinyl alcohol (PVA) as surfactant. The resulting catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Braun-Emmet-Teller (BET) analysis of surface area techniques. The photocatalytic activities of all samples were evaluated by degradation of 4-chlorophenol (4CP) in aqueous solution under UV irradiation. 50 wt% V2O5-TiO2 photocatalyst exhibited much higher photocatalytic activity than pure V2O5, TiO2 and P-25. The interaction between V2O5 and TiO2 affected the photocatalytic efficiency of binary oxide catalysts. In addition, CTAB and HTABassisted samples significantly enhanced the efficiency of 50V2O5-TiO2 binary oxide catalyst. The highest percentage of 4-chlorophenol degradation (100%) and highest reaction rate (1.69mg L−1 min−1) were obtained in 30 minutes with (50V2O5-TiO2)-CTAB catalyst. It is concluded that the addition of surfactant to binary oxide remarkably enhanced the photocatalytic activity by modifying the optical and electronic properties of V2O5 and TiO2.
Keywords: Photocatalysis; 4-Chlorophenol; V2O5-TiO2 ; UV Irradiation; Characterization
A new process of acidic hydrolysis of residual chlorosilane liquid for the preparation of silica and hydrochloric acid by Jixiang Cai; Bing Huang; Qikun Ma; Wenwen Zhang (1793-1800).
We propose a novel process for the preparation of silica and concentrated hydrochloric acid using chlorosilane residual liquid originating from the polysilicon production process. The process was designed and optimized after conducting pilot plant tests. The effects of circulating acid concentration, flow rate, chlorosilane residual liquid treatment load and other factors on silica products were studied. The results showed that the circulating acid flowrate can effectively control the formation of gel, and the amount of chlorosilane residual liquid has significant influence on the hydrolysis efficiency and operation of the hydrolysis tower. The prepared silica was characterized using XRD, XRF, FT-IR, SEM, DLS, TG-MS and N2 adsorption/desorption experiments. The results indicated that silica consisted of amorphous particles, which were spherical, had surface hydroxyl, and showed heterogeneous distribution. The average particle size was 50-80 μm and had high specific surface area (565.049 m2g−1), large pore volume (0.449 cm3g−1), and a narrow pore size distribution (3.419 nm). The new technology provides a simple, efficient and environmentally friendly way for treating chlorosilane residual liquid, as well as a cost-effective method for the preparation of silica.
Keywords: Chlorosilane Residual Liquid; Silica; Hydrochloric Acid; Acidic Hydrolysis Process; Polysilicon
Silver nanoparticle loaded silica adsorbent for wastewater treatment by Vaidyanathan Thamilselvi; Kuravappulam Vedhaiyan Radha (1801-1812).
Our aim was to prepare silver nanoparticle loaded silica adsorbent for the removal of pollutants and pathogens in wastewater. The pathogens were inactivated by silver nanoparticles loaded with silica by wet impregnation method. Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, and X-ray Diffraction studies confirmed the silver nanoparticle loaded on silica. Inductively coupled plasma atomic emission spectroscopy showed 0.6 mg/g silver nanoparticle in the prepared adsorbent. The prepared adsorbent has potential against Escherichia coli and was described through Chick, Chick-Watson and Homs inactivation kinetic models. Five-hundred (500) ppm concentration of the prepared adsorbent showed complete inhibition with the shouldering or lag curve of inactivation and the k′ values of 0.019 min−1. After treatment, tannery, dairy and canteen effluents showed significant COD reduction with maximum adsorption capacity of 145, 142 and 69 mg/g visa versa. Regeneration of the spent adsorbent used alkali washing and reused up to three cycles.
Keywords: Amine Functionalized Silica; Adsorption; Impregnation; Inactivation; Isotherm
Developing thin film heterogeneous ion exchange membrane modified by 2-acrylamido-2-methylpropanesulfonic acid hydrogel-co-super activated carbon nanoparticles coating layer by Mahsa Nemati; Sayed Mohsen Hosseini; Meisam Shabanian (1813-1821).
