The catalytic activity of zeolites was studied in the esterification of oleic acid with methanol in soybean oil. The influences of acidity and pore structure of the zeolites were investigated in relation to conversion of the oleic acid on the zeolite catalysts. H+ ion exchanged ZSM-5 (HMFI) and mordenite (HMOR) zeolites conducted with different Si/Al ratio were employed to examine an influence of acidity in the reaction. Conversion of oleic acid was about 80% on HMOR zeolites and HMFI(25) zeolite. The conversion of oleic acid was improved as the amount of acid site increased. The amount of acid site of the zeolites affected significantly the catalytic activity in the esterification of oleic acid.
Activated sludge model no. 1 (ASM1) was applied to an aerobic membrane bioreactor (MBR) treating dilute municipal wastewater. The model for the aerobic MBR was calibrated using the data collected from a lab-scale aerobic MBR using AQUASIM 2.0. The performance of MBR process in terms of chemical oxygen demand (COD) removal and ammonia nitrogen (SNH) nitrification was studied at different operating conditions such as hydraulic retention time (HRT), solid retention time (SRT) and mixed liquor suspended solids (MLSS) concentrations. The characteristics of influent wastewater, pre-settled primary effluent from a wastewater treatment plant (City of Elmhurst WWTP, Elmhurst, IL, USA), were determined in the laboratory and used for the calibration of the model. The results from the simulations provided a better understanding of the mechanisms and kinetics of the MBR process including sludge removal.
Carbon-doped titanium dioxide (TiO2) nano-powders were synthesized by the aerosol flame deposition (AFD) process using 2-butanol liquid sol containing 20 wt% of titanium isopropoxide (TTIP). They were mesoporous nano-powders with particle size ranging from 20 to 40 nm, the specific surface area of 36 m2/g, and the pore size of 19 nm. They had the anatase structure and showed high photocatalytic activity not only under UV-A light but also under fluorescent light. They reduced the concentration of methylene blue (MB) from 5.0 to 1.5 ppm within 2 h under UV-A light and from 5.0 to 2.0 ppm within 4 h under fluorescent light. And, they killed 99% of Escherichia coli (E. coli) cells within 2 h and bacterial growth of the E. coli was not observed for 12 h under both UV-A and fluorescent lights.
The aliphatic energetic plasticizers with three and four –CH2 between nitrate ester and nitramine were synthesized to obtain a plasticizer that is more stable than N-butyl-N-nitratoethyl nitramine (BuNENA) with two –CH2. First, amino alcohol compounds such as propylamino propanol (PAP) and ethylamino butanol (EAB) as a precursor of energetic plasticizer were synthesized. However, unlike in BuNENA synthesis, various side reactions occurred in the nitration of amino alcohols. Fortunately, it was possible to considerably suppress the formation of side products in the nitration of PAP by using a solvent and an appropriate concentration of nitric acid. In addition, an energetic plasticizer with higher oxygen content was obtained through the nitration of intermediate, amide alcohol, which was formed in the synthesis of EAB.
The carbon materials, having different degree of the graphitization, were oxidation-treated with a sodium chlorate and 70 wt.% of nitric acid to achieve an electrochemically active material with a larger capacitance. Among non-graphitizable pitch, needle coke and natural graphite, the structure of needle coke was easily changed to the graphite oxide after oxidation treatment, and the inter-layer distance of the oxidized needle coke was expanded to 6.8 nm. This oxidized needle coke has exhibited largest specific capacitance per weight and volume of 29.5 F/g and 24.5 F/ml, respectively, at the two-electrode system in the potential range of 0–2.5 V. The electrochemical performance of the oxidized needle coke was discussed with the phenomenon of the electric field activation, and was compared with the results of KOH-activated needle coke as previously reported.
Rawhide split was hydrolysed separately by two proteolytic enzymes, papain and neutrase. The effects of enzymatic conditions of the hydrolysis reaction were investigated. During the first 10 min of the enzymatic hydrolysis, the yield of the hydrolysed protein increased sharply, then it slowly increased or became essentially constant due to the limited availability of the substrate. The optimum hydrolysis conditions of papain and neutrase for highest protein yield are at 70 °C, pH 6–7 and 40–50 °C, pH 6–7, respectively. The product from papain hydrolysis is a gelatin with low gel strength and viscosity, while that from neutrase hydrolysis is collagen hydrolysate with viscosity as low as water. This is considered to indicate that longer fragments of protein are obtained from papain hydrolysis than that from neutrase implying different mechanisms of papain and neutrase hydrolysis.
This work concerns catalyst screening for the synthesis of tert-amyl ethyl ether (TAEE) from a liquid-phase reaction between tert-amyl alcohol (TAA) and ethanol (EtOH). Various commercial catalysts, i.e., Amberlyst 15, Amberlyst 16, Amberlyst 36, Amberlyst 131, β-zeolite with Si/Al = 13.5 and 40, and Dowex 50WX8, were tested by performing the reaction in a semi-batch reactor operated at temperature of 353 K and pressure of 810.4 kPa. The dehydration of TAA to IA was found to be a major side reaction in this system. Amberlyst 16 shows the best performance in terms of selectivity and yield. Therefore, it was further investigated in the kinetic study. Three temperature levels of 333, 343 and 353 K were performed to obtain the parameters in the Arrhenius's equation of the reaction rate constant and the Van’t Hoff equation of water and ethanol sorption equilibrium. Two activity-based kinetic models of Langmuir–Hinshelwood (L–H) and Power Law (PL) were fitted with the experimental results. It was observed that the L–H model showed the best reaction rate description. The mole fraction-based PL model is also included in this study to follow the requirement of the ASPEN PLUS program.
