Showing papers in "Journal of Chemical Engineering of Japan in 2011"
TL;DR: The aim of this article is to summarize the efforts placed on using ionic liquids in pharmaceutical applications and shows that ionic liquid-assisted drug carrier or active pharmaceutical ingredients synthesized as IL form or many drug compounds produced using ILs as reaction media provide many unique and attractive properties compared to conventional counterparts.
Abstract: The pharmaceutical industries are undoubtedly experiencing a series of challenges. One of these is the administration of solid form of many drugs due to many well known drawbacks including low solubility, polymorphic conversion and low bioavailability. Such problems are further aggravated when drug molecules or starting materials for synthesis of drugs are insoluble or sparingly soluble in aqueous media and most of pharmaceutical acceptable organic solvents. To overcome these problems, some times, highly polar organic solvents including pyridine, dimethylformamide (DMF) and N-methylpyrrolidone (NMP) which are not considered as environmental benign solvents have been used. These restrictions demand superior solvent systems and/or new drug forms that can be used as reaction media to avoid volatile organic solvents and/or as new forms of drugs. Much effort is being invested in such approaches to find new delivery technologies or development of new controlled-release dosage forms. In recent years, ionic liquids (ILs) that are salts of low melting point and consist only of ions have been increasingly exploited as solvents and/or (co)solvents and/or reagents in a wide range of pharmaceutical applications due to their tailor-made chemical, physical and biological properties. Studies have shown that ionic liquid-assisted drug carrier or active pharmaceutical ingredients (APIs) synthesized as IL form or many drug compounds produced using ILs as reaction media provide many unique and attractive properties compared to conventional counterparts. Furthermore, ILs could be employed as potential antimicrobial agents for various microorganisms. The aim of this article is to summarize the efforts placed on using ionic liquids in pharmaceutical applications.
105 citations
TL;DR: In this article, a new extractant, N,N-dioctyldiglycol amic acid (DODGAA), which is highly soluble in the ionic liquids, has been synthesized.
Abstract: In the present review article, we summarize recent advances in extraction and separation of rare-earth metals using ionic liquids. Rare-earth metals have unique electronic and magnetic properties. In Japan, increasing amounts of rare-earth metals are being used every year in industries employing cutting-edge technology. Therefore, maintaining a stable supply of rare-earth metals is important. In recent times, extensive research has been carried out on the use of ionic liquids for the extraction of rare-earth metals; this is because the extraction ability and/or selectivity for rare-earth metals have been found to increase when using hydrophobic ionic liquids, which have potential applications in liquid–liquid extraction processes. In the octyl(phenyl)-N,N-diisobutyl carbamoylmethyl phosphine oxide (CMPO) extraction system using ionic liquids, the extraction ability was more than 103 times better than that when using n-dodecane; however, stripping of the extracted metal ions was difficult in the former case. In initial research on the extraction processes based on ionic liquids, industrial extractant PC-88A was employed as well as CMPO, but issues resulting from the low solubility of these extractants and their metal complexes remain to be addressed. To overcome this problem, a new extractant, N,N-dioctyldiglycol amic acid (DODGAA), which is highly soluble in the ionic liquids, has been synthesized. DODGAA shows better performance for the separation of rare-earth metals in ionic liquids than in n-dodecane. Furthermore, a liquid membrane system based on ionic liquids has been developed for the separation and recovery of rare-earth metals. The use of a liquid membrane system may help in reducing the amount of ionic liquids required for metal recovery.
76 citations
TL;DR: The use of dicyclohexano-18-crown-6 (DC18C6) as an extractant in imidazolium-based ILs significantly improves the extraction efficiency for rare earth metals as mentioned in this paper.
