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  • Hexavalent chromium removal by polyacrylic acid-grafted Macadamia nutshell powder through adsorption–reduction mechanism: Adsorption isotherms, kinetics and thermodynamics
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-05
    Themba Dominic Ntuli; Vusumzi Emmanuel Pakade

    Hydrochloric acid-treated Macadamia nutshell (AMM) powder was grafted with acrylic acid monomers at different doses of 0.5, 1.0 and 2.0 M to incorporate the carboxylic groups on its surface. The grafted materials were labeled 0.5 GAM, 1 GAM and 2 GAM signifying the grafting ratios. The incorporation of acrylic acid was demonstrated by an increase in oxygen content from 0.18% to 1.20% in the elemental analysis. The splitting and shifting of the alcohol intermolecular bonded –OH functional groups at 3330 cm−1 to 3396 and 3321 cm−1 observed after grafting was further proof of the addition of acrylic acid. Scanning electron microscopy (SEM) images revealed that the materials exhibited stacked sheets with spherical halo openings typical of biomaterials. The maximum conditions for chromium(VI) removal were obtained at pH 2, 180 min contact time, 7.5 g/L adsorbent dosage concentration and a temperature of 40 °C. The adsorption mechanism was best described by the monolayer sorption postulated by Langmuir with reported adsorption capacity of 39.21 mg/g. The best fit for the kinetic data was obtained with the pseudo-second-order rate model suggesting a chemisorption nature of interaction. Accordingly, the thermodynamic factors were feasible, spontaneous and endothermic. The acrylic acid-functionalized Macadamia adsorbent showed greater potential compared to other biosorbents in the removal of hexavalent chromium from aqueous solution in the presence of competing anions.

    更新日期:2020-01-02
  • Effect of selected process parameters on the electrodialytic separation and concentration of sulfuric acid using graphite electrodes
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-25
    Beena Sheth; Kaushik Nath

    Present work explored the effect of current density and applied voltage along with the performance of graphite and SS 316 L as electrodes in the electrodialytic separation of sulfuric acid from model spent acidic solution. The study established that applied voltage in the range of 2–12 V was most suitable for maintaining current densities in the range 2–50 mA/cm2 for different initial catholyte concentration. Around 90% acid separation could be achieved with more than 70% current efficiency. The electrical energy (kJ/l) required for the concentration enhancement of sulfuric acid by electrodialysis (ED) was estimated and was compared with the thermal energy required for the same by evaporation (EV). ED was found to be less energy intensive process. An economic evaluation of the integrated ED and EV was also carried out under present experimental conditions and the likelihood of which was found to be 21% and 24% more economical than standalone ED or EV respectively.

    更新日期:2020-01-02
  • Solvent extraction studies of nickel(II) by capric acid from sodium sulfate solution
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-19
    H. Benalia; D. Barkat

    The extraction of nickel(II) from sulfate medium of the ionic strength of 0.33 M by capric acid dissolved in chloroform has been carried out at 25 °C. The stoichiometry of the organometallic complexes extracted was given by using the slope analysis method. Nickel(II) complexes exist as mononuclear species NiL2.2HL and as dinuclear species (NiL2.2HL)2 in low and high capric acid concentrations, respectively. Extraction constants for each species were determined. UV–visible and FT-IR spectroscopy have also been performed for the study of the ligand and their complexes. Electronic spectra of nickel(II) caprate species suggest the octahedral geometry. The present results have been compared with the previous results for the extraction of cobalt(II) and copper(II) and found that the extraction order for capric acid for the three metals is as follows: Cu > Ni > Co.

    更新日期:2020-01-02
  • A facile one pot synthesis of highly stable PVA–CuO hybrid nanofluid for heat transfer application
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-19
    Annie Aureen Albert; D.G. Harris Samuel; V. Parthasarathy; K. Kiruthiga

    In this paper, we report in-situ preparation of polyvinyl alcohol (PVA)–copper oxide (CuO) nanocomposite by sol–gel method and the preparation of highly stable PVA–CuO hybrid nanofluid. This novel method combines the advantages of both the single step and two step methods of preparation of nanofluid. The prepared nanofluid is found to be stable up to 12 months under static conditions. Fourier Transform Infrared (FTIR) spectroscopy and X-Ray Diffraction (XRD) pattern confirmed the formation of monoclinic CuO and the interaction between PVA and CuO nanoparticles. The nanofluid was characterized by Transmission Electron Microscope (TEM) and it revealed the formation of ribbon shaped CuO embedded in PVA. High resolution TEM (HRTEM) image shows that the nanoribbons are actually made up of about 4 nm sized CuO crystallites. Stability of the nanofluids for various concentrations of the PVA was investigated by Zeta Potential measurements, UV–Vis spectroscopy, and photo capturing methods. It shows that 0.5 wt% PVA–CuO hybrid nanofluid results in highest stability. Particle size analysis using Dynamic Light Scattering (DLS) showed that 0.125 wt% of PVA resulted in large agglomerates due to insufficient capping. Thermal conductivity of the nanofluid was also measured using hot wire method and it showed enhancement over the base fluid.

    更新日期:2020-01-02
  • Kinetics of p-toluene-sulfonic acid catalyzed direct esterification of pentaerythritol with acrylic acid for pentaerythritol diacrylate production
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-23
    Li Sun; Lin Zhu; Weilan Xue; Zuoxiang Zeng

    Pentaerythritol diacrylate (PEDA) is synthesized by p-toluene-sulfonic acid (p-TSA) catalyzed direct esterification of pentaerythritol (PER) with acrylic acid (AA). Based on the direct esterification reaction mechanism and the corresponding two simplified reaction steps, the kinetic model is derived. The kinetic parameters are determined by Global Optimization Method-Genetic Algorithm procedure with an error minimization algorithm. It is found that the model can fit the reaction data very well. Furthermore, the effects of operating conditions such as reaction temperature and catalyst concentration are also investigated. The results show that the reaction rate constants increase with the temperature in the range of 373–403 K, and they increase with the catalyst concentration up to 1.12 wt% and then change slightly. The activation energy of mono-esterification is 34.57 kJ·mol−1, which is higher than di-esterification (23.23 kJ·mol−1), indicating that mono-esterification step is more sensitive to the temperature variation.

