Korean Journal of Chemical Engineering (v.30, #12)
Advances in cultivation and processing techniques for microalgal biodiesel: A review by Mizhang Xiao; Hyun-Jae Shin; Qiuhua Dong (2119-2126).
The key technologies for producing microalgal biodiesel include microalgae screening, economical cultivation, and efficient methods in lipid extraction and conversion. Recent advances in microalgae cultivation, lipid extraction, and biodiesel preparation are reviewed in this work, with emphasis on photosynthetic metabolisms, separation efficiency and catalytic kinetics. The mutual exclusion between lipid accumulation and fast growth limits total lipid productivity, while only triglycerides in neutral lipids are converted to biodiesel through transesterification. The hurdles in large scale culture and low neural lipids yield are discussed, as well as the relationship between high unsaturation and fuel properties. This review aims to provide technical information to guide strain screening and lipid conversion for microalgal biodiesel industry.
Keywords: Microalgal Oil; Poly-unsaturated Fatty Acids (PUFAs); Biodiesel; Lipid Extraction; Purification
Characterization of crystalline cellulose in biomass: Basic principles, applications, and limitations of XRD, NMR, IR, Raman, and SFG by Seong H. Kim; Christopher M. Lee; Kabindra Kafle (2127-2141).
Cellulose is among the most important and abundant biopolymers in biosphere. It is the main structural component of a vast number of plants that carries vital functions for plant growth. Cellulose-based materials have been used in a variety of human activities ranging from papers and fabrics to engineering applications including production of biofuels. However, our understanding of the cellulose structure in its native form is quite limited because the current experimental methods often require separation or purification processes and provide only partial information of the cellulose structure. This paper aims at providing a brief background of the cellulose structure and reviewing the basic principles, capabilities and limitations of the cellulose characterization methods that are widely used by engineers dealing with biomass. The analytical techniques covered in this paper include x-ray diffraction, nuclear magnetic resonance, and vibrational spectroscopy (infrared, Raman, and sum-frequency-generation). The scope of the paper is restricted to the application of these techniques to the structural analysis of cellulose.
Keywords: Cellulose; Biomass; XRD; NMR; IR; Raman; SFG
A facile approach to preparing palladium nanoparticles-embedded polyvinylpyrrolidone (PVP) heterogeneous hybrid nanofibers mats by electrospinning by Liping Guo; Jie Bai; Haiou Liang; Tong Xu; Chunping Li; Qingrun Meng; Huan Liu; Yarong Huang (2142-2150).
Well-dispersed palladium nanoparticles (Pd NPs) were prepared under the condition that trisodium citrate was the reduction agent and polyvinylpyrrolidone (PVP) was the stabilizing agent via sol-gel process. By making good use of the advanced electrospinning technology we obtained Pd NPs/PVP composite nanofibers films. Optical properties were examined by UV-visible absorbance spectra (UV-vis) and Fourier transform infrared spectroscopy (FTIR). The morphology and distribution of Pd NPs in/on PVP matrix were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that Pd NPs presented as spherical spots and distributed in/on PVP nanofibers uniformly; their diameter was 4–10 nm and decreased with the increase of PVP. The as-prepared Pd NPs/PVP hybrid mats possess catalytic activity, stability and reusability, as verified by performance in Heck reaction.
Keywords: Sol-gel Process; Pd Nanoparticles; Electrospinning; Hybrid Nanofibers
Analytical design of proportional-integral controllers for the optimal control of first-order processes with operational constraints by Hien Cao Thi Thu; Moonyong Lee (2151-2162).
A novel analytical design method of industrial proportional-integral (PI) controllers was developed for the optimal control of first-order processes with operational constraints. The control objective was to minimize a weighted sum of the controlled variable error and the rate of change in the manipulated variable under the maximum allowable limits in the controlled variable, manipulated variable and the rate of change in the manipulated variable. The constrained optimal servo control problem was converted to an unconstrained optimization to obtain an analytical tuning formula. A practical shortcut procedure for obtaining optimal PI parameters was provided based on graphical analysis of global optimality. The proposed PI controller was found to guarantee global optimum and deal explicitly with the three important operational constraints.