Abstract: Liquid–liquid extraction is now widely used in industrial and analytical fields for the separation and purification of metal ions. However, in conventional solvent extraction, toxic and/or volatile diluents are commonly employed. In recent years, industrial wastes and scrap such as spent TV displays, fluorescent lamps, batteries, and cellular phones have been highlighted as valuable secondary resources of rare metals. Therefore a highly efficient separation technique for the recovery of these metals from such potentially complex mixtures is required (Nakamura et al., 2007; Kubota et al., 2009; Li et al., 2009; Pranolo et al., 2010). Growing attention has recently focused on room temperature ionic liquids (ILs) as alternatives to conventional organic solvents (Huddleston et al., 2001; Anderson et al., 2002; Rogers and Seddon, 2002; Zhao et al., 2005; Kubota and Goto, 2006; Plechkova and Seddon, 2008; Liu et al., 2009; Sun and Armstrong, 2010). ILs, which are molten salts generally composed of organic cations and various anions, have unique properties such as high thermal stability, negligible vapor pressure, and nonflammability, and are thus regarded as eco-friendly solvents. Their greatest appeal is that their physicochemical properties such as polarity, viscosity, density, and affinity with other solvents are extensively tunable by varying the combination of cationic and anionic partners (Huddleston et al., 2001; Anderson et al., 2002). Water immiscible ILs have a variety of potential applications in separation and analytical chemistry as separation media (Zhao et al., 2005; Kubota and Goto, 2006; Liu et al., 2009; Sun and Armstrong, 2010). Since Dai et al. (1999) first reported that the use of ILs as extraction diluents for metal ions offered significant improvements in extraction efficiency, IL-based extraction systems for metal ions have been intensively investigated using several conventional commercial extractants. The use of dicyclohexano-18-crown-6 (DC18C6) as an extractant in imidazolium-based ILs significantly improves the extraction efficiency for Sr compared to that the use in a traditional organic solvent system. Enhancement Application of Ionic Liquids to Extraction Separation of Rare Earth Metals with an Effective Diglycol Amic Acid Extractant
64 citations
TL;DR: In this article, the effect of metal ions such as Na+, Mg2+, Fe2+, and Pb2+ on the cyanide generation efficiency of C. violaceum was investigated.
Abstract: As an alternative using cyanide chemicals for gold extraction, the application of a cyanogenic bacterium viz. Chromobacterium violaceum (C. violaceum) in YP medium has been investigated. The catalytic roles of metal ions such as Na+, Mg2+, Fe2+, and Pb2+, as well as the effect of Na2HPO4 nutrient addition on the cyanide generation efficiency of the bacterium in this medium have been elucidated. While MgSO4 and FeSO4 added to the medium were equally effective for cyanide generation, improved efficiency was obtained in the presence of Na2HPO4 and Pb(NO3)2. In order to examine the effectiveness of C. violaceum cultured in YP medium for the generation of cyanide ions, the dissolution of gold and copper from waste mobile phone printed circuit boards (PCBs), a good source of gold and copper in alkaline conditions, was tested at 30°C, for various pH values and metal ion contents. Gold leaching was found to be 11% in 8 d at pH 11.0 in presence of 4.0 × 10−3 mol/L MgSO4, whereas; copper recovery was high (11.4%) at pH 10.0. Addition of 1.0 × 10−2 mol/L Na2HPO4 and 3.0 × 10−6 mol/L Pb(NO3)2 to the YP medium increased copper leaching to 30.3% and 38.1%, respectively, at pH 10.0 in 8 d. However, this effect was not observed for gold leaching.
40 citations
TL;DR: In this article, the power consumption and mixing performance of a coaxial mixer consisting of a wall-scraping anchor and different inner dispersion impellers (Rushton turbine, 45° pitched blade turbine and CBY) operating in inner impeller-only, co-and counter-rotating modes have been experimentally characterized in viscous non-Newtonian fluids.