    更新日期:2020-01-02
  • The effect of water type on the absorption and desorption of carbon dioxide in bubble columns
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-23
    Mahmoud Al-Hindi; Fouad Azizi

    This study investigates the effect of alkalinity and salinity on the transfer rate of carbon dioxide, CO2, from/to several aqueous phases. The CO2 absorption and desorption experiments were performed for several water types including distilled, reverse osmosis, brackish, and brackish reject waters in addition to seawater, inside a bubble column contactor. Findings indicated that the direction of transfer (i.e. absorption or desorption) had a strong influence on the rate of mass transfer with higher values recorded for the absorption experiments. The results also showed that for the absorption and desorption experiments the volumetric mass transfer coefficient, kLa, values always decreased with increased salinity until a “threshold” value was attained, above which kLa increased again. The effect of alkalinity on kLa values was not as conclusive where the experimental results indicated that for adsorption kLa values decreases almost linearly with the increase in water alkalinity while no discernible trends were observed for the effect of alkalinity in the desorption experiments.

    更新日期:2020-01-02
  • Rapid quantification of degraded products from methyldiethnolamine solution using automated direct sample analysis mass spectrometry and their removal
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-04-02
    Priyabrata Pal; Abdul Fahim Arangadi; Anjali Achazhiyath Edathil; Vinu Pillai; Fawzi Banat

    Natural gas sweetening using methyldiethanolamine (MDEA) solution requires a specific and accurate technique for quantifying organic degraded products and their removal to overcome operating problems such as corrosion and foaming issues. Some of the techniques presently available are gas chromatography, liquid chromatography, and proton-transfer-reaction with mass spectrometry. However, these analytical methods require extensive sample preparation, standards, and long analysis time. The present work aimed at developing an analytical technique using Direct Sample Analysis Time of Flight (DSA-TOF) mass spectrometry for quantifying the degradation products in the industrial grade lean MDEA solution. This technique involves instant sample introduction, rapid analysis, and offers immediate results. The DSA and TOF parameters were optimized to quantify the degraded products accurately. The high correlation coefficient ( R2) obtained for the calibration of different wt. % diethanolamine (DEA) in 50 wt. % MDEA solution justified the accuracy of the developed method. Finally, the removal of these organic degraded products were carried out using batch and column adsorption experiments. Carbon impregnated on calcium alginate (CAC) bio-polymer was used as an adsorbent to remove the degraded products. Thus, the method developed using DSA-TOF provided the basis to quantify the degraded products and the CAC adsorbent easily removed the contaminants from the lean MDEA solution.

    更新日期:2020-01-02
  • Geometry segregated CFD model solving framework for complex geometry calculation
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-29
    Attila Egedy

    The computational fluid dynamics (CFD) simulators emerged as an excellent tool to support engineering problem-solving in the past decades. There are limits to the application of a CFD simulator, for example, the validation need of the model, and the computation demand of the simulation. With multiple core computers, the computation time can be lowered, and GPU computing can also be a way to decrease the computation demand. But in some cases, for example in catalyst beds, the number of individual particles is too high to calculate with a CFD simulator. In this study, we show a way to segregate the geometry of the device into smaller parts (decomposition of the geometry) and calculate only the parts of the simulation at a time, instead of whole. In this way, the computation need can be significantly lowered, without losing the crucial information, which can be stored between the geometrical steps. In this article, a framework was developed for the segregation of the geometry. The operation of the framework is shown using different case studies.

    更新日期:2020-01-02
  • Adsorption of crystal violet from aqueous solution in continuous flow system using bone char
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-04-02
    Maria Alexandra Pires Cruz; Luanna Cristina Matos Guimarães; Esly Ferreira da Costa Júnior; Sônia Denise Ferreira Rocha; Patrícia da Luz Mesquita

    In the face of water scarcity and more strict environmental regulation, water treatment is a demand and reuse is being encouraged in diverse production processes. Advanced treatments, such as adsorption, may be indicated for specific and/or recalcitrant contaminants removal, such as dyes, present in textile industries wastewater, for example. However, the conventional adsorbents cost may be unattractive for such a purpose. In this context, bone char, 0.5–1.4 mm particle size, mesoporous structure, produced from tannery, food and cattle breeding waste, was tested to remove crystal violet dye from synthetic effluent, in a lab scale fixed bed adsorption column. A complete removal was observed up to 74 min of column operation. The greatest adsorption capacity (qo = 20.63 mg·g−1) was observed for the lowest flow rate evaluated (Q = 15.4 ± 0.8 mL·min−1) and intermediate bed depth (h = 24 cm) at 27.1 ± 0.9 °C. At the same operational conditions, the experimental breakthrough curve was better predicted by Yan model (qo = 20.42 mg·g−1; a = 1.667; b = 2.93 and R2 = 0.955) compared to Thomas model (qo = 22.44 mg·g−1; kTH = 0.056 mL·mg−1·min−1 and R2 = 0.878).

    更新日期:2020-01-02
  • Characterization and purification of waste phosphogypsum to make it suitable for use in the plaster and the cement industry
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-04-11
    Yassine Ennaciri; Ilham Zdah; Hanan El Alaoui-Belghiti; Mohammed Bettach

    The phosphoric acid production in Morocco generates a large amount of phosphogypsum (PG) which is a significant source of environmental contamination. In this work, PG has been characterized by different analysis techniques that allow to study the effect of the impurities on its physical and chemical properties. Thus, a method to purify the PG from phosphates and fluorides was proposed in order to improve its quality and to make it usable in plaster and cement. The purification process consists to sieve PG under 200 μm and to treat it by sulfuric acid to dissolve the insoluble impurities. The obtained results show that the treatment of PG by sulfuric acid 20 and 50% at 60 °C for 2 h is sufficient to make it suitable for used in the plaster and the cement respectively.