Lewis acid supported Nanopore Silica catalysts for microwave-assisted Biginelli reaction under solvent-free conditions were prepared by impregnating FeCl3 dissolved in ethanol to Nanopore Silica at 40 °C. Biginelli reaction under solvent-free conditions, one-pot three-component condensation of urea, benzaldehyde, and ethyl acetoacetate, catalyzed with porous material or Lewis acid supported porous material, such as MCM-41, SBA-15, VSB-5, Nanopore Silica, FeCl3/MCM-41, FeCl3/Nanopore Silica, CeCl3/Nanopore Silica and InCl3/Nanopore Silica, was investigated. Our recent results of the microwave-assisted Biginell reaction of some benzaldehyde derivatives starting materials using MCM-41, Nanopore Silica, FeCl3/Nanopore Silica, under solvent-free conditions are also reported. Aromatic aldehydes carrying either electron releasing or electron withdrawing substituents in the ortho, meta, and para positions afforded good yields of the products using MCM-41 as a catalyst. When Nanopore Silica was used as a catalyst, the yield of the Biginelli product was in the range of 27–56%. However FeCl3/Nanopore Silica has been employed as a catalyst, the yield of the Biginelli product was increased dramatically. Thus it has been found that the use of FeCl3/Nanopore Silica as heterogeneous catalyst has made this method very cost effective.
The dithienosilole (DTS) derivatives containing para-substituted phenyl with methyl, vinyl, or dimethylamino groups connected to the bithiophene moiety of the DTS was successfully synthesized by nickel-catalyzed Grignard coupling reactions. For the evaluation of the electroluminescent properties of these DTS derivatives, they were used as electron-transporting, emitting, or hole-transporting layers, respectively, in electroluminescent (EL) device fabrication processes. The device structures were ITO/TPD (40 nm)/Alq3 (50 nm)/DTS derivative (50 nm)/Al (type I), ITO/TPD (40 nm)/DTS derivative (50 nm)/Alq3 (20 nm)/Al (type II), and ITO/DTS derivative (50 nm)/Alq3 (50 nm)/Al (type III). Although its maximum current density was small, the 2,6-bis[4-(N,N-dimethylamino)phenyl]-4,4-diphenyldithienosilole (5) possessing a strong electron-donating group provided apparently lower turn-on voltage, although its maximum current density was small, in comparison with the one of previously reported TMS-DTS (2,6-bis(trimethylsilyl)-4,4-diphenyldithienosilole). The EL spectra of the DTS derivatives 3–5 exhibited maximum peaks at 512, 517, and 560 nm which correspond to green to yellowish-green light. The luminance of the devices containing the DTS derivatives 3–5 as an emitting layer shows 680, 515, and 250 cd/m2, respectively, at 10 V. From the evaluation of the utilities of the synthesized DTS derivatives 3–5, the derivative 3 among these materials can be used efficiently as an emitting material in the type II EL device.
The experiments were performed in a countercurrent packed column in a continuous mode to study the absorption of nitric oxide in sodium chlorite/urea solutions. Sodium chlorite mainly works as an agent to oxidize NO to NO2. A combined SO2/NO removal system was also tested. On the basis of high SO2 removal efficiency, the NO removal efficiencies under various experimental conditions were emphatically measured. Among the operating variables such as initial NaClO2 concentration, urea concentration, temperature and initial pH value, the pH value of the absorbing liquid was found to have a great impact on both NO removal efficiency and NO2 concentration. NO removal efficiency was increased with increasing NaClO2 concentration and temperature. Urea almost has no negative effect on NO removal efficiency, however it aids the abatement of NO2 greatly. The anions in the spent scrubbing liquor were analyzed by ion chromatography.
The conjugated cyclopolymer, poly(9,9-dipropargylfluorene), was prepared by the ring-forming polymerization of 9,9-dipropargylfluorene by (bicyclo[2.2.1]hepta-2,5-diene)dichloropalladium(II) in high yield. The chemical structure of poly(9,9-dipropargylfluorene) was characterized by such instrumental methods as NMR (1H, 13C), IR, UV–vis spectroscopies, and elemental analysis to have the conjugated polymer backbone bearing fluorene moieties. Poly(9,9-dipropargylfluorene) showed characteristic UV–vis absorption band at 307 and 324 nm and violet-blue PL spectrum at 411 nm, corresponding to a photon energy of 3.01 eV. The cyclic voltamograms of the polymer exhibited reversible electrochemical behaviors between the doped and undoped peaks. It was found that the kinetics of the redox process of polymer is controlled by the diffusion process mixed with the electron transfer process from the experiment of the oxidation current density of polymer vs. the scan rate.
To examine the characteristics of absorption and regeneration, the simultaneous removal efficiency of carbon dioxide/sulfur dioxide (CO2/SO2), the CO2 absorption amount, and the CO2 loading value of an ammonia (NH3) solution added to 2-amino-2-methyl-1-propanol (AMP) were investigated using the continuous absorption and regeneration process. The performances of this system, such as the removal efficiency of CO2 and SO2, absorption amount, and CO2 loading, were evaluated under various operating conditions. Based on the experimental study, the optimum conditions were a liquid circulation rate of 90 mL/min and gas flow rate of 7.5 L/min. The addition of NH3 into aqueous AMP solution increased the absorption rate and loading ratio of CO2 and raised the removal efficiencies of CO2 and SO2 to over 90% and over 98%, respectively.