Abstract: Experiments have been carried out in a transparent dished bottom stirred tank with a diameter T of 0.48 m and liquid level of 0.6T. The power consumption and mixing performance of a coaxial mixer consisting of a wall-scraping anchor and different inner dispersion impellers (Rushton turbine, 45° pitched blade turbine and CBY) operating in inner impeller-only, co- and counter-rotating modes have been experimentally characterized in viscous Non-Newtonian fluids (2% and 3% w/w CMC solutions) with different rheology behaviors. The results show that, for the co-rotating modes, the power consumption of the anchor could decrease up to 5% of that for the anchor rotating-only mode, whereas for the counter-rotating dispersion modes, it could increase to two times of that for the anchor rotating-only. However, the power consumption of the inner impellers is almost independent of the anchor rotation. We propose new correlations to give better fitted power curves between the generalized Reynolds number and the power number by considering not only the impeller geometry and the characteristic speed, but also the speed ratio. For each coaxial mixer, one reasonable power curve can be generated for different experimental speed ratios and different rotation modes. Impellers in co-rotating mode are more efficient than the inner impeller-only and the counter-rotating modes in the mixing of non-Newtonian fluids. Among the above three dispersion impellers, the power consumption of the CBY-anchor combination is the lowest compared with those for the other two combinations giving the similar mixing performance.
36 citations
TL;DR: In this article, the vapor-liquid equilibrium of the ethyl acetate/ethanol system was determined under isobaric conditions at 0.1, 0.5, and 0.7 MPa using a modified stainless-steel ebulliometer, which works continuously with the recirculation of both phases.
Abstract: The vapor–liquid equilibrium (VLE) of the ethyl acetate/ethanol system has been determined under isobaric conditions at 0.1, 0.5, and 0.7 MPa using a modified stainless-steel ebulliometer, which works continuously with the recirculation of both phases. The activity coefficients in the liquid phase are predicted using the ASOG model and different versions of the UNIFAC model; these values are quantified with respect to the experimental data, which are verified using the Van Ness point-to-point test.
29 citations
TL;DR: This paper proposes an urgent proposal to Counter Tackling Power Outages in Japan: the Earthquake Compels a Swift Transformation of the Power Supply.
Abstract: 11, 2011, ten nuclear reactors have become unavailable for supplying power to eastern Japan, i.e., the area whose power is supplied by the Tokyo Electric Power Company (TEPCO) and the Tohoku Electric Power Company. Of the existing 22 reactors in this area, only four remain operating as of May 20, 2011. In response to this crisis, we published “Urgent Proposal to Counter Tackling Power Outages in Japan: The Earthquake Compels a Swift Transformation of the Power Supply
25 citations
TL;DR: In this paper, a single constant pressure filtration test for dilute colloidal dispersions has been developed for easily determining the pressure dependence of the permeability characteristics such as the average specific cake resistance.
Abstract: The single constant pressure filtration test for dilute colloidal dispersions has been newly developed for easily determining the pressure dependence of the permeability characteristics such as the average specific cake resistance. The method made use of the gradual variation of the effective pressure drop across the filter cake with time generated by using the filter medium with a high medium resistance. The correlations between the average specific cake resistance and the effective pressure were obtained from the flux decline data. The data of the flux decline behavior obtained for the various values of the slurry concentration, applied pressure and medium resistance were largely merged by the normalized form of the reciprocal filtration rate vs. the filtrate volume. The validity of the method was confirmed not only for slurries of bentonite, Hara-Gairome clay, and polymethyl methacrylate (PMMA), but also for nanoparticle colloids of bovine serum albumin (BSA) and silica sol.
23 citations
TL;DR: In this article, the influence of the frequency of introducing undersaturation, and the time at which undersaturation was introduced, on crystal size distribution was investigated by computational simulation, which successfully reproduced the order of the values of average crystal size in the experimental results.
