Simultaneous Dehydration Research Articles

Technological aspects of the development of thermal vacuum installation for drying grain with simultaneous dehydration and disinsection

The Ukraine is one of the largest producers of grain products. Its natural and climatic conditions are such that annually from 50 to 80 % of the harvested crop of grain crops is subject to drying and disinfection. Drying and simultaneous disinsection of grain are the main technological operations for removing harmful moisture from grain material and freeing it from barn pests, which on a national scale makes it possible to avoid millions of losses. The article provides materials on the development of a highly efficient environmentally friendly installation and energy-saving technology of dehydration with simultaneous disinfection of wet grain, which makes it possible to dry grain in a short period of time to a moisture content of 12...14 % and destroy pests. A brief review discusses the main drying units, which are of the convective type and mainly use heated air. Their main positive and negative aspects of use are analyzed. An experimental model of the developed highly efficient environmentally friendly grain drying plant with physical and mathematical justification is presented. Thus, at the same time, such indicators as the speed of grain swirling (υВ) at different temperatures, the value of the centrifugal force of the grain (F) moving in the cavity of the heating element through a spiral channel were calculated. The instantaneous process of thermal energy transfer from the heater wall to the wet grain is substantiated.Thus, the surface element (dS) of a wet grain receives a flow of thermal energy (dQ) with a temperature (Т) in a short period of time (∆τ) with a heat transfer coefficient (a). It has been experimentally proven that grain dehydration is affected by at least three parameters: the heating temperature, its humidity, and the pressure in the vacuum chamber. All parameters are interconnected and affect technological indicators. Thus, the use of thermovacuum technology is an alternative to traditional high-temperature methods of drying grain crops. Key words: thermovacuum dehydration of grain, drying, disinsection.

Simultaneous catalytic dehydration of methanol and ethanol: How ZSM-5 acidity addresses conversion and products distribution

The sustainable chemistry based on acid-catalysed alcohol conversion reaction is a promising route to contribute to the de-fossilization strategies completion. In this concern, C1 and C2 alcohols are both well recognised sources for the production of ethers and olefins from sustainable sources in acid catalysed dehydration reaction pathway. Most of the literature is devoted to the investigation of pure alcohols conversion, whilst the simultaneous dehydration of alcohol in mixture can broad the product panel (contributing to the enlargement of bio-alcohols based chemistry) also elucidating the role of acidity (type and distribution) on the reaction mechanism. This paper is the first contribution analysing the role of acid sites (amount and distribution) on the simultaneous methanol/ethanol dehydration using ZSM-5 zeolites. ZSM-5 materials with different aluminium content were synthesised and used in catalytic test. The obtained results showed how Lewis acid sites are less important when dealing with ethanol (also in mixture with methanol) and how the different methylated- ethylated species formation can affect the product composition and the coke amount and composition.

Simultaneous Dehydration of Glucose and Xylose Present in a Process-Relevant Biorefinery Hydrolysate to Furfurals Using Heterogeneous Solid Acid Catalysts

Simultaneous Dehydration of Glucose and Xylose Present in a Process-Relevant Biorefinery Hydrolysate to Furfurals Using Heterogeneous Solid Acid Catalysts

Thermal Conversion of Nanocrystalline Metal Hydroxide Salts to Metal Carbides, Pnictides, Chalcogenides, and Halides.

A general procedure for synthesizing various inorganic compounds in a similar manner is required in the field of material chemistry. The use of solid-state reactive agents with inorganic precursors is a successful approach in this direction. In this study, organic-inorganic hybrid metal hydroxide salts (MHSs) were utilized to synthesize various inorganic compounds by a simple heat treatment method because they can be assumed to be "premixed" inorganic precursors and solid-state reactive agents. Comparative studies revealed that the nanocrystalline characteristics and coordination of the carboxylate of the synthesized MHSs enabled simultaneous dehydration of hydroxides and decomposition of carboxylates and subsequent formation of metals and metal sulfides. Manganese, iron, cobalt, nickel, and zinc sulfides, as well as nickel carbides, pnictides, chalcogenides, and halides were obtained using the same procedure. We believe that using nanocrystalline organic-inorganic hybrid MHSs as both inorganic precursors and organic reactive agents will be a simple and versatile way to prepare a wide variety of inorganic complex compounds.

