Korean Journal of Chemical Engineering (v.32, #11)
Catalytic propane dehydrogenation: Advanced strategies for the analysis and design of moving bed reactors by Kamlesh Ghodasara; Sungwon Hwang; Robin Smith (2169-2180).
A moving bed reactor (MBR) is one of the most innovative reactors that are commonly used in industry nowadays. However, the modeling and optimization of the reactor have been rarely performed at conceptual design stage due to its complexity of design, and it has resulted in increased capital and operating costs of the overall chemical processes. In this work, advanced strategies were introduced to model an MBR and its regenerator mathematically, incorporating catalyst deactivation, such as coke formation. Various reactor designs and operating parameters of the MBR were optimized to increase the overall reactor performance, such as conversion or selectivity of the main products across the reactor operating period. These optimization parameters include: (1) reactant flow inside a reactor, (2) various networks of MBRs, (3) temperature of the feed stream, (4) intermediate heating or cooling duties, (5) residence time of the catalyst or velocity of catalyst flow, and (6) flow rate of the fresh make-up catalyst. The propane dehydrogenation process was used as a case study, and the results showed the possibility of significant increase of reactor performance through optimization of the above parameters. For optimization, the simulated annealing (SA) algorithm was incorporated into the reactor modeling. This approach can be easily applied to other reaction processes in industry.
Keywords: Modeling; Optimization; Kinetics; Moving Bed Reactor
A new horizontal distillation for energy saving with a diabatic rectangular column by Dae Jin Jang; Young Han Kim (2181-2186).
Energy saving distillation using a horizontal distillation column was experimentally examined, and the improvement of the technique has been investigated by utilizing a rectangular column. The rectangular column provides larger cross-sectional area for increased throughput and larger heat transfer area for diabatic operation. The proposed technique saves about 13.6% of energy demand compared with the vertical distillation column calculated from the HYSYS simulation. The result indicates that improved capacity of feed processing is possible with the rectangular column.
Keywords: Energy Saving in Distillation; Energy-efficient Distillation; Horizontal Distillation; Diabatic Distillation
Flow and heat transfer characteristics in a channel having furrowed wall based on sinusoidal wave by Jiansheng Wang; Xiaoming Gao; Weiyi Li (2187-2203).
The effect of wall geometry on the flow and heat transfer in a channel with one lower furrowed and an upper flat wall kept at a uniform temperature is investigated by large eddy simulation. Three channels, one with sinusoidal wavy surface having the ratio (amplitude to wavelength) α/λ=0.05 and the other two with furrowed surface derived from the sinusoidal curve, are considered. The numerical results show that the streamwise vortices center is located near the lower wall and vary along the streamwise on various furrow surfaces. The furrow geometry increases the pressure drag and decreases the friction drag of the furrowed surface compared with that of the smooth surface; consequently, the total drag is increased for the augment of pressure drag. As expected, the heat transfer performance has been improved. Finally, a thermal performance factor is defined to evaluate the performance of the furrowed wall.
Keywords: Channel Flow; Furrowed Surface; Recirculation Zone; Heat Transfer
Performance evaluation and mass transfer study of CO2 absorption in flat sheet membrane contactor using novel porous polysulfone membrane by Nima Nabian; Ali Asghar Ghoreyshi; Ahmad Rahimpour; Mohsen Shakeri (2204-2211).
The performance of gas-liquid membrane contactor for CO2 capture was investigated using a novel polysulfone (PSF) flat membrane prepared via non-solvent phase inversion method. Polyvinyl pyrrolidone (PVP) was used as an additive in the dope solution of PSF membranes. Morphological studies by scanning electron microscopy (SEM) analysis revealed that PSF membrane with PVP has a finger-like structure, but the PSF membrane without PVP has a sponge-like structure. Also, characterization results through atomic force microscopy (AFM) and contact angle measurement demonstrated that the porosity, surface roughness and hydrophobicity of the PSF membrane increased with addition of PVP to the dope solution. Mass transfer resistance analysis, based on CO2 absorption flux, displayed that addition of PVP to the dope solution of PSF membrane decreased membrane mass transfer resistance, and significantly improved CO2 absorption flux up to 2.7 and 1.8 times of absorption fluxes of PSF membrane without PVP and commercial PVDF, respectively.