Abstract: In cooling-type batch crystallization, the influence of undersaturation operation on crystal size distribution (CSD) was investigated by computational simulation. The model used considered the primary and secondary nucleation rates, size-dependent growth rate, and size-dependent dissolution rate limited by mass transfer; the crystal size dependence of the dissolution rate was determined by a Frossling-type equation. The population balance equation was directly solved by computational simulation by using the Cubic Interpolated Pseudo-particle method. The simulation successfully reproduced the order of the values of average crystal size in the experimental results for different temperature profiles. The model proved to be efficient for evaluating the influence of undersaturation operation on the CSD. In this paper, the influence of the frequency of introducing undersaturation, and the time at which undersaturation was introduced, on CSD was also discussed.
21 citations
TL;DR: In this paper, mixtures of glucose and 5-hydroxymethylfurfural (5-HMF) were used as a feedstock; 5-HF at concentrations of 0.01 to 0.05 M was added to 1.5 wt% (0.083 M) glucose.
Abstract: Tar and char are by-products in the supercritical water gasification of biomass, and they reduce the carbon gasification efficiency of the process. The compound 5-hydroxymethylfurfural (5-HMF), a well-known dehydration product of glucose, is suspected to be a chief intermediate in the polymerization pathway that results in the formation of tar and char. In this study, mixtures of glucose and 5-HMF were used as a feedstock; 5-HMF at concentrations of 0.01 to 0.05 M was added to 1.5 wt% (0.083 M) glucose. The reaction occurred under subcritical conditions (i.e., 350°C and 25 MPa). The gas and char formation rates were observed and compared with those in the case of pure glucose. The experimental results show no significant change in the gas and char yields, even though the 5-HMF concentration was increased by a factor of up to 5; this is an unexpected result. An n-th order kinetic model was developed to describe the gasification and polymerization pathways of glucose under subcritical conditions. The main intermediates for gas and char formation remain as TOC (a lumped liquid product).
20 citations
TL;DR: The membranes developed in this research will be useful as a pre-filter in biochemical processes to enhance the life time of the final filters and to reduce industrial wastes due to being made of a compostable polymer.
Abstract: Microfiltration membranes of poly(L-lactic acid) (PLLA), which is a major biodegradable plastic, were prepared from PLLA–1,4-dioxane–water solutions via the thermally induced phase separation. The resulting membranes are used to retain bacterial cells and permeate protein molecules. Only 20% of the bacterial cells in cell suspensions were retained by the membranes prepared from 10–12.5% polymer solution. Increasing the polymer concentration from 12.5 to 15% markedly elevated the bacterial cell retention to 60%. The retention further increased to 90% by elevating the casting temperature from 40 to 50°C. By drying the polymer solution for 2 min before quenching, the cell retention reached 99%. Casting at temperatures of 60°C or higher and drying for periods of 5 min or longer made the membrane uneven and/or increased the membrane resistance. By drying the polymer solution before quenching, the porous structure near the membrane surface was altered so that the membrane retains the bacterial cells. The membrane retained bacterial cells in the manner of a screen filter. The membranes developed in this research will be useful as a pre-filter in biochemical processes to enhance the life time of the final filters and to reduce industrial wastes due to being made of a compostable polymer.
TL;DR: In this article, a novel technique using a swirl-flow was developed to obtain a high throughput of dispersed phase flux in membrane emulsification, and a stable emulsion was obtained.
Abstract: A novel technique using a swirl-flow was developed to obtain a high throughput of dispersed phase flux in membrane emulsification. Shirasu porous glass (SPG) was used as a microporous membrane, methyl laurate was used as dispersed oil phase, and sodium dodecyl sulfate (SDS) was used as an emulsifier. The SPG membrane was a tubular membrane with inner diameter, length, and pore size of 9 × 10−3 m, 1.5 × 10−1 m, and 5.2 μm, respectively. The continuous phase (water) was introduced into the inner space of the tubular membrane through an inlet tangential to the membrane axis to create swirl-flow. The swirl-flow velocity ranged from 0.85 to 5.4 m s−1, and the dispersed phase flux ranged from 0.3 to 3 m3 m−2 h−1. Size-controlled droplets devoid of satellite droplets were produced at specific swirling velocities, and the droplet size dispersal coefficient was between 0.45 and 0.64. The oil-phase-to-water-phase volume ratio reached a value of 0.4 after a single passage through the membrane module. The mean droplet diameter was about four times the membrane pore diameter, and was hardly influenced by the dispersed phase flux and the continuous phase swirling velocity.Swirl-flow membrane emulsification helped achieve extremely high throughput of the dispersed-phase flux and a stable emulsion was obtained.
