Dehydration Rate Research Articles

An Experimental Study on Efficient Demulsification for Produced Emulsion in Alkaline/Surfactant/Polymer Flooding

Abstract Tertiary oil recovery technologies, for example, alkaline/surfactant/polymer (ASP) flooding, can enhance oil recovery as an important oil displacement technology noteworthy in the present oilfields. However, it is the fact that the produced emulsion droplets have strong electronegativity, which will lead to the destabilization of electric field and affect the dehydration effect in the process of electric dehydration. This article innovatively proposed an efficient demulsification scheme, which uses polyaluminum chloride (PAC) as a chemical regulator to control electric field destabilization through the charge neutralization mechanism and then introduces demulsifier to promote oil–water separation. Furthermore, the dehydration temperature, power supply mode, and electric field parameters are optimized so as to achieve superior dehydration effect of ASP flooding produced liquid. The results indicate that PAC as a chemical regulator by exerting charge neutralization and electrostatic adsorption mechanism could reduce the electronegativity of the emulsified system, decrease the peak current of dehydration, shorten the duration of peak current of dehydration, improve the response performance of the electric field, and increase dehydration rate in the ASP flooding dehydration process. When the demulsifier dosage is 100–120 mg/l, using the composite separation process with the dehydration temperature of 45–50 °C for the thermochemical separation stage and 60 °C in the electrochemical dehydration stage and AC–DC composite electric field or pulse electric field can achieve better dehydration effect. The investigations in this study will provide support and basis for the efficient treatment of ASP flooding produced emulsion.

冬小麦-夏玉米轮作“双晚”种植模式下的品种匹配与资源效率

<p id="C3">It is of great significance that exploring the characteristics of wheat-maize varieties combination suitable for stress resistance, high yield, and stable yield under the “double delay” system and their matching properties with natural resources, for ensuring the high yield and high efficiency production of winter wheat and summer maize in this region. In this study, field experiments were conducted from 2017 to 2019. Eight winter wheat and eight summer maize varieties were the main varieties in the North China Plain under winter wheat-summer maize “double delay” system with different irrigation treatments. Based on the analysis and evaluation of water use efficiency, grain filling characteristics, growth process, annual light, temperature, and water use efficiency, etc., the characteristics of wheat-maize varieties combination and resource use efficiency under the “double delay” system of winter wheat and summer maize were explored. The results suggested that among the tested wheat varieties, the yields of Jimai 325, Shimai 15, Nongda 3486, and Jimai 22 under conventional water-saving irrigation and rain-fed mode were higher than the average yield of the tested varieties druing the two growing seasons. In addition, the drought resistance index of Jimai 325 and Shimai 15 were higher than that of Jimai 22. Meanwhile, the grain-filling rate, grain number per spike, grain weight, and high stability coefficients of Jimai 22, Jimai 325, and Shimai 15 were higher than the mean of the tested varieties under different irrigation modes. Among the tested maize variaties, the yield and high stability coefficients of Denghai 605, Weike 702, MC670, and Nonghua 816 were all higher than the means of the tested varieties. The grain-filling rate of MC670, Denghai 605, and Xianyu 335 were higher than the means of the tested varieties during the two growing seasons. While, Dika 517 and Xianyu 335 had the lowest grain water content at harvest stage but the highest average dehydration rate among the tested varieties. Based on the comprehensive analysis of the yield and yield stability, drought resistance, grain-filling properties, and dehydration characteristics, the variety combination of Jimai 325-MC670 was selected with the highest annual yield and resource use efficiency. Compared with the local control combination of Jimai 22-Zhengdan 958, the annual yield increased by 17.2% and 17.9%, the light, temperature and irrigation water use efficiency increased by 18.6% and 20.0%, 18.1% and 18.9%, 17.4% and 18.1%, and increased economic benefit 8800 Yuan hm ^-2 and 9600 Yuan hm ^-2, respectively; to fit the whole-process mechanized management mode of wheat-maize double cropping system, maize could use varieties with fast dehydration rate and low grain water content when harvest, such as Dika 517 or Xianyu 335. Compared with the current local combination of Jimai 22-Zhengdan 958, this combination could increase the annual yield by 4.7% and 14.4%, and increase the light, temperature, and irrigation water use efficiency by 5.6% and 16.3%, 4.7% and 15.4%, 5.0% and 14.6%, and increased economic benefit by 2080 Yuan hm ^-2 and 7080 Yuan hm ^-2, respectively. In summary, optimizing the wheat-maize variety combination under the “double delay” cropping system can further improve the annual yield and resource use efficiency synergistically compared with the local staple wheat-maize variety combination.

