Korean Journal of Chemical Engineering (v.34, #2)

Principal component analysis (PCA) has been widely used in monitoring industrial processes, but it is still necessary to make improvements in having a timely and effective access to variation information. It is known that the transformation matrix generated from real-time PCA model indicates inner relations between original variables and new produced components, so this matrix would be different when modeling data deviate due to the change of the operating condition. Based on this theory, this paper proposes a novel real-time monitoring approach which utilizes polygon area method to measure the variation degree of the transformation matrices and then constructs a statistic for monitoring purpose. The on-line data are collected through a combined moving window (CMW), containing both normal and monitored data. To evaluate the performance of the proposed method, a simple numerical simulation, the CSTR process and the classic Tennessee Eastman process are employed for illustration, with some PCA-based methods used for comparison.
Keywords: Principal Component Analysis; Combined Moving Window; Polygon Area; Real-time Process Monitoring; Fault Detection

Dynamic matrix control applied on propane-mixed refrigerant liquefaction process by Hyunjun Shin; Yu Kyung Lim; Se-Kyu Oh; Seok Goo Lee; Jong Min Lee (287-297).
This study proposes a dynamic matrix control strategy that produces control input sequences which are more robust and reduce power consumption than conventional proportional-integral (PI) controllers when applied to the C3MR liquefaction process. First, a rigorous process dynamic model was constructed in Aspen HYSYS Dynamics 7.3 and MATLAB 2014a which calculates dynamic responses for two different scenarios of unmeasured step disturbances increasing the load of liquefaction energy. Then, a DMC module including the manipulation of the compressor speed was formulated. The simulations using the proposed DMC module demonstrate that the multivariable optimal control increases the energy efficiency and robustness of a complex liquefaction cycle process.
Keywords: LNG Liquefaction; C3MR Process; DMC; APC; Cascade PI Control

Synthesis and characterization of a K/K2CO3-based solid superbase as a catalyst in propylene dimerization by Haibo Jin; Heng Jiang; Qiwei Wang; Suohe Yang; Guohua Luo; Guangxiang He (298-304).
A novel solid superbase 3%K/K2CO3 was prepared by loading metallic potassium on K2CO3. The optimized preparation conditions included a loading time of 1.5 h, loading temperature of 150 °C, loading amount of 3wt% and average carrier size of 120 μm. Under the optimum conditions, the conversion of propylene is about 60% with the selectivity of dimers 98.5% and the selectivity of 4MP1 86.3%. In addition, the superbase 3%K/K2CO3 has a base strength of H ≥37, and the concentration of basic sites of H ≥35 is approximately 0.3mmol·g CAT −1 . The microcrystal of metallic potassium was determined using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was assumed that the oxygen species, which are adjacent to lattice defects, such as the crystalline corners, edges and vacancies of metallic potassium micro-crystals, constituted the superbasic sites.
Keywords: Solid Superbase; Superbasic Site; Base Catalysis; Propylene Dimerization

Ni/La2O3-ZrO2 catalyst for hydrogen production from steam reforming of acetic acid as a model compound of bio-oil by Ya-ping Xue; Chang-feng Yan; Xiao-yong Zhao; Shi-lin Huang; Chang-qing Guo (305-313).
Hydrogen production from steam reforming of acetic acid was investigated over Ni/La2O3-ZrO2 catalyst. A series of Ni/La2O3-ZrO2 catalysts were synthesized by sol-gel method coupled with wet impregnation, which was characterized by XRD, BET, TEM, EDS, TG, SEM and TPR. Catalytic activity of Ni/La2O3-ZrO2 was evaluated by steam reforming of acetic acid at the temperature range of 550-750 °C. The tetragonal phase La0.1Zr0.9O1.95 is formed through the doping of La2O3 into the ZrO2 lattice and nickel species are highly dispersed on the support with high specific surface area. H2 yield and CO2 yield of Ni/La2O3-ZrO2 catalyst with 15%wt Ni reaches 89.27% and 80.41% at 600 °C, respectively, which is attributed to high BET surface area and sufficient Ni active sites in strong interaction with the support. 15%wt Ni supported on La2O3-ZrO2 catalyst maintains relatively stable catalytic activities for a period of 20 h.
Keywords: Hydrogen Production; Ni/La2O3-ZrO2 Catalyst; Steam Reforming; Bio-oil; Acetic Acid

X-ray absorption spectroscopies of Mg-Al-Ni hydrotalcite like compound for explaining the generation of surface acid sites by Hong Khanh Dieu Nguyen; Toan Dang Nguyen; Dung Ngoc Hoang; Duc Sy Dao; Thao Tien Nguyen; Limphirat Wanwisa; Lan Linh Hoang (314-319).
Hydrotalcite-like compound containing metal cations such as Mg2+, Al3+ and Ni2+ was characterized using Ni K-edge EXAFS and in situ Ni K-edge XANES techniques for clarifying its bonding environment around Ni2+ sites and structure changes during calcination from room temperature to 550 °C, respectively. At the fixed molar ratio of Mg/Ni/Al of 2/1/1, the results obtained from EXAFS analysis showed a slight blue shift before and after the calcination at 550 °C and a reduction in white line peak; the best fits of the two samples revealed tiny change in coordination number about 7 for Ni-O path but considerable difference for Ni-Mg(Al) path from about 4.5 to 9.5, confirming a modification from brucite like to mixed oxide structure. On the other hand, bond distances of the Ni-O and Ni-Mg paths nearly fixed at about 2.06 Å to 3.0 Å reflected stability of the cationic bond order on each plane, but partial collapse and decomposition of the interlayer formed by water molecules and anion CO 3 2− after the calcination. Linear combination fit extracted from the in situ Ni K-edge XANES also confirmed the changes along with the calcination such as slow and fast decreases of brucite fraction at 150 °C and 330 °C, respectively, in corresponding to the mixed oxide fraction increases. The achieved bonding structures were also applied to explain acid-base occurrence of the hydrotalcite-like material, especially the acid sites generated by different static charges along with the bonds. The explanation was illustrated by NH3-TPD method.
Keywords: EXAFS; XAS; XANES; Hydrotalcite; Brucite