TL;DR: In this article, a kinetic investigation of the polymerization of 5-hydroxymethylfurfural (5-HMF) during solid char formation in an acidic environment is reported.
Abstract: 5-Hydroxymethylfurfural (5-HMF) is one of the intermediates in char polymerization, a side reaction that occurs in the supercritical water gasification (SCWG) of biomass. In this paper, we report the kinetic investigation of the polymerization of 5-HMF during solid char formation in an acidic environment. This is due to the fact that 5-HMF coexists with other product acids during biomass decomposition. Mixtures of 5-HMF and HCl were treated under subcritical conditions (350°C; 25 MPa). The concentration of 5-HMF ranged from 0.01 to 0.05 M, while that of HCl was 0.01 M (at room temperature). The rates of gas and char production from 5-HMF in experiments with and without acid addition were compared. The acid catalyzed the gasification and polymerization pathways of 5-HMF, especially the decomposition of 5-HMF to TOC, the rate constant of which was increased by two orders of magnitude.
TL;DR: In this paper, the authors extended the Tao and Mason equation of state (TM EOS) to refrigerant fluids using speed of sound data, and employed the TM EOS to predict volumetric properties of multi-component mixtures of liquefied natural gas (LNG).
Abstract: In a previous paper, we extended the Tao and Mason equation of state (TM EOS) to refrigerant fluids using speed of sound data. Herein, we employ the TM EOS to predict volumetric properties of multi-component mixtures of liquefied natural gas (LNG). The second virial coefficient, B2(T), necessary for the mixture version of the TM EOS, in the absence of sufficient experimental data on B2(T), were calculated from the corresponding state correlation. Analysis of our predicted results shows that the TM EOS is capable of accurately predicting the densities of multi-component liquefied natural gas mixtures over wide range of temperatures and pressures. The overall average absolute deviation (AAD) of the calculated densities from the literature ones for 222 data points was found to be 2.37%. Furthermore, the densities of LNG mixtures obtained from the TM EOS have been compared with those calculated from Peng–Robinson (PR) and Ihm–Song–Mason (ISM) equations of state. Generally, our results show that the TM EOS is favorable over the two other equations of state. The overall average absolute deviation for the 222 data points calculated by ISM and PR equations of state were of the order of 2.90% and 4.85%, respectively.
TL;DR: In this paper, the swelling and non-swelling effects on bentonite particles play an important role in their applications and the instrumental and experimental analyses for specifying bentonite for each application include pH, Methylene blue (M.B.) test, Cation Exchange Capacity (C.E.C.) measurements; Swell, M.B., sediment, and colloid indices, dry screen analysis (granulometric analysis), XRD (Xray diffraction), XRF (X-ray fluorescence).