Spatio-Temporal Variation of Elemental Contamination and Health of Mya arenaria Clam in the Saguenay–St. Lawrence Marine Park

The impacts of pollution and long-term effects of local clam populations are misunderstood in estuaries. The purpose of this study was to follow inorganic contamination in tissues, changes of physiological health indicators, such as condition factor (CF), growth index (GI), resistance in air emersion and dehydration rate, for 5 years in Mya arenaria clams. The sampling scheme comprised one reference site, two sites impacted by human activity (thereafter polluted) and one site recognized as a Saint-Lawrence Estuary (SLE) beluga whale feeding area without known pollution source (Baie Sainte-Marguerite (BSM)). This study revealed that the elemental contamination profiles in clams were increased but differed between the polluted and BSM compared to the reference site. At polluted sites, clams were contaminated by Ag (2.4-fold of reference site), Mn (2.5-fold) and V (6.3-fold). With respect to BSM, clams were mainly contaminated by Ce (2.5-fold), Co (2-fold), Ga (2-fold), La (2.8-fold), Hg (2.5-fold), Ni (2.2-fold), Sm (2-fold) and V (20-fold). This contamination profile suggests sources of pollution from particulate combustion products of gasoline/diesel, crude oil and urban inputs of pollution. The CF, GI and air survival time were all reduced in clams at the polluted sites, while only the CF and dehydration rates were decreased and increased, respectively, at BSM. Long-term analysis revealed that CF and GI tended to decrease over time with episodes of strong amplitude changes and became more resilient to air survival time. In conclusion, the long-term contamination of clams towards metals and elements could compromise the health status of local clam populations. The increased contamination of clams at BSM could represent a risk to the endangered SLE beluga whale population.

Dehydration rate of the glycine‐MgSO4·5H2O complex and the stability of glycine expelled from the complex by in situ Raman spectroscopy under Mars‐relevant conditions

AbstractIn this work, we studied the dehydration process of the glycine‐MgSO4·5H2O complex under Mars‐relevant conditions (99% CO2 and 0.6% H2O under ultra violet (UV) irradiation exposure at 7‐mbar pressure and high vacuum conditions: 8 × 10−5 and 5 × 10−5 mbar) by in situ Raman spectroscopy inside a planetary atmosphere and surface chamber (PASC). This work provides quality Raman spectra taken under simulated planetary conditions (to be integrated in a database), as Raman spectroscopy forms part of the current and upcoming NASA and ESA Mars planetary missions. The results demonstrate that Raman spectroscopy can be used to calculate rates of dehydration of the glycine‐MgSO4·5H2O compound to study the chemical stability with respect to photodecomposition (1) of metal‐bound glycine molecules forming the complex and (2) glycine expelled from the complex, both under Mars‐simulated conditions; finally, Raman spectroscopy can also be used to quantify intermolecular interactions in terms of local pressures. Importantly, advanced detection of water molecules as part of a complex with astrobiological interest under planetary conditions plays a crucial role in planetary missions.

Simulation of air/vacuum desiccation process for high‐quality preservation of proteins