This work reports some new findings for organoclay dispersion and its effect on the cure behavior of ethylene acrylate rubber (EAR)/clay nanocomposites, which were prepared by melt mixing procedure. Based on the X-ray diffraction (XRD) and transmission electron microscopy (TEM) observation, the organoclay-filled EAR composites showed a fairly good dispersion composed of a mixture of intercalated and exfoliated clay layers at relatively lower clay contents below 10 phr, but a partial re-aggregation of clays was formed with further increase of organoclay. While the organoclay enhanced the rate of cure of EAR based on the cure rheometer, the pristine clay showed much smaller effect. The autocatalytic model showed a close fitting with experimental values for cure rates with the correlation coefficient (R2) of ∼0.98, proving the validity of the model for describing the cure behavior of the system. The glass transition temperature slightly shifted to higher temperatures by employing the organoclay because of the restriction in motion of EAR chain segments in the clay galleries.
In this study, a new process for preparation of CdS/polymer nanocomposite films using a new amphiphilic oligomer chain (Urethane Acrylate Nonionomer: UAN) is presented. UAN chains have hydrophilic polyethylene oxide segments and polypropylene oxide-based hydrophobic segments as part of the same backbone. In addition, these chains also have reactive vinyl groups at their hydrophobic segments. For the preparation of CdS nano-colloid solutions, UAN chains acted as a stabilizer for CdS nanoparticles dispersed in a solvent. For the fabrication of CdS/polymer nanocomposite films, UAN chains in CdS nano-colloid solutions were polymerized through reactions between their vinyl groups, resulting in the formation of CdS nanoparticle dispersed films swollen by the solvent. The nature of the solvent used strongly influenced the size of the CdS nanoparticles, which was confirmed by UV absorption spectra, PL emission spectra and TEM images. Smaller sized CdS nanoparticles were formed in higher polar solvents such as DMAc and methanol, which can be explained by the higher solubility of UAN chains and the more effective dissociation and stabilization of cadmium salts and CdS nanoparticles by UAN chains in the polar solvent.
Two bio-filters packed with cork, an organic macroporous material and activated carbon, an inorganic microporous one were compared in terms of operative performance on biological degradation of VOC, which was a mixture of benzene, toluene, ethylbenzene and xylene (BTEX) vapors. Two filters were successfully operated for 4 months with three different periods. In general, the bio-filter with packed cork in the long thin glass was distinguishably better than the one with biological activated carbon (BAC). During the first period in which 150 ppm of the gas was flown in at 90 s of empty bed retention time (EBRT), the cork bio-filter performed better except for the first 2 weeks, the biological adaptation phase, which provided the BAC bio-filter with its much greater adsorption capacity as to lead to nearly perfect removal. Despite the shorter breakthrough point for cork, however, the cork bio-filter overwhelmed the BAC after that; even three times higher BTEX load at the shorter EBRT guaranteed the cork filter 90% or more removal. The maximum elimination capacities were 86 g/(m3 h) for the cork and 67 g/(m3 h) for the BAC around 94 g/(m3 h) of inlet load. The higher biomass in the cork column could be resulted from organic surfaces, pore structure with sufficient room for sound microbial film or clumps even though its specific surface area was only 1/12 of BAC. This finding was supported by the model calculation in which the effective surface area of cork bed turned out to be 33% more than that of BAC. The derived relationship between consumption of BTEX and growing cell mass was found to be logarithmically proportional to each other, which was confirmed experimentally in here. We also found that through one-third of the whole length of the packed columns, as much as 79% of the inlet concentration of BTEX gas in the cork bio-filter was eliminated, which well agreed to our data and model depicting concentration versus column height, showing 1st order gradient.
A study on the effects of the COD/sulfate ratio on characteristics of sulfate-reducing bacteria (SRB) and methane-producing bacteria (MPB), using waste activated sludge (WAS), were performed in batch anaerobic digestion. The methane production rates of untreated and thermal treated WAS were 0.21–1.23, and 0.64–2.02 mL/day VSS, respectively. In the meantime, the hydrogen sulfide gas production rates of untreated and thermal treated WAS were 0–0.36, and 0–0.21 mL/day VSS, respectively. The methane production rate decreased as about 60% at the 11.6 of COD/sulfate ratio. In the case of high influent CODs, the methane production rate increased while the hydrogen sulfide rate decreased. It is thought that it is necessary to regulate the COD concentration in influent wastewaters in order to decrease the effects of SRB. The concentrations of various components such as sulfate should be properly controlled to reduce the methane production inhibition caused by the SRB in the anaerobic digestion using WAS.
Synergetic removal of aqueous phenol by decomposition with ozone and adsorption on activated carbon was experimentally investigated. To enhance phenol removal performance, two activated carbons (AC1 and AC2) with BET surface areas of 1106 and 1150 m2 g−1 and average pore diameters of 2.3 and 1.7 nm, respectively, were employed. While the slowest initial removal of phenol was achieved with introduction of ozone only, the much better removal of phenol was obtained with utilization of activated carbon with ozone. Some intermediate products, which were detected as total organic carbon (TOC), were found to remain even after phenol was completely decomposed. Regarding to higher mesopore fraction, AC1 could better remove intermediates than AC2. With the synergetic performance of AC1 and ozone it was found that the highest removal of phenol and TOC was up to 100% and 89%, respectively.
