Characteristics of a Supersonic Swirling Dehydration System of Natural Gas

A new type of dehydration unit for natural gas was briefly described and its basic structure and working principles were presented. An indoor test rig for testing the unit performance was set up and the experimental results were given. The results showed that the unit could attain a maximum dew point depression of about 20℃ without any need of external mechanical power and chemicals. The pressure loss ratio, shock wave and the flow rate had great influence on the dehydration characteristics. From the systematic analysis of the factors that affect the dehydration efficiency of the unit, the suggestions for improving the unit are put forward.

Simulation and Analysis on Multiple Steady States of an Industrial Acetic Acid Dehydration System

In this work, an industrial acetic acid dehydration system via heterogeneous azeotropic distillation is simulated by Aspen Plus software. Residue curves are used to analyze the distillating behavior, and appropriate operating region of the system is determined. Based on steady states simulation, a sensitivity analysis is carried out to detect the output multiple steady states in the system. Different solution branches are observered when the flow rates of the feed stream and the organic reflux stream are selected as manipulated variables. The performance of the column under different steady states is different. A method is oroposed to achieve the desired steady state.

Dehydration of xylose to furfural over niobium phosphate catalyst in biphasic solvent system

Phosphoric acid treated niobic acid(NbP)was used for the dehydration of xylose to furfural in biphasic solvent system,which was found to exhibit the best performance among the tested catalysts.The excellent performance of NbP could be explained by the better synergistic cooperation between Bro¨nsted and Lewis acid sites.Moreover,NbP showed good stability and no obvious deactivation or leaching of Nb could be observed after six continuous recycles.

AB080.Exercise induced changes in intraocular pressure is related to systemic dehydration

Background:A transient reduction in intraocular pressure(IOP)after an aerobic exercise is found time and again across studies in literature.It has been suggested that systemic dehydration could be a possible mechanism driving these hypotensive effects of exercise.However,IOP reduction never had been examine in hyper versus hypo-hydration conditions for a same group of participants.The purpose of this study is to examine the influence of hyper and hypo hydration conditions on exercise-induced fluctuations in intraocular pressure.Methods:Thirteen participants rode an ergocycle in a temperate room for 90 minutes,at 59%of their maximal aerobic capacity,in a state of both hyper and hypo-hydration.IOP was measured at 0,5,30,60 and 90 minutes,and 30 minutes after exercise.Reduction in body weight was measured at 0,30,60 and 90 minutes.Results:There is an initial drop in IOP under both conditions followed by a rise in IOP at 30 minutes that is nearly equal to the baseline.From that point on,IOP hovers around baseline values in the hypo-hydrated condition and increases until the end of the exercise protocol in the hyper-hydrated condition.A repeated-measures ANOVA showed a significant interaction between time and condition F(5,60)=3.99,P=0.003,as well as a main effect of time F(5,60)=7.90,P<0.001,and a main effect of condition F(1,12)=5.83,P=0.033.Conclusions:The results of this study,when taken with others that looked specifically at factors of exercise,hydration and IOP suggest that fluctuations in IOP during exercise are likely a homeostatic response related fluid intake and not because of any specific benefit incurred through exercise.

Adipokinetic hormone signaling regulates adult dehydration resistance in the migratory locust

Drought events have become more severe under climate change,and this can pose a major threat to the survival of various organisms.The molecular mechanisms involved in dehydration resistance are not well known.Here,adults of the migratory locust,Locusta migratoria,were subjected to food-mediated dehydration,and adipokinetic hormone(AKH)signaling was found to play a key role in regulating dehydration resistance.Specifically,dehydration shortened the lifespan,increased the body weight loss,and reduced the water loss rate in adult locusts.Global transcriptome profiles revealed variations in tissue-specific gene expression between dehydration-resistant locusts and normal locusts.Importantly,dehydration selection and exposure induced prominent expression of AKH genes in the retrocerebral complex of adult locusts.Furthermore,individual knockdown of AKH1,AKH2,or AKH receptor(AKHR)accelerated water loss and shortened the lifespan of adult locusts under dehydration conditions,and trehalose supplementation ameliorated the negative effects caused by interference with AKH or AKHR.These findings demonstrated that AKH/AKHR signaling-dependent trehalose metabolism plays a crucial role in regulating locust dehydration resistance and thus provide novel insights into the regulatory mechanism underlying drought resistance.