AbstractTo achieve high‐quality preservation of biopharmaceuticals in dried state which are originally solved in solutions including protective agents, the dried biopharmaceuticals are expected to be in a vitrified state through a simple and low‐cost drying process at room temperature. In this work, we calculated the drying process (water evaporation) of solution including protective agents, trehalose, to predict the probabilities of crystallization and bubble generation in one dimensional (1D) system. From past research, we know that proteins can be preserved in a good state when the mass ratio of TRE/protein is several hundreds. Thus, the interaction between proteins and water/TRE system are neglected because the same mass ratio of TRE/protein was used in this work. Water transportation in both preservative solution and surrounding ambient gas during desiccation process was calculated using the super‐saturated water diffusion coefficient which was previously measured by authors group. The water molarity distribution as well as the amount of retained water were obtained both for the vacuum desiccation processes, and the results were compared with the experimental results. The probabilities of dihydrate and bubble nucleation in trehalose solution during the desiccation were predicted based on the classical nucleation theory. The calculated results of the water molarity distribution and the probabilities of crystallization and bubble nucleation agree well with the experimental results, which suggests that the proposed evaporation model may help to find an ideal desiccation process of preservative solution.Practical ApplicationsDrying is a conventional technology for stabilizing the pharmaceutics and foods. The preservative solution including biomaterials is expected to be vitrified uniformly to preserve their function. Freeze‐drying is widely used to remove the water without deteriorating the materials. However, the freeze‐drying has several drawbacks, including the long drying process and the high cost. Thus, considering the disadvantage of the freeze‐drying, a simple high quality vacuum desiccation at room temperature is an ideal technique. Vacuum desiccation utilizes the application of low pressure to enhance the rate of dehydration, and it does not require the solution to be spread in an open environment. Thus, concerning these advantages, vacuum desiccation at room temperature may lead to improve the quality of desiccated biomaterials.

Production aspects of hay of tropical pasture of

Context Tropical pasture have been little explored for haymaking, due to lack of information regarding loss of nutrients and of forage dehydration. Aims This study aimed to evaluate the production aspects of tropical pasture hays. Methods To characterise forage dry mass yield and dehydration rate, we studied the grasses Marandú, Xaraés, Massai, Paredão, Planaltina and Tupã. The water soluble carbohydrates concentration curve, chemical composition and in situ rumen degradability of dry mass, crude protein and neutral detergent fibre were also determined. Key results The highest forage dry mass yield was observed in 2018, when Planaltina and Paredão performed best (6.28 and 5.26 ± 0.41 t of dry matter ha−1, respectively). There was no genotype × dehydration time interaction (P = 0.81) on water soluble carbohydrates. Exposure to sun resulted in a linear decreasing effect (P &lt; 0.01) on water soluble carbohydrates content, with loss of 5.03 g kg−1 for each hour of exposure to the sun during the haymaking process. There was an interaction effect (P &lt; 0.01) between type of material and genotype on the content of dry matter, mineral matter, crude protein and neutral detergent fibre (P &lt; 0.01). In situ degradability of Massai grass dry mass was higher for the hay (758.0 and 253.8 ± 7.9 g kg−1 for hay and in natura material, respectively). Conclusions and implications The greater amount of leaves in relation to stem indicates that Massai grass is more efficient in dehydration during the first hours of exposure to the sun, as well as sustaining lower losses.

Effect of Microwave Vacuum Drying on the Drying Characteristics and Chemical Compositions of Turkish Gall Residues

Recently, the secondary use of waste has received increasing attention. The raw material of Xipayi mouth rinse is Turkish gall. During the industrial production of Xipayi mouth rinse, a lot of gall residues are produced. If these drugs are directly discarded, it will cause waste of resources and also bring pressure to the ecological environment. Previous studies have found that the active ingredient content of Turkish gall residues remains high, therefore the residues are still a valuable resource for exploitation. This study aimed to evaluate the effect of the chemical compositions and drying characteristics of Turkish gall residues during microwave vacuum drying (MVD). Different vacuum degrees, sample loads and sample sizes were used to investigate the drying characteristics of Turkish gall residues, and a kinetics model was established to describe the drying characteristics. We determined gallic acid (GA), methyl gallate (MG) and ellagic acid (EA) contents, total phenolic content (TPC) and total sugar content (TSC) of dried Turkish gall residue powder and investigated the influence of different MVD conditions on components. The results showed the good fit of the Page model equation in describing the drying kinetics of Turkish gall residues during MVD. Different conditions of MVD have different effects on the main components of residue. Thus, MVD can be used to desiccate Turkish gall residues. The Page kinetics model predicts the changes in dehydration rate during MVD of Turkish gall residues, providing a proven drying method for gall residues, and provides a theoretical basis for the industrial mass production of pharmaceutical residues.