Keywords: Analytical Design Rules; Constrained Optimization; First Order Process; Optimal Servo Control; Proportional-Integral (PI) Controller; Controller Tuning; Smith Predictor
Simulation and optimization of extractive distillation sequence with pre-separator for the ethanol dehydration using n-butyl propionate by Sanjay Pralhad Shirsat; Shrikant Devidas Dawande; Seema Sudhakar Kakade (2163-2169).
Extractive distillation is the most promising alternative for the ethanol-water separation than azeotropic and pressure swing distillation using suitable solvent n-Butyl propionate. We have studied, simulated, optimized and economically evaluated the separation of a mixture of 50 mole% ethanol and 50 mole% water to treat the 16 Kmol/hr (512.67 kg/hr) of the original mixture. Rigorous simulation and optimization has been carried out by means of a software CHEMCAD version 6.5 using thermodynamic model UNIQUAC with binary interaction parameters. The simulations allow us to conclude that extractive distillation is more economical and trustworthy than pressure swing distillation due to the relative pressure insensitive nature of the ethanol-water mixture after the azeotropic composition. The separation of 99.7% of ethanol from ethanol water mixture claim by Mulia-Soto, Flores-Tlacuahuac, 2011 is contradictory as the feasibility for the operating pressure of 10 atm with or without heat integration.
Keywords: Simulation; Optimization; Ethanol Dehydration; n-Butyl Propion
Selective catalytic reduction converter design: The effect of ammonia nonuniformity at inlet by Thiyagarajan Paramadayalan; Atul Pant (2170-2177).
A three-dimensional CFD model of SCR converter with detailed chemistry is developed. The model is used to study the effects of radial variation in inlet ammonia profile on SCR emission performance at different temperatures. The model shows that radial variation in inlet ammonia concentration affects the SCR performance in the operating range of 200–400 °C. In automotive SCR systems, ammonia is non-uniformly distributed due to evaporation/reaction of injected urea, and using a 1D model or a 3D model with flat ammonia profile at inlet for these conditions can result in erroneous emission prediction. The 3D SCR model is also used to study the effect of converter design parameters like inlet cone angle and monolith cell density on the SCR performance for a non-uniform ammonia concentration profile at the inlet. The performance of SCR is evaluated using DeNO x efficiency and ammonia slip.
Keywords: Catalytic Converter; SCR Converter; CFD; Numerical Modeling; Monolith Reactor; Chemical Kinetics
Statistical optimization for oxidation of ethyl benzene over Co-Mn/SBA-15 catalyst by Box-Behnken design by Vahid Mahdavi; Ali Monajemi (2178-2185).
A series of cobalt and manganese catalysts supported on SBA-15 with different loading of Mn+2 and Co+2 were synthesized. These samples were characterized by SEM and XRD techniques. The catalytic activity of these samples was evaluated in the oxidation of ethylbenzene (EB) to produce acetophenone (AP) and benzoic acid (BA) in the liquid phase using tert-butylhydroperoxide (TBHP) as an oxidant. The effects of Co-Mn loading, TBHP: EB molar ratio and temperature on acetophenone and benzoic acid yields were studied by Box-Behnken experimental design to optimize the production of acetophenone and benzoic acid in liquid system.
Keywords: Benzoic Acid; Acetophenone; SBA-15; Cobalt-manganese Catalyst; Box-Behnken Design
Catalytic synthesis of biodiesel from pongamia glabra over zirconia and its modified forms by Manjunatha Shyamsundar; Sathgatta Zaheeruddin Mohamed Shamshuddin; Jaya Narayan Sahu (2186-2190).