    更新日期:2020-01-02
  • Encapsulation of antioxidant compounds in biopolymer micelles
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-04-10
    Jolanta Pulit-Prociak; Małgorzata Kabat; Ewelina Węgrzyn; Michał Zielina; Marcin Banach

    This manuscript presents the method for encapsulation of antioxidant agents in micelles of biopolymeric origin. The role of antioxidant agents is played by tannic acid or birch leaf extract, which is a natural source of polyphenolic compounds. The products were obtained in the form of o/w nanoemulsions. The obtained nanoemulsions were characterized by studying their physicochemical and utility properties. The size and electro-kinetic potential of the micelles were measured by dynamic light scattering (DLS). The creaming index and encapsulation efficiency are also provided. The use of statistical tools enabled analysis of the influence of independent parameters on the limits describing the emulsions’ properties. Nanoemulsions with birch leaf extract reached an encapsulation efficiency equal to 80–90%, which remained quite constant over time. It was possible to obtain nanoemulsions with birch extract that were homogeneous over the whole observation period. The values of electro-kinetic potential ranged up to −40 mV, which proves the high stability of these nanoemulsions. More desirable results were achieved in the case of obtaining nanoemulsions with tannic acid. In the beginning, the encapsulation efficiency was very effective (approximately 70%), but after a few days it decreased to values of around 30%. That meant that the tannic acid was released from the micelles with time. After 14 days of observation, the creaming index values were very low, which proves their high homogeneity. These nanoemulsions were stable in time, which was reflected by their electro-kinetic potential values (>20 mV).

    更新日期:2020-01-02
  • Static turbulence promoters in cross-flow membrane filtration: a review
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-29
    Chiranjit Bhattacharjee; V. K. Saxena; Suman Dutta

    The main problems of membrane-based separation methods especially pressure driven ones are fouling and concentration polarization. After increasing cross-flow velocity, use of promoters for inducing turbulence in filtration zone is one of the easiest ways of mitigating concentration polarization in membrane separation processes. Turbulence promoters have the ability to significantly increase the permeate flux in membrane filtration systems by generating alterations in the flow path of the feed. The complexities involved in fluid dynamics which lead to flux enhancement are still not been clearly conceptualized. Various researchers have investigated the effectiveness of promoters on the overall improvement of the filtration efficiency in membrane filtration processes. The flow field generated by these promoters creates turbulence and secondary flows which lead to high shear rates in the vicinity of the filtration surface resulting in scouring of foulant materials and reduction of cake thickness. This ultimately helps in attaining higher levels of flux and mass transfer. Turbulence promoters such as static mixers, Kenics mixers, helical elements, cylindrical rods, thin wires, spacers are widely used in filtration systems to induce turbulence in order to control polarization. This paper reviews the utilization of promoters in membrane-based separation systems, dependence of flux on operational parameters, and effects of different type of promoters on membranes. The effects of cross-flow velocity, Reynolds number, feed properties, membrane properties, pressure, and temperature are reviewed.

    更新日期:2020-01-02
  • Photocatalytic decolorization of Basic Blue 41 using TiO2-Fe3O4-bentonite coating applied to ceramic in continuous system
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-21
    Restu Kartiko Widi; Inez Suciani; Emma Savitri; Rafael Reynaldi; Arief Budhyantoro

    Photocatalytic degradation/decolorization of Basic Blue 41 dye assisted by UV radiation has been studied over TiO2-Fe3O4 supported by bentonite. In this experiment, photocatalytic decolorization process was performed continuously; where dye feed solution was supplied to a coated-ceramic vessel. The influence of the initial concentration, pH, and flow rate of the dye feed solution on the degradation efficiency process was examined in this study. The results showed that the increase in the dye concentration and flow rate reduces decolorization efficiency. The highest decolorization efficiency was at pH of 5.5. The kinetic study of this photo-decolorization indicated that under the experimental condition, the photocatalytic kinetic process followed first-order kinetics on the basis of Langmuir–Hinshelwood heterogeneous reaction mechanism, where the reaction rate constant, namely kr, is 0.7707 and the adsorption rate constant, namely K, is 0.01298.

    更新日期:2020-01-01
  • Terephthalic acid decomposition by photocatalytic ozonation with VxOy/ZnO under different UV-A LEDs distributions
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-01
    Iliana Fuentes; Julia L. Rodriguez; Hugo Tiznado; José M. Romo-Herrera; Isaac Chairez; Tatyana Poznyak

    In this work, the degradation of terephthalic acid (TA) by vanadium oxide (VxOy) supported on zinc oxide (ZnO) was evaluated in a photocatalytic ozonation treatment based on two UV-A LEDs distributions. TEM analysis and specific surface area measurement suggest that VxOy is not supported on ZnO, while the EDXRF and XPS analysis indicated the presence of VxOy. The XPS analysis on VxOy/ZnO catalyst showed non-significant surface change between fresh and used catalyst. However, ozone decomposition showed a higher reaction rate constant for catalytic (230%) and photocatalytic ozonation (310%) in comparison with single ozone treatment. Photocatalytic ozonation with central and external irradiation arrays was evaluated in TA elimination by a kinetic study. The irradiation arrays had not statistical differences in the TA decomposition or oxalic acid formation. These results suggest that the construction of central bodies inside the reactor could be not necessary for photocatalytic processes.