Keywords: CO2 Absorption; Polysulfone; PVP Additive; Membrane Contactor; Mass Transfer
Propane combustion over Pt/Al2O3 catalysts with different crystalline structures of alumina by Jung Eun Park; Bo Bae Kim; Eun Duck Park (2212-2219).
-The effects of the crystalline phases (α-Al2O3, κ-Al2O3, δ-Al2O3, θ-Al2O3, η-Al2O3, and γ-Al2O3) of the alumina support of Pt/Al2O3 catalysts on the catalyst activity toward propane combustion were examined. The catalysts were characterized by N2 physisorption, CO chemisorption, temperature-programmed reduction (TPR), temperatureprogrammed oxidation (TPO), transmission electron microscopy (TEM), and infrared spectroscopy (IR) after CO chemisorption. The Pt dispersion of the catalysts (surface Pt atoms/total Pt atoms), measured via CO chemisorption, was more dependent on the crystalline structure of alumina than on the surface area of alumina. The highest catalytic activity for propane combustion was achieved with Pt/α-Al2O3, which has the lowest Brunauer, Emmett, and Teller (BET) surface area and Pt dispersion. The lowest catalytic activity for propane combustion was exhibited by Pt/γ-Al2O3, which has the highest BET surface area and Pt dispersion. The catalytic activity was confirmed to increase with increasing Pt particle size in Pt/δ-Al2O3. The apparent activation energies for propane combustion over Pt/α-Al2O3, Pt/κ-Al2O3, Pt/δ-Al2O3, Pt/θ-Al2O3, Pt/η-Al2O3, and Pt/γ-Al2O3 were determined to be 24.7, 21.4, 24.3, 22.1, 24.0, and 19.1 kcal/mol, respectively.
Keywords: Propane Combustion; Pt; Alumina; Support; Oxidation
Co-Mn-Ru/Al2O3 catalyst for the production of high-calorific synthetic natural gas by Yong Hee Lee; Hyoungsik Kim; Hyun Sook Choi; Dae-Won Lee; Kwan-Young Lee (2220-2226).
Standard heating value for natural gas of South Korea, which imports LNG with high heating value is 10,400 kcal/Nm3, while the heating value of conventional SNG is less than 9,500 kcal/Nm3. Then the heating value of SNG should be enhanced to be used as city gas. In this study, Co-Mn-Ru/Al2O3 was applied in methanation to increase the heating value of the product gas. The role of each component and optimum composition where C2-C4 yield was highest were revealed. Mn enhanced the surface acidity, and promoted carbon-rich environment on the surface, which resulted in the increase of C2-C4 yield. Ru enhanced the reducibility of catalysts, and it resulted in high activity at lower temperature. As a result, optimum composition was 10Co-6Mn-2.5Ru/Al2O3. In addition, to replace Ru component, the reducibility of Co was enhanced by being reduced at higher temperature of 700 °C, and 20Co-Mn/Al2O3 catalysts achieved similar activity results to 10Co-6Mn-2.5Ru/Al2O3 without Ru.
Keywords: Methanation; Fischer-Tropsch; Cobalt Catalyst; Heating Value
Desulfurization of coke oven gas using char-supported Fe-Zn-Mo catalysts: Mechanisms and thermodynamics by Jinxiao Dou; Xianchun Li; Arash Tahmasebi; Jing Xu; Jianglong Yu (2227-2235).