STUDY OF THE HEAT OF DEHYDRATION OF D–FRUCTOSE SOLUTION

The heat of evaporation of water is the main component of the consumption during the drying of bio raw materials. Its share in the consumption depends not only on the initial moisture content of the drying object. As our previous studies have shown, the state of water in the material affects the total heat consumption. The state of water is determined by its chemical composition and structure. Drying objects rich in sugars deserve special attention. Sugars have a high tendency to hydration, are concentrated in the juice and determine both the kinetics and heat of dehydration. The most reliable data on glucose and fructose hydration are analyzed and presented. Measurement of the specific heat of evaporation of water r from fructose solutions with an initial concentration of 12.5 wt. % was performed in the evaporation calorimeter. Continuous registration of changes in heat flows and mass of the sample was ensured during the measurement process. The dependence of the reduced specific heat of evaporation of water (R = r/rtab) on the concentration of fructose was obtained in the isothermal mode at 40, 60 and 80 °C. The presented curves reflect the thermal processes occurring in the solution during water removal. The processes are characterized by an endothermic period of dehydration and an exothermic period of simultaneous dehydration and spontaneous homogeneous crystallization of fructose. It was found that the change in the degree of hydration of fructose in solution from 12.5 to 5 mol/mol occurs with increasing, almost linear, specific heat consumption. Removal of water from the first coordination sphere, when the degree of hydration decreases to values <5, the increase in specific heat of evaporation is steeper and reaches the excess over the tabular values of heat of evaporation of pure water rtab by 6 – 7 %. The heat of spontaneous crystallization of fructose has a power greater than the power of endothermic heat consumption for dehydration, therefore, a general exothermic effect is recorded. It is shown that the measured specific heat of water evaporation increases with increasing concentration of solutions despite a decrease in the degree of hydration of fructose. It was established that water has a strong hydrogen bond with sugar in solutions in which the degree of hydration of fructose is less than ~5. Assumptions about strongly and weakly bound hydrated water in solutions of monosaccharides are substantiated.

A data compensation method for reducing impact of scalp dehydration in electrical impedance tomography

Electrical impedance tomography (EIT) has shown its potential in the monitoring of cerebral edema. It is found that scalp is also dehydrated when dehydration of brain tissue is conducted. Simultaneous dehydration of the brain tissue and scalp would greatly affect the image quality. To solve this problem, this work proposes a data compensation method which aims to reduce the influence of scalp dehydration on image reconstruction. Firstly, a rabbit head which is simulated by a three-layer elliptical model is established. The relationship between boundary measurement and dehydration degree in the case of simultaneous dehydration is investigated. Then a prior matrix representing variation of boundary voltage against degree of dehydration when only scalp is dehydrated is established. With the determination of dehydration degree and establishment of the prior information, it is able to reduce the impact of scalp dehydration on measured voltage data. To validate the performance of the proposed method, reconstruction of four different models when scalp and brain are simultaneously dehydrated is conducted. Image reconstruction is performed under noiseless condition and different noise level conditions. Also, reconstructed images under brain dehydration are given for comparison. The performance of the proposed method is also experimentally tested. The results show that the impact of scalp dehydration on image reconstruction can be effectively reduced with the proposed data compensation method. • A novel data compensation method and a simple L1 regularization method is proposed for accurate image reconstruction in EIT. • By analyzing boundary data measured from electrodes, dehydration degree is determined and a prior matrix is obtained. • In the case of simultaneous dehydration of scalp and brain, reconstruction quality is improved with the proposed method.

Biotechnology of families’ strength influence on the processes of sucrose inversion, dehydration and accumulation of monosaccharides