Developing a new heat strain evaluation index to classify and predict human thermal risk in hot and humid environments

• The effect of water-salt metabolism was considered in heat strain evaluation. • A heat strain evaluation index incorporating the dehydration rate was proposed. • Human thermal risk in hot and humid environments was classified into five levels. • A prediction model of human thermal risk in hot and humid environments was built. Hot and humid environments (HAHEs) can jeopardize the health and safety of humans. Accurately evaluating and predicting heat strain contribute to reducing the human thermal risk (HTR). Nevertheless, the traditional evaluation indexes ignore the importance of water-salt metabolism system in resisting heat, and the sweating rate cannot fully reflect heat strain. Furthermore, extant methods of classification and prediction of HTR have defects in objectivity, accuracy, and practicability. To fill these gaps, an experimental study with 24 conditions and 120 person-times was conducted in a climate chamber. During the experiment, the subjects’ oral temperature, heart rate, and dehydration rate were recorded. Based on the experimental data, two principal components with explained variance of 92.773% were extracted by principal component analysis, and with the determination of weightings, a new evaluation index of heat strain in HAHEs was proposed. The HTR was further classified into five levels, from “no risk” to “extremely severe risk” using the K-means cluster. Moreover, a prediction model of the HTR in HAHEs with the goodness of fitting of 0.782 was established using the multiple linear regression, and the weightings of predictors were determined. The results of this study could provide a reference for safety and health at work.

The amphiphilic nanostructure of ionic liquids affects the dehydration of alcohols.

The effect of the amphiphilic nanostructure of ionic liquids on the dehydration of secondary alcohols to alkenes has been investigated. The influence of these nanostructures was inverted when an acid catalyst was added to the reaction. This phenomenon was ascribed to a balance between ion-solute interactions and the formation of solute-catalyst hydrogen bonds, highlighting the complex interplay between interactions and reaction outcomes in these nanostructured solvent systems.

Pectin self-assembly and its disruption by water: insights into plant cell wall mechanics.

Plant cell walls undergo multiple cycles of dehydration and rehydration during their life. Calcium crosslinked low methoxy pectin is a major constituent of plant cell walls. Understanding the dehydration-rehydration behavior of pectin gels may shed light on the water transport and mechanics of plant cells. In this work, we report the contributions of the microstructure to the mechanics of pectin-Ca gels subjected to different extents of dehydration and subsequent rehydration. This is investigated using a pectin gel composition that forms 'egg-box bundles', a characteristic feature of the microstructure of low methoxy pectin-Ca gels. Large amplitude oscillatory shear (LAOS) rheology along with small angle neutron scattering and near infrared (NIR) spectroscopy on pectin gels is used to elucidate the mechanical and microstructural changes during dehydration-rehydration cycles. As the extent of dehydration increases, the reswelling ability, strain-stiffening behavior and yield strain decrease. These effects are more prominent at faster rates of dehydration and are not completely reversible upon rehydration to the initial undried state. Microstructural changes due to the aggregation of egg-box bundles and single chains and the associated changes in the water configurations lead to these irreversible changes.

Acute effects of a typical rhythmic gymnastic training session on physiological parameters in Olympic athletes

The aim of this study was to evaluate the effects of a day with two separate training sessions (morning and afternoon) of rhythmic gymnastics on erythrocytes, leukocytes, muscle damage, oxidative stress, and hydration of Brazilian team [age 17.7 (±1.1) years; body height 165 (±0.5) cm; body mass 49.7 (±4.2) kg]. Heart rate and session-ratings of perceived exertion were used to monitor training intensity. Blood samples were collected immediately before (M1) and after (M2) the training day for analyzing erythrocytes, leukocytes, plasma creatine kinase activity, lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, ferric reducing ability plasma, thyroid-stimulating hormone, and free T4. Saliva was collected for cortisol analysis. After 24 hours rest (M3), blood collection was performed to analyze creatine kinase and lactate dehydrogenase. The moderate-intensity training day induced significant elevations of total leukocytes (5,163.3 to 9,617.8), lymphocytes (1,752.7 to 2,729.7), neutrophils (2,873.9 to 6,163.6), monocytes (255.7 to 519.1), platelets (280,000.0 to 300,666.7), aspartate aminotransferase (13.1 to 25.6), lactate dehydrogenase (102.5 to 249.1), thyroid-stimulating hormone (1.0 to 3.2), and ferric reducing ability plasma (136.8 to 165.4), as well as significant reductions in red cells (4,691,111.1 to 4,497,777.8), hematocrit (42.1 to 39.3), and hemoglobin (12.9 to 12.5) at M2. There were also significant increases in creatine kinase (144.2 to 519.3) and lactate dehydrogenase (102.5 to 538.2) at M3. The average dehydration rate was 1.3%. A moderate-intensity day of training in rhythmic gymnastics of 8h21min duration caused hemolysis, leukocytosis, muscle damage, redox status perturbations, and insufficient hydration status. These findings show that athletes are exposed to physiological vulnerabilities that can possibly harm their performance and health.