Sulfidation properties of char-supported Fe-Zn-Mo sorbents prepared by ultrasonic impregnation method were investigated during simultaneous removal of H2S and COS from coke oven gas (COG) using a fixed-bed quartz reactor. Sorbent samples before and after sulfidation were analyzed using X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The experimental results showed that the addition of Mo significantly improved the desulfurization properties (i.e., breakthrough time, sulfur capacity and desulfurization efficiency) of Fe-Zn sorbents. Desulfurization reactions were exothermic and thermodynamically favorable in the temperature range of 200–400 °C. Thermodynamic analysis of the sorbents indicated that higher concentration of H2S and lower concentration of H2 favors the reaction of metal oxides with H2S to form metal sulfides.
Keywords: Coke Oven Gas; Sulfidation; Char-supported Sorbents; Sulfur Capacity
Effect of combined slow pyrolysis and steam gasification of sugarcane bagasse on hydrogen generation by Prakash Parthasarathy; Sheeba Narayanan (2236-2246).
The present work aims at improving the generation of H2 from sugarcane bagasse in steam gasification process by incorporating slow pyrolysis technique. As a bench scale study, slow pyrolysis of sugarcane bagasse is performed at various pyrolysis temperature (350, 400, 450, 500 and 550 °C) and feed particle size (90P <212, 212< D P <355, 355P <500, 500P <850 µm) to determine effective conditions of char generation. In the combined process (slow pyrolysis of biomass followed by steam gasification of char), first slow pyrolysis is carried out at the effective conditions (pyrolysis temperature and particle size) of char generation (determined from bench scale study) and steam gasification is at varying gasification temperature (600, 650, 700, 750 and 800 °C) and steam to biomass (S/B) ratio (1, 2, 3, 4, 5 and 6) to determine the effective conditions of H2 generation. The effect of temperature and S/B on gas product composition and overall product gas volume was also investigated. At effective conditions (gasification temperature and S/B) of H2 generation, individual slow pyrolysis and steam gasification were also experimented to evaluate the performance of combined process. The effective condition of H2 generation in combined process was found to be 800 °C (gasification temperature) and 5 (S/B), respectively. The combined process produced 35.90% and 23.60% more gas volume (overall) than slow pyrolysis and steam gasification process, respectively. With respect to H2 composition, the combined process generated 72.37% more than slow pyrolysis and 17.91% more than steam gasification process.
Keywords: Sugarcane Bagasse; Slow Pyrolysis; Steam Gasification; Combined Process; H2 Generation
Removal of Co(II) from aqueous solutions by sulfonated magnetic multi-walled carbon nanotubes by Juanjuan Yang; Yunhui Dong; Jun Li; Zhengjie Liu; Fanlian Min; Yueyun Li (2247-2256).
Sulfonated magnetic multi-walled carbon nanotubes (SMMWCNTs) were applied in the sorption of Co(II) from aqueous solutions. The SMMWCNTs were prepared and characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR), and X-ray diffractometer (XRD) test. A large number of influencing factors to the sorption process were investigated, such as pH, ionic strength, contact time, cations, anions, humic acid (HA), fulvic acid (FA) and temperature. The results indicated that the Co(II) sorption was strongly controlled by the pH and ionic strength. Moreover, foreign anions, such as F-, Cl- and Br-, had an obvious effect on the sorption process, which depended on the electronegativity of the anions. On the other hand, cations restrained sorption strongly, such as Mg2+ and Ca2+. The existence of HA/FA enhanced sorption process at pH<8 while weakened at pH>8. As revealed by the sorption results, the Langmuir adsorption model was more favorable than the Freundlich adsorption model, and the pseudo-second-order model could fit the data much better than the pseudo-first-order. The thermodynamic analysis suggested that sorption was spontaneous and endothermic. What’s more, the stability experiments of the SMMWCNTs showed that SMMWCNTs could maintain excellent magnetic stability and dispersion stability. Thus, this SMMWCNTs sorbent was believed to be a promising material for the selective removal of Co(II) from heavy metal-containing waste-water.