An Fe2O3 catalyst was applied to the production of high-calorie synthetic natural gas (SNG). With this catalyst, the product distribution changed as the surface composition of the Fe2O3 catalyst changed. The effect of these changes on the catalytic activity was investigated. The active phases of the Fe2O3 catalyst were a mixture of low-carbon FeCx and Fe3C, which was maintained for 10 h, accompanied by the regeneration of Fe3O4. The surface Fe concentration increased after 10 h reaction, and this increased the CO conversion. In addition, the amounts of adsorbed C2H4 and C3H6 increased, which resulted in an increase in carbon chain growth. The surface concentration of oxygen also increased due to the regeneration of Fe3O4, thus reducing the C3H6 adsorption strength; in contrast, C2H4 adsorption increased, resulting in an enhanced paraffin-to-olefin (p/o) ratio for C2 hydrocarbons and reduced p/o ratio for C3 hydrocarbons.
Keywords: Methanation; Fischer-Tropsch; Fe Catalyst; Iron Carbide; Paraffin-to-olefin Ratio

Composite membranes of sulfonated poly(ethersulfone)/1,1-carbonyl diimidazole/1-(3-aminopropyl)-silane/silica (SPES/CDI/AS/SiO2) with silica of various contents (3, 5 and 8 wt%) were prepared as electrolytes for direct methanol fuel cells (DMFCs). Comparison was made with pure SPES and SPES/SiO2. The properties of the composite membranes were studied by FTIR, TGA, XRD, water and methanol uptake, proton conductivity. SPES/CDI/AS/SiO2 membranes were also characterized by scanning electron microscopy (SEM), which showed good adhesion between the modified sulfonic acid (-SO3H) groups of SPES and silica because of cross-linking with covalent bond formation and reduced cavities in the composites. This effect played an important role in reducing water uptake, methanol uptake and methanol permeability of the SPES/CDI/AS/SiO2 composites. The water and methanol uptake and also methanol permeability of the SPES/CDI/AS/SiO2 composite membrane with 8% SiO2 were found in the order 3.58%, 2.48% and 1.91×10−7 (cm2s−1), lower than those of SPES and Nafion 117. In SPES membrane of 16.94% level of sulfonation, the proton conductivity was 0.0135 s/cm at 25 °C, which approached that of Nafion 117 under the same conditions. Also, the proton conductivity of the SPES/CDI/AS/SiO2 8% membrane was 0.0186 s/cm, which was higher than that of SPES at room temperature. The preparation of SPES/SiO2 composites in the presence of AS and CDI, led to 63%, 56% and 64% reduction of water uptake, methanol uptake and methanol permeability, respectively without a sharp drop in proton conductivity of the composite membranes which featured a good balance between high proton conductivity, water and methanol uptake of SPES/CDI/AS/SiO2 membranes.
Keywords: Membrane; Sulfonated Poly(ethersulfone); Silica; Nafion 117; Methanol Permeability; Proton Conductivity

Oleander oil has been used as raw material for producing biodiesel using ultrasonic irradiation method at the frequency of 20 kHz and horn type reactor 50 watt. A two-step transesterification process was carried out for optimum condition of 0.45 v/v methanol to oil ratio, 1.2% v/v H2SO4 catalyst, 45 °C reaction temperature and 15min reaction time, followed by treatment with 0.25 v/v methanol to oil ratio, 0.75% w/v KOH alkaline catalyst, 50 °C reaction temperature and 15 min reaction time. The fuel properties of Oleander biodiesel so obtained confirmed the requirements of both the standards ASTM D6751 and EN 14214 for biodiesel. Further Oleander biodiesel-diesel blends were tested to evaluate the engine performance and emission characteristics. The performance and emission of 20% Oleander biodiesel blend (B20) gave a satisfactory result in diesel engines as the brake thermal efficiency increased 2.06% and CO and UHC emissions decreased 41.4% and 32.3% respectively, compared to mineral diesel. Comparative investigation of performance and emissions characteristics of Oleander biodiesel blends and mineral diesel showed that oleander seed is a potential source of biodiesel and blends up to 20% can be used for realizing better performance from an unmodified diesel engine.
Keywords: Biodiesel; Oleander Oil; Ultrasonic Cavitation Method; Performance Testing

The pretreatment of Helianthus tuberosus residue was studied for fermentable sugar production. The pretreatment was performed by varying the temperature, type of chemical solution, and concentration. Two different catalytic pretreatments using sulfuric acid and aqueous ammonia were operated and compared in a flow-through column reactor system. The flow-through process was required to increase the sugar production yield of biomass. To selectively remove the lignin of biomass and achieve fractionation of hemicellulose in the liquid phase to produce pentose, the flow-through process could be controlled by the pretreatment conditions. Furthermore, the remaining solid underwent enzymatic hydrolysis for hexose production. The mass balances of biomass pretreated with aqueous ammonia and sulfuric acid solution were compared in terms of production of fermentable sugars. The glucose recovery compared to the initial biomass was 71.2% in the pretreatment using aqueous ammonia at 170 °C, and pretreatment using sulfuric acid solution at 150 °C was 52.3%.
Keywords: Cellulosic Biomass; Pretreatment; Flow-through; Helianthus tuberosus Residue; Aqueous Ammonia; Sulfuric Acid