    更新日期:2020-01-01
  • Kinetics and modeling of L-cysteine effect on the Cu(II)-induced oxidation of quercetin
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-21
    Angelos Photiades, Spyros Grigorakis, Dimitris P. Makris

    This study aimed at investigating the effect of L-cysteine on the Cu2+-induced oxidation of quercetin, within a pH range varying from 6.7 to 8.3 and temperatures varying from 53 to 87 °C. Initial examinations showed that quercetin degradation obeyed apparent first-order kinetics and it was significantly temperature-dependent. Modelling of the effect of L-cysteine by implementing response surface methodology suggested that L-cysteine did not inhibit quercetin oxidation, but it acted as an oxidation stimulant. Liquid chromatography-diode array-mass spectrometry analyses revealed the presence of typical quercetin degradation and oxidation products, including protocatechuic acid, 2-(hydroxybenzoyl)-2-hydroxybenzofuran-3(2H)-one and a quinone methide. However, the presence of two tentative quercetin/L-cysteine adducts evidenced the implication of L-cysteinyl radicals in the relevant reactions. It was concluded that the formation of L-cysteinyl radicals may promote quercetin oxidation, giving rise to substances with unknown biological significance. This fact merits further attention to illuminate possible beneficial or adverse nutritional consequences of such reactions in foods.

    更新日期:2019-11-26
  • Production and characterization of bio-oil and biochar from ablative pyrolysis of lignocellulosic biomass residues
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-20
    Nattawut Khuenkaeo, Nakorn Tippayawong

    Agricultural residues are one of the large untapped sources of bio-energy in Thailand, with over 30 million tons available per year. They may be utilized to generate renewable liquid and solid fuels. In this work, pyrolysis of lignocellulosic biomass residues (corncobs, coconut shells, and bamboo residue) was carried out in an ablative pyrolysis reactor with rotating blades. Influences of inert carrier gas flows (5–15 L/min) and rotating frequency (4–8 Hz) at a fixed hot plate temperature of 500 °C on generating bio-oil were investigated. Characterization of bio-oil as well as biochar products was performed. Maximum bio-oil yield was found to be about 50% w/w for coconut shell at 5 L/min of flowrate and 8 Hz of the rotating frequency, and 45% w/w for bamboo residues at the same condition. For corncob, the highest bio-oil yield was 72% w/w at 5 L/min of flowrate and 6 Hz of the rotating frequency. Solid char yields were around 23–28% w/w. The heating values of the liquid oil and solid char were about 20–25 and 23–30 MJ/kg, respectively. Rotating blade ablative reactor was able to generate high yields of bio-oil for agricultural residues. The main compounds of the bio-oil obtained were phenolics, including furfuran, organic acids, aldehydes, alcohols, ethers, and ketones.

    更新日期:2019-11-26
  • Application of X-ray diffractometry and scanning electron microscopy to study the transformation of carnallite and thenardite to schoenite at 25 °C
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-26
    Qingyu Hai, Huaide Cheng, Haizhou Ma, Jun Li, Xiwei Qin

    An experimental study was carried out on the preparation of schoenite from carnallite and thenardite by the double-decomposition method. According to the metastable phase diagram for the quinary system, Na+, K+, Mg2+//Cl–, and SO42−-H2O at 25 °C, three theoretical models were established for the double-decomposition processes. The mineralogy and morphology of schoenite, sylvite, epsomite/hexahydrite, and halite were studied by X-ray powder diffractometry and scanning electron microscopy during the double-decomposition processes. It is confirmed the preparation of schoenite via carnallite and thenardite is feasible. The double-decomposition reactions processes were described by three model equations. First, sylvite was obtained by carnallite decomposition in aqueous solution; second, epsomite/hexahydrite was obtained by a conversion reaction via thenardite and an MgCl2-rich mother liquor; third, schoenite was obtained via sylvite and epsomite/hexahydrite. The results suggest that (1) sylvite exists in the primary reaction time, epsomite/hexahydrite form simultaneously, and their contents decrease as the reaction time increase. (2) The terminal product of the double-decomposition is schoenite, and its formation results from conversion via sylvite and epsomite/hexahydrite. (3) A tendency for the X-ray diffraction intensity of sylvite and epsomite/hexahydrite to weaken increases visibly with reaction time, and its change agrees well with the third model. (4) Scanning electron microscopy images of the halite, sylvite, epsomite/hexahydrite, and schoenite are clear and integrated, and their formation results from the precipitation of the three model conversion reactions. Results showed that a good agreement exists between the experimental and theoretical models.

    更新日期:2019-11-26
  • Effects of acetic acid addition methods on butyl acetate enzymatic synthesis
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-14
    Nathália G. Duarte, Danielle Simas de Queiroz, Cláudia de Oliveira Veloso, Aline Machado de Castro, Marta Antunes Pereira Langone

    Butyl acetate is a versatile chemical due to its excellent solvency for polymers, resins, and oils. In this work, the butyl acetate synthesis was studied by the esterification of n-butanol with acetic acid using the commercial immobilized lipase Novozym® 435. The acetic acid and n-butanol concentrations have to be limited in the enzymatic synthesis of this ester due to the deleterious effects caused by these reagents on the enzyme. Three methods of acetic acid addition (single, stepwise and continuous addition) were investigated to minimize the acid concentration. A significant drop on acid conversion was observed in the presence of a higher concentration of the reagents when single or stepwise acid addition was used. However, a solvent-free system using a continuous addition of acetic acid favored butyl acetate synthesis, reaching a conversion of 84% at 60 °C, employing 5 wt% of enzyme and n-butanol/acetic acid final molar ratio equal to 1/1.

    更新日期:2019-11-26
  • Experimental measurements and thermodynamic modelling of hydrate phase equilibrium conditions for CF4+TBAB aqueous solutions
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-04-12
    Saeideh Babaee, Hamed Hashemi, Amir H. Mohammadi, Paramespri Naidoo, Deresh Ramjugernath

    In this study, CF4 hydrate dissociation conditions in the presence of different TBAB aqueous solutions with the concentrations of 0.05, 0.10, 0.20, and 0.3 mass fractions were experimentally measured. Measurements were performed using a high pressure equilibrium cell with an approximate inner volume of 40 cm3. Hydrate measurements were performed in the temperature and pressure ranges of (273.8–285.6) K and (1.03–11.57) MPa, respectively. The results show that TBAB aqueous solutions with the concentration of 0.05, 0.10, and 0.20 (mass fractions) do not have a major promotion effect on the CF4 hydrate phase equilibrium. However, the aqueous solution with 0.30 mass fraction TBAB exhibited a significant promotion effect on CF4 hydrate formation. The model of Chen and Guo (1998) and Joshi et al. (2012) were used to estimate the hydrate dissociation conditions. The errors between the experimental and calculated data resulted in acceptable absolute relative deviations (ARD%) below 0.1%.