Keywords: Co(II); Sorption; Sulfonated Magnetic Multi-walled Carbon Nnanotubes
Promoting role of sulfur groups in selective catalytic reduction of NO with NH3 over H2SO4 modified activated carbons by Qianqian Guo; Wen Jing; Shangzeng Cheng; Zhanggen Huang; Dekui Sun; Yaqin Hou; Xiaojin Han (2257-2263).
To determine the role of sulfur groups formed on activated carbon (AC) in the selective catalytic reduction (SCR) of NO with NH3, coal-based AC was modified by H2SO4 under various conditions and then treated in N2 atmosphere at 400 °C. The resulting carbons were characterized by N2 adsorption, elemental analysis, temperature programmed desorption and X-ray photoelectron spectroscopy, and tested for the SCR of NO with NH3 in the temperature range of 30–250 °C. Results reveal that H2SO4 modification has little effect on the textural properties, but promotes the formation of sulfur and oxygen groups. The sulfur groups incorporated by H2SO4 modification are mainly sulfonic groups and then sulfates. In particular, these sulfur groups play a predominant role in improving NH3 adsorption and then enhancing the SCR activity of modified carbons above 150 °C. However, the contribution of oxygen groups to NO reduction is very limited under the conditions employed in this work.
Keywords: Activated Carbon; NO; H2SO4 Modification; Sulfur Groups; Oxygen Groups
Effect of solution properties on the interaction of 90Sr(II) with GMZ bentonite by Xin Chen; Jin Wang; Shaowei Wang; Fengliang Ma; Xiaopeng Chen; Jiaxing Li (2264-2272).
The bentonite from gaomiaozi county (Inner Mongolia, China) (GMZ bentonite) has been selected as the candidate of backfill material in China for nuclear waste repository. Herein, the sorption of 90Sr(II) on GMZ bentonite was investigated as a function of contact time, solid content, pH, ionic strength, foreign ions, humic acid (HA) and temperature. The results indicated that the sorption of 90Sr(II) was mainly dominated by ion exchange or outer-sphere surface complexation at low pH, whereas inner-sphere surface complexation was the main sorption mechanism at high pH values. The thermodynamic parameters (ΔH0, ΔS0 and ΔG0) calculated from the temperature-dependent sorption isotherms indicated that the sorption of 90Sr(II) on GMZ bentonite was an endothermic and spontaneous process. The results provided important information for the interaction mechanism of 90Sr(II) with GMZ bentonite, and is crucial for the evaluation of GMZ bentonite as backfill material.
Keywords: GMZ Bentonite; 90Sr(II); Sorption; Kinetic; Thermodynamic Data
Removal of cesium ions from waste solution using sericite incorporated into nickel hexacyanoferrate by Choong Jeon; Ju-Hyun Cha (2273-2279).
To increase adsorption capacity and selectivity for cesium ions from waste solution, sericite was chemically modified by means of nickel hexacyanoferrate (NiHCF) with a high selectivity trap agent for cesium. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were used for the characteristic analysis of surface onto the NiHCF-sericite. The adsorption capacity of cesium ions for the NiHCF-sericite increased about 2.5 times, as compared with natural sericite at initial pH 5.0 of waste solution. Adsorption equilibrium was investigated by Langmuir and Freundlich isotherm model, respectively. Maximum adsorption capacity was estimated as 16.583mg/g, and the Langmuir isotherm fits the adsorption data better than Freundlich model. The adsorption process was determined as an exothermic reaction and all adsorption was completed in 30 min. In addition, the adsorption capacity of cesium ions was not greatly affected by ionic strength (~0.1M NaCl concentration) and other metals in mixed waste solution.
Keywords: Sericite; Nickel Hexacyanoferrate (NiHCF); Cesium; Adsorption; Selectivity
Furfural production from hydrolysate of barley straw after dilute sulfuric acid pretreatment by Sung Bong Kim; Ja Hyun Lee; Xiaoguang Yang; Jiwon Lee; Seung Wook Kim (2280-2284).
