Effect of Pulsed Electric Field and Osmotic Dehydration Pretreatment on the Convective Drying of Carrot Tissue

The influence of pulsed electric field (PEF) and subsequent centrifugal osmotic dehydration (OD) on the convective drying behavior of carrot is investigated. The PEF was carried out at an intensity of E = 0.60 kV/cm and a treatment duration of t_PEF = 50 ms. The following centrifugal OD was performed in a sucrose solution of 65% (w/w) at 40°C for 0, 1, 2, or 4 h under 2400 × g. The drying was performed after the centrifugal OD for temperatures 40-60°C and at constant air rate (6 m³/h).

With the increase of OD duration the air drying time is reduced spectacularly. The dimensionless moisture ratio Xr = 0.1 is reached for PEF-untreated carrots after 370 min of air drying at 60°C in absence of centrifugal OD against 90 min of air drying after the 240 min of centrifugal OD. The PEF treatment reduces additionally the air drying time. The total time of dehydration operations can be shortened when OD time is optimized. For instance, the minimal time required to dehydrate untreated carrots until Xr = 0.1 is 260 min (120 min of OD at 40°C and 140 min of drying at 60°C). It is reduced to 230 min with PEF-treated carrots.

The moisture effective diffusivity D_eff is calculated for the convective air drying based on Fick's law. The centrifugal OD pretreatment increases drastically the value of D_eff. For instance, 4 h of centrifugal OD permitted increasing the value of D_eff from 0.93 · 10^-9 to 3.85 · 10^-9 m²/s for untreated carrots and from 1.17 · 10^-9 to 5.10 · 10^-9 m²/s for PEF-treated carrots.     

Effect of Pulsed Electric Field and Osmotic Dehydration Pretreatment on the Convective Drying of Carrot Tissue

The influence of pulsed electric field (PEF) and subsequent centrifugal osmotic dehydration (OD) on the convective drying behavior of carrot is investigated. The PEF was carried out at an intensity of E = 0.60 kV/cm and a treatment duration of t _PEF  = 50 ms. The following centrifugal OD was performed in a sucrose solution of 65% (w/w) at 40°C for 0, 1, 2, or 4 h under 2400 × g. The drying was performed after the centrifugal OD for temperatures 40–60°C and at constant air rate (6 m³/h).

With the increase of OD duration the air drying time is reduced spectacularly. The dimensionless moisture ratio Xr = 0.1 is reached for PEF-untreated carrots after 370 min of air drying at 60°C in absence of centrifugal OD against 90 min of air drying after the 240 min of centrifugal OD. The PEF treatment reduces additionally the air drying time. The total time of dehydration operations can be shortened when OD time is optimized. For instance, the minimal time required to dehydrate untreated carrots until Xr = 0.1 is 260 min (120 min of OD at 40°C and 140 min of drying at 60°C). It is reduced to 230 min with PEF-treated carrots.

The moisture effective diffusivity D _eff is calculated for the convective air drying based on Fick's law. The centrifugal OD pretreatment increases drastically the value of D _eff . For instance, 4 h of centrifugal OD permitted increasing the value of D _eff from 0.93 · 10^?9 to 3.85 · 10^?9 m²/s for untreated carrots and from 1.17 · 10^?9 to 5.10 · 10^?9 m²/s for PEF-treated carrots.     

Determination of thermodynamic interaction in mixed polymer solutions by a rapid and precise osmotic method. The system dextran/polyvinylpyrrolidone/water

An accurate and simple osmotic method for determination of thermodynamic interaction in ternary solutions (polymer A/polymer B/solvent) is described. The equipment consists of a membrane osmometer of a special design with small chambers and a pressure-sensing device to monitor the pressure difference across the membrane. A procedure has been developed to measure osmotic pressures up to rather high concentrations in both quasi-binary and quasi-ternary systems. The osmotic method is compared with results from light scattering. Different methods are utilized to extract ordinary virial coefficients as well as mixed virial coefficients from the primary data. The system dextran/polyvinylpyrrolidone/water (two different molecular weights of dextran) was chosen as a model.     