Study on the splitting by hot-air drying of Camellia oleifera fruit

Abstract In order to explore the feasibility of hot air splitting of Camellia oleifera fruit, the effect of hot air temperature on peel splitting, the moisture state and moisture migration in peel, the peel microstructure and the seed color were studied. The results showed that higher hot air temperature could accelerate the splitting rate, the optimum temperature for splitting C. oleifera fruit was 90–110 °C considering the seed quality. Page model was the most suitable for describing the drying kinetic characteristics of C. oleifera fruit. Nuclear magnetic resonance (NMR) revealed the changing of the dehydration rate, the migration rate of bound water, immobilized water and free water in peel during hot air drying. The expansion of micro-channels in peel was conducive to moisture migration in the early splitting stage, but microstructure damaged in the late splitting stage accompanied by loose disorder of micro pores, serious shrinkage and deformation of peel.

Quantifying Effects of Active Site Proximity on Rates of Methanol Dehydration to Dimethyl Ether over Chabazite Zeolites through Microkinetic Modeling.

Control of the spatial proximity of Brønsted acid sites within the zeolite framework can result in materials with properties that are distinct from materials synthesized through conventional crystallization methods or available from commercial sources. Recent experimental evidence has shown that turnover rates of different acid-catalyzed reactions increase with the fraction of proximal sites in chabazite (CHA) zeolites. The catalytic conversion of oxygenates is an important research area, and the dehydration of methanol to dimethyl ether (DME) is a well-studied reaction as part of methanol-to-olefin chemistry catalyzed by solid acids. Published experimental data have shown that DME formation rates (per acid site) increase systematically with the fraction of proximal acid sites in the six-membered ring of CHA. Here, we probe the effect of acid site proximity in CHA on methanol dehydration rates using electronic structure calculations and microkinetic modeling to identify the primary causes of this chemistry and their relationship to the local structure of the catalyst at the nanoscale. We report a density functional theory-parametrized microkinetic model of methanol dehydration to DME, catalyzed by acidic CHA zeolite with direct comparison to experimental data. Effects of proximal acid sites on reaction rates were captured quantitatively for a range of operating conditions and catalyst compositions, with a focus on total paired acid site concentration and reactant clustering to form higher nuclearity complexes. Next-nearest neighbor paired acid sites were identified as promoting the formation of methanol trimer clusters rather than the inhibiting tetramer or pentamer clusters, resulting in large increases in the rate for DME production due to the lower energy barriers present in the concerted methanol trimer reaction pathway. The model framework developed in this study can be extended to other zeolite materials and reaction chemistries toward the goal of rational design and development of next-generation catalytic materials and chemical processes.

Formation of texture quality of raspberry snack under microwave puffing.

Raspberry snack, as a novel berry product, has rich favor and high crisp taste, where controllable texture quality is conducive to the palatability of the snack. Determinative factors of microwave puffing in microwave intensity and duration and key property of material in Young's modulus were introduced to investigate the formation of texture quality of berry snack under microwave puffing. The results indicate that the microwave intensity has negative correlation with Young's modulus of raspberry chips, which causes the more porosity inside under microwave puffing. Reasonable Young's modulus of raspberry chips enhances the interior porosity and exterior expansion volume of raspberry snack due to the water vapor wrapped other than escaped. The greater microwave intensity results in the higher volume expansion of raspberry chips, in which the great volume expansion from porous pores structure confers moderate hardness. In microwave puffing, the formation of hardness and crispness of raspberry snack depend on microwave puffing parameters, leading to high temperature and great dehydration rate in quick puffing duration, in addition to Young's modulus of raspberry chips, where high dehydration rate accelerates water removal inside raspberry chips to form a harder texture with decreasing springiness, whereas low dehydration rate leads to the gentle change of springiness. Raspberry snack with uniform internal pores and regular shape forming desirable texture may be achieved under the microwave intensity of 7.5 W/g and the puffing duration of 6 min. This study indicates that high-quality raspberry snack may be achieved via controlling heating rate in microwave puffing.