Highly selective cation exchange membranes were prepared by coating a thin 2-acrylamido-2-methylpropanesulfonic acid based hydrogel layer and super activated carbon nanoparticles-co-hydrogel layer on polyvinyl chloride based cation exchange membranes. FTIR analysis proved hydrogel formation on membrane surface successfully. Scanning electron microscopy images and swelling ratio measurement were used to study the effect of super activated carbon nanoparticles on properties of formed hydrogel. The surface morphology, surface hydrophilicity and roughness analysis were also used in membrane characterization. Membrane water content was increased by formation of modified layer on the membranes surface. Modified membranes showed a remarkable improvement in potential, permselectivity and transport number compared to pristine type. Membrane ionic flux and permeability were improved initially by using modifier layer on membrane surface, and then showed decreasing trend at high nanoparticles loading ratios in hydrogel layer. Modified membranes showed lower electrical resistance compared to unmodified membrane.
Keywords: Cation Exchange; Thin Film; Coating Layer; Hydrogel; Super Activated Carbon Nanoparticles
Enhanced photoactivity of stable colloidal TiO2 nanoparticles prepared in water by nanosecond infrared laser pulses by Yu Kwon Kim; Gyuseong Lee; Yuna Kim; Hyuk Kang (1822-1826).
A simple laser ablation technique was used to prepare a stable colloidal TiO2 suspension in pure water. A transparent TiO2 aqueous solution was obtained within a few minutes and its photoactivity for the degradation of methylene blue was measured to be higher than that of commercial TiO2 nanoparticles. SEM analysis revealed that the average size of the nanoparticles increased from 20 to 40 nm as the laser power was raised from 0.5 to 2 W. The variation in size, however, had little influence on the resulting photodegradation rate under the given condition. Instead, the photodegradation rate is related to the number of colloidal TiO2 particles in the aqueous solution, which increases proportionally to the ablation time. As the TiO2 particle density increases, however, the photoactivity is measured to be gradually reduced due to the formation of TiO2 aggregates. Thus, the optimum ablation time is 10-30 min under our ablation condition. Our results show that well-dispersed small TiO2 nanoparticles of about a few tens nm can be readily formed by laser ablation within only a few minutes and can be used as highly efficient photocatalysts for photocatalytic remediation of water.
Keywords: Laser Ablation; TiO2 Nanoparticles; Photocatalyst; Methylene Blue; Water Remediation
Iso-propanol assisted preparation of individualized functional palygorskite fibers and its impact on improving dispersion abilities in polymer nanocomposites by Lingli Ni; Pengyin Zhang; Jing Chen; Jinglong Jiang; Shijie Ding (1827-1833).
Palygorskite (PAL) as a natural one-dimensional nanomaterial has attracted tremendous attention as reinforcement agent in polymer nanocomposites. But its intrinsic existing form of aggregates or bundles and hydrophilic properties, highly requires an eco-efficient and environmentally benign approach for both of the disaggregation and organo-modification of PAL. We report a facile and effective process to achieve individualized organo-modified PAL fibers. It was carried out through surface modification reactions in the form of PAL iso-propanol gels with various alkyl and functional silanes. In contrast to the modifications in highly toxic solvent of toluene, reactions in iso-propanol make it possible to modify the surface of individual PAL fibers to obtain isolated organo-modified PAL fibers. With such a relatively green procedure, even higher amount of organic substituent has been grafted on to the surface of PAL fibers. Consequently, excellent dispersion of modified PAL nanofibers in acrylate polymer coatings was achieved, which exhibits outstanding corrosion protection properties.
Keywords: Palygorskite; Organosilane; Iso-propanol Gel; Modification; Nanocomposite
Development of osmotic repulsive potential using lattice fluid model on ligand capped metallic nanoparticles in gas expanded liquid system by Seong Rae Noh; Seong-Sik You (1834-1839).