Mass transfer coefficient and the characteristics of coated apples in osmotic dehydrating

In a dynamic osmotic dehydration from 0 to 180 min, the influence of different edible coating materials such as Low-Methoxyl Pectinate (LMP), Carboxyl-Methyl Cellulose (CMC), Corn Starch, and an osmotic sucrose solution with two concentration of 50% and 60% (w/w) on apple rings and their physical characteristics were studied, which included: moisture loss (ML), solid gain (SG), ML/SG ratio, effective diffusivity of solute and water (D_es, D_ew). The qualitative characteristics such as: firmness of the texture or shear stress (SS), and Browning index (BI) were also tested. Using Fick's first and second laws, the effective diffusion coefficient of water and solute were calculated. Osmosed apples in solution with 60% sucrose concentration, showed higher ML/SG ratio than other samples and, apples coated with 2% CMC and osmodehydrated in 60% sucrose, showed not only higher ML/SG ratio but higher diffusivity coefficient as well. The results showed that in comparison with non-coated samples, coating process can cause to improve the textural structure of the apple rings. By increasing the concentration of osmotic solutions, the Browning index (BI) of both coated and uncoated samples decreased.     

Osmotic pretreatment for instant controlled pressure drop dried apple chips: Impact of the type of saccharides and treatment conditions

Instant controlled pressure drop (ICPD) is an emerging drying technique that can produce fruit chips with crispy texture. To improve the qualities of ICPD-dried apple chips, six types of saccharides with different polymerization were used for osmotic pretreatment on apple slices. Firstly, the effects of different saccharides on the osmotic behavior and texture of ICPD-dried apple chips were evaluated. Then, the effects of osmotic conditions of a selected saccharide, i.e. stachyose, on the qualities of ICPD-dried apple chips were studied. The results showed that sucrose, raffinose, and stachyose could significantly enhance the crispness of the ICPD-dried apple chips. In addition, the ICPD-dried apple chips pretreated with stachyose possessed the highest T_g (29.74?°C) and superior porous structure compared with pretreatments using the other saccharides. Moreover, limited color change (ΔE) was found in the samples pretreated with stachyose at 40?°C for 30?min, as well as higher retention of polyphenols. In conclusion, it is confirmed that the types of saccharides significantly influence the qualities of the ICPD-dried apple chips, and osmotic pretreatment at 40?°C for 30?min using stachyose was suggested for improving the overall quality of ICPD-dried apple chips.     

Investigations of the coupled effect of cake-enhanced osmotic pressure and colloidal fouling in RO using crossflow sampler-modified fouling index ultrafiltration

The aim of this study was to investigate the potential of using the resistivity and deposition rate data from Crossflow Sampler-Modified Fouling Index Ultrafiltration (CFS-MFI_UF) measurements to determine the coupled effects of colloidal fouling and cake enhanced osmotic pressure (CEOP) effect. Cake filtration derived from CFS-MFI_UF was combined with a CEOP model to predict the crossflow RO fouling profile under constant flux filtration. The prediction based on resistivity, I′ from CFS-MFI_UF measurement alone was found to underestimate the RO fouling for high salinity solutions. However, when incorporating the mass information from the CFS-MFI_UF test to account for the CEOP effect, the prediction showed good agreement with the TMP profile of the RO system. The results indicated that the CFS-MFI_UF test which includes the CEOP effect is a very promising technique to provide an estimation of the RO colloidal fouling profile. When the changes of cake thickness and porosity throughout the filtration were considered, the predicted TMP profile based on the model clearly indicated a two-stage of fouling profile which agreed well with the experimental data. Additional studies on the effects of cake thickness and porosity on CEOP highlighted the important influence of cake structure on CEOP.     