In this study, activated carbon fibers (ACFs) were surface modified with fluorine and mixed oxygen and fluorine gas to investigate the relationship between changes in surface properties by nitrogen and hydrogen adsorption capacity. The changes in surface properties of modified activated carbon fibers were investigated using X-ray photoelectron spectroscopy (XPS) and compared before and after surface treatment. The specific surface area and pore structures were characterized by the nitrogen adsorption isotherm at liquid nitrogen temperature. Hydrogen adsorption isotherms were obtained at 77 K and 1 bar by a volumetric method. The hydrogen adsorption capacity of fluorinated activated carbon fibers was the smallest of all samples. However, the bulk density in this sample was largest. This result could be explained by virial coefficients. The interaction of hydrogen-surface carbon increased with fluorination as the first virial coefficient. Also, the best fit adsorption model was found to explain the adsorption mechanism using a nonlinear curve fit. According to the goodness-of-fit, the Langmuir–Freundlich isotherm model was in good agreement with experimental data from this study.
Single and binary metal systems were employed to investigate the removal characteristics of Pb2+, Cu2+, Cd2+, and Zn2+ by Chlorella sp. HA-1 that were isolated from a CO2 fixation process. Adsorption test of single metal systems showed that the maximum metal uptakes were 0.767 mmol Pb2+, 0.450 mmol Cd2+, 0.334 mmol Cu2+ and 0.389 mmol Zn2+ per gram of dry cell. In the binary metal systems, the metal ions on Chlorella sp. HA-1 were adsorbed selectively according to their adsorption characteristics. Pb2+ ions significantly inhibited the adsorption of Cu2+, Zn2+, and Cd2+ ions, while Cu2+ ions decreased remarkably the metal uptake of Cd2+ and Zn2+ ions. The relative adsorption between Cd2+ and Zn2+ ions was reduced similarly by the presence of the other metal ions.
The main objective of this study is to evaluate ammonium nitrogen removal characteristics of zeolite media in Biological Aerated Filter (BAF) process for treatment of textile wastewater. Several biofilters were conducted to compare the performance of natural zeolite with sand and granular activated carbon (GAC) as packing media. The removal of NH4+-N on the BAF reactor packed with natural zeolite media was more efficient than that with sand and GAC. After biofilm was well developed on the surface of zeolite media, the removal of NH4+-N by ion exchange, nitrification, and biological synthesis was estimated as 35.1%, 40.2%, and 22.3%, respectively. The natural zeolite pretreated with heat and HCl solution showed higher ammonium removal efficiency than that with NaOH solution. No significant difference on ammonium adsorption capacity was observed when nature zeolite was neither pretreated by heat nor hydrochloric acid solution. This study shows that natural zeolites has the feasibility to be chosen as a useful media in BAF process for the treatment of textile wastewater.
A novel charring agent, bis(2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-1-oxo-4-hydroxymethyl) phenylphosphonate (BCPPO), was synthesized and characterized by FT-IR, 1H NMR and 31P NMR spectroscopies. Moreover, the novel charring agent combining with ammonium polyphosphate (APP) as well as melamine (MA) was adopted as intumescent flame retardants (IFR) to impart flame retardance and dripping resistance to polypropylene (PP). Flammability and thermal behaviors of the treated PP were investigated by Limiting Oxygen Index (LOI), Vertical Burning Test (UL-94), Thermogravimetric Analysis (TGA) and Cone Calorimeter test. Results indicate that the intumescent flame retardant with the novel charring agent shows both excellent flame retardance and anti-dripping abilities for PP when the three main components of IFR coexist at appropriate proportions, and the optimum flame retardant formulation is APP:MA:BCPPO = 3:1:1 that gives an LOI of 30.3 and UL-94 V-0 rating, moreover, both the heat release rate (HRR) and the total heat release (THR) of IFR-PP with the optimum formulation decrease significantly relative to PP from cone calorimeter analysis. The residues from decomposition of the IFR-treated PP was characterized by FT-IR spectroscopy and SEM micrograph, and it was found that the char yield as well as char properties have direct effects on the flame retardance and anti-dripping behaviors of the treated PP.
Effect of cobalt and rhodium promoter on NOx storage and reduction (NSR) kinetics was investigated over Pt/BaO/Al2O3. Kinetics of 2% cobalt loading over Pt/BaO/Al2O3 demonstrated highest NOx uptake during lean cycle, while reduction efficiency during rich cycle appeared most poor. In contrast to this, rhodium showed suppressing effect of NOx uptake during lean cycle and demonstrated an enhanced effect for the higher efficiency of NOx reduction during rich cycle. DRIFT study for NOx uptake and regeneration confirmed formation of surface BaNOx from the band at 1300 cm−1 and formation of bulk BaNOx from the band at 1330 cm−1.