Not only obtaining nano-sized particles, but controlling mono-dispersed nanoparticles has been regarded as one of the important techniques to employ nano-engineering in many disciplines. To fractionate the nanoparticles synthesized, the gas expanded liquid system (GXLs) has proven to be very useful and effective. Many researchers considered the total interaction energy model comprised as a summation of van der Waals attractive potential, the elastic repulsive potential, and the osmotic repulsive potential as a promising thermodynamic model. In previous models, osmotic contribution was modeled based on the rigid lattice model. Consequently, it was impossible to consider the effect of pressure on GXL operation because osmotic repulsive potential based on rigid lattice modal intrinsically could not reflect the pressure influence. We applied a lattice fluid model in the presence of holes to derive better osmotic repulsive potential. Thus, the effect of pressure on nanoparticle synthesis in GXL process has been successfully investigated. A nanoparticle size predicted using this improved model is in a better agreement to that obtained experimentally.
Keywords: Gas Expanded Liquid (GXL); Nanoparticle; Lattice Fluid (LF); Steric Stabilization
Phase separation characteristics in biphasic solvents based on mutually miscible amines for energy efficient CO2 capture by Jun Lee; Yeon Ki Hong; Jong Kyun You (1840-1845).
One of the challenges with regard to the aqueous amine-based CO2 capture process is the considerable energy requirement for solvent regeneration. To overcome this challenge, a biphasic solvent was employed in this study. Here, the phase separation behavior of amine blends depending on the characteristic structures of the solvent component was investigated using a turbidity measurement apparatus. Amines were classified as (1) primary/secondary amines or tertiary/sterically hindered amines depending on the CO2 reaction species, such as carbamate and bicarbonate (2) alkyl and alkanolamines, depending on the presence of a hydroxyl group, (3) chain and cyclic amines, and (4) mono- and polyamines depending on the molecular structure. Easy phase separation occurred in solvent blends containing polyamines such as DETA (diethylenetriamine), TETA (triethylenetetramine), and DEEA (2-(diethylamino) ethanol). The types with the greatest potential were the DETA/DEEA blended solvents. A phase separation could be determined based on the difference in the reaction rate with CO2 and the low solubility between the carbamate species of DETA and DEEA.
Keywords: Biphasic Solvents; Solvent Screening; CO2 Capture; Regeneration; DEEA; DETA
Propagation speed of wrinkled premixed flames within stoichiometric hydrogen-air mixtures under standard temperature and pressure by Zuo-Yu Sun; Guo-Xiu Li (1846-1857).
To explore the influence mechanism of initial turbulence on propagation speed of wrinkled flames, the turbulent combustion behavior of wrinkled stoichiometric hydrogen premixed flames was studied in a spherical fanstirred closed vessel under standard temperature and pressure. The variations on flame structure were first observed; turbulent flames first were distorted and then became cellular, and both first and second critical flame radii of cellularity declined with a increased rate as turbulent intensity rose. Then, the variations of stretch effects were compared to laminar flame; the global stretch rate on turbulent flame at a same flame size was raised while the enhancement extent was obviously enlarged with the increase of initial turbulent intensity and/or the growth of flame size. Finally, the variation regulations of propagation speed induced by varying turbulent intensity were analyzed; the nexus between propagation speed and initial turbulence was discussed with the considerations of cellularity phenomenon and stretch effects.
Keywords: Cellularity Phenomenon; Hydrogen Premixed Flame; Stretch Effects; Turbulent Flame Speed; Wrinkled Flame
Iron-manganese-magnesium mixed oxides catalysts for selective catalytic reduction of NO x with NH3 by Kang Zhang; Liting Xu; Shengli Niu; Chunmei Lu; Dong Wang; Qi Zhang; Jing Li (1858-1866).
SCR activity at low temperature over iron oxide catalyst was prominently optimized by adding manganese and magnesium. Fe0.7Mn0.15Mg0.15O z (n(Mn)/[n(Fe)+n(Mn)+n(Mg)])=0.15 and n(Mg)/[n(Fe)+n(Mn)+n(Mg)]=0.15) presented better performance in the low temperature SCR and NO x conversion of 90% could be achieved over 125 °C. Meanwhile, part of manganese and magnesium oxides were highly dispersed on the catalyst surface in an amorphous phase to react with iron oxide to form solid solution. Manganese and magnesium dopants could optimize the pore structure and distribution of γ-Fe2O3 to enhance the surface area and pore volume. Moreover, O2 participated in SCR reaction at a faster rate than NH3. In addition, the effect of SO2 was proved to be irreversible, whereas the inhibition of H2O could be rapidly removed after its removal.