Fouling study of nanofiltration membranes for sugar control in grape must: Analysis of resistances and the role of osmotic pressure

Three membranes are analyzed attending to their retention, flux, and fouling when used to nanofiltrate sugars in red grape musts. In the presence of high molecular weight compounds, that is, when filtering must, fouling develops from initial pore blocking to final cake deposition. A decrease of resistance appears due to a decrease of the effective transmembrane pressure and cake compaction. The final effective pore size corresponds to that of the compacted cake. Attending to flux decay and sugar retention, two membranes, HL and SR3, are appropriate to reduce the content of sugar of red must. Specifically SR3 shows the best passage of sugar and less fouling.     

Dehydration modeling of Cordyceps militaris in mid-infrared-assisted convection drying system: Using low-field nuclear magnetic resonance with the aid of ELM and PLSR

Abstract

The changes in moisture content and shrinkage ratio of Cordyceps militaris during mid-infrared-assisted convection drying (MIRCD) with different drying temperatures (40, 50, and 60?°C) and velocities of airflow (1 and 2?ms^?1) were studied. The relationship between low-field nuclear magnetic resonance (LF-NMR) information and moisture content/shrinkage ratio was modeled using partial least-squares regression (PLSR) and extreme learning machine (ELM). Results indicated that the influence of drying temperature was more pronounced than that of air flow velocity. Both types of models showed good predictive ability with R²>0.90. The ELM models exhibited superior predictive performance than that of the PLSR models.     

Lyotropic liquid crystalline solutions of hydroxypropyl cellulose in water: Effect of salts on the turbidity and viscometric behavior

Effect of addition of salt on the viscometric behavior of the dilute or concentrated aqueous solution of hydroxypropyl cellulose (HPC) was determined by means of an Ubbelohde or a cone-plate viscometer. That effect on the turbidity of the dilute system was also determined. As salts, NaCl, LiCl, and thiourea were chosen. The turbidity and viscometric behavior for the dilute system, and the viscometric behavior for the concentrated system were greatly affected by salt type and concentration. With increasing NaCl or LiCl concentration, the cloud point decreased, [η] showed a maximum, Huggins' constant k′ showed a minimum, and the shear viscosity for concentrated isotropic solutions showed a maximum. The 45 wt % solution with no salt showed a viscometric behavior which was characteristic of lyotropic liquid crystals; however, with increasing NaCl concentration, a critical temperature at which the shear viscosity showed a maximum with respect to temperature shifted to lower temperature. This behavior was due to an increase in the turbidity, not due to a phase transformation. On the other hand, an addition of thiourea did not affect so greatly the turbidity and viscometric behavior as an addition of NaCl or LiCl did. We speculated different actions of NaCl and thiourea.     

Effect of pyridine and its derivatives on the electrodeposition of nickel from aqueous sulfate solutions. Part II: Polarization behaviour

The electrochemical reactions occurring during electrodeposition of nickel from acidic sulfate solutions were examined by cyclic and linear sweep voltammetry techniques. The effect of pyridine, 2-picoline and 4-picoline on the electrode polarization behaviour and electron transfer parameter of the cathodic reduction process was also investigated. Strongest electrode polarization was seen with 4-picoline. The order of cathodic polarization was 4-picoline > 2-picoline > pyridine. Kinetic parameters such as Tafel slope, transfer coefficient and exchange current density were determined to analyse the nature of the electrode reactions. The exchange current density for nickel deposition on nickel and stainless steel substrates was in the order 4-picoline < 2-picoline < pyridine.     

Acoustic damping flexible polyurethane foams: Effect of isocyanate index and water content on the soundproofing

High-efficiency sound absorbing flexible polyurethane foams (FPUFs) are manufactured using nonpolar polyester resin, methylene diphenyl diisocyanate, and other reagents by one-shot bulk polymerization. In this study, the impact of the isocyanate index (90, 100, and 110) and water content (2.5 and 5%) on the microphase separation and soundproofing behavior of FPUFs are examined using atomic force microscopy, Fourier transform infrared spectroscopy, optical microscope, and an impedance tube device. The results reveal that the increase of the isocyanate index and water content leads to the increase of the cell size, cell size distribution, open-cell content, cell wall roughness, and microphase separation. Also, maximum sound absorption coefficient (α) reaches to 0.98 and the average of α in the frequency range of 1500–4000 Hz increases from 0.7 to 0.87 by increasing the water content from 2.5 to 5% and isocyanate index from 90 to 110; therefore, acoustic damping performance enhances up to 26.24% due to the synergic effects of microphase separation on the viscose media formation, open-cell content, cell wall roughness, cell size, and cell size distribution. In conclusion, FPUFs with an optimal amount of microphase separation and drainage flow can be a promising candidate for sound insulating materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47363.     