To enhance the dispersibility of clay in polypropylene (PP) matrix, PP-g-(maleic anhydride/styrene) (MA/ST) was prepared as a compatibilizer by graft copolymerization of maleic anhydride (MA) and styrene (ST) with PP. The addition of ST was known to be effective in improving the graft degree. PP/clay nanocomposites with the compatibilizer were prepared by melt intercalation. The X-ray diffraction (XRD) peaks of (0 0 1) plane of the organo-modified montmorillonite (O-MMT) were shifted to lower angles by an addition of PP-g-(MA/ST), indicating the intercalation capability of PP-g-(MA/ST) in the silicate layers. Transmission electron microscopy (TEM) photographs showed that the O-MMT in the presence of PP-g-(MA/ST) was intercalated and partly exfoliated during melt mixing. The addition of O-MMT and PP-g-(MA/ST) improved the thermal stability, tensile and rheological properties of the nanocomposites.
The aim of this study was to compare the efficiency of conventional ozonation and catalytic ozonation (ozone/activated carbon (O3/AC) and ozone/TiO2/activated carbon (O3/TiO2/AC)) in the degradation of methylene blue (MB) component from MB aqueous solution. The removal rates of color and chemical oxygen demand (CODCr) were assessed to screen the most appropriate oxidative process of MB treatment. In this experiment conditions, the color was completely disappeared in the presence of TiO2/AC catalyst, after 40 min of reaction time. However, only ozone system still existed 11.8% MB in aqueous solution, while in case of O3/AC system MB of 4.6% was not removed. In the COD removal experiment, the catalytic ozonation process showed a superior performance, compared to that of the conventional ozonation. COD removal efficiency was significantly promoted in the presence of catalysts such as AC and TiO2. O3/TiO2/AC was found to be the most effective approach to eliminating the color and enhancing COD removal efficiency. The catalyst of TiO2/AC was characterized by using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).
The sol–gel derived polymer/silicate hybrid materials have attracted considerable attention in recent years. The incorporation of silicate phase into polymeric materials may constitute an important tool to either enhance mechanical properties or provide more biocompatibility to the resulting hybrids. PHEA, α,β-poly(N-2-hydroxyethyl-dl-aspartamide), is a class of poly(amino acid)s that has been widely studied as a biodegradable functional polymer with potential biomedical and pharmaceutical applications. Hydrogels from PHEA are formed easily by a chemical or physical crosslinking reaction but the resulting gels are mechanically weak and less thermally stable. In this study, hybrid materials were prepared based on PHEA and silicate. A sol–gel process was employed using TEOS and modified PHEA to introduce inorganic silicate phase within the polymer gel matrix. FT-IR and NMR were used to analyze the chemical structure of the PHEA derivatives. In addition, the morphology, thermal and swelling properties of the hybrid gels were examined.
The characteristics of hydrogen production by four different hydrogen-producing bacteria (Clostridium beijerinckii, Rhodobacter sphaeroides, anaerobic bacteria isolated from sludge digester and Bacillus megaterium) were investigated quantitatively. The mathematical analysis using Gompertz equation showed that C. beijerinckii was the best hydrogen producer from glucose in terms of hydrogen-production potential and specific hydrogen-production rate. However, the bacteria required relatively long lag time at high-initial glucose concentration. The anaerobic bacteria showing the highest maximum hydrogen-production rate and relatively short lag time have a limit of low-hydrogen-production potential because they are mixed culture and produce some amount of methane gas. C. beijerinckii will be used in the actual system for hydrogen production from carbohydrate but the anaerobic bacteria may be a good choice for the production of hydrogen from wastewater containing innumerable compounds.
Disposal of poultry litter such as chicken litter and turkey litter is becoming a major problem in the USA poultry industry because of environmental pressures and health concerns. Poultry litters form wood chips, chicken litter (flock 1, flock 2 and broiler) and turkey litter were converted into bio-oil, gas and char in a fluidized bed reactor at the temperature ranges of 450–550 °C. The bio-oil yield of poultry litter was relatively low (15–30 wt%) compared to wood derived bio-oil (34–42 wt%). The gas yield was increased from 32 to 61 wt% with increasing reaction temperature, and char yield was between 22 and 45 wt% depending on age and reaction conditions. The higher heating value (HHV) of the poultry litter bio-oil were between 26 and 29 MJ/kg, whereas that of the bedding material (wood chips) was 24 MJ/kg. The dynamic viscosities of bio-oil were varied from 0.01 to 27.9 Pa s at 60 °C, and those of values were decreased with increasing shear rate.
Influence of fluidizing air velocity, temperature and atomizing air pressure, as well as types of raw materials on the size distribution, shape and flow properties of pharmaceutical granules, which were tabletized using a single punch tableting machine, was experimentally investigated. The granules prepared at the fluidizing air velocity of 0.8 m/s had average particle size larger than those obtained at higher air velocity. Meanwhile the fluidizing air temperature had moderate effect on the average particle size of the granules. However, an increase in the atomizing air pressure resulted in an increase in amount of fine particles, leading to the smaller mean particle size. From microscopic analysis, a primary lactose particle wetted by binder had several contact points with other particles inside the prepared granules. Based on granule morphology, it can be implied that the granules are formed by the so-called snowballing mechanism, leading to the relatively spherical structure. In tabletization, the granules with higher average particle size provided tablets with the less weight variation and friability. Meanwhile, the tablets produced from lactose–corn starch mixture had shorter disintegration time than those of lactose powder only.