Lignocellulosic biomass contains various fermentable sugars and versatile compounds, and should be isolated selectively. In this study, a two step process for furfural production is suggested. Dilute acid pretreatment, which solubilizes hemicellulose, was performed on barley straw at 110–190 °C temperature with 0.1–2% sulfuric acid for 2–20 min and a liquid portion of the hydrolysate was utilized. Using this hydrolysate, furfural production was conducted. Approximately 140–200 °C temperature induced the hydrolysis and pyrolysis of the hydrolysate. The initial reaction rate was found to be 2.84×10−5 mol/L·sec at 180 °C when reacted for 5min, 48.5% of theoretical furfural production was obtained, and it was faster than the generally used one step furfural production methods. In addition, a high temperature gradient for pre-heating showed improvement of temperature control.
Keywords: Furfural; Dilute Acid Pretreatment; Hydrolysate; Pyrolysis; Barley Straw
Cost-efficient cultivation of Spirulina platensis by chemical absorption of CO2 into medium containing NaOH by Joo-Young Jung; Ji-Won Yang; Kyochan Kim; Kwon-Tack Hwang; Simon MoonGeun Jung; Jong-Hee Kwon (2285-2289).
Spirulina is one of the promising photosynthetic microorganisms as the source for food, cosmetic, and other value-added products such as phycocyanin. However, its production cost associated with cultivation is expensive because of high concentration of bicarbonate (76wt%) in standard Zarrouk medium for Spirulina. Bicarbonate not only acts as a carbon source but also helps maintaining culture medium in alkaline condition, which is essential for growth of Spirulina. The present study demonstrates that bicarbonate (16.8 g/L) in standard Zarrouk medium was completely replaceable by chemical CO2 absorption using 0.2M NaOH and 154.2 mmol CO2 gas could be absorbed in the form of NaHCO3/Na2CO3 into 1 L medium during the process. This process was incorporated into Spirulina cultivation, which enabled us to reduce the total cost of preparation of Zarrouk medium by 34.3% without sacrificing biomass and pigments production. In addition, another important use of NaOH is achievement of cost-efficient and ecofriendly sanitization of culture medium.
Keywords: Chemical Absorption; Sodium Hydroxide; Carbon Ddioxide; Zarrouk Medium; Spirulina platensis
Biodiesel production from palm oil using a non-catalyzed supercritical process by Seok-Hwan Park; Jae-Hee Park; Sriramulu Gobikrishnan; Gwi-Taek Jeong; Don-Hee Park (2290-2294).
The effects of free fatty acid (FFA) and moisture contents in palm oil, as well as working volume ratio on the production of biodiesel (fatty acid methyl esters; FAMEs), were investigated using palm oil and a non-catalytic supercritical process. FAME content obtained using anhydrous palm oil was 95.8% during the non-catalytic supercritical process. FAME content produced with 15% moisture content and 15% FFA content was 94.4% and 95.1% respectively, which was similar to that of anhydrous palm oil with no FFA. The non-catalytic supercritical process was not affected by FFA or moisture content in oil. By increasing working volume ratio, reaction temperature decreased from 340 °C to 260 °C at the same pressure, whereas FAME content increased from 69.9% to 95.5%.
Keywords: Biodiesel Production; Non-catalytic Supercritical Process; Palm Oil
Absorption of carbon dioxide in aqueous solutions of imidazolium ionic liquids with carboxylate anions by Stefan Baj; Tomasz Krawczyk; Aleksandra Dąbrowska; Agnieszka Siewniak; Aleksander Sobolewski (2295-2299).