Experiments and kinetic modeling of the sorbitol dehydration to isosorbide catalyzed by sulfuric acid under conditions of non-constant volume

Isosorbide is a novel bio-based material derived as a secondary dehydration product of sorbitol.This work focuses on the kinetics of sulfuric acid-catalyzed dehydration of sorbitol under conditions of nonconstant volume.Herein,the effects of stirring rate,catalyst dosage,reaction temperature,and reaction time on the dehydration reaction of sorbitol were investigated.The yield of isosorbide up to 77.13%was obtained after 1.5 h of reaction time under conditions of 2 kPa,1.0%(mass)catalyst dosage,and 413.15 K.Based on the sorbitol dehydration reaction mechanism and a simplified reaction network,a kinetic model was developed in this work.A good agreement was accomplished between kinetic modeling and experiments between 393.15 and 423.15 K.The fitting results indicate that side reactions with higher activation energies are more affected by reaction temperatures,and the main side reaction that influences the selectivity of isosorbide is the oligomerization reaction among the primary dehydration products of sorbitol.The model fitting of the catalyst amounts effect shows that the effective concentration of sulfuric acid would be reduced with the increase of dosage due to the molecular agglomeration effect.Hopefully,the kinetic experiments and modeling results obtained in this work will be helpful to the design and optimization of the industrial sorbitol dehydration process.

Study on the effect of four kinds of raw materials in hypertonic dehydration cell model

It aims to investigate the protective effects of sodium hyaluronate,panthenol,Portulaca oleracea L.and Calendula officinalis L.on hyperosmotic dehydration-induced injury of human immortalized keratinocytes(HaCaT).The safety mass concentrations of four raw materials were screened by detecting cell viability,and the secretion of hyaluronic acid(HA)was determined using the ELISA method.The expression of HaCaT barrier function related genes(OVOL1,EREG,TGM1,TGM2,IVL,IRF6,THBS1,CASP14)was detected at the mRNA level to explore the regulatory effect of four raw materials on these genes.The results demonstrate that pretreatment with the four kinds of raw materials could increase the cell viability after hyperosmotic dehydration,promote the secretion of HA,and improve the expression of barrier function related genes after hyperosmotic dehydration,among which panthenol and Calendula officinalis L.are better.The results show that the four raw materials have a certain protective effect on the hyperosmotic dehydration cell model,which provides data support for its application in cosmetics.

MgSO_(4)·7H_(2)O for thermochemical energy storage:Hydration/dehydration kinetics and cyclability

In recent decades,MgSO_(4)·7H_(2)O(epsomite)has attracted significant attention as a promising thermochemical-based thermal energy storage material due to its high theoretical energy density,wide availability,and affordability.Despite extensive research efforts,progress in achieving high-energy density has been limited,primarily due to inadequate understanding of its reaction mechanisms and unfavorable dehydration/hydration kinetics.This study systematically investigated the hydration/dehydration kinetics and cyclability of MgSO_(4)·7H_(2)O.The results reveal that the dehydration process is influenced by the heating rate,with an optimal rate of 5℃/min,resulting in a seven-step MgSO_(4)·7H_(2)O dehydration process with a dehydration heat close to the theoretical value.The reaction kinetic analysis indicated that the rate of hydration was approximately 50%lower than that of dehydration.In addition,thermal cycling tests of MgSO_(4)·7H_(2)O under the conditions of this study(small sample size)indicated good cyclability,with hydration rates increasing with increasing cycling numbers up to approximately 10 cycles where level-off occurs.These results are consistent with scanning electron microscopy analyses,which revealed the formation of cracks and channels in the salt hydrate particles,facilitating mass transfer and improved kinetics.