Abstract: Bentonites contain a large amount of nano-porous and nano-structured montmorillonite, which is the dominant clay mineral determining the swelling properties of bentonites. In this study, bentonites are categorized into three types, namely swelling (Na-montmorillonite), nonswelling-swelling (Ca,Na-montmorillonite), and nonswelling (Ca-montmorillonite). Soda activation with the optimum parameters also increases the swelling properties of bentonites. The instrumental and experimental analyses for specifying bentonite for each application include pH, Methylene Blue (M.B.) test, Cation Exchange Capacity (C.E.C.) measurements; Swell, M.B., sediment, and colloid indices, dry screen analysis (granulometric analysis), XRD (X-ray diffraction), XRF (X-ray fluorescence). pH results showed higher values for swelling bentonites (group 3) and these values increased after soda activation. The values of C.E.C., M.B. test, and indices are normally higher for group 3 than for group 2 (nonswelling-swelling type). These values were directly related with the amount of clay minerals (montmorillonites) in dry screen analysis. Finally, swelling and non-swelling effects on bentonite particles play an important role in their applications. Swelling bentonites like ES3 are good for applications such as barriers, drilling mud, and plethorapy. Group 2 (nonswelling-swelling) such as S2, G1, and GH1 are good bentonites for use as a filtering agent in juice industries due to being lower voluminous material than that of production with group 3. For pharmaceutical applications, in addition to the swelling index, sediment and colloid indices must be considered.
TL;DR: In this article, an experimental study has been conducted for TiB and TiB2 nanoparticle fabrication by radio frequency induction plasmas, and the nanoparticles were characterized based on phase composition in the product and crystalline diameter.
Abstract: An experimental study has been conducted for TiB and TiB2 nanoparticle fabrication by radio frequency induction plasmas. TiB and TiB2 nanoparticles were selected as the model for the investigation. In the thermal plasma, the mixed powders of titanium with boron were evaporated immediately and nanoparticles were produced through the cooling process. The parameters of powder feed rate and boron content in the feed powders played an important role in the formation of boride nanoparticles. The nanoparticles were characterized based on phase composition in the product and crystalline diameter. The nanoparticles of TiB and TiB2 nanoparticles had an average crystalline diameter from 10 to 45 nm. The diameter of TiB was smaller than that of TiB2. The mass fraction of TiB had the range from 0 to 99.58%. These results suggest that boride nanoparticles can be produced by induction thermal plasma and also that the crystalline diameter and composition were controllable.
TL;DR: In this paper, the effect of convection in an electromagnetically levitated molten iron droplet on the thermal conductivity of the droplet measured by the electromagnetic levitation (EML) technique in the presence of a static magnetic field was investigated.
Abstract: In order to quantitatively investigate the effect of convection in an electromagnetically levitated molten iron droplet on the thermal conductivity of the droplet measured by the electromagnetic levitation (EML) technique in the presence of a static magnetic field, numerical simulations of the melt convection in the droplet and measurements of the thermal conductivity with the periodic laser heating method were carried out. In addition, the thermal conductivity of molten iron was measured by the EML technique, and then compared with values obtained numerically. It was found that the numerical simulations could sufficiently explain the measurement of thermal conductivity by the EML technique in a static magnetic field. It is suggested that a static magnetic field of 10 T is enough to measure the real thermal conductivity of molten iron by the EML technique. Moreover, the correlation between the static magnetic field and the contribution of melt convection to the measured thermal conductivity was investigated by using a nondimensional parameter, which is the ratio of the electromagnetic force operated by the static magnetic field to that produced by the alternating current in the RF coils.
TL;DR: A method for estimating Wilson parameters on the basis of solubility parameters and molar volumes has been adopted to correlate vapor-liquid equilibria of polar mixtures such as binary systems containing ethers, ketones, ethanol, and water.
Abstract: A method for estimating Wilson parameters on the basis of solubility parameters and molar volumes has been adopted to correlate vapor–liquid equilibria of polar mixtures such as binary systems containing ethers, ketones, ethanol, and water. The correlation performances are examined and discussed.
TL;DR: In this article, power numbers in a baffled stirring tank with paddle-type impellers were measured over a range of Reynolds numbers, from laminar to turbulent-flow regions.