FAME was produced by a two-step in-situ transesterification of acid oil (AO) with methanol in a novel continuous flow ultrasonic reactor system composed of four ultrasonic reactors with different frequency. The hydrodynamic behavior of the reactor was investigated by a step response technique, and the effect of ultrasonic frequency on mono-alkyl esters of long chain fatty acids (FAMEs) formation was also investigated. The production process includes an in-situ sulfuric acid-catalyzed esterification of AO with methanol in the first two ultrasonic reactors successively followed by an in-situ base-catalyzed transesterification in the other two ultrasonic reactors. The AO initial free fatty acids (FFA) content about 17.5 w% was cut down to less than 1 w% by sulfuric acid-catalyzed esterification. FAME yields in excess of 97.0% identified by gas chromatography/mass spectrometry (GC/MS) were obtained by the two-step in-situ reaction. The maximum and minimum volumetric productivity could reach 13.76 L·h−1 and 10.24 L·h−1 respectively.
Keywords: Novel Reactor; Ultrasonic-enhanced; Continuous Production; Biodiesel; Waste Acid Oil

Biodiesel production from blended sewage sludge (BSS) by a one-step direct process was investigated, and optimal conditions for this process were determined. The one-step direct process comprises extraction of lipids from BSS and simultaneous transesterification of these lipids with methanol. Among the organic solvents evaluated, pure methanol showed higher biodiesel yields compared with other solvents or solvent mixtures. The optimum conditions determined included 10 mL of methanol/g-BSS, 0.7% (g/g-BSS) of H2SO4, 60 °C, 4 h of reaction time and 300 rpm of agitation speed. Under these conditions, biodiesel yield was 3.1% (g-biodiesel/g-BSS), which was 63.2% higher than that obtained under initial conditions, and 24.0%-63.2% higher than those obtained in previous studies.
Keywords: Biodiesel; Blended Sewage Sludge; One-step Direct Process; Transesterification; Optimization

Carbonization and CO2 activation of scrap tires: Optimization of specific surface area by the Taguchi method by Zakaria Loloie; Mehrdad Mozaffarian; Mansooreh Soleimani; Neda Asassian (366-375).
This research demonstrates the production of activated carbon from scrap tires via physical activation with carbon dioxide. A newly constructed apparatus was utilized for uninterrupted carbonization and activation processes. Taguchi experimental design (L16) was applied to conduct the experiments at different levels by altering six operating parameters. Carbonization temperature (550–700 °C), activation temperature (800–950 °C), process duration (30–120 min), CO2 flow rate (400 and 600 cc/min) and heating rate (5 and 10 °C/min) were the variables examined in this study. The effect of parameters on the specific surface area (SSA) of activated carbon was studied, and the influential parameters were identified employing analysis of variance (ANOVA). The optimum conditions for maximum SSA were: carbonization temperature=650 °C, carbonization time=60 min, heating rate=5 °C/min, activation temperature= 900 °C, activation time=60 min and CO2 flow rate=400 cc/min. The most effective parameter was activation temperature with an estimated impact of 49%. The activated carbon produced under optimum conditions was characterized by pore and surface structure analysis, iodine adsorption test, ash content, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The process yield for optimized activated carbon was 13.2% with the following properties: specific surface area=437 m2/g, total pore volume=0.353 cc/g, iodine number=404.7 mg/g and ash content=13.9% along with an amorphous structure and a lot of oxygen functional groups. These properties are comparable to those of commercial activated carbons.
Keywords: Scrap Tires; Activated Carbon; Physical Activation; Taguchi; Specific Surface Area; Optimization

Optimization of arsenite removal by adsorption onto organically modified montmorillonite clay: Experimental & theoretical approaches by Anoushiravan Mohseni Bandpei; Seyed Mohsen Mohseni; Amir Sheikhmohammadi; Mahdieh Sardar; Maryam Sarkhosh; Mohammad Almasian; Moayad Avazpour; Zahra Mosallanejad; Zahra Atafar; Shahram Nazari; Soheila Rezaei (376-383).
Arsenic is a critical contaminant for aqueous environments as it poses harmful health risks. To meet the stringent regulations regarding the presence of arsenic in aqueous solutions, the feasibility of montmorillonite clay modified with hexadecyltrimethyl ammonium chloride as the adsorbent was tested for the removal of arsenic ions from aqueous solutions. A scanning electron microscopy (SEM) study confirmed that the organically modified nanoclay (ONC) adsorbent had a porous structure with a vast adsorbent surface.The x-ray fluorescence (XRF) analysis proved the presence of carbon in the structure of the modified nanoclay that can be evidence for the creation of ONC. The x-ray diffraction (XRD) analysis results confirm the existence of four main groups of minerals, carbonate (Calcite), clay (Askmtyt and Kandyt), silicate (Quartz), and phyllosilicate (Kaolinite), in the ONC structure.The influence of various parameters such as solution pH, adsorbent dosage, initial arsenite concentration, and contact time on arsenic adsorption onto ONC was investigated. A 25 full factorial central composite experimental design was applied. A central composite design under response surface methodology (RSM) was employed to investigate the effects of independent variables on arsenite removal and to determine the optimum condition. The experimental values were in a good fit with the ones predicted by the model. The optimal operating points (adsorbent dosage: 3.7 g L−1, surfactant dosage: 3 g L−1 and the contact time: 37.2min) giving maximum arsenite removal (95.95%) were found using Solver “Add-ins” in Microsoft Excel 2010.
Keywords: Modeling; Response Surface Methodology; Organic Nanoclay; Arsenite; Optimization