Zirconia & its modified forms such as Mo(VI)/ZrO2, Pt-SO 4 2− /ZrO2, MgO & MgO-ZrO2 mixed oxide were prepared by impregnation method. These catalysts were analyzed for surface acidity, surface basicity and crystallinity by using techniques such as TPD & powder X-ray diffraction. Mo(VI)/ZrO2, Pt-SO4 2−/ZrO2 were used as solid acid catalysts for esterification of pongamia glabra (karanja) oil to reduce the concentration of free fatty acid and MgO and MgO-ZrO2 mixed oxide were used as solid base catalysts for transesterification of karanja oil to produce biodiesel. These zirconia catalysts were found to be highly efficient for the synthesis of biodiesel with more than 90% yield of biodiesel. These solid catalysts can be effectively reactivated and reused.
Keywords: Mo(VI)/ZrO2 ; Pt-SO 4 2− /ZrO2 ; MgO; MgO-ZrO2 ; Transesterification; Biodiesel; Karanja Oil; Pongamia Glabra
Polyhydroxybutyrate production accompanied by the effective reduction of chemical oxygen demand (COD) and biological oxygen demand (BOD) from industrial effluent by Ramanathan Muralidharan; Pillaibakkam Bahukudumbi Sindhuja; Aswathi Sudalai; K. V. Radha (2191-2196).
Industrial effluents are major pollution-causing agents for our environment. Our study focuses on utilizing effluents from different industries for efficient production of Polyhydroxybutyrate (PHB). Presence of PHB was identified by Sudan Black staining method. The PHB production parameters for Pseudomonas aeruginosa MTCC 4673 were studied critically, and it was found that glucose with 8.5 mg/L (0.0550 g PHB/g substrate) PHB concentration yielded the highest among the carbon sources used. Peptone with 8.9 mg/L (0.0524 g PHB/g substrate) of PHB concentration, an incubation period of 48 h and at a pH of 7 yielded the optimum results. These studies were compared with those of Alcaligens latus MTCC 2311. Dairy effluents (DE) and tannery effluents (TE) were considered for the best possible substrate, for the production of PHB in an optimized media. The results indicated that the dairy effluents gave a higher yield of PHB. Amongst various dilution levels studied from 10–100% (v/v), 50% (v/v) concentration of the dairy effluent showed maximum PHB productivity of 0.0582 g PHB/g substrate. A comparison of the chemical oxygen demand (COD) and biological oxygen demand (BOD) from the results, showed a significant removal percentage of 78.97% BOD and 53.482% COD, which highlighted the importance of utilizing effluents for PHB production, in order to reduce the risk of toxic effluent discharge. FT-IR analysis was carried out to confirm the presence of PHB.
Keywords: Industrial Effluents; Sudan Black; Chemical Oxygen Demand (COD); Biological Oxygen Demand (BOD)
Modeling of corrosion reaction data in inhibited acid environment using regressions and artificial neural networks by Anees Abdullah Khadom (2197-2204).
This paper reports the results of mass loss measurements in the corrosion inhibition of mild steel in different concentrations of H3PO4 in the temperature range 30–60 °C using potassium iodide as an inhibitor. The present work is focused on determining the optimum mathematical equation and the ANN architecture in order to gain good prediction properties. Three mathematical equations and three ANN architectures are suggested. Computer aided program was used for developing these models. The results show that the polynomial mathematical equation and multi-layer perception are able to accurately predict the measured data with high correlation coefficients.
Keywords: Corrosion; Computer Program; Neural Network; Mild Steel; Acid; Regression
An electrostatic sensor for the continuous monitoring of particulate air pollution by Panich Intra; Artit Yawootti; Nakorn Tippayawong (2205-2212).