Non-isothermal kinetic analysis of thermal dehydration of La_2(CO_3)_3·3.4H_2O in air

The single phase La2（CO3）3·3.4H2 O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2（CO3）3·3.4H2O from 30 to 1000 °C were characterized by XRD, FTIR and DTA-TG. The kinetics of dehydration of La2（CO3）3·3.4H2O in the temperature range of 30-366 °C was investigated under non-isothermal conditions. Flynn-Wall-Ozawa and Friedman isoconversion methods were used to calculate the activation energy and analyze the reaction steps; multivariate non-linear regression program was applied to determine the most probable mechanism and the kinetic parameters. The results show that the thermal dehydration of La2（CO3）3·3.4H2O is a kind of three-step competitive reaction, and controlled by an n-order initial reaction followed by n-order competitive reaction（FnFnFn model）. The activation energy matching with the most probable model is close to value obtained by Friedman method. The fitting curves match the original TG-DTG curves very well.

Three-stage Transformation of Chlorophyll Transient Fluorescence Pattern Under Sustained Dehydration and the Discovery of Critical Water Content in Seaweeds

The chlorophyll fluorescence kinetics of marine red alga Grateloupia turutunt Yamada, green alga Ulva pertusa Kjellm and brown alga Laminaria japonica Aresch during natural sustained dehydration were monitored and investigated. The pulse amplified modulation (PAM) system was used to analyze the distinct fluorescence parameters during thallus dehydration. Results proved that the fluorescence kinetics of different seaweed all showed three patterns of transformation with sustained water loss. These were: 1) peak kinetic pattern (at the early stage of dehydration fluorescence enhanced and quenched subsequently, representing a normal physiological state). 2) plateau kinetic pattern (with sustained water loss fluorescence enhanced continuously but quenching became slower, finally reaching its maximum). 3) Platform kinetic pattern (fluorescence fell and the shape of kinetic curve was similar to plateau kinetic pattern). A critical water content (CWC) could be found and defined as the percentage of water content just prior to the fluorescence drop and to be a significant physiological index for evaluation of plant drought tolerance. Once thallus water content became lower than this value the normal peak pattern can not be recovered even through rehydration, indicating an irreversible damage to the thylakoid membrane. The CWC value corresponding to different marine species were varied and negatively correlated with their desiccation tolerance, for example. Laminaria japonica had the highest CWC value (around 90%) and the lowest dehydration tolerance of the three. In addition, a fluorescence 'burst' was found only in red algae during rehydration. The different fluorescence parameters F-o, F-v and F-v, F-m were measured and compared during water loss. Both F-o and F-v increased in the first stage of dehydration but F-v/F-m. kept almost constant. So the immediate response of in vivo chlorophyll fluorescence to dehydration was an enhancement. Later with sustained dehydration F-o increased continuously while F-v decreased and tended to become smaller and smaller. The major changes in fluorescence (including fluorescence drop during dehydration and the burst during rehydration) were all attributed to the change in F-o instead of F-v This significance of F-o indicates that it is necessary to do more research on F-o as well as on its relationship with the state of thylakoid membrane.

Efficient production of 5-hydroxymethylfurfural from hexoses using solid acid SO_4^(2-)/In_2O_3-ATP in a biphasic system

A natural attapulgite （ATP）‐based catalyst, sulfated In2O3‐ATP （SO42-/In2O3‐ATP）, was obtained by an impregnation‐calcination method and was used to efficiently and selectively produce the useful platform chemical 5‐hydroxymethylfurfural （HMF） from hexoses. Some important reaction param‐eters were studied, revealing that Lewis and Br-nsted acid sites on SO42-/In2O3‐ATP catalyze glu‐cose isomerization and fructose dehydration. The yields of HMF from glucose and fructose were 40.2%and 46.2%, respectively, using the optimal conditions of 180℃ for 60 min with 10 wt%of solid acid catalyst in a mixture of γ‐valerolactone‐water （9：1）.