    更新日期:2019-11-26
  • Analytic Pade-like approximations of exp(–sqrt(s)) for simulations of diffusion processes in the semi-infinite geometry
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-05
    Jietae Lee, Dong Hyun Kim

    Detailed transient behaviors of mass and heat transfer processes are required to solve partial differential equations. When those partial differential equations are coupled, they are still difficult to solve in time domain. For linear mass and heat transfer processes, their Laplace-domain solutions are obtainable and, when they are approximated by rational polynomials in the Laplace variable s, the problems can be transformed to a set of ordinary differential equations solved easily in time domain for various initial conditions. In this approximation, the conventional Pade method based on the Tayler series expansion of the Laplace-domain solutions has been well developed and effective. However, for some mass and heat transfer processes in the semi-infinite geometry, the Pade approximation is not applicable because the Laplace-domain solutions involving exp(–sqrt(s)) are not analytic at s = 0. Here, for such processes, analytical methods to approximate exp(–sqrt(s)) by rational polynomials are proposed. First it is expanded in series in terms of cosh–1(2ksqrt(s)) which converges fast. This series, when truncated, is analytic at s = 0 and its Pade approximations are available. The proposed method enables partial differential equations be replaced to a set of ordinary differential equations, reducing computations considerably for coupled partial differential equations. Performances of the proposed method are illustrated with several realistic mass and heat transfer processes.

    更新日期:2019-11-26
  • Artificial intelligence (AI)-based friction factor models for large piping networks
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-22
    Nusrat Parveen, Sadaf Zaidi, Mohammad Danish

    In large piping networks, evaluation of friction factor is a time-consuming process and poses computational complexity. This is because the friction factor has to be evaluated for every pipe segment and that too by using implicit correlations. In the present study, this issue has been addressed by developing artificial intelligence (AI)-based friction factor models namely, support vector regression (SVR), artificial neural networks (ANN) and gene expression programing (GEP) to predict the friction factor for the turbulent flow regime. The developed models have been compared with the existing correlations based on the statistical parameters and have shown excellent prediction accuracy with the lowest average absolute relative error (AARE), root mean square error (RMSE) and highest correlation coefficient (R) as 1.43%, 0.0003, 0.9993 for SVR while for ANN they are 2.11%, 0.00095, 0.9978 and for GEP they are 7.14%, 0.0024, 0.9864, respectively. Leave-one-out cross-validation on the test set Qext2 for SVR, ANN, and GEP are obtained as 0.9976, 0.9957, and 0.9726, respectively. Furthermore, the performance of these AI-based models, i.e. SVR, ANN, and GEP models and the various well-known correlations have been studied for estimating pipe friction factor in both smooth and rough pipes with different values of relative roughness. The SVR-based model significantly outperforms the existing correlations and the GEP-based model and marginally the ANN-based model. AI approach reduces the computational complexity and the time-consuming iterative solution of implicit correlations for large pipe networks without compromising the accuracy.

    更新日期:2019-11-26
  • Integral process for obtaining acetins from crude glycerol and their effect on the octane index
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-21
    Juan A. Herrada-Vidales, Juan M. García-González, Rafael Martínez-Palou, Javier Guzmán-Pantoja

    The improvement of the combustion process in gasoline spark engines has been a painstaking task focused on developing chemical compounds. These ones have to be capable of bettering the engine performance and meeting standards set by environmental and health regulations aimed at reducing the emission of hazardous pollutants. Among the molecules synthesized for reaching these goals, oxygenating agents have been used to increase the octane number and make more efficient the combustion reaction by reducing the emissions of CO, polyaromatic hydrocarbons (PAHs), and particulate matter. As a result of this quest, MTBE has been used as a solution, but in recent years, negative effects of its use polluting water bodies and, as a consequence, the human health, have proven the opposite. For this reason, alternative oxygenating compounds to MTBE such as alcohols, ethers, and esters are being studied. According to the aforementioned, in the present paper, alternative oxygenating agents belonging to glycerol acetates (GAs) were synthesized from crude glycerol (CG) obtained as a biodiesel by-product and conditioned as starting material to perform esterification reactions with acetic acid or acetic anhydride. In order to assess the performance of these compounds as octane index enhancers, measurements using the same composition of ethanol, MTBE and the as-obtained GAs, in reference gasoline, were made, yielding comparable results that encourage the potential use of acetins as a replacement of MTBE.

    更新日期:2019-11-26
  • Effect of sodium dodecyl benzene sulfonate (SDBS) on the performance of anaerobic co-digestion with sewage sludge, food waste, and green waste
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-01
    Xiaofang Pan, Jian Sun, Youchi Zhang, Gefu Zhu

    The anionic detergent sodium dodecyl benzene sulfonate (SDBS) inhibits anaerobic solid waste fermentation process in mesophilic anaerobic digesters. In this study, the effect SDBS on the performance of anaerobic digestion (AD) of mixture of sewage sludge, food waste, and green waste serving as substrate was investigated. The batch experiments were conducted with five SDBS concentrations namely 0, 0.01, 0.02, 0.05, 0.1, and 0.2 g/g (SDBS/dry sludge) under mesophilic condition (37 ± 1 °C) and lasted for 63 days. The results showed that the presence of SDBS remarkably increased the release of protein and carbohydrate, and resulting in the serious accumulation of volatile fatty acids (VFAs), especially for propionate accumulation. Likewise, the observed variations in enzyme activities associated with different stage of AD revealed that methanogenesis was quite sensitive to SDBS and inhibited by the increase of SDBS addition. Meanwhile, the presence of SDBS decreased the pH value and the concentration of free ammonia, but increased the concentration of NH4+-N. Furthermore, the production of biogas was reduced by SDBS. In conclusion, SDBS addition has a negative impact on anaerobic co-digestion. On the one hand, methanogens were severely inhibited and biogas yield decreased remarkably, on the other hand, the accumulation of VFAs was excessive. Thus, the presence of surfactant (SDBS) in the municipal organic waste should be concerned during the waste disposal via anaerobic digestion process.