Pre-dehydration treatments and quality of processed potatoes during storage

ABSTRACT The aim of this work was to study pre-dehydration treatments to maintain consumption quality of processed potatoes (Solanum tuberosum) over a long storage period. Tubers of the cultivars Asterix, Macaca and Agata were cut into cubes and submitted to the following pre-dehydration treatments: water (control), blanching, and blanching with different doses of sodium metabisulfite. Sulphur dioxide residue and microorganism detection were determined right after the dehydration process was completed. Water activity, color, rehydration ratio, cooking time and rehydration ratio after cooking were determined at the beginning and after one and two years of storage. Blanching, cultivar and storage affected rehydration ratio, an important parameter used to measure the quality of dehydrated products. Tubers with higher dry mass content resulted in lower water activity and rehydration ratio, longer cooking time and higher rehydration ratio after cooking than those with lower dry mass. The combination of blanching with sodium metabisulfite improves product quality, reduces microbial load, enhances dehydration rate and prevents oxidation and browning reactions during processing and storage. The effects of the structural damages of pre-dehydration and dehydration treatments on the rehydration ratio and the rehydration ratio after cooking increase with storage of processed potatoes.

Impact of the Local Concentration of Hydronium Ions at Tungstate Surfaces for Acid-Catalyzed Alcohol Dehydration.

Tungstate domains supported on ZrO2, Al2O3, TiO2, and activated carbon drastically influence the hydronium-ion-catalyzed aqueous-phase dehydration of alcohols. For all catalysts, the rate of cyclohexanol dehydration normalized to the concentration of Brønsted acid sites (turnover frequencies, TOFs) was lower for monotungstates than for polytungstates and larger crystallites of WO3. TOFs were constant when reaching or exceeding the monolayer coverage of tungstate, irrespective of the specific nature of surface structures that continuously evolve with the surface W loading. However, the TOFs with polytungstates and large WO3 crystallites depend strongly on the underlying support (e.g., WOx/C catalysts are 10-50-fold more active than WOx/Al2O3 catalysts). The electrical double layer (EDL) surrounding the negatively charged WOx domains contains hydrated hydronium ions, whose local concentrations change with the support. This varying concentration of interfacial hydronium ions ("local ionic strength") impacts the excess chemical potential of the reacting alcohols and induces the marked differences in the TOFs. Primary H/D kinetic isotope effects (∼3), together with the substantially positive entropy of activation (111-195 J mol-1 K-1), indicate that C-H(D) bond cleavage is involved in the kinetically relevant step of an E1-type mechanistic sequence, regardless of the support identity. The remarkable support dependence of the catalytic activity observed here for the aqueous-phase dehydration of cycloalkanols likely applies to a broad set of hydronium-ion-catalyzed organic reactions sensitive to ionic strength.

Controlled Measurement Setup for Ultra-Wideband Dielectric Modeling of Muscle Tissue in 20-45 °C Temperature Range.

In order to design electromagnetic applicators for diagnostic and therapeutic applications, an adequate dielectric tissue model is required. In addition, tissue temperature will heavily influence the dielectric properties and the dielectric model should, thus, be extended to incorporate this temperature dependence. Thus, this work has a dual purpose. Given the influence of temperature, dehydration, and probe-to-tissue contact pressure on dielectric measurements, this work will initially present the first setup to actively control and monitor the temperature of the sample, the dehydration rate of the investigated sample, and the applied probe-to-tissue contact pressure. Secondly, this work measured the dielectric properties of porcine muscle in the 0.5–40 GHz frequency range for temperatures from 20 °C to 45 °C. Following measurements, a single-pole Cole–Cole model is presented, in which the five Cole–Cole parameters (, , , , and ) are given by a first order polynomial as function of tissue temperature. The dielectric model closely agrees with the limited dielectric models known in literature for muscle tissue at 37 °C, which makes it suited for the design of in vivo applicators. Furthermore, the dielectric data at 41–45 °C is of great importance for the design of hyperthermia applicators.