The purpose of the work is an experimental substantiation of biotechnological processes that ensure the maturation of honey during the processing of nectar by bees. During the whole period (7–9 days) of nectar treatment by bees there is a simultaneous partial dehydration of the liquid and biochemical transformations, among which the hydrolysis of sucrose and the accumulation of monosaccharides have the most significant effect on the quality of the mature product. In all series of experiments, the maturity of processed honey in the beehive at the water limit of less than 20 % occurs after 5–6 days of treatment by bees. The mature product in terms of water content remains open in almost completely filled cells for another 3–5 days, slightly reducing the water content from 19.78–20.07 % up to 16.40–18.38 %. Dynamic changes in the ratio of monosaccharides and sucrose in the process of nectar processing by bees, starting from the honey stomach during gathering from flowers to sealing in honeycomb cells have been detected. At the honey stomach-cell stage, a small amount of sucrose is hydrolyzed during the incomplete first day of processing and, as a rule, 0.48–4.11 % of monosaccharides calculated relative to the dry weight of the product are added. Sucrose inversion is more intense during the next 5–6 days, when a total of 12.94–31.42 % of splitted sugars are added, depending on their initial number and strength of families. The main processes of conversion of nectar into honey by bees are characterized by the advance of the reduction of water content in comparison with the splitting of sucrose and the accumulation of monosaccharides. According to the water content (less than 20 %), honey becomes suitable for pumping 3–5 days before it is sealed in the cells. The influence of the mass of bees of different families on the intensity of sucrose inversion in the cells and the accumulation of monosaccharides in the product has been experimentally proved. The maturity of honey in the ratio of sugars in the beehives of strong families is better than in weak ones.

Sustainable short-chain olefin production through simultaneous dehydration of mixtures of 1-butanol and ethanol over HZSM-5 and γ-Al2O3

Dehydration reactions of alcohols are of prime importance in biomass conversions. Although bio-alcohols are generally obtained as mixtures, the dehydration of alcohol mixtures is barely reported. In this work the ability of HZSM-5 and γ-Al2O3 to dehydrate a 1-butanol/ethanol mixture in a 6/1 mass-ratio was studied, corresponding to the butanol/ethanol ratio in typical ABE mixtures, at temperatures from 513 to 613 K. For HZSM-5 the difference in reactivity of the alcohols is too high to fully convert both alcohols to their respective alkenes without catalyzing secondary reactions. For dehydration over γ-Al2O3, the reactivity of ethanol and 1-butanol is more similar, which can be attributed to the lower acid strength and larger pore size, causing lower fractional coverages and diminished competition for adsorption sites, allowing both alcohols to react more simultaneously. Above conversions of 0.6, the difference in reactivity of both alcohols increases due to a shift in dominant reaction pathways towards ether decomposition and the intramolecular dehydration on γ-Al2O3. Approaching full conversion, the selectivity towards olefins is high (>0.95) for both HZSM-5 and γ-Al2O3. Since no secondary reactions occur when using γ-Al2O3, it is deemed the best of both catalysts to dehydrate mixtures of alcohols simultaneously to their corresponding alkenes.

Factors influencing the thermal stability of azo and bisazo compounds

The present study investigates the effects of substituents, structural rigidity, tautomerism, hydrogen bonding interaction, and spatial hindrance on the thermal stability of some azo compounds including bisazo Troger base analogs (BATBAs). The relatively large structures of BATBAs allow assessing their thermal stability before reaching the sublimation or boiling point. BATBAs carry two identical azo groups per molecule resulting in an intense and detectable sign of decomposition. Unlike most azo dyes, BATBAs are not ionic and prevent the complexity of decomposition associated with simultaneous dehydration. A few commercial azo dyes are also analyzed to evaluate the generality of the conclusion.

Optimization of furfural production from millet husk using response surface methodology

ABSTRACTBiomass has been recognized as a viable source for energy and bio-based chemicals. This study reported furfural production from millet husk via simultaneous hydrolysis and dehydration processes. Effect of reaction variables such as temperature (120–200°C), resident time (15–45 min), and acid concentration (5–10%) was studied using central composite design. Furfural yield (71.55%) was achieved at 184°C, 39 min, and 9% acid concentration. FT-IR spectrum of the produced furfural showed absorption at 1,697 and 2,880 cm−1 indicating a conjugated carbonyl functional group and aldehydic hydrogen. The results revealed that millet husk could be a potential substrate for furfural production.

Experimental hydration of natural volcanic clinopyroxene phenocrysts under hydrothermal pressures (0.5–3 kbar)