We developed and evaluated a particulate air pollution sensor for continuous monitoring of size resolved particle number, based on unipolar corona charging and electrostatic detection of charged aerosol particles. The sensor was evaluated experimentally using combustion aerosol with particle sizes in the range between approximately 50 nm and several microns, and particle number concentrations larger than 1010 particles/m3. Test results were very promising. It was demonstrated that the sensor can be used in detecting particle number concentrations in the range of about 2.02×1011 and 1.03×1012 particles/m3 with a response of approximately 100 ms. Good agreement was found between the developed sensor and a commercially available laser particle counter in measuring ambient PM along a roadside with heavy traffic for about 2 h. The developed sensor proved particularly useful for measuring and detecting particulate air pollution, for number concentration of particles in the range of 108 to 1012 particles/m3.
Keywords: Aerosol; Particulate Matter; PM2.5; Faraday Cup; Electrometer
Removal of 4-nitro-phenol from wastewater using synthetic zeolite and kaolin clay by Nada Sadoon Ahmedzeki; Haider Abdulkarem Rashid; Asir Abduljabbar Alnaama; Maha Hadi Alhasani; Zainab Abdulhussain (2213-2218).
Adsorption techniques are widely used to remove certain classes of pollutants from wastewater. Phenolic compounds represent one of the problematic groups. Na-Y zeolite has been synthesized from locally available Iraqi kaolin clay. Characterization of the prepared zeolite was made by XRD and surface area measurement using N2 adsorption. Both synthetic Na-Y zeolite and kaolin clay have been tested for adsorption of 4-Nitro-phenol in batch mode experiments. Maximum removal efficiencies of 90% and 80% were obtained using the prepared zeolite and kaolin clay, respectively. Kinetics and equilibrium adsorption isotherms were investigated. Investigations showed that both Langmuir and Freundlich isotherms fit the experimental data quite well. On the other hand, the adsorption of phenol was found to obey first-order kinetics.
Keywords: Pollutants; Phenolic Compounds; Adsorption; Zeolite Na-Y
Synthesis of single azo disperse dye containing double ester and determination of crystal structure by Zhengyu Zhang; Hong Xu; Chunling Zheng (2219-2222).
The synthesis, crystal structure analysis and characterization of a monoazo dye, 4-((2,6-dichloro-4-nitro phenyl)azo)-N-(diacetyl oxygen ethyl)aniline, are reported. The dye crystallised in the triclinic system, space group P-1 with a=8.1663(3) Å, b= 9.4222(3) Å, c=15.4694(5) Å, α=78.9130(10)°, β=75.019(2)°, γ=70.787(2)°, V=1078.26(6) Å3 and Z=2. There is only one molecule in the asymmetric unit. The dihedral angle between the two phenyl rings is 53.4 Å. In the crystal structure, intermolecular C-H…O hydrogen bonds link the molecules into centrosymmetric dimers, forming R22(30) ring motifs, in which they may be effective in the stabilization of the structure. Between the phenyl rings, the π…π stacking (interactions) may further stabilize the structure.
Keywords: Crystal Structure; Monoazo Dye; Dihedral Angle; Hydrogen Bonds; π…π Stacking
Production of polyhydroxyalkanoates by Ralstonia eutropha from volatile fatty acids by Jung Hyun Yun; Shailesh S. Sawant; Beom Soo Kim (2223-2227).
Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible thermoplastics that can be synthesized in various microorganisms. Volatile fatty acids (VFAs) are produced by anaerobic treatment of organic wastes that can be utilized as inexpensive substrates for PHA synthesis. In this study, several Ralstonia eutropha strains were grown on the mixture of VFAs (acetic, propionic, and butyric acid) as its carbon and energy source for growth and PHA synthesis. R. eutropha KCTC 2658 accumulated PHAs up to 50% of dry cell weight from total 5 g/L of mixed VFAs (acetic acid: propionic acid: butyric acid=1: 2: 2). In batch culture of R. eutropha KCTC2658 in a 5 L fermentor, a homopolymer of poly(3-hydroxybutyrate) [P(3HB)] was produced from 20 g/L glucose as a sole carbon source with dry cell weight of 8.4 g/L and PHA content of 30%. In fed-batch culture, two feeding strategies, pulse or pH-stat, were applied to add VFAs to the fermentor. When VFAs were fed using pH-stat feeding strategy after 40 h, a copolymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] was produced with dry cell weight of 8.1 g/L, PHA content of 50%, and 3HV fraction of 20 mol%.