Abstract: Power numbers in a baffled stirring tank with paddle-type impellers were measured over a range of Reynolds numbers, from laminar- to turbulent-flow regions. The impellers studied included a two-blade flat-paddle impeller, a 45° two-blade pitched-paddle impeller, a 45° four-blade pitched-blade turbine, and a two-stage pitched-blade turbine. The impeller-diameter-to-tank-diameter ratio was 0.5 to 0.6. The measured power numbers were compared with those derived from two other methods: prediction by using correlations and computational fluid dynamics (CFD). Power number correlations showed that the values estimated from the empirical correlations proposed by Nagata agreed closely with those measured in the laminar-flow region but deviated significantly in the transitional- and turbulent-flow regions. The power numbers derived from the correlation proposed by Kamei and Hiraoka agreed well with the experimental results in the laminar- and turbulent-flow regions. The power number in a stirring tank was also simulated by the CFD method. The numerical results showed satisfactory agreement with the experimental data over a wide range of Reynolds numbers.
TL;DR: In this paper, the optimal pore size and topology for the quantum sieving of hydrogen isotopes at 77 K was investigated using the grand canonical Monte Carlo method with the Feynman-Hibbs variational approach.
Abstract: We investigate the adsorption of D2/H2 and HD/H2 binary mixtures in carbon slit pores and carbon cylindrical pores using equilibrium molecular simulations, and determine the optimum pore size and topology for the quantum sieving of hydrogen isotopes at 77 K. We show that the grand canonical Monte Carlo method with the Feynman–Hibbs variational approach (FH-GCMC) can be used as an alternative to that with the rigorous Feynman path-integral formalism (PI-GCMC) for exploring quantum H2 adsorption at 77 K. Further, we employ FH-GCMC to investigate the adsorption of D2/H2 and HD/H2 binary mixtures at 77 K. We show that, under the separation conditions of adsorption/desorption cycling between 0.1 and 1 MPa at 77 K, the optimum pore topology for quantum sieving of hydrogen isotopes is a cylindrical pore, and the pore sizes that yield the largest recoverable adsorption amounts with high selectivity are 0.623 nm for D2 and 0.625 nm for HD. We also demonstrate, by comparing the results with those from the binary-mixture FH-GCMC simulations, that the ideal adsorbed solution theory can effectively predict the selectivity of D2 and HD over H2 in nanopores at 77 K (below 1 MPa).
TL;DR: In this paper, a carbon dioxide reforming of methane to synthesis gas over an alumina-supported 1% Ni-based catalyst has been investigated at atmospheric pressure at reaction temperatures of 500-800°C.
Abstract: Carbon dioxide reforming of methane to synthesis gas over an alumina-supported 1% Ni-based catalyst has been investigated at atmospheric pressure. The reforming reactions were carried out at reaction temperatures of 500–800°C. The catalyst activity and stability, carbon deposition, and synthesis gas H2/CO ratio were determined. XRD, SEM, TGA and TPD techniques were employed to characterize the spent and fresh catalysts calcined at 900°C. Further experiments were performed at 600°C to reduce catalyst deactivation by coking. It was observed that, although increasing reaction temperatures from 500 to 600°C increased the formation of carbon, a further increase in reaction temperature to 800°C decreased the formation of carbon. The highest CH4 and CO2 conversion drops were recorded at 600°C. Experiments at 600°C revealed that addition of Ca promoter decreased coke formation and, therefore, enhanced the stability of the catalyst. Also, the combined partial oxidation increased the activity and reduced carbon formation. The optimum catalyst performance with respect to O2 addition was obtained with a feed containing 20% O2. On other hand, when the CO2/CH4 feed ratio was increased from 0.65 to 1.50, the drop in CH4 conversion with time-on-stream was reduced from 65 to 15%. The best catalytic performance was achieved with a space velocity of 33 mL/min · gcat.
TL;DR: In this paper, the authors examined the desulfurization performances of a sorbent derived from waste concrete through thermal gravimetric analysis in the temperature range from 303 to 1173 K.