Water is a key parameter in mantle rheology, magma genesis, magma evolution, and resulting eruption styles, because it controls the density and the viscosity, as well as the melting and crystallization behavior of a melt. The water content in nominally anhydrous minerals (NAMs) such as clinopyroxene recently has been used as a proxy for magmatic water contents. NAMs, however, may dehydrate during magma degassing and eruption. We performed rehydration experiments on potentially degassed clinopyroxene phenocrysts from various volcanic settings. The experiments were conducted in hydrogen gas at 1 atm or hydrothermal pressures ranging from 0.5 to 3 kbar to test the incorporation of water into natural clinopyroxene under water fugacities similar to those in a volcanic system. Our results show a dependence of the water content in the clinopyroxene crystals with pressure as the phenocrysts begin to dehydrate upon lower water fugacities in the experiments. Water loss or gain in a crystal occurs according to the relatively fast redox-reaction OH − + Fe 2+ ↔ O 2− + Fe 3+ + ½ H 2 , which was confirmed by Mossbauer spectroscopy. The kinetics of this redox-process are independent of pressure and thus water fugacity. Water contents in rehydrated clinopyroxene crystals can be related to magmatic water contents at various levels in a volcanic system. Our results thus show that the water content in erupted clinopyroxene phenocrysts cannot be taken for granted to be representative of magmatic water contents prior to magma degassing. The conducted experiments indicate the simultaneous dehydration of clinopyroxene along with magma ascent and degassing. Rehydration experiments under hydrothermal pressures, however, may be able to reconstruct clinopyroxene water contents at crystallization prior to dehydration.

Production of propylene via simultaneous dehydration and skeletal isomerisation of isobutanol on acid catalysts followed by metathesis

The catalytic performance of KOH/mordenite has been studied for transesterification of palm oil using a batch reactor and a packed-bed reactor at 60 °C and atmospheric pressure. The KOH/mordenite processed transesterification in the batch reactor gave the highest methyl ester yield of 96.7% under optimum conditions, while a methyl ester content over 94.5% was obtained in the packed-bed reactor. This comparison indicates that transesterification in a batch-type reactor gives a higher methyl ester yield than that of a continuous-flow reactor. Dealumination was found in the calcined catalysts and had a significant effect on the physical structure and chemical composition of the catalysts. Leaching of the potassium species was negligible, whereas depositing and washing of the reacted mixture with acetone on the catalyst surface were observed by FTIR.

Concurrent Osmotic Dehydration and Vacuum Drying of Kiwi Fruit (Actinidia Deliciosa cv. Hayward) Under Far Infrared Radiation: Process Optimization, Kinetics and Quality Assessment

AbstractA novel dehydration protocol for Kiwi fruit (KF) involving simultaneous osmotic dehydration (OD) and vacuum drying (VD) viz. ODVD under far‐infrared (FIR) radiation has been developed. This is the first report for OD of KF using fructose as osmotic solution. The ODVD process had been optimized using Taguchi orthogonal design to obtain KF with minimum moisture content in minimum time. Dehydrated KF with 4.70% (w/w) moisture content was produced in 100 min ODVD time at 50°B, 40°C radiator temperature and 20 mbar chamber pressures. The optimally dehydrated KF demonstrated a significant increase in the ascorbic acid content (16.60%), total phenolic content (13.09%), total flavonoid content (21.01%) and radical scavenging activity (5.85%). At optimal condition, Newton's drying model could best represent the dehydration kinetics. The high moisture diffusivity viz. 9.78 × 10−10 m2/s and low activation energy viz. 10.78 kJ/mol computed through Fick's law in ODVD indicated a fast and energy‐efficient process.Practical ApplicationsKiwi is an important commercial, seasonal and tropical fruit. It is marketed in the forms of marmalade, jam, jellies, etc. which are usually prepared using chemical preservatives. The use of such preservatives may be avoided through effective dehydration of Kiwi by concurrent osmotic‐dehydration (OD) and vacuum drying (VD) [ODVD]. The application of simultaneous ODVD under far‐infrared (FIR) radiation improves the mass and heat transfer rates and thereby hastens the inflow of external solute and outflow of internal moisture facilitating faster dehydration and compositional reforms. The application of FIR radiation reduces the drying time appreciably making the process energy‐efficient and economically sustainable. The evaluated optimal conditions and associated drying kinetics of the novel ODVD process enables design of drying equipment for similar foodstuffs. The qualities of the dehydrated Kiwi fruit viz. ascorbic acid, phenols, flavonoids and antioxidant activity conform to market status.