Waste coffee grounds were used as an adsorbent to efficiently adsorb silver ions in actual industrial waste-water. It was found that the functional groups like -COO and -OH groups in coffee grounds play an important role in the adsorption of silver ions from the FT-IR spectra, and the SEM images and EDX spectra were used to investigate the surface onto waste coffee grounds and confirm the existence of silver ions onto the waste coffee grounds after adsorption of silver ions. The highest adsorption capacity and removal efficiency was achieved as about 46.2mg/g and 92.4% at the initial pH 6 of wastewater. Two adsorption isotherm models, Langmuir and Freundlich, were used to analyze the equilibrium data. The Langmuir isotherm, which provided the best correlation for silver adsorption onto coffee grounds, showed that the maximum adsorption capacity and affinity constant was calculated as 49.543mg/g and 1.134 L/mg, respectively. The adsorption was an exothermic reaction and the most equilibrium was achieved at less than 60min. From these results, the waste coffee grounds have high possibility to be used as effective and economical adsorbent for silver adsorption.
Keywords: Coffee Grounds; Silver Ions; Adsorption; Industrial Wastewater; Removal

Extraction and quantification of phenolic compounds from Prunus armeniaca seed and their role in biotransformation of xenobiotic compounds by Ismat Bibi; Aneela Sultan; Shagufta Kamal; Shazia Nouren; Yusra Safa; Kashif Jalani; Misbah Sultan; Sadia Atta; Fariha Rehman (392-399).
The current research project has been devoted to isolating new low cost and eco-friendly phenolic compounds from fruit seeds, peels and vegetables to reduce the atmospheric pollution. Natural phenolic compounds were extracted from different fruit seeds and agriculture waste: P. armeniaca, P. persica, P. domestica and Triticum aesativum. The total phenolic content was quantified, and the maximum value (1 mL extract having 1,933 μg) was found in P. armeniaca seed extract. Phytochemical screening showed that P. armeniaca seeds contain higher amount of alkaloid, tannins, saponins and flavonoid. P. armeniaca seeds enhanced the biotransformation of reactive yellow dye up to 69.89% with maximum laccase (322.45 IU/mL) production. Biodegradation of reactive yellow was only 23.34% without natural redox mediator at sixth day of incubation. Use of P. armeniaca seed stimulators resulted in maximum laccase activity (894.4 IU/mL) with 99.5% rate of removal. UV-Vis, HPLC & FTIR analysis confirmed the transformation of parent dye into various new products. Phytotoxicity study indicated 0% germination index of Avena sativa seeds with reactive yellow, whereas 83% germination index having 100% seed germination while 83% root elongation with treated sample. Thus, the study revealed that the natural phenolic compounds could serve as high potential redox mediators for enhanced laccase-mediated decolorization of reactive yellow dye.
Keywords: Enzyme Catalysis; Natural Redox Mediators; Phytotoxicity; Hazardous Pollutants

An optimized, ceramide-based, nanostructured lipid carrier (NLC) formulation was developed for isoliquiritigenin (ILTG), and its potential as a transdermal delivery system was evaluated. ILTG-loaded NLCs were prepared by blending solid (ceramide, cholesterol) and liquid lipids (caprylic/capric triglyceride) in various proportions using a hot homogenization and ultrasonication method. The physicochemical characteristics were investigated by DLS, ZP, EE%, TEM, DSC and XRD analyses and in vitro skin permeation studies. The results showed that the particle size of the formulation was 150.19–251.69 nm with a ZP>−20mV. The EE% was 56.45–89.97%. The NLC structure was influenced by lipid ratio, and increasing the caprylic/capric triglyceride ratio caused a less ordered structure, as confirmed by DSC. The XRD analysis indicated that ILTG was not in the crystalline state in all formulations. The skin permeation study showed that the ILTG-NLCs promoted ILTG permeation. In conclusion, ceramide-based NLCs could be a promising vehicle for the ILTG transdermal delivery of ILTG.
Keywords: Nanostructured Lipid Carrier; Transdermal Delivery System; Ceramide; Isoliquiritigenin; MEL

Modeling of reverse osmosis flux of aqueous solution containing glucose by Narjess Zaghbani; Mitsutoshi Nakajima; Hiroshi Nabetani; Amor Hafiane (407-412).
The aim of the paper is to model the permeate flux during reverse osmosis (RO) of a highly concentrated glucose solution using the osmotic pressure model. Such a model accounts for the effect of the concentration polarization phenomenon on the permeate flux. To apply this model the viscosity, the osmotic pressure of solution and the diffusion coefficient of glucose were estimated. Using mathematical simulation software, the values of mass transfer coefficient for different concentrations of glucose (5, 10, 15 and 20 wt%) and at different feed flow rate were determined. The experimental permeate flux values conducted on flat RO membranes (Type HR-99) agreed well with the values calculated by the osmotic pressure model, as shown by statistical analysis.
Keywords: Mass Transfer Coefficient; Reverse Osmosis; Glucose; Permeate Flux