    更新日期:2019-11-26
  • Role of surfactant-induced chromia barriers on performance characteristics of Pd composite membranes
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-05
    Murali Pujari, Amrita Agarwal, Ramgopal Uppaluri, Anil Verma

    The article elaborates upon the optimality of electroplating and surfactant coupled electroplating based chromium oxide barriers on the process and product characterization variables of Pd electroless plating during dense Pd composite membranes fabrication. Porous stainless steel discs with 100 nm pore size were deployed to fabricate Pd composite membranes on chromium oxide diffusion barriers prepared with electroplating (7.8 and 20 µm thickness) and surfactant assisted electroplating (7.1 and 12.5 µm thickness). These diffusion barrier films were obtained by subsequent oxidation of chrome plated films at 700 °C. Eventually, palladium films were achieved using rate enhanced Pd electroless plating associated with coupled surfactant and sonication under dropwise addition mode of reducing agent. The surfactant inclusion during chrome plating enabled higher Pd metal film thickness and plating rates but could not provide better pore densification characteristics of dense Pd-chromia-PSS membranes.

    更新日期:2019-11-26
  • Boiling points of the propylene glycol + glycerol system at 1 atmosphere pressure: 188.6-292 °C without and with added water or nicotine.
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-20
    Anna K Duell,James F Pankow,Samantha M Gillette,David H Peyton

    In electronic cigarettes ("electronic nicotine delivery systems", ENDS), mixtures of propylene glycol (PG) and/or glycerol (GL; aka "vegetable glycerin", VG) with nicotine are vaporized to create a nicotine-containing aerosol. For a given composition, the temperature required to boil the liquid at 1 atmosphere must be at least somewhat greater than the boiling point (BP). The use of ENDS is increasing rapidly worldwide, yet the BP characteristics of the PG + GL system have been characterized as the mixtures; here we re-do this, but significantly, also study the effects of added water and nicotine. BP values at 1 atmosphere pressure were measured over the full binary composition range. Fits based on the Gibbs-Konovalov theorem provide BP as a function of composition (by mole-percent, by weight-percent, and by volume-percent). BPs of PG + GL mixtures were then tested in the presence of additives such as water (2.5 and 5 mol% added) and nicotine (3 mol%). Water was found to decrease the BP of PG + GL mixtures significantly at all compositions tested, and nicotine was found to decrease the BP of PG + GL mixtures containing ~75 GL: 25 PG (by moles) or more. The effect of added water (5, 10, and 15 mol% added) on electronic cigarette degradation production (some aldehydes and formaldehyde hemiacetals) was examined and found to have no significant impact on solvent (PG or GL) degradation for the particular device used.

    更新日期:2019-11-01
  • Dry reforming of methane over palladium-platinum on carbon nanotube catalyst.
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2018-12-24
    Yuan Zhu,Kun Chen,Chen Yi,Somenath Mitra,Robert Barat

    A dry reforming (DR) catalyst based on bimetallic Pd-Pt supported on carbon nanotubes is presented. The catalyst was prepared using a microwave-induced synthesis. It showed enhanced DR activity in the 773-923 K temperature range at 3 atm. Observed carbon balances between the reactant and product gases imply minimal carbon deposition. A global three-reaction (reversible) kinetic model-consisting of DR, reverse water gas shift, and CH4 decomposition (MD)-adequately simulates the observed concentrations, product H2/CO ratios, and reactant conversions. Analysis shows that, under the conditions of this study, the DR and MD reactions are net forward and far from equilibrium, while the RWGS is near equilibrium.

    更新日期:2019-11-01
  • Ordering Transitions in Liquid Crystals Permit Imaging of Spatial and Temporal Patterns Formed by Proteins Penetrating into Lipid-Laden Interfaces.
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2008-01-01
    Maren Daschner De Tercero,Nicholas L Abbott

    Recent studies have reported that full monolayers of L-α-dilaurylphosphatidylcholine (L-DLPC) and D-α-dipalmitoylphosphatidylcholine (D-DPPC) formed at interfaces between thermotropic liquid crystals (LCs) and aqueous phases lead to homeotropic (perpendicular) orientations of nematic LCs and that specific binding of proteins to these interfaces (such as phospholipase A2 binding to D-DPPC) can trigger orientational ordering transitions in the liquid crystals. We report on the nonspecific interactions of proteins with aqueous-LC interfaces decorated with partial monolayer coverage of L-DLPC. Whereas nonspecific interactions of four proteins (cytochrome c, bovine serum albumin,immunoglobulins, and neutravidin) do not perturb the ordering of the LC when a full monolayer of L-DLPC is assembled at the aqueous-LC interface, we observe patterned orientational transitions in the LC that reflect penetration of proteins into the interface of the LC with partial monolayer coverage of L-DLPC. The spatial patterns formed by the proteins and lipids at the interface are surprisingly complex, and in some cases the protein domains are found to compartmentalize lipid within the interfaces. These results suggest that phospholipid-decorated interfaces between thermotropic liquid crystals and aqueous phases offer the basis of a simple and versatile tool to study the spatial organization and dynamics ofprotein networks formed at mobile, lipid-decorated interfaces.