Abstract: This study examines the desulfurization performances of a sorbent derived from waste concrete through thermal gravimetric analysis in the temperature range from 303 to 1173 K The sorbent is fine particles having a mean diameter distribution of 10–200 μm generated as a byproduct in a recycling process of aggregates from waste concrete The sorbent is mainly composed of hydrated cement component, ie calcium silicate hydrate (C-S-H) and calcium hydroxide (Ca(OH)2) The sorbent showed SO2 removal activity over the temperature range studied The desulfurization rate was lower under a lower temperature range up to 773 K, where the desulfurization rate gradually decreased with increasing temperature The desulfurization activity at the lower temperatures can be attributed to the direct reaction of SO2 with C-S-H and Ca(OH)2 For the higher temperature range, the desulfurization rate was much higher, being almost half that for pure calcium carbonate, a conventional sorbent for dry desulfurization
TL;DR: In this paper, the tetrahydrofuran (THF) was used to measure the Isobaric vapor-liquid equilibria (VLE) of four binary systems containing THF: THF + water, water and three different mixtures of THF+n-alkane (n-pentane, n-hexane, and n-heptane).
Abstract: Isobaric vapor–liquid equilibria (VLE) were measured for four binary systems containing tetrahydrofuran (THF): THF + water, and three different mixtures of THF + n-alkane (n-pentane, n-hexane, and n-heptane). Measurements were conducted at pressures in the range 40.0–101.3 kPa using a simple, automatic apparatus developed in our laboratory. From the experimental VLE data it was confirmed that the THF + water and THF + n-hexane systems formed minimum-boiling-point azeotropes, whereas the THF + n-pentane and THF + n-heptane systems were non-azeotropic mixtures. Non-random two-liquid (NRTL) parameters were also determined on the basis of the experimental VLE data.
TL;DR: In this article, the authors proposed a new method for determining the representative viscosity of a pseudoplastic liquid in a stirred vessel using a weight of dissipation function on the basis of numerical simulation results without any power correlation with a Newtonian liquid.
Abstract: It is difficult to determine the representative apparent viscosity of a pseudoplastic liquid in a stirred vessel because the viscosity of the liquid varies with on the shear rate in the vessel. Until now, the method proposed by Metzner and Otto has exclusively been applied to the determination of this value. In this study, we proposed a new method for determining the representative viscosity, ηa, by averaging the viscosity distribution in the vessel using a weight of dissipation function on the basis of numerical simulation results, without any power correlation with a Newtonian liquid. Further, we calculated the representative shear rate, Γ, from ηa using a rheological equation presenting the pseudoplasticity; then, we found that Metzner's constant, B, can be expressed as the function of the impeller Reynolds number, Red. The reliability of this method was ascertained by comparing the results with those obtained when using the conventional Metzner's method: better conservation of flow similarity was achieved when scaling up the vessel using the proposed method than when employing the conventional method.
TL;DR: In this paper, the authors evaluated a reaction process in which waste concrete was used to recover phosphorus from wastewater and found that the removal ratios of orthophosphate ions from actual wastewater samples were higher than those in the case of model wastewater for which the initial concentrations of Orthophosphates ions (131−161 mgP L−1) were equal to those for the actual wastewater sample and the Ca/P ratio (approx. 5 g g−1).
Abstract: We evaluated a reaction process in which waste concrete was used to recover phosphorus from wastewater. We conducted experiments using various actual wastewater samples obtained by the sludge dewatering process at a sludge disposal plant. The removal ratios of orthophosphate ions from actual wastewater samples were higher than those in the case of model wastewater for which the initial concentrations of orthophosphate ions (131–161 mgP L−1) were equal to those for the actual wastewater sample and the Ca/P ratio (approx. 5 g g−1). This result indicates that the high concentration of calcium ions originally contained in the wastewater samples promotes the reaction of HAP. The novel phosphorus recovery process developed in this study, which is based on the use of waste concrete, has the potential to contribute to the inexpensive recycling of phosphorus resources.