Preparation of Magnetic Nanoparticles via a Chemically Induced Transition: Presence/Absence of Magnetic Transition on the Treatment Solution Used

The dependence of magnetic transition on the treatment solution used in the preparation of magnetic nanoparticles was investigated using as-prepared products from paramagnetic FeOOH/Mg(OH)2via a chemically induced transition. Treatment using FeCl3and CuCl solutions led to a product that showed no magnetic transition, whereas the product after treatment with FeSO4or FeCl2solutions showed ferromagnetism. Experiments revealed that the magnetism was caused by the ferrimagneticγ-Fe2O3phase in the nanoparticles, which had a coating of ferric compound. This observation suggests that Fe2+in the treatment solution underwent oxidation to Fe3+, thereby inducing the magnetic transition. The magnetic nanoparticles prepared via treatment with an FeSO4solution contained a larger amount of the nonmagnetic phase. This resulted in weaker magnetization even though these nanoparticles were larger than those prepared by treatment with an FeCl2solution. The magnetic transition of the precursor (FeOOH/Mg(OH)2) was dependent upon treatment solutions and was essentially induced by the oxidation of Fe2+and simultaneous dehydration of FeOOH phase. The transition was independent of the acid radical ions in the treatment solution, but the coating on the magnetic crystallites varied with changes in the acid radical ion.

Monitoring by in situ neutron diffraction of simultaneous dehydration and Ni2+ mobility in partially exchanged NaY zeolites

The incoherent signal in neutron diffraction patterns allows correlating in real time hydration–dehydration levels and structural changes in zeolites.

Simultaneous dehydration and infiltration with (2-hydroxyethyl)-methacrylate (HEMA) for lipid preservation in plant tissues

Although this study aims to develop an improved method for the preservation of reserve lipids in plant tissues for different uses in plant anatomy, it mostly aims to develop an improved method for the identification of lipid reserves where synthesis or storage occurs. The proposed procedures entail only the utilization of (2-hydroxyethyl)-methacrylate (HEMA) as a dehydration agent. One of the procedures is based on the gradual exchange of aqueous HEMA solutions with increasing concentrations. In another procedure, dehydration and infiltration are induced by the presence of silica gel around a modified microcentrifuge tube containing the aqueous HEMA solution with the plant tissues, thus allowing efficient lipid preservation. Both procedures resulted in simultaneous dehydration and infiltration of the endosperm and embryo of Ricinus communis, while eliminating the use of ethyl alcohol, thus providing better lipid preservation.

Synthesis of 5-hydroxymethylfurfural (HMF) by acid catalyzed dehydration of glucose–fructose mixtures

Synthesis of 5-hydroxymethylfurfural (HMF) from hexoses has been studied extensively in the scientific literature. However, a process has yet to be implemented at industrial scale. In this paper the simultaneous dehydration of glucose and fructose was investigated, in order to develop a process allowing the use of the cheapest available source of fructose: high fructose corn syrup. The dehydration was catalyzed by hydrochloric acid and conducted in acetone–water mixtures, which ensured good selectivity towards HMF and eliminated precipitation of polymer by-products (insoluble humins). Through a detailed experimental investigation a reaction network was proposed, and subsequently the corresponding kinetic model was fitted to experimental data in order to obtain estimates of the reaction kinetic parameters. The kinetic model is capable of predicting the formation of HMF along with the important by-products: soluble humins, glucose dimers, anhydroglucose, and formic acid. The reaction conditions in four different reactor configurations were optimized and compared using the kinetic model. It was found that a recirculating reactor setup is preferable, where the equilibrium controlled by-products (anhydroglucose and glucose dimers) are recirculated to the dehydration reactor. The model predicts an HMF selectivity of close to 70% in a recirculating reactor at conditions where HMF degradation is avoided.

Efficient catalysts for simultaneous dehydration of light alcohols in gas phase

We report the simultaneous dehydration of light alcohols over rare earth phosphate catalysts.

Autocatalytic one pot orchestration for the synthesis of α-arylated, α-amino esters

A novel acetyl chloride-mediated cascade transformation involving three components (benzyl carbamate, ethyl glyoxylate and arene nucleophiles) is reported. Aryl orthogonally protected α-amino acids are obtained in a one pot cascade, using a mild AcOH-AcCl system, via a critical autocatalytic dehydration-activation step ensuring an original and efficient Friedel-Crafts orchestration.

Simultaneous dehydration of biomass-derived sugars to 5-hydroxymethyl furfural (HMF) and reduction of graphene oxide in ethyl lactate: one pot dual chemistry

Biomass-based sugars were dehydrated in ethyl lactate in the presence of graphene oxide, choline chloride and betaine hydrochloride resulting in the formation of HMF and rGO.