This paper studied the liquid phase hydroxylation of benzene to phenol with hydrogen peroxide catalyzed by ternary metal oxide catalysts (Fe(III), V(V) and Cu(II)) supported on TiO2 at room temperature. The effects of V(V) and Cu(II) metal oxide loading were investigated. The catalysts were prepared by co-impregnation method and characterized by BET, XRD, XRF, SEM-EDX, NH3-TPD techniques. It was reported that the presence of V(V) and Cu(II) influenced the acid property on the catalyst. The increase of the metal loading increased the acidity of the catalyst. TiO2 loaded with Fe, V and Cu of 5, 2.5 and 2.5 wt%, respectively offered the highest yield of phenol. Although the increase of the metal loading improved the yield of phenol, the TOF reduced due to the reduction of dispersion of the catalyst metal. The optimum condition for the system is a reaction time of 4 h, catalyst weight of 0.2 g, the H2O2:benzene molar ratio of 2 and 6.25 g of ascorbic acid per mole of benzene.
In this study, two types of Beta zeolites having different Si/Al ratios (11.7 and 24.5) were synthesized hydrothermally using tetraethyl ammonium hydroxide (TEAOH) as a template. Different amounts of platinum (0.2%, 0.5% and 1.2%) were loaded on the protonated form of zeolite by incipient wet impregnation method applying hexachloroplatinic acid in 0.2N Cl− progressive ion solutions. Catalytic hydroisomerization reactions were carried out at atmospheric pressure in a fixed bed reactor with vertical placing and downward flow at three different temperatures, various WHSV (weight hourly space velocity) and n-H2/n-HC (molar hydrogen/hydrocarbon) ratio. Increase in Si/Al ratio in zeolites structures from 11.7 to 24.5 promoted selectivity and yield. It was found that optimum platinum content depends on the Si/Al ratio (zeolite acidity) in catalysts. Monobranched to dibranched isomers ratio were correlated with a linear function of n-heptane conversion. Such a correlation was found to be valid for various Si/Al ratios, metal content, processing temperature and pressure, WHSV and hydrogen to hydrocarbon ratio. This observation may indicate that in isomerization reactions, the monobranched isomers are first produced but subsequently transformed into multi-branched isomers.
Chiral epoxides are one of the increasingly used intermediates for the production of chiral pharmaceuticals. Chiral epoxides can react with a variety of reagents because of the polarity and ring-strain of the epoxide ring. Chiral epoxides can be prepared based on various chemical and biological approaches. Chemo-catalytic asymmetric epoxidation of prochiral olefin substrates and Co(III)-salen-catalyzed hydrolytic kinetic resolutions of racemic epoxides have been successfully implemented as production methods in industrial scales. Bio-catalytic transformations including direct epoxidation of prochiral substrates by monooxygenase or peroxidase, enantioselective hydrolysis of racemic epoxides by epoxide hydrolase, and lipase-mediated kinetic resolutions have been considered as alternatives due to their excellent enantioselectivity and regioselectivity. In this paper, bio- and chemo-catalytic preparations of chiral epoxides are reviewed. Industrial applications of chemo- and bio-catalytic preparations of chiral epoxides will be discussed herein.
The objective of this research is to draw the optimal cycle length and evaluate the effect of the fraction of anoxic and anaerobic phases in a cycle maximizing the nutrients removal in a modified temporal and spatial phase separated process. A pilot-scale system operated at HRTs of 10–21 h, SRTs of 16–34 d, cycle times of 2–8 h, and mixed liquor temperature from 9 to 30 °C showed average removals of BOD, TN, and TP as high as 93, 79, and 86%, respectively. Higher nitrogen removal could be achieved for shorter cycle time, while better phosphorus removal could be accomplished for longer cycle time. Optimal cycle time for simultaneous removal of nitrogen and phosphorus conflicted with each other. The effect of ratio of cycle time to system HRT on system performance was also shown to have the same tendency as that of cycle time. Higher TN removal of phased isolation technology could be achieved relative to that of SBR as the cycle length became longer in the same HRT. As the fraction of anoxic/anaerobic phase in a cycle became larger, the removal efficiency of TN and TP simultaneously decreased because of the discharge of untreated ammonia nitrogen and released phosphorus.
We have investigated the decomposition of excess sludge generated in a membrane bioreactor using a turbulent jet flow ozone contactor (TJC), which induced both hydrodynamic cavitation and ozonation reactions. We monitored the effects of various TJC operating parameters on the properties of the sludge, including the particle sizes, the particle size distribution, and the levels of soluble COD, total COD, and mixed liquor suspended solids. The TJC enhanced the degree of sludge reduction while consuming less energy, relative to conventional ozonation treatment systems, because of the synergic effects of hydrodynamic cavitation and ozonation. The hydrodynamic cavitation generated in the TJC increased the ozone mass transfer efficiency, which in turn promoted the rate of disintegration and solubilization of the sludge particles.
In our study, mesoporous carbon fibers were prepared by using electrospinning and physical activation. In order to develop mesoporous structure, silica was used as a physical activation agent due to meso-size of particle. The diameter of activated carbon fibers increased and surface became rougher after physical activation. Textural properties of carbon fibers were evaluated by using surface pore structure analysis apparatus. The specific surface area increased 12 times and total pore volume increased about 57 times through physical activation using silica. The development of mesoporous structure was confirmed by pore size distribution and fraction of micropore volume. From the DFT pore size distribution, it is sure that broad meso-sized porous carbon fibers were obtained from physical activation in our experiment. The fact that fractions of micropore volume are too low showing less than 2% by the results of total pore volume and HK pore volume concedes that silica activated CFs are pretty mesoporous. Eventually activated carbon fibers having broad meso-sized pores were obtained successfully.