Keywords: Polyhydroxyalkanoates; PHA; Ralstonia eutropha ; Volatile Fatty Acids
Role of microporosity and surface functionality of activated carbon in methylene blue dye removal from water by Mohammad Asadullah; Mohammad Shajahan Kabir; Mohammad Boshir Ahmed; Nadiah Abdul Razak; Nurul Suhada Abdur Rasid; Airin Aezzira (2228-2234).
Activated carbons have been prepared from jute stick by both chemical and physical activation methods using zinc chloride and steam, respectively. They were characterized by evaluating surface area, iodine number, pore size distribution, and concentration of surface functional groups. The chemically activated carbon largely featured micropore structure, while the physically activated carbon mainly featured macropore structure. The specific surface area of chemically and physically activated carbons was 2,325 and 723 m 2 /g, while the iodine number was 2,105 and 815mg/g, respectively. The concentration of surface functional groups was determined by Boehm titration method, which suggested that different types of surface functional groups are randomly distributed on chemical activated carbons, while it is limited for physical activated carbon. The microporosity along with surface functional groups provided a unique property to chemically activated carbon to adsorb Methylene Blue dye to a large extent. The adsorption of dye was also affected by the adsorption parameters such as adsorption time, temperature and pH. Comparatively, higher temperature and pH significantly facilitated dye adsorption on chemically activated carbon.
Keywords: Activated Carbon; Jute Stick; Chemical Activation; Methylene Blue; Adsorption
Adsorption of heavy metal ions in ternary systems onto Fe(OH)3 by Syed Mustafa; Muhammad Irshad; Muhammad Waseem; Khizar Hussain Shah; Umer Rashid; Wajid Rehman (2235-2240).
The adsorption behavior of amorphous Fe(OH)3 has been studied in multicomponent metal system. The metal ions uptake in the ternary system is lower than in the single system, suggesting that certain sites on the surface of the solid are blocked due to competition. The selectivity trend in the ternary system is observed to be Ni2+>Zn2+>Cd2+ which is, however, lost with increase in the temperature of the aqueous solution. Further, the observed selectivity trend is neither related to electronegativity of the metal ions nor to the pH of the hydrolysis, but has been found dependent on charge to radius ratio. The metal ions adsorption is found to increase with pH, while the converse is true with the rise in temperature. The uptake of metal ions data has been interpreted in terms of stoichiometry, binding constants and adsorption capacities. The negative values of ΔG show that uptake of metal ions is favored at lower temperatures, indicating that the adsorption mechanism essentially remains ion exchange in nature.
Keywords: Ternary System; Metal Adsorption; Modeling; Thermodynamic Parameters
Sequestration of carbon dioxide by m-xylylenediamine with forming a crystalline adduct by Se Woong Lee; Seong Wook Lim; Soon Hee Park; Kwang Ha; Keun Sik Kim; Se Min Oh; Jin Yong Lee; Gon Seo (2241-2247).
The reaction of m-xylylenediamine (mXD) with carbon dioxide was examined and its feasibility as a sequestration material of carbon dioxide was discussed. The reaction was monitored by using the FT-IR and gravitational methods, while the crystalline structure of the reaction product was investigated with elemental analysis, powder Xray diffraction, single crystallography, and 13C MAS NMR spectroscopy. Even at ambient temperature, mXD reacted with carbon dioxide of low partial pressure in the atmosphere and produced a 1: 1 molar adduct which appeared as a white crystalline material. The hydrogen bonds that formed between the adduct molecules resulted in the formation of a stable crystal. The sequestration capacity of mXD was very great, ∼280 mg g mXD −1 below 50 °C. An adsorbent prepared by dispersing mXD on silica was capable of capturing carbon dioxide, but it could be regenerated by evacuating at 25 °C.