The solubility of carbon dioxide at atmospheric pressure in aqueous mixtures of 1,3-alkyl substituted imidazolium ionic liquids (ILs) containing carboxylic anions was studied. The ILs showed increased solubility of CO2 with decreasing water concentration. The relationship between the CO2 concentration in solution and the mole fraction of water in the ILs describes a sigmoidal curve. The regression constants of a logistic function were used to quantitatively assess the absorbent capacity and the effect of water on CO2 absorption. ILs containing the most basic anions, such as pivalate, propionate and acetate, had the best properties. It was observed that the impact of water on absorption primarily depended on the cation structure. The best absorption performance was observed for 1,3-dibutylimidazolium pivalate and 1-butyl-3-methyl imidazolium acetate.
Keywords: Absorption; Carbon Dioxide; Carboxylate Ionic Liquids; Solubility; Water Content
Prediction of the rejection of organic compounds (neutral and ionic) by nanofiltration and reverse osmosis membranes using neural networks by Yamina Ammi; Latifa Khaouane; Salah Hanini (2300-2310).
This work investigates the use of neural networks in modeling the rejection processes of organic compounds (neutral and ionic) by nanofiltration and reverse osmosis membranes. Three feed-forward neural network (NN) models, characterized by a similar structure (eleven neurons for NN1 and NN2 and twelve neurons for NN3 in the input layer, one hidden layer and one neuron in the output layer), are constructed with the aim of predicting the rejection of organic compounds (neutral and ionic). A set of 956 data points for NN1 and 701 data points for NN2 and NN3 were used to test the neural networks. 80%, 10%, and 10% of the total data were used, respectively, for the training, the validation, and the test of the three models. For the most promising neural network models, the predicted rejection values of the test dataset were compared to measured rejections values; good correlations were found (R= 0.9128 for NN1, R=0.9419 for NN2, and R=0.9527 for NN3). The root mean squared errors for the total dataset were 11.2430% for NN1, 9.0742% for NN2, and 8.2047% for NN3. Furthermore, the comparison between the predicted results and QSAR models shows that the neural network models gave far better.
Keywords: Nanofiltration; Reverse Osmosis; Organic Compounds; Rejection; Neural Networks; Modeling
Mass transfer intensification of nanofluid single drops with effect of temperature by Javad Saien; Mahdi Zardoshti (2311-2318).
The hydrodynamics and mass transfer of organic nanofluid single drops in liquid-liquid extraction pr°Cess were investigated within temperature range of 20 to 40 °C. Nanofluid drops of toluene+acetic acid, containing surface modified magnetite nanoparticles (NPs) with concentration within the range of (0.0005-0.005) wt%, were conducted in aqueous continuous phase. The rate of solute mass transfer was generally enhanced with NPs until about 0.002wt%, and small drops benefited more. The enhancement reached 184.1% with 0.002 wt% of NPs at 40 °C; however, adding more NPs led to the mass transfer to either remain constant or face a reduction, depending on the applied temperature. The mass transfer coefficient was nicely reproduced using a developed correlation for enhancement factor of molecular diffusivity as a function of Reynolds and Schmidt numbers.
Keywords: Liquid-liquid Extraction; Nanofluid; Single Drops; Temperature; Mass Transfer Enhancement
Preparation and characterization of PES/SiO2 composite ultrafiltration membrane for advanced water treatment by Mimi Suliza Muhamad; Mohamad Razman Salim; Woei-Jye Lau (2319-2329).