A low-cost activated carbon (AC) was produced from the broom sorghum stalk using KOH as the chemical activating agent, and then the surface of AC was functionalized with diethanolamine to enhance CO2/CH4 selectivity. Characteristics of pristine and DEA-functionalized ACs were determined through different analyses such as Boehm’s method, BET, FT-IR, SEM, and TGA. The adsorption behavior of pure carbon dioxide and pure methane on these adsorbents was investigated in a temperature range of 288-308 K and pressure range of 0-25 bar using an apparatus based on a volumetric method. Results indicated that amine functionalization significantly improved the selectivity of CO2/CH4. The enhancement of CO2 ideal adsorption selectivity over CH4 from 1.51 for the pristine AC to 5.75 for the AC-DEA was attributed to adsorbate-adsorbent chemical interaction. The present DEA-functionalized AC adsorbent can be a good candidate for applications in natural gas and landfill gas purifications.
Keywords: Activated Carbon; Broom Sorghum; Carbon Dioxide; Methane; Functionalization; Diethanolamine

Implementation of soft computing approaches for prediction of physicochemical properties of ionic liquid mixtures by Saeid Atashrouz; Hamed Mirshekar; Abdolhossein Hemmati-Sarapardeh; Mostafa Keshavarz Moraveji; Bahram Nasernejad (425-439).
The main objective of this study was to develop soft computing approaches for prediction of physicochemical properties of IL mixtures including: density, heat capacity, thermal conductivity, and surface tension. The proposed models in this study are based on support vector machine (SVM), least square support vector machines (LSSVM), and group method of data handling type polynomial neural network (GMDH-PNN) systems. To find the LSSVM and SVM adjustable parameters, genetic algorithm (GA) as a meta-heuristic algorithm was utilized. The results showed that LSSVM is more robust and reliable for prediction of physicochemical properties of IL mixtures. The proposed GA-LSSVM model provides average absolute relative deviations of 0.38%, 0.18%, 0.77% and 1.18% for density, heat capacity, thermal conductivity, and surface tension, respectively, which demonstrates high accuracy of the model for prediction of physicochemical properties of IL mixtures.
Keywords: Physicochemical Properties; Ionic Liquid; GMDH-PNN; LSSVM; SVM

Modified ultra-porous ZIF-8 particles were used to prepare novel ZIF-8/Pebax 1657 mixed matrix membranes (MMMs) on PES support for separation of CO2 from CH4 using spin coating method. TEM and SEM were used to characterize modified ZIF-8 particles. SEM was also used to investigate the morphology of synthesized MMMs. The MMMs with thinner selective layer showed higher CO2 permeability and lower CO2/CH4 selectivity in permeation tests compared to MMMs with thicker selective layer. The plasticization was recognized as the main reason for rise in CO2 permeability and drop in CO2/CH4 selectivity of thinner MMMs. The gas sorption results showed that the high permeability of CO2 in MMMs is mainly due to the high solubility of this gas in MMMs, leading to high CO2/CH4 solubility selectivity for MMMs. The fractional free volume and void volume fraction of MMMs increased as the thickness of membrane decreased. Applying higher mixed feed pressures and permeation tests temperatures resulted in increase in CO2 permeability and decrease in CO2/CH4 selectivity. At highest testing temperature (60 °C), the CO2 permeability of synthesized MMMs with thinner selective layer remarkably increased.
Keywords: ZIF-8; Modification; Pebax 1657; Spin Coating; CO2 Separation

Natural pumice (NP), FeCl3·6H2O modified pumice (FEMP) and hexadecyl trimethyl ammonium bromide (HDTM.Br) modified pumice (HMP) were used for fluoride adsorption. The effect of pH (3-11), initial concentration (2-15mg/L), and adsorbent dosage (0.2-0.8 g/L) on the defluoridation was optimized by using central composite design (CCD) in the response surface methodology (RSM). Results showed optimum condition in the pH=3, initial concentration=2mg/L, and adsorbent dosage=0.71, 0.75, 0.70 g/L with the maximum removal efficiency of 9.39, 76.45, and 95.09% for NP, FEMP, and HMP, respectively. The adsorption equilibrium and kinetic data was in good agreement with Freundlich and pseudo-second order reaction. Thermodynamic parameters indicated a non-spontaneous nature for NP and spontaneous nature for FEMP and HMP. Positive enthalpy illustrated the endothermic nature of the process. On the basis of results, modification of pumice led to an increase in the fluoride removal efficiency.
Keywords: Thermodynamic; Central Composite Design; Response Surface Methodology; Fluoride Adsorption; Pumice Modification

The isothermal vapor-liquid equilibrium data for the binary systems of cyclopentene (1)+cyclopentyl methyl ether (2) were measured at 313.15, 323.15, 333.15, 343.15 and 353.15 K using a dynamic-type equilibrium apparatus and online gas chromatography analysis. For all the measured VLE data consistency tests were performed for the verification of data using Barker’s method and the ASPEN PLUS Area Test method. All the resulting average absolute values of residuals [δ ln (γ 1/γ 2)] for Barker’s method and D values for the ASPEN PLUS area test method were comparatively small. So, the VLE data reported in this study are considered to be acceptable. This binary system shows negative deviation from Raoult’s law and does not exhibit azeotropic behavior at whole temperature ranges studied here. The measured data were correlated with the P-R EoS using the Wong-Sandler mixing rule. The overall average relative deviation of pressure (ARD-P (%)) between experimental and calculated values was 0.078% and that of vapor phase compositions (ARD-y (%)) was 0.452%.
Keywords: Vapor Liquid Equilibria (VLE); Cyclopentyl Methyl Ether (CPME); Cyclopentene (CPEN); Peng-Robinson Equation of State (PR-EoS); Wong-Sandler Mixing Rule (WS-MR)