Keywords: Fe0.7Mn0.15Mg0.15O z Catalyst; γ-Fe2O3 Catalyst; Low-temperature SCR; H2O and SO2 Resistance; Catalyst Activity
Study on adsorption characteristics of biochar on heavy metals in soil by Hong Wang; Wen Xia; Ping Lu (1867-1873).
Three kinds of biochars (called poplar branch biochar (PBC), water hyacinth biochar (WHC), and corn straw biochar (CSC)) were prepared in a fixed-bed pyrolyzer at different pyrolysis temperature of 300-700 °C. The effects of biochar species, pyrolysis temperature and biochar addition on adsorption characteristics of typical heavy metals (HMs) of Pb and Zn in vegetable soil (collected from lead-zinc-silver mining area, Nanjing, China) were investigated. The obtained results indicate that WHC presents the best adsorption ability at the same experimental conditions, whose adsorption efficiency on HMs of Zn and Pb is 21.83% and 44.57%, and the relative adsorption capacity of Zn and Pb is 227.65 μg/g and 363.76 μg/g, respectively. The adsorption efficiency of biochar on HMs of Zn and Pb in soil increases gradually with the increasing of pyrolysis temperature. The increasing of biochar addition is beneficial to increase adsorption efficiency of soil HMs, but unhelpful for adsorption capacity.
Keywords: Biochar; Soil; Heavy metals; Adsorption characteristics
Poisoning effect of CaO on CeO2/TiO2 catalysts for selective catalytic reduction of NO with NH3 by Ye Jiang; Xuechong Wang; Changzhong Bao; Shanbo Huang; Xiuxia Zhang; Xinwei Wang (1874-1881).
The effect of CaO on CeO2/TiO2 catalysts prepared by a single step sol-gel method for selective catalytic reduction of NO with NH3 was investigated. The results showed that CaO could severely deactivate the CeO2/TiO2 catalysts. Based on the characterization results obtained by BET, XRD, XPS, H2-TPR and NH3-TPD, the deactivation by CaO of CeO2/TiO2 catalysts should be attributed to pore blockage, lower concentration of Ce on catalyst surface, reduction of Ce3+ and surface adsorbed oxygen, degradation of redox ability and decrease in NH3 adsorption capacity. The theoretical DFT results demonstrated that Ca atom could strongly interact with cerium oxygen, which inhibits the formation and hydrogenation of oxygen vacancies on catalyst surface.
Keywords: Selective Catalytic Reduction; CaO; CeO2/TiO2 ; Single Step Sol-gel Method; DFT
Study on the mechanism of desulfurization and denitrification catalyzed by TiO2 in the combustion with biomass and coal by Shu-Qin Wang; Ming-Zhu Liu; Li-Li Sun; Wei-Liang Cheng (1882-1888).
The effects of Ca/S molar ratio, catalyst type, catalyst dosage, temperature on desulfurization and denitrification efficiency were investigated in the coal-powder combustion with corn cobs as biomass. The thermal characteristics of Shanxi coal and corn cob blends with V-TiO2 were evaluated by thermogravimetric analyzer. The catalytic mechanisms of V-TiO2 on combustion, desulfurization and denitrification were discussed, suggesting that the mechanisms are in good agreement with the experimental data. The results show that the control parameters of the ideal desulfurization and denitrification efficiency should follow that the dosage of V-TiO2 catalyst is 8% with a Ca/S ratio of 2.3 at a treatment temperature 850 °C. Meanwhile, the combustion efficiency could be effectively improved with the mixture of corn cob and V-TiO2. The thermal characteristics of coal char and corn cob char blends with V-TiO2 were evaluated using thermogravimetric analysis and derivative thermogravimetry methods to discuss the heterogeneous NO reduction mechanisms. The results show that the biomass chars were more active than coal chars in reducing NO, and the specific surface area of the chars was increased with V-TiO2, which indicates that V-TiO2 exhibits significant influence on catalytic combustion, desulfurization and denitrification.
Keywords: Biomass and Coal Co-combustion; Desulfurization; Denitrification; Doping TiO2