Effect and mechanism of Fe2O3 decomposition in the preparation of foaming ceramics from industrial solid waste

MgO–Al₂O₃–SiO₂ foam ceramics were prepared by direct sintering of asbestos tailings and coal fly ash by spontaneous bubble process. By X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermodynamic analysis, the effect of Fe₂O₃ decomposition on the preparation of foaming ceramics from industrial solid waste and the pore-forming process was studied. The results show that the foaming effect of foaming ceramics with higher raw iron content is better when the roasting temperature is higher. Increasing the content of iron is beneficial to the formation of cordierite, and increasing the roasting temperature is beneficial to the relative content of spinel in foaming ceramics. Combined with the change in the Fe valence state, content in porous ceramic samples, and thermodynamic analysis of the product, it is found that Fe₂O₃ decomposition is the fundamental cause of ceramic foaming at high temperature. Fe²⁺ produced after decomposition replaces Mg²⁺ into spinel and cordierite structures, and the O₂ produced by decomposition cannot be discharged in time to cause ceramic foaming. The research results can provide theoretical basis for the preparation of industrial solid waste foamed ceramics.     

Effect of Pyridine and its Derivatives on the Electrodeposition of Nickel from Aqueous Sulfate solutions Part I: Current Efficiency, Surface Morphology and Crystal Orientation

The effects of pyridine and its derivatives on current efficiency, surface morphology and crystallographic orientations of electrodeposited nickel from acidic sulfate solutions were investigated. The results indicated that the presence of pyridine and picolines had no significant effect on current efficiency. The deposits obtained were smoother, more compact and uniform with picolines than with pyridine. A significant change in surface morphology of the electrodeposits was observed and picolines were found to be better additives than pyridine, 4-picoline being the best. X-ray diffraction revealed that the (200) plane was the most preferred plane and was not affected by the presence of any of these additives in the electrolyte.     

水中Ca2+和Mg2+对镜铁矿和绿泥石可浮性的影响机理

为研究水质对镜铁矿和绿泥石分离效果的影响,通过单矿物浮选实验、Zeta电位测量、玻尔兹曼理论分析、溶液化学计算和分子动力学模拟,分别在去离子水和自来水浮选环境中,研究了十二胺(DDA)体系中镜铁矿和绿泥石的浮选行为及Ca2+, Mg2+对镜铁矿和绿泥石浮选规律及作用机理。结果表明,自来水对镜铁矿和绿泥石有一定的抑制作用,与去离子水浮选环境相比,镜铁矿和绿泥石的回收率分别下降了8.01和8.99个百分点;模拟自来水环境中,Ca2+, Mg2+使镜铁矿回收率分别下降11.91和18.88个百分点,绿泥石回收率分别降低7.44和15.45个百分点。自来水浮选环境中镜铁矿和绿泥石可浮性降低主要由于自来水中Ca2+, Mg2+的抑制作用。Ca2+, Mg2+对镜铁矿的抑制作用比绿泥石强,且Mg2+的抑制效果比Ca2+明显。机理检测结果表明,Ca2+, Mg2+吸附使镜铁矿和绿泥石表面电位升高,减弱了DDA与矿物之间的静电吸附作用,促使镜铁矿和绿泥石接触角减小亲水性增大、界面层内RNH3+浓度降低,使DDA与镜铁矿和绿泥石的吸附间距增大,且DDA分子分布松散度增大,一定程度上抑制了镜铁矿和绿泥石的上浮。     