Synthesis and characterization of polypyrrole doped by cage silsesquioxane with carboxyl groups by Gang Shi; Youxin Che; Luyan Wu; Yao Rong; Caihua Ni (470-475).
Cage silsesquioxane with carboxyl groups (POSS-COOH) was successfully synthesized, after which it was added to polypyrrole (PPy) as a dopant to produce the doped PPy (PPy/POSS-COOH) solution. The PPy/POSS-COOH composites were characterized by FTIR (Fourier transformation infrared spectroscopy), SEM (Scanning electron microscopy), TGA (Thermo-gravimetric analysis), CV (Cyclic voltammetry) and RL (Reflection loss). Compared to PPy without POSS-COOH (un-PPy), the conductivity of PPy/POSS-COOH composites could be improved dramatically, reaching up to 0.850 S/cm at 25 °C. Under N2 atmosphere, the residual rate of PPy/POSS-COOH was 68% at 700 °C, 14% higher than the one of un-PPy. Meanwhile, PPy/POSS-COOH had a reflection loss below −8 dB over 9.35 to 11.20GHz, with a minimum value of −10.32 dB at 10.54 GHz, thus demonstrating higher microwave absorption than un-PPy. This method may provide a facile route to produce doped conducting polymers with POSS-COOH.
Keywords: Cage Silsesquioxane; Polypyrrole; Thermal Stability; Electrochemical Activity; Microwave-absorbing Ability

Fabrication of carbon nanotube-loaded TiO2@AgI and its excellent performance in visible-light photocatalysis by Liu Yang; Yang An; Bin Dai; Xuhong Guo; Zhiyong Liu; Banghua Peng (476-483).
Novel, visible light driven CNTs-TiO2@AgI hybrid materials were synthesized by a simple solvothermaldissolution-precipitation method, during which the acid vapor treated carbon nanotubes (CNTs) as template, AgI as sensitizer and TiO2 as the bridge unified them to form a ternary composite. The morphology and chemical components of as-prepared samples were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and XPS characterizations indicated that anatase TiO2 and crystal AgI co-existed in the composite. HRTEM demonstrated CNTs were decorated with well-dispersed AgI and TiO2 nanoparticles (NPs), and TiO2 had an intimate connection with both AgI and CNTs. Diffusive reflectance UV-vis spectroscopy of CNTs-TiO2@AgI nanocomposite was extended to the whole UV-visible region due to adding of CNTs and AgI NPs. Degradation of Rhodamine B (RhB) polluted water using CNTs-TiO2@AgI NPs was carried out under visible light irradiation, and it showed higher degradation efficiency than CNTs-TiO2, TiO2@AgI, and CNTs@AgI NPs. The primary reason for the enhanced photocatalytic property was attributed to the synergic effect in CNTs-TiO2@AgI, which included the good adsorption ability and electrical conductivity of CNTs as well as the intimate connection and hetero-junctions among AgI, TiO2, and CNTs. Meanwhile, the as-prepared hybrid materials can be easily separated and reclaimed from the liquid phase, and the recycling tests indicated CNTs-TiO2@AgI had renewable performance.
Keywords: Titanium Dioxide; Carbon Nanotubes; Silver Iodide; Photocatalysis

To avoid a poor mixing rate and local inhomogeneities in batch reactor systems, and to shorten the length of microchannels in microreactor systems, a new combined micromixer/microreactor/batch reactor system was used for the synthesis of colloidal silica particles. The silica particles with different sizes (from 20 nm to 2 μm) and size distributions (which were characterized by PDI from 0.01 to 0.40) were controllably synthesized by varying the concentration of reactants and the operating parameters in this system. The long microchannel with small diameter demonstrated a good mixing efficiency, and which produced small and uniform silica particles. In addition, the introduction of inert gas into the system intensified the mixing, and the silica particles with decreased size and narrow distribution were obtained. It was clearly demonstrated that the high mixing efficiency in the microchannel led to small and uniform silica particles. Furthermore, a theoretical foundation for the synthesis of nanoparticles in microreactors was established after illustrating the relationship of mass transfer and reaction in the system.
Keywords: Nanoparticle; Silica; Silica Nanoparticle; Microreactor; Monodispersity

Polyol-mediated synthesis of ZnO nanoparticle-assembled hollow spheres/nanorods and their photoanode performances by Soon Wook Kim; Tri Khoa Nguyen; Doan Van Thuan; Dinh Khoi Dang; Seung Hyun Hur; Eui Jung Kim; Sung Hong Hahn (495-499).
ZnO nanoparticle-assembled hollow spheres (raspberry-like) and elliptical nanorods (rice-like) were synthesized via a facile polyol process. Employing ethylene glycol as a polyol led to a ZnO nanoparticle-assembled hollow sphere structure, while diethylene glycol resulted in an elliptical nanorod structure. The ZnO hollow spheres had a higher Brunauer-Emmett-Teller (BET) surface area, better dye adsorption, more incident light trapping, and lower defect density than the ZnO elliptical nanorods. The ZnO hollow sphere-based dye-sensitized solar cells (DSSCs) exhibited a three-times higher current density than the ZnO elliptical nanorod-based DSSCs.
Keywords: ZnO Hollow Spheres; ZnO Elliptical Nanorods; Polyol Process; Dye-sensitized Solar Cells