Keywords: m-Xylylenediamine; Carbon Dioxide; Adduct; Crystal Structure; Sequestration
Experimental and theoretical investigations on the carbon dioxide gas hydrate formation kinetics at the onset of turbidity regarding CO2 capture and sequestration processes by Bahman ZareNezhad; Mona Mottahedin; Farshad Varaminian (2248-2253).
The carbon dioxide gas hydrate formation kinetics at the onset of turbidity is experimentally and theoretically investigated. It is shown that the time-dependent heterogeneous nucleation and growth kinetics are simultaneously governing the hydrate formation process at the onset of turbidity. A new approach is also presented for determination of gas hydrate-liquid interfacial tension. The CO2 hydrate-liquid interfacial tension according to the suggested heterogeneous nucleation mechanism is found to be about 12.7 mJ/m2. The overall average absolute deviation between predicted and measured CO2 molar consumption is about 0.61%, indicating the excellent accuracy of the proposed model for studying the hydrate-based CO2 capture and sequestration processes over wide ranges of pressures and temperatures.
Keywords: CO2 ; Sequestration; Energy; Nucleation; Growth; Interfacial Tension; Gas Hydrate; Kinetics
Extinction effectiveness of pyrogenic condensed-aerosols extinguishing system by Kyungok Kwon; Younggeun Kim (2254-2258).
We studied the extinction effectiveness of pyrogenic condensed-aerosols in gaseous fire extinguishing systems through the ISO (International Organization for Standard) 15779. The thermal characteristics of solid aerosols as an extinguishing agents were evaluated by using TG and DTA. The modified closed pressure vessel test (MCPVT) and the conductivity of the solid aerosol extinguishant were also measured to ensure the safety of extinguishant. The TG and DTA result showed that the resin added to the main component of Potassium Nitrate (PN) has the effectiveness to mitigating the exothermic reaction of the pyrogenic condensed-aerosol extinguishant. The results of maximum height test revealed the extinguishing capability of a pyrogenic condensed-aerosol extinguishing agent as a gaseous extinguishing system.
Keywords: Pyrogenic Condensed-aerosol Extinguishant; Halon 1301; Gaseous Extinguishing System; GWP
Synthesis and properties of aqueous polyurethane dispersions: Influence of molecular weight of polyethylene glycol by Fatima Mumtaz; Mohammad Zuber; Khalid Mahmood Zia; Tahir Jamil; Rizwan Hussain (2259-2263).
Aqueous polyurethane dispersions (PUDs) have recently emerged as important alternatives to their solvent-based counterparts for various applications due to increasing health and environmental awareness. A series of aqueous polyurethane dispersions containing carboxylate anion as hydrophilic pendant groups were synthesized through step growth polymerization reaction using hexamethylene diisocyanate (HDI), 1,4-butanediol (1,4-BDO), dimethylol propionic acid (DMPA) and polyethylene glycol (PEG) of different molecular weight. Effect of PEG molecular weight was investigated on molecular structure, contact angle measurement, and physical and adhesive properties of PU emulsions. Fourier transform infrared spectroscopy (FT-IR) was used to check the completion of polymerization reaction. Contact angle measurement indicated that the hydrophilicity of polymer increases by increasing molecular weight of PEG with a corresponding decrease in contact angle. Results of T-peel test showed a decrease in peel strength by increasing molecular weight of PEG. Moreover, solid contents%, drying time and storage stability suggested fast drying properties and greater stability of aqueous PU dispersions.
Keywords: Polyurethane; FT-IR; Adhesive Properties; Hydrophilicity; T-peel Test