    更新日期:2019-11-01
  • Photocatalytic degradation of ciprofloxacin antibiotic by TiO2 nanoparticles immobilized on a glass plate
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-07
    Mohammad Malakootian, Alireza Nasiri, Majid Amiri Gharaghani

    This research investigated the photocatalytic degradation of ciprofloxacin by titanium dioxide nanoparticles immobilized on a glass plate in an aqueous solution. The important point about this process is immobilization on glass plate, which resolves difficulties related to separation of catalysts from the solution in the application of sole nanoparticles as well as reusability of nanoparticles. Application of nanoparticles without immobilization on a support medium causes toxic effects in aqueous solutions, which was fixed through immobilization on a glass plate in this study. In this research, 1 gL−1 of TiO2 was immobilized on a glass plate. XRD and SEM indicated that the TiO2 immobilized on the glass plate was highly pure and uniform in size (39.2–74.9 nm). The maximum ciprofloxacin removal efficiency from the synthetic aqueous solution was obtained at the optimal pH of 5, contact time of 105 min, and ciprofloxacin initial concentration of 3 mgL−1. The extent of ciprofloxacin removed under optimal conditions was obtained as 92.81% and 86.57% from the synthetic and real samples, respectively. Evaluation of linear models of kinetics and adsorption isotherms indicated that the data followed pseudo-first-order kinetics as well as Langmuir–Hinshelwood and Freundlich isotherms. Thermodynamic studies revealed that the adsorption of ciprofloxacin on TiO2 nanoparticles immobilized on glass plate is an endothermic and physical process. Considering the high efficiency of this process under real conditions, it can be used for the removal of resistant pollutants from industrial wastewater.

    更新日期:2019-10-25
  • A new method of measuring the oil–air–water three-phase flow rate
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-08-29
    Yanjun Wang, Haoyu Li, Xingbin Liu, Lei Li, Chunhui Huang, Jinhai Hu

    Oil–air–water three-phase flow patterns in small-diameter vertical measurement channels are complex, making it difficult to establish techniques for interpretation of logging information. In this study, dynamic experiments involving oil–air–water three-phase flows were performed using a novel production logging tool that combined a petal-type turbine flowmeter, a conductance sensor, and an optical fiber sensor in a simulation well. Sensor response characteristics were researched, and a new method of measuring the oil–air–water three-phase flow rate was proposed. The measurement range and resolution of the gas flow rate were 3–20 and 1 m3/d, respectively, and the relative error range of gas flow rate interpretation was 5–10%. The measurement range and relative interpretation error range of the total liquid flow rate were 10–60 m3/d and 5–10%, respectively. The measurement range and resolution of the water cut were 50–100% and 2%, respectively. The absolute error range of interpretation of the water cut ranged from 3.2% to 5%. Currently, the technique is valid for laboratory use under ideal conditions.

    更新日期:2019-10-25
  • Reuse of the alginate extraction waste from Sargassum filipendula for Ni(II) biosorption
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-01-25
    Bárbara Paulino Moino, Camila Stefanne Dias Costa, Meuris Gurgel Carlos da Silva, Melissa Gurgel Adeodato Vieira

    This study was developed based on the possibility of reusing and valuing the alginate extraction residue (RES) from the algae Sargassum filipendula. The adsorptive properties of RES were explored through kinetic and equilibrium assays in batch mode, in which the kinetic equilibrium time (200 min) was not influenced by the increase of the initial concentration of Ni solutions and the sorption process was favored by the temperature increase. The modeling revealed the simultaneous occurrence of physical and chemical interactions with the external diffusion as the predominant step. The Langmuir model was more representative for the equilibrium results, with an uptake capacity comparable to that of other biomaterials. The thermodynamic study indicated a spontaneous, favorable, and endothermic process, besides the presence of the ion exchange. The isoelectric point was found at pH 5.3, and the pore size distribution allowed the classification of RES as macroporous. The simplified bath sorption design revealed that the required mass of RES become greater for higher quality degrees. However, it is tenable to consider this process viable due to the easy access to the algae biomass and the large amount of the solid waste generated from the alginate extraction (∼50%), termed as residue (RES).

    更新日期:2019-10-25
  • Optimization of the solid-state fermentation conditions and characterization of xylanase produced by Penicillium roqueforti ATCC 10110 using yellow mombin residue (Spondias mombin L.)
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-11
    José Lucas de Almeida Antunes Ferraz, Lucas Oliveira Souza, André Gustavo de Araújo Fernandes, Marcio Luiz Ferreira Oliveira, Julieta Rangel de Oliveira, Marcelo Franco

    Yellow mombin residue was investigated as a substrate for the production of xylanase by Penicillium roqueforti ATCC 10110 in solid-state fermentation. The parameters incubation temperature, initial moisture, and fermentation time were optimized using the Box–Behnken design, with a maximum yield of 14.03 IU g−1 at 25.55 °C, 60.55% moisture and 141.80 h, respectively. The xylanases produced showed higher activity and stability in pH in the range of 3–5 and temperature ≤ 60 °C. The respective Km and VMax values found were 1.96 mg mL−1 and 16.23 μmol min−1 mL−1. The addition of the Mn2+, Al3+, Zn2+, Na+, Ca2+ and Trolox and Triton X-100 compounds increased xylanase activity, whereas Mg2+, Pb2+, Cu2+ and SDS species behaved as inhibitors. Freezing at −20 or 4 °C maintained more than 94% of the enzymatic activity after 120 days of storage. Solid-state fermentation in yellow mombin residue, without any additives, using P. roqueforti ATCC 10110 allowed the acquisition of xylanases with characteristics similar to those obtained from processes using synthetic substrates, indicating a promising alternative for the xylanase obtaining.