We present systematic investigations on the relationship between interface formation and enhanced photocatalytic activity of ZnO-BiVO4 nanocomposite based on experimental techniques supported by theoretical calculations. The interaction between ZnO (101) nanosheet and BiVO4 surface at the heterojunction was explored to study the charge transfer and separation mechanism responsible for enhanced photocatalytic response. XPS results and DFT computations mutually validate the reasonable existence of ZnO-BiVO4 interface. The nanocomposite photocatalytic activity, tested for various weight ratios, was found to be highest for ZnO-BiVO4 (1 : 1) under visible-light irradiation. Moreover, the percentage removal of MB was found to be greater than RhB for the same time duration. Steady state and time resolve photoluminescence were employed to understand the carrier lifetime and emissivity. Visible light driven high photoactivity exhibited by ZnO-BiVO4 (1 : 1) was ascribed to the formation of intermediate band and comparatively low recombination rate, which facilitates the separation of electron-hole pairs. Based on the theoretical outcome, we found that valence band maximum was occupied by Bi s orbital and conduction band minimum was occupied by Zn s orbital, which indicates the maximum electron transition from BiVO4 valence band to ZnO conduction band in ZnO-BiVO4 composite. These results demonstrated that heterojunction semiconductors are an effective strategy that can be successfully applied to develop photocatalysts that respond to visible light for organic pollutant degradation.
Keywords: Zinc Oxide; Monoclinic-bismuth Vanadate; Intermediate Band; DFT; Time Resolved PL

Heterogeneous photocatalytic degradation of phenol and derivatives by (BiPO4/H2O2/UV and TiO2/H2O2/UV) and the evaluation of plant seed toxicity tests by Léa Elias Mendes Carneiro Zaidan; Joan Manuel Rodriguez-Díaz; Daniella Carla Napoleão; Maria da Conceição Branco da Silva de Mendonça Montenegro; Alberto da Nova Araújo; Mohand Benachour; Valdinete Lins da Silva (511-522).
We examined the photocatalytic degradation of phenol from laboratory samples under UV radiation by using BiPO4/H2O2 and TiO2/H2O2 advanced oxidation systems. Both catalysts prepared were characterized by scanning electron microscopy, Fourier transform infrared and X-ray diffraction. Surface area tests showed about 3.46 and 31.33m2·g−1, respectively, for BiPO4 and TiO2. A central composite design was developed with the following variables--catalyst concentration, time and concentration of hydrogen peroxide--to optimize the degradation process. Removal rates of 99.99% for phenol degradation using BiPO4 and TiO2 were obtained, respectively. For mineralization of organic carbon were obtained 95,56% when using BiPO4 and 63,40% for TiO2, respectively. The lumped kinetic model represented satisfactorily the degradation of phenol process, using BiPO4/H2O2/UV (R 2=0.9977) and TiO2/H2O2/UV (R 2=0.9701) treatments. The toxicity tests using different seed species showed the benefits of the proposed advanced oxidation process when applied to waste waters containing these pollutants.
Keywords: Phenol; Effluents; Heterogeneous Photocatalysis; Reactor

Study of UV aging on the performance characteristics of vegetable oil and palm oil derived isocyanate based polyurethane by Sonalee Das; Priyanka Pandey; Smita Mohanty; Sanjay Kumar Nayak (523-538).
The impact of UV aging on the characteristic properties of synthesized polyurethane (PUs) from castor oil and transesterified castor oil with palm oil based isocyanate and 1,4 butanediol was investigated at different exposure time of 0, 250, 500, 750 and 1,000 h, respectively. The aging properties of the PU films were analyzed through differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and Tensile tests. The PU films derived from castor oil showed noticeable changes in chemical structure after 250 h of UV exposure owing to chain scission of the urethane group. A considerable decrease in the thermal and tensile properties of the developed PU films was observed due to the plasticization phenomenon. SEM micrographs revealed morphological changes through the appearance of cracks and blisters composed of primary amines on the surface of exposed PU films. However, PUs derived from transesterified castor oil with a higher hydroxyl value exhibited improved UV resistance characteristics due to higher crosslinking and degrade only after 750 h of exposure. Thus, the synthesized green PUs based on transesterified castor oil with palm oil based isocyanate compositions can be candidate materials for developing UV resistant coating material.
Keywords: Transesterified Castor Oil; UV Aging; Chain Scission; Blisters; Palm Oil Based Isocyanate

Poly(vinyl alcohol) (PVA)/ linear low-density polyethylene (LLDPE) composite films were prepared using PVAs of various molecular weights and degrees of hydrolysis. The crystallinity, water permeability, mechanical properties, and optical properties of the composite films were analyzed based on the absorption properties of the different PVAs. The formation of the composite film became increasingly difficult with increase in the molecular weight and the degree of hydrolysis of PVA, because the resulting crystallinity increased the intramolecular hydrogen bonding of the hydroxyl groups on the main chains of PVA. The 4-98/LLDPE composite film absorbed water gradually and continuously for a long time, and its water vapor absorption rate was similar to that of the 4-88/LLDPE film but lower than that of the PVA 205/LLDPE film. The mechanical properties of the 4-98/LLDPE film were slightly better than those of the 4-88/LLDPE film but inferior to those of the PVA 205/LLDPE film.
Keywords: PVA/LLDPE Composite Films; Water Vapor Permeability; Optical Transmittance; Hydrolysis; Water Vapor Absorption

Polyurethane foam-cadmium sulfide nanocomposite with open cell structure: Dye removal and antibacterial applications by Mir Saeid Seyed Dorraji; Hamid Reza Ashjari; Mohammad Hossein Rasoulifard; Mehrdad Rastgouy-Houjaghan (547-554).
A new way to synthesize open cell polyurethane foam using cadmium ions has been described. By converting to cadmium sulfide nanoparticles, cadmium ions have been fixed on the open cell polyurethane foam. Open cell polyurethane foam containing CdS nanoparticles (PUF-CdS) was characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The SEM results showed foam containing nanoparticles unlike pure foam (PUF) has an open cell structure. In the following, the applicability of synthesized nanocomposite in wastewater treatment was investigated. The dye removal efficiency of PUF-CdS was investigated with the objective of removing Reactive Orange 122 (RO122) as a model pollutant from aqueous solution. The effects of adsorbent dosage, initial dye concentration and initial pH of solution on RO122 removal were studied. Kinetics and equilibrium isotherms for adsorption of dye on PUF-CdS were analyzed. The maximum adsorption capacity obtained from Langmuir isotherm equation was 22.7 mg g−1. The experimental data were adjusted to the pseudo-second-order kinetic model. The antibacterial activity of PUF-CdS was also investigated against E. coli and S. aureus.
Keywords: Polyurethane Foam; Adsorption; Dye; Antibacterial Properties; Cadmium Sulfide