Polyethersulfone (PES) is a commonly used polymeric material for the fabrication of ultrafiltration (UF) membranes. However, the hydrophobic nature of PES leads to poor membrane performance with low anti-fouling properties during filtration process. Hence, for this study, the PES-based hollow fiber membrane was modified with inorganic silicon dioxide (SiO2) nanoparticles of various loading (from zero to 4 wt%), aiming to improve the membrane properties for advanced water treatment process. The characterization of the surface morphology, physical and chemical properties of novel PES/SiO2 composite membranes was performed by SEM, FTIR-ATR, TGA and contact angle analyzer. The SEM images show the changes in membrane structure as well as skin layer thickness upon addition of SiO2 nanoparticles. The FTIR-ATR analysis shows the functional group of SiO2 in the polymer matrices. Results further show that the presence of 2 wt% SiO2 in the membrane matrix is the best loading to improve the water flux and bovine serum albumin (BSA) rejection, achieving 87.2 L/m2·h and 94%, respectively. As a comparison, the control PES membrane only exhibits water flux of 44.2 L/m2·h and rejection of 81%. Results also show that the flux recovery percentage of the membrane was improved from 82% in the control membrane to 93% in the membrane incorporated with 2 wt% SiO2, indicating improved membrane anti-fouling property. Furthermore, the PES/SiO2 membrane shows huge potential for advanced water treatment, as the qualities of the permeate samples treated by this membrane could meet the limit set by a local water company.
Keywords: Polyethersulfone; Ultrafiltration; Silicon Dioxide; Advanced Water Treatment; Anti-fouling Performance
Simple boron removal from seawater by using polyols as complexing agents: A computational mechanistic study by Min-Kyung Kim; Ki Heon Eom; Jun-Heok Lim; Jea-Keun Lee; Ju Dong Lee; Yong Sun Won (2330-2334).
The complexation of boric acid (B(OH)3), the primary form of aqueous boron at moderate pH, with polyols is proposed and mechanistically studied as an efficient way to improve membrane processes such as reverse osmosis (RO) for removing boron in seawater by increasing the size of aqueous boron compounds. Computational chemistry based on the density functional theory (DFT) was used to manifest the reaction pathways of the complexation of B(OH)3 with various polyols such as glycerol, xylitol, and mannitol. The reaction energies were calculated as −80.6, −98.1, and −87.2 kcal/mol for glycerol, xylitol, and mannitol, respectively, indicating that xylitol is the most thermodynamically favorable for the complexation with B(OH)3. Moreover, the 1: 2 molar ratio of B(OH)3 to polyol was found to be more favorable than the ratio of 1: 1 for the complexation. Meanwhile, latest lab-scale actual RO experiments successfully supported our computational prediction that 2 moles of xylitol are the most effective as the complexing agent for 1 mole of B(OH)3 in aqueous solution.
Keywords: Boron Removal; Boric Acid; Polyol; Complexation; Density Functional Theory; Computational Chemistry
Novel perpendicularly cross-rectangular CuO architectures: Controlled synthesis, enhanced photocatalytic activity and catalytic thermal-decomposition of NH4ClO4 by Hanmei Hu; Xinqing Ge; Qiang Zheng; Chonghai Deng (2335-2341).
Novel perpendicularly cross-rectangular CuO architectures have been successfully fabricated on a large scale by a facile microwave-assisted chemical aqueous route. The as-synthesized CuO products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM) and UV-vis absorption spectroscopy. An individual CuO microstructure is mainly assembled by two rectangle-shaped nanosheets with different sizes, which is perpendicularly intersected through the center. A possible formation mechanism of perpendicularly cross-rectangular CuO architectures was proposed based on the comparative experimental results. The prepared CuO nanoarchitectures exhibited excellent photocatalytic activity for the decolorization of Rhodamine B (RhB) under visible light irradiation. Simultaneously, the prepared CuO products, acting as an additive, also showed effective catalytic activity on the thermal decomposition of ammonium perchlorate (NH4ClO4).
Keywords: Crystal Growth; CuO Nanosheets; Green Synthesis; Catalytic Performance
Study of struvite crystallization in a semi-batch jet loop fluidized bed reactor by Dae-Yeop Kang; Jun-Heok Lim; Tae-Yoon Lee; Jea-Keun Lee (2342-2346).