Various attempts have been made to capture visible light of solar energy for TiO2 activation in photocatalytic degradation and other applications. In this present work we made an attempt on the synthesis and characterization of anatase TiO2 with carbon for gaining importance for this purpose. Carbon covered TiO2 photocatalyst was successfully prepared by an in situ process employing sucrose as carbon source and H2SO4 as dehydrating agent. The prepared materials were thermally post treated at 723 K. The resulting C-covered TiO2 catalyst materials were characterized by SEM, EDX, FT-IR, XRD, UV-DRS and XPS. The C-covered samples show UV shift to longer region compared to pristine TiO2. The materials were tested for its solar light induced degradation of methylene blue dye and found to be active. The prepared C-covered titania catalysts can be used for degradation of dyes and other pollutants using solar light.
In order to increase the conductivity of carbon nanofiber sheet, conductive multi wall carbon nanotubes (MWCNTs) was added into the carbon fibers. The dispersion of MWCNTs into the fibers and adhesion between carbon fibers and MWCNTs were improved through fluorine modification on surface of MWCNTs. By fluorination treatment, hydrophobic functional group was introduced on the surface of MWCNTs improving the affinity on interface between two carbon materials. These nanofibers made by electrospinning method were treated at different temperature in order to investigate the effect of temperature. According to the increment of temperature, the better conductivity of carbon nanofibers sheet was obtained due to the better oriented carbon structure. Eventually, the improved conductivity of carbon nanofiber sheet was resulted showing 27 S/cm.
The carbon dioxide reforming of methane over commercial Ni/SiO2·MgO catalyst under periodic and steady state operations was investigated at a temperature range of 650–750 °C. Under steady state operation, methane conversions tended to be constant with reaction time but increased with increasing reaction temperature. It was then observed that at low temperature (650 °C) under the periodic operation, methane conversion was also constant at approximately 48% throughout reaction time, but for the operation at a higher temperature, i.e. 750 °C, higher methane conversion (about 67%) was initially achieved but decreased dramatically with reaction time (to 27% in 240 min). The reason for the catalyst deactivation particularly for the periodic operation was further investigated by TPO, BET and XRD. It is suggested that at different operating temperatures, various types of coke occurred on the surface of catalyst and affected the catalytic activity.
10.0 wt.% tourmaline mineral was loaded onto amorphous TiO2 and treated at 100–900 °C to obtain anatase and rutile structures, respectively, and were used for the photodecomposition of 2-chlorophenol. Tourmaline (10.0 wt.%)/TiO2 (anatase) and pure TiO2 (anatase) adsorbed 2-chlorophenol at 15 ppm and 8 ppm, respectively. 2-Chlorophenol was completely decomposed after 42 h in 10.0 wt.% tourmaline/TiO2 (anatase), by a first-order rate equation. The decomposition rate increased with increasing catalyst amount and tourmaline concentration to give optimal conditions of 1.0 g/L and 12.5 wt.%, respectively. The decomposition of 2-chlorophenol was also affected by H2O2 addition and pH regulation. The decomposition rate reached 40.0 ppm/h when 10.0 mL/L of H2O2 was added to the feed solution, and 100 ppm of 2-chlorophenol was completely removed after 21 h at pH 11.0.
An affordable composite was prepared from jute fibers and polypropylene (PP) in this study. Jute fibers are echo-friendly, low-density materials yielding considerably lightweight composites with highly specific properties. The surfaces of the jute fibers were silanized to increase the interfacial adhesion between the jute fiber and the polymer matrix. During the fracture process of the silanized composites, the jute fibers were broken without complete pullout; much of the PP matrix still coated the fibers, indicating the enhanced degree of adhesion. The tensile and dynamic mechanical properties of the jute–PP composites were enhanced by the silane treatment as a result of the improved interfacial adhesion between the silanized jute fiber and the PP matrix.
Nanocrystalline titania was prepared by solvothermal reaction of titanium butoxide in toluene at 300 °C for 2 h. Thus obtained-powder was calcined at 300 °C in box furnace for 1 h and then quenched in various media at different temperature. The physiochemical properties of samples were investigated by using X-ray diffraction (XRD), nitrogen adsorption, CO2-Temperature Programmed Desorption (CO2-TPD), UV–visible scanning spectrophotometer, Transmission electron microscopy (TEM) and electron spin resonance spectroscopy (ESR) techniques. All physical properties such as phase, BET surface area and crystal size were not changed after quenching processes. While the CO2-TPD and ESR results indicate the changing of Ti3+ contents on the surface of TiO2 after quenching process. The amounts of Ti3+ increased as the quenching temperature decreased. Photocatalytic decomposition of water was carried out to evaluate the catalytic activity of quenched TiO2. The activity of quenched-powder increased corresponding to the increasing of Ti3+ contents increased by following order: air at 77 K > air at RT > air at 373 K > 30 wt% H2O2 at RT = 30 wt% H2O2 at 373 K > H2O at RT > H2O at 373 K.