Nonspherical particles resembling sea pineapples were synthesized by successive growth technique during soapless emulsion polymerization for various applications. First, highly cross-linked seed particle dispersion was synthesized by emulsifier-free emulsion polymerization with acrylic acid as co-monomer for the formation of surface carboxylic groups. Then, a successive growth scheme was applied to the seeds by swelling the particles with monomer droplets, followed by polymerization. The sea pineapple-shaped particles could be produced by adjusting the amount of monomer during the swelling step of the third growth. As a demonstrative application, the seed or sea pineapple-shaped particles could be used as templates for the synthesis of porous inorganic particles by spray drying technique. The resulting porous particles could be adopted as photocatalyst for the decomposition of organic molecules such as methylene blue. As another application, the dye molecules could be adsorbed onto the second grown particles to produce dye-doped nanospheres. Finally, the sea pineapple-shaped particles could be self-organized into supra-aggregates using toluene emulsions as confining geometries. Collectively, successively grown particles were found to be efficient building blocks to prepare the unusually packed structures or functionalized into colored products.
Keywords: Nonspherical Particles; Monomer Swelling; Successive Growth; Emulsion Polymerization; Self-assembly

Bubble characteristics by pressure fluctuation analysis in gas-solid bubbling fluidized beds with or without internal by Keon Bae; Jong Hun Lim; Joon-Hwan Kim; Dong-Ho Lee; Joo-Hee Han; Sung-Hee Park; Dong Hyun Lee (566-573).
Bubble flow characteristics were investigated in gas-solid bubbling fluidized beds (0.3 m-I.D×2.4m-high) with or without internals by power spectral analysis of absolute pressure fluctuation. Metallurgical grade silicon particles (MG-Si) were used as bed materials. The particle density and mean particle diameter were 2,328 kg/m3 and 154 μm, respectively. Absolute pressure fluctuations were measured simultaneously at two different positions: plenum chamber and beds. Absolute pressure fluctuation in the beds was measured according to the axial bed height in the range of 0.1 to 0.8m. The total sampling time of each data set was 60 s, and the sampling rate was 200Hz. Absolute pressure fluctuation data were converted to a power spectral density (PSD) by a Fast-Fourier transform (FTT) algorithm. The PSD in the beds was separated into coherent and incoherent output power. The bubble size was estimated from the standard deviation of the spectrum of incoherent output power, which occurred due to the bubble flow. The estimated bubble size determined by incoherence component analysis was compared to various empirical correlations to determine the bubble size without internals. The estimated bubble size agreed well with the correlation by Choi et al. [19]. The internals were installed 0.45 m above the distributor. With the installation of the internals, and at the bed height of 0.5m, the bubble diameter was decreased by 77% compared to the bubble without the internal at U0=0.15m/s.
Keywords: Pressure Fluctuation; Power Spectral Density (PSD); Bubble Diameter; Incoherent Component; Vertical Internal

An experimental study of laminar combustion characteristics of ethanol-air premixed mixtures was conducted with different ignition methods, including laser induced spark ignition (LISI) and electric spark ignition (SI) at an initial condition of 358 K temperature and 0.1MPa pressure. Flame propagation with the two different ignition methods was analyzed and discussed. The laminar flame speed was extrapolated with a nonlinear extrapolation method. Results indicate that the laminar speed of ethanol-air mixtures with LISI is faster than that with SI at lean mixtures, but slower at stoichiometric and rich mixtures. The peak values of the laminar burning velocity for SI and LISI with nonlinear extrapolation are 50.1 cm/s and 47.6 cm/s at the equivalence ratio of 1.1, respectively. Laser-induced spark ignition is able to ignite leaner ethanol-air mixtures.
Keywords: Laser Induced Spark Ignition (LISI); Electric Spark Ignition (SI); Laminar Flame Speed; Propagating Spherical Flame; Ethanol

CO2 capture performance of cement-modified carbide slag by Xiaotong Ma; Yingjie Li; Changyun Chi; Wan Zhang; Zeyan Wang (580-587).
A novel and low-cost synthetic CO2 sorbent for calcium looping process, cement-modified carbide slag (CMCS), was synthesized from carbide slag, aluminate cement and by-product of biodiesel by combustion. The effects of synthesis conditions such as combustion temperature, combustion duration, hydration, by-product of biodiesel and cement addition and regeneration temperature on CO2 capture performance of CMCS were investigated. The comprehensively optimum preparation conditions of CMCS were obtained. The highest CO2 capture capacity is 0.62 g/g after 10 cycles, which is 2.18 times as high as that of carbide slag. The addition of aluminate cement improves the CO2 capture performance of CMCS, while excessive aluminate cement is adverse for CO2 capture due to the reduced CaO content in CMCS. The addition of by-product of biodiesel contributes to a uniform sol mixing of carbide slag and cement. The CMCS exhibits higher carbonation and calcination rates than CS. The porous and stable pore structure leads to the better CO2 capture performance and cyclic stability of CMCS.
Keywords: Cement; Carbide Slag; By-product of Biodiesel; Calcium Looping; CO2 Capture