Microwave drying of foamed tomato pulp: Optimization and mass transfer modelling

The experiments were conducted to optimize different process parameters (microwave power, foam-mat thickness, and air temperature) based on physico-chemical properties (drying time, vitamin C, acidity, pH, and color difference) for foam mat drying of tomato pulp using microwaves. Egg albumin at 10% was incorporated as a foaming agent followed by 5 min of whipping to form a stable foam. The foam in different thicknesses (5, 10, and 15 mm) was dried in a modified microwave dryer at 480, 640, and 800 W power levels. The air temperature was varied between 40℃ and 50℃. Decrease in foam thickness and increase in microwave power levels and air temperature accelerated the rate of dehydration of the foam. Face-centered response surface methodology predicted 769.58 W power, 5 mm thickness, and 45.76℃ air temperature as the optimum values of process parameters. Besides, eight mass transfer models were fitted to the drying combinations. Practical applications Tomato powder is widely used ingredient and is produced widely throughout the world. Production of tomato powder using microwave foam mat drying is better in quality that conventional foam mat drying. The heating of foam with microwaves speeds up the drying process. This technology has the potential to be a fast and reliable method of drying at commercial level.

Rice-Husk-Ash-Based Geopolymer Coating: Fire-Retardant, Optimize Composition, Microstructural, Thermal and Element Characteristics Analysis.

Geopolymer using aluminosilicate sources, such as fly ash, metakaolin and blast furnace slag, possessed excellent fire-retardant properties. However, research on the fire-retardant properties and thermal properties of geopolymer coating using rice husk ash (RHA) is rather limited. Additionally, the approach adopted in past studies on geopolymer coating was the less efficient one-factor-at-a-time (OFAT). A better approach is to employ statistical analysis and a regression coefficient model (mathematical model) in understanding the optimum value and significant effect of factors on fire-retardant and thermal properties of the geopolymer coating. This study aims to elucidate the significance of rice husk ash/activated alkaline solution (RHA/AA) ratio and NaOH concentration on the fire-retardant and thermal properties of RHA-based geopolymer coating, determine the optimum composition and examine the microstructure and element characteristics of the RHA-based geopolymer coating. The factors chosen for this study were the RHA/AA ratio and the NaOH concentration. Rice husk was burnt at a temperature of approximately 600 °C for 24 h to produce RHA. The response surface methodology (RSM) was used to design the experiments and conduct the analyses. Fire-retardant tests and thermal and element characteristics analysis (TGA, XRD, DSC and CTE) were conducted. The microstructure of the geopolymer samples was investigated by using a scanning electron microscope (SEM). The results showed that the RHA/AA ratio had the strongest effect on the temperature at equilibrium (TAE) and time taken to reach 300 °C (TT300). For the optimization process using RSM, the optimum value for TAE and TT300 could be attained when the RHA/AA ratio and NaOH concentration were 0.30 and 6 M, respectively. SEM micrographs of good fire-resistance properties showed a glassy appearance, and the surface coating changed into a dense geopolymer gel covered with thin needles when fired. It showed high insulating capacity and low thermal expansion; it had minimal mismatch with the substrate, and the coating had no evidence of crack formation and had a low dehydration rate. Using RHA as an aluminosilicate source has proven to be a promising alternative. Using it as coating materials can potentially improve fire safety in the construction of residential and commercial buildings.

Intrinsic kinetics of the methanol dehydration to dimethyl ether over laboratory and commercial γ‐alumina: a comparative study

AbstractThe intrinsic kinetics of the methanol dehydration to dimethyl ether over the laboratory‐synthesized and commercial γ‐alumina is studied. A set of kinetic models admitting different mechanisms of the reaction is developed. The developed kinetic models, as well as the kinetic models of the methanol dehydration presented in the literature, are experimentally verified. It is shown that the kinetic model admitting Langmuir–Hinshelwood mechanism with associative methanol adsorption is the only model which describes intrinsic methanol dehydration rate over either laboratory or commercial γ‐alumina catalyst. The estimated activation energies are 121 and 128 kJ/mol, methanol adsorption heats are 45 and 70 kJ/mol, and methanol adsorption entropies are 72 and 131 J/(mol × K) for the laboratory and commercial samples, respectively. The laboratory‐synthesized γ‐alumina may be successfully used for modeling and scaling the process that utilizes the commercial γ‐alumina catalysts.