Effect of fluid velocity and temperature on the corrosion mechanism of low carbon steel in industrial water in the absence and presence of 2-hydrazino benzothiazole

This work was carried out to study the inhibition mechanism of volatile corrosion inhibitors (VCIs) such as 2-hydrazinobenzothiazole (2-HBTA) on the corrosion of low carbon steel in industrial water by using polarization and mass loss measurement. It was found that 2-HBTA revealed good performance as inhibitor for low carbon steel corrosion in industrial water. After some time, the performance decreased due to the volatility of these kinds of inhibitors away from the open system unlike the closed system. The experimental data indicated that the inhibitive performance of 2-HBTA for low carbon steel was improved with increasing of concentration up to the critical concentration (4.24×10⁻³M). The adsorption behavior of 2-HBTA was found to obey Langmuir’s adsorption isotherm. The thermodynamic parameters of adsorption process and activation energy were obtained from polarization technique. Scanning electron microscopy (SEM) was performed to characterize the film formed on the surface. Box-Wilson statistical method was employed to correlate the results obtained, and the optimization of fluid velocity, temperature and concentration of inhibitor by using Box-Wilson statistical method was evaluated.     

Waste water treatment using reverse osmosis: real osmotic pressure and chemical functionality as influencing parameters on the retention of carboxylic acids in multi-component systems

The influence of chemical functionality in carboxylic acids and osmotic pressure of multi-component solutions on the retention in the reverse osmosis process are discussed. Therefore formic-, acetic-, propionic-, glycolic-, acrylic- and methoxyacetic acid (target substances) were combined with one or two other carboxylic acids (active substances), chosen out of a pool of 16. All investigations were carried out with an aromatic polyamide membrane and the operating conditions were kept constant. Although the combination of all effects is extremely complex, the experiments showed that the influence on the retention of a substance equate as an outcome of molecular mass, acidity, functionality and spatial requirement. The influence of functionality in the active substances could be further divided into an additional carboxylic group, double bond and aromaticity. The calculation of the osmotic pressure demonstrated that there was no observable difference between the real and ideal one when the solution contained the same number of components. Therefore it can be concluded that in this study the osmotic pressure has no influence on the retention of the target substance.     

Nuclear magnetic relaxation of water in ionic‐liquid solutions: determining the kosmotropicity of ionic liquids and its relationship with the enzyme enantioselectivity

The nuclear magnetic relaxations of water in ionic‐liquid (IL) solutions were examined at various IL concentrations in order to better understand their hydration behaviors (in terms of nuclear magnetic resonance (NMR) B′‐coefficients). From these B′‐values of ILs, the individual ion's B′‐coefficients were further calculated based on the additivity. These coefficients represent the hydration behavior (‘kosmotropicity’) of ILs in aqueous solutions. Using these data, a linear correlation was found between enzyme enantioselectivity in aqueous solution and the δ′ parameter (difference in NMR B′‐coefficients of anion and cation). In general, high enzyme enantiomeric ratios (E) could be achieved in solutions of ILs with high δ′ values. Copyright © 2007 Society of Chemical Industry     

Valorization of Al slag in the production of green ceramic tiles: Effect of experimental conditions on microstructure and crystalline phase composition

This work reports the results of an investigation aimed at the development of sintered glass-ceramic tiles by the sinter-crystallization of mixtures composed of aluminum slag and reclaimed packaging glass. The thermal behaviors of mixtures incorporating 50 and 60 wt% Al slag were established by differential thermal analysis (DTA). Green compacts were sintered in a temperature range of 800°C-1050°C and then soaked for 10-60 minutes. The mineralogical characterizations of the sintered materials were obtained by X-ray diffraction (XRD). The achieved results indicated that the sintering of aluminum slag and packaging glass reclaimed led to a glass-ceramic material composed mainly of needle-like crystals of wollastonite (CaSiO₃). The bloating of samples during firing was evaluated according to a Cougny predictive diagram. After initial observations and according to bending strength characterizations, sintered tiles prepared from aluminum slag and glassy sand are appropriate for floor pavement and wall covering.