Chlorella Resistance to Dehydration Conditions and Protection Effect of Different Cryoprotecants on Chlorella Cells

[Objective] The aim was to study on the chlorella resistance to dehydration conditions and effect of different cryoprotecants on drying of chlorella cells.[Method]The protection effect of seven kinds of cryoprotecants on chlorella cells was analyzed.[Result]The protection effect of trehalose on chlorella cells was the best,and the survival rate of chlorella cells had improved by 50% with the applied trehalose concentration of 5%.[Conclusion]The result in this study had important guidance effect on the mutation breeding of chlorella.

Dehydration of bio-ethanol to ethylene over iron exchanged HZSM-5

Iron exchanged ZSM-5 with Si/Al ratio from 25 to 300 prepared by three consecutive ion exchanges was used for the dehydration of ethanol to ethylene.The iron exchanged ZSM-5（Si/Al=25） catalyst with an iron content of 0.46 wt%gave 97%-99%yield of ethylene at 98%-99%conversion of ethanol at 260℃ and 0.81 h^-1 liquid hourly space velocity.The high performance was maintained for60 d on-stream.X-ray diffraction,Fourier transform infrared spectroscopy of pyridine adsorption,NH3 temperature-programmed desorption and diffuse reflectance UV-vis spectroscopy were used for catalyst characterization.Ion exchange with iron decreased the total acidity of the zeolite,especially the strong acid sites and Bronsted acid sites.The doped iron species were distributed over Fe-ZSM-5 as predominantly isolated Fe^3＋.Therefore,the catalytic performance for ethanol dehydration to ethylene was improved.

Alkali-metal-modified ZSM-5 zeolites for improvement of catalytic dehydration of lactic acid to acrylic acid

Various ZSM-5 zeolites modified with alkali metals （Li, Na, K, Rb, and Cs） were prepared using ion exchange. The catalysts were used to enhance the catalytic dehydration of lactic acid （LA） to acrylic acid （AA）. The effects of cationic species on the structures and surface acid-base distributions of the ZSM-5 zeolites were investigated. The important factors that affect the catalytic performance were also identified. The modified ZSM-5 catalysts were characterized using X-ray diffraction, tempera- ture-programmed desorptions of NH3 and CO2, pyridine adsorption spectroscopy, and N2 adsorption to determine the crystal phase structures, surface acidities and basicities, nature of acid sites, specific surface areas, and pore volumes. The results show that the acid-base sites that are adjusted by alkali-metal species, particularly weak acid-base sites, are mainly responsible for the formation of AA. The KZSM-5 catalyst, in particular, significantly improved LA conversion and AA selectivity because of the synergistic effect of weak acid-base sites. The reaction was conducted at different reaction temperatures and liquid hourly space velocities （LHSVs） to understand the catalyst selectivity for AA and trends in byproduct formation. Approximately 98% LA conversion and 77% AA selectivity were achieved using the KZSM-5 catalyst under the optimum conditions （40 wt% LA aqueous solution, 365 ℃, and LHSV 2 h-1）.

Role of Bridge-bonded Formate in Formic Acid Dehydration to CO at Pt Electrode： Electrochemial in-situ Infrared Spectroscopic Study

Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded formate （HCOOD） is the reactive intermediate for COad for-mation from HCOOH molecules. When switching from HCOOH-free solution to HCOOH- containing solution at constant potential （E=0.4 V vs. RHE）, we found that immediately upon solution switch COad formation rate is the highest, while surface coverage of formate is zero, then after COad formation rate decreases, while formate coverage reaches a steady state coverage quickly within ca. 1 s. Potential step experiment from E=0.75 V to 0.35 V, reveals that formate band intensity drops immediately right after the potential step, while the COad signal develops slowly with time. Both facts indicate that formate is not the reactive intermediate for formic acid dehydration to CO.