N,N-Dimethylformamide (DMF) was used as a drying control chemical additive (DCCA) in spray pyrolysis in order to improve the luminous properties of Y2O3:Eu particles. It was found that the addition of DMF to the spray solution containing citric acid (CA) and ethylene glycol (EG) greatly enhances the photoluminescence intensity as well as the morphology of Y2O3:Eu particles. According to BET analysis, the surface area of Y2O3:Eu particles prepared from the solution containing only the organic additives was not reduced, whereas, the surface area of the Y2O3:Eu particles prepared from the solution containing both DMF and organic additives was decreased gradually as increasing the concentration of DMF. From these results, it was concluded that the adding of DMF to the spray solution containing the organic additives is a very effective way to reduce the porosity of phosphor particles, keeping the spherical morphology. As a result, the densification of porous structure led to greatly improve the photoluminescence intensity of Y2O3:Eu particles under ultraviolet (254 nm) excitation. Finally, the prepared Y2O3:Eu particles with dense structure showed about 208% improved photoluminescence intensity compared with the particles which have a spherical shape but porous structure.
An amphiphilic bipyridyl ligand, 4,4′-dicarboxy-octyl-2,2′-bipyridine, and its ruthenium(□) complex (termed as S8) were synthesized and characterized by UV/Vis, IR and NMR spectroscopy. The performance of this S8 complex as charge transfer photo-sensitizer in TiO2-based dye-sensitized solar cells was studied under standard AM 1.5 sunlight and by using an electrolyte consisting of 0.70 M 1,2-dimethyl-3-propyl-imidazolium iodide, 0.10 M LiI, 40 mM iodine and 0.125 M 4-tert-butylpyridine in acetonitrile. Aliphatic chains linking to carboxylate groups of S8 act as an effective electron donor and carboxylate groups act as an effective electron withdrawing between the TiO2 layer and the carboxylate linking TiO2 layer leading to increasing of electron density at this interface, which is attributed to increasing efficiency of electron injection to the TiO2 conduction band from the excited state of dye. The complex, S8, gave a photocurrent density of 13.02 mA/cm2, 0.60 V open circuit voltage and 0.69 fill factor yielding 5.36% efficiency. The S8 dye with aliphatic chain improved conversion efficiency of the resulting DSSCs compared with a cell fabricated using the N3 dye.
In this work, rice husk, an agricultural waste in Korea, was pyrolyzed under different reaction conditions (temperature, flow rate, feed rate, and fluidizing medium) in a fluidized bed with the influence of reaction conditions upon characteristics of the bio-oil studied. The optimal pyrolysis temperature for bio-oil production was found to be between 400 and 450 °C. Higher flow rates and feeding rates were more effective for its production. The use of the product gas as the fluidizing medium led to the highest bio-oil yield. With the exception of temperature, no single operation variable largely affected the physicochemical properties of the bio-oil.
The characteristics of all heterogeneous polymer systems including composites containing either micro or nanofillers are determined by four factors: component properties, composition, structure and interfacial interactions. The most important filler characteristics are particle size, size distribution, specific surface area and particle shape, while the main matrix property is stiffness. Segregation, aggregation and the orientation of anisotropic particles determine structure. Interfacial interactions lead to the formation of a stiff interphase considerably influencing properties. Interactions are changed by surface modification, which must be always system specific and selected according to its goal. Under the effect of external load inhomogeneous stress distribution develops around heterogeneities, which initiate local micromechanical deformation processes determining the macroscopic properties of the composites. In filled polymers the dominating deformation mechanism is usually debonding. Nanocomposites represent one of the new classes of materials, but further research and development is needed before they gain significant position in the market.
The surface of silica nanoparticles was modified with poly(ethylene glycol) methacrylate (PEGMA) or poly(propylene glycol) methacrylate (PPGMA) in order to improve the dispersion of nanoparticles in a polymer matrix. Nanosized silica particles were synthesized by the Stöber method with tetraethyl orthosilicate (TEOS). Silica nanoparticles were treated with triethoxyvinylsilane (VTES) as a coupling agent to introduce reactive groups and the PEG or PPG were then grafted onto the particle surface via UV-photopolymerization. Various analytical methods, i.e., scanning electron microscopy (SEM), thermogravimetry (TG), zeta potential measurement, and water vapor adsorption measurement were used to comprehensively characterize the unmodified(pure) and modified silica particles. The SEM images of the pure and modified particles demonstrated that both particles have a spherical shape and a uniform size without agglomeration. The silica particles modified with polymers showed higher weight loss than unmodified silica particles because of the decomposition of the organic polymers grafted onto the particles. The surface modification of silica particles with polymers decreased the zeta potential values of the silica surface. Modified silica particles had lower water vapor adsorption due to the hydrophobic surface property resulting from the polymers grafted onto the silica surface. In addition, we have developed an electrical conductivity measurement as a novel method to analyze the surface properties of silica nanoparticles. The modified silica particles had lower electrical conductivity than that of unmodified silica particles.
Fundamental and applied researches, based on the seeded polymerization techniques, have offered new ways for synthesizing more advanced polymer colloids, thereby widening their applicability in industries. The robustness of these techniques enables the production of a wide variety of functional polymer colloids while maintaining their excellent monodispersity in size from hundreds of nanometers to hundreds of micrometers. In this review, we demonstrate the seeded polymerization techniques provide the synthesis of many types of polymer colloids, including surface-functional polymer particles, microcapsules, porous polymer particles, and non-spherical polymer particles. Finally, we show that the network properties play a crucial role in determining morphological, chemical, and mechanical properties of the resulting particles.