    更新日期:2019-10-25
  • Enzymatic fatty acid ethyl esters synthesis using acid soybean oil and liquid lipase formulation
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-20
    Kelly Cristina Nascimento Rodrigues Pedro, Igor Estolano Pinto Ferreira, Cristiane Assumpção Henriques, Marta Antunes Pereira Langone

    Acid oils represent a low-cost feedstock for biodiesel synthesis. The aim of this work was to study a single-step enzymatic esterification and transesterification process for fatty acid ethyl esters (FAEEs) production employing acid oils, ethanol, and liquid lipase formulation. The effects of lipase source (CALB, Palatase 20000 L, Lipolase 100 L, and Callera Trans L), temperature and enzyme ratio were studied in the transesterification of refined soybean oil with ethanol. The highest yield esters content (97%) was obtained at 30 °C with 10% vol/vol of Lipolase 100 L. The ethanolysis of acid soybean oil, using soybean oils with different acid contents (acid value (AV): 8.5, 50, and 90), was investigated using 10% vol/vol of lipase at 30 °C. The highest esters content (71%) was obtained employing acid oil with AV 50 and Palatase 20,000 L. The results showed the significant performance of soluble lipases in transesterification reactions of acid oils aiming for FAEEs synthesis.

    更新日期:2019-10-25
  • Liquid–liquid separation of zirconium and hafnium from nitric liquor in order to obtain nuclear zirconium oxide using TBP as extractant
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-03-23
    Janúbia C. B. S. Amaral, Adalberto L. Souza, Carlos A. Morais

    A specific process to obtain nuclear grade zirconium oxide from a nitric acid liquor is described in this work. The liquor was obtained after alkali fusion and water leaching of a zircon concentrate. The production of nuclear zirconium oxide is possible when tributyl phosphate (TBP) is used as extractant with a high acidity nitric liquor. This study comprises steps: (i) batch experiments in order to select the best conditions for the process and (ii) continuous experiments carried out in counter current mixer-settler circuits. The batch experiments indicated that an increase in nitrate concentration did not correspond to a rise in the separation factor among Zr and Hf. Acidity has a significant influence on the Zr/Hf separation. For the organic phase containing 2.5 mol L−1 of TBP and an aqueous/organic ratio of the 1/1, 94% of the Zr was extracted and a separation factor of the 13.8 was obtained in one contact of the aqueous and organic phase. In the optimized continuous circuit, a product containing 99% of Zr and 0.03% of Hf (200 mg kg−1), which meets the nuclear zirconium specifications, was obtained.

    更新日期:2019-10-25
  • Voltage–current characteristics of high-density polyethylene conductive composites
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-21
    Ji-Zhao Liang

    The high-density polyethylene (HDPE) conductive composites filled separately with carbon fibers (CFs), ethylene-vinyl acetate copolymer (EVA), and three kinds of carbon blacks (CBs) (including different diameter, BET specific area, and DBP value) were prepared, to investigate the influence of the property, size, and content of the conductive fillers on the nonlinear voltage–current characteristics of the HDPE conductive composites. The results showed that the relationship between the electric current density and the electric field intensity of the three HDPE/CB composites including the HDPE/CF composites, the HDPE/CB/CF composites, and the HDPE/EVA/CB composites was nonlinear. The nonlinear conductivity index of the HDPE/CF composites was kept a low level comparing to the HDPE/CB composites, the HDPE/CB/CF composites, and the HDPE/EVA/CB composites. Moreover, the nonlinear conductive behavior mechanisms were discussed.

    更新日期:2019-10-25
  • Dynamic optimization for the enzymatic production of acylglycerols
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-13
    Laís Koop, Lorena I. Soares, Fernando Augusto Pedersen Voll, Adrian Bonilla-Petriciolet, Marcos Lúcio Corazza

    Optimal control of substrate feed rate in glycerolysis of vegetable oils was studied as a tool to improve monoacylglycerols (MAG) and diacylglycerols (DAG) production. Stochastic optimization strategy (Differential Evolutionary algorithm) was used to deal with the high complexity of the enzyme-catalyzed reactions dynamic behavior. Depending on the reaction system, optimal control of glycerol feed rate into the reaction showed to avoid enzymatic inhibition by the glycerol and improve acylglycerols yields up to 50% when compared to batch system. The obtained results showed that optimal control strategy can be used as an efficient tool to maximize the amount of desired product obtained by enzyme-catalyzed glycerolysis, particularly when the biocatalyst activity is significantly affected by substrate concentration.

    更新日期:2019-10-25
  • Simulation studies on homogenously catalyzed finishing reactive distillation for ethyl acetate production
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-20
    Damandeep Singh, Raj Kumar Gupta, Vineet Kumar

    A finishing reactive distillation (RD) column (50 stage), used for enhanced ethanol conversion, in an ethyl acetate production plant was simulated. This RD column followed a pre-reactor, wherein, homogeneously catalyzed esterification reaction for the production of ethyl acetate using acetic acid and ethanol was carried out. The simulation results of the RD column using equilibrium and rate-based models are compared with the plant data. The column design data for tray holdup, required for the rate-based model, was used. Effects of some design and operation parameters of the simulation results are also discussed.

    更新日期:2019-10-25
  • Recent developments in purification techniques and industrial applications for whey valorization: A review
    Chem. Eng. Commun. (IF 1.431) Pub Date : 2019-02-07
    Navpreet Kaur, Poorva Sharma, Seema Jaimni, Bababode Adesegun Kehinde, Shubhneet Kaur

    Whey is considered as a by-product of dairy industries and commonly regarded as waste. Despite being a good source of nutrients (lactose, minerals, and bioactive peptides), it is commonly discarded as effluent. Innovative techniques such as membrane filtration, chromatography (affinity and ion exchange), chemical treatments, and/or combination of these are used for the extraction of these constituents. The presence of these components in whey makes it functional in food and pharmaceutical industries. This article is aimed at supplementing recent information to available literature about different novel techniques used for the separation of whey constituents and their industrial application. In future, information reviewed will be helpful for the processors to select the best technique for the separation of individual constituents for the attainment of maximum yield and purity.

    更新日期:2019-10-25
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