A semi-batch jet loop fluidized bed reactor (JLFBR) was used as a crystallization reactor to remove nitrogen and phosphorus from synthetic wastewater through struvite crystallization. The reactor performance obtained in the JLFBR was compared with that in a same-size jet loop reactor (JLR). The time required to increase the initial pH of the synthetic wastewater from 7.3 to 8.0 by aeration in the JLFBR was shorter than in the JLR. Moreover, the removal rates of ammonium nitrogen (NH4-N) and total phosphorus (T-P) were faster in the JLFBR. This may be due to the enhanced turbulent intensity that promoted struvite formation, as well by the fluidized particles in the JLFBR.
Keywords: Jet Loop Fluidized Bed Reactor; Struvite Crystallization; Ammonium Nitrogen Removal; Total Phosphorous Removal; Fluidized Particles
Cassava starch graft copolymer as an eco-friendly corrosion inhibitor for steel in H2SO4 solution by Xianghong Li; Shuduan Deng (2347-2354).
Cassava starch graft copolymer (CSGC) was prepared by grafting acryl amide (AA) onto cassava starch (CS). The inhibition effect of CSGC on the corrosion of cold rolled steel (CRS) in 1.0M H2SO4 solution was first studied by weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM) methods. The results show that CSGC is a good inhibitor, and inhibition efficiency of CSGC is higher than that of CS or AA. The adsorption of CSGC on steel surface obeys Langmuir adsorption isotherm. CSGC is a mixed-type inhibitor at 20 °C, while mainly a cathodic inhibitor at 50 °C.
Keywords: Corrosion Inhibitor; Sulfuric Acid; Steel; Graft Copolymer; Adsorption
Highly selective magnetic polymer particles via molecular imprinting by Xiaobing Wang; Guihua Qiu; Yi Ge; Wei Zheng; Lingmei Kong; Yajuan Xue; Bin Ren; Yuxing Peng (2355-2360).
Magnetic hydrophilic molecularly imprinted polymer (MIP) particles were successfully synthesized via an inverse suspension polymerization in silicone oil, by employing methacryloxypropyltrimethoxysilane(MPS)-modified Fe3O4 nanoparticles as magnetic particles, 2,4-dichlorophenoxyacetic acid (2,4-D) as template, hydroxyethyl methacrylate (HEMA) as hydrophilic monomer, and acetonitrile as high polar porogen. The synthesized magnetic hydrophilic MIP particles could be separated rapidly under an external magnetic field. About 94% transmittance of the particlewater suspension could be reached within 20 min by magnetic separation, whereas about 84% transmittance was achieved after at least 180 min by sedimentation. The adsorption capacity of the particles was also studied in pure aqueous environments. These hydrophilic MIP particles had a higher selectivity for templates. Hydrophilic MIP particles took on a higher imprinting factor than hydrophobic MIP particles and 2,4-D were able to rebind hydrophilic MIP particles more easily than 4-Chorophenoxyacetic acid.
Keywords: Molecular Imprinting; Magnetic Particles; Suspension Polymerization; Hydrophilic Particles; Selectivity
Hydrodynamics of multi-sized particles in stable regime of a swirling bed by Chin Swee Miin; Shaharin Anwar Sulaiman; Vijay Raj Raghavan; Morgan Raymond Heikal; Muhammad Yasin Naz (2361-2367).
Using particle imaging velocimetry (PIV), we observed particle motion within the stable operating regime of a swirling fluidized bed with an annular blade distributor. This paper presents velocity profiles of particle flow in an effort to determine effects from blade angle, particle size and shape and bed weight on characteristics of a swirling fluidized bed. Generally, particle velocity increased with airflow rate and shallow bed height, but decreased with bed weight. A 3° increase in blade angle reduced particle velocity by approximately 18%. In addition, particle shape, size and bed weight affected various characteristics of the swirling regime. Swirling began soon after incipience in the form of a supra-linear curve, which is the characteristic of a swirling regime. The relationship between particle and gas velocities enabled us to predict heat and mass transfer rates between gas and particles.
Keywords: Fluidized Bed; Swirling Regime; Particle Technology; Bed Weight; Blade Angle