Mass transfer model,preparation and applications of zeolite membranes for pervaporation dehydration:A review

Pervaporation(including vapor permeation) is a kind of new membrane separation technology, possessing the advantages of high efficiency, energy saving and convenient operation. It has promising application in the separation and purification of organic solvents. Dehydration is an important step in the production and recovery of organic solvents. Zeolite membranes have attracted wide attention for pervaporation dehydration due to their high separation performance and good thermal/chemical stability. So far, zeolite membranes have been preliminarily industrialized for dehydration of organic solvents. This paper reviews the recent development of zeolite membranes for pervaporation dehydration, including mass transfer models, preparation and applications of zeolite membranes. The review also discusses the current industrial applications of zeolite membranes and their future development in pervaporation.

Comparison of three methods for natural gas dehydration

This paper compares three methods for natural gas dehydration that are widely applied in industry：（1） absorption by triethylene glycol, （2） adsorption on solid desiccants and （3） condensation. A comparison is made according to their energy demand and suitability for use. The energy calculations are performed on a model where 105 Nm3/h water saturated natural gas is processed at 30 °C. The pressure of the gas varies from 7 to 20 MPa. The required outlet concentration of water in natural gas is equivalent to the dew point temperature of -10 °C at gas pressure of 4 MPa.

Pretreatment of Isopropanol Solution from Pharmaceutical Industry and Pervaporation Dehydration by NaA Zeolite Membranes

NaA zeolite membranes with 80 cm in length and 12.8 mm in outer diameter were prepared by our research group cooperating with Nanjing Jiusi Hi-Tech Co., China. The influence of dissolved inorganic salts and pH value in the feed of isopropanol （IPA） solution on NaA zeolite membranes was investigated. It was found that both factors exhibited strong influence on the stability of NaA zeolite membranes. A set of pretreatment steps such as pH adjustment and distillation of the IPA solution were proposed to improve stability for pervaporation dehydration. An industrial-scale pervaporation facility with 52 m2 membrane area was built to dehydrate IPA solution from industrial cephalosporin production. The facility was continuously operated at 368-378 K to dehydrate IPA solution from water mass content of 15%-20% to less than 2% with a feed flow rate of 400-500 L·h^-1 and an average water flux of 1-1.5 kg·m^-2·h-1. The successful application of this facility suggested a promising application of NaA zeolite mem-brane for IPA recovery from pharmaceutical production.

Evaluation of Catalysts and Optimization of Reaction Conditions for the Dehydration of Methyl Lactate to Acrylates

The production of acrylates from biomass-originated lactic acid is of extraordinary importance, to overcome the increasing worldwide shortage of petroleum. In this study, the catalytic dehydration of methyl lactate over a calcium sulfate catalyst, with various promoters, has been carried out to identify potential catalyst/promoter combinations for acrylate production. The best catalyst for methyl acrylate formation in this study has been calcium sulfate, with cupric sulfate and phosphates as promoters. The optimal mass ratio of m（CaSOa） ： m（CuSOa） ： m（Na2HPO4） ： m（KH2PO4） is 150.0 ： 13.8 ： 2.5 ： 1.2. Effects of carrier gas, reaction temperature, feed concentration as well as contact time on the dehydration of methyl lactate have been investigated. With nitrogen as a carrier gas, a combined yield of acrylic acid and methyl acrylate is 63.9% from 60% （by mass） methyl lactate at 400℃ with 7.7 seconds contact time.

Lewis base-assisted Lewis acid-catalyzed selective alkene formation via alcohol dehydration and synthesis of 2-cinnamyl-1,3-dicarbonyl compounds from 2-aryl-3,4-dihydropyrans

Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often pla-gued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4- di-hydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.