Dehydration Behavior Research Articles

Investigating base-catalyzed aldol condensation reactions on alkali-free hydrotalcites and the role of thermal decomposition

Aldolization is a crucial carbon–carbon coupling reaction used in the conversion of biomass-derived platform molecules into valuable chemicals and fuels. In this work, we combine experiment and theory to explore the role thermal decomposition has in controlling the structure of alkali-free Mg-Al layered double hydroxides (LDHs) and their subsequent performance in the base-catalyzed aldol condensation of acetone, focusing on the constituent aldolization and dehydration steps. LDHs were synthesized via co-precipitation and subjected to calcination at temperatures up to 600 °C to produce mixed metal oxides of the form Mg3AlOz which were further examined by SEM, N2 physisorption, XRD, and CO2-TPD. Aldolization and dehydration behaviors were examined in a batch reactor and fit with kinetic models to capture the sensitivities of both reactions to calcination temperature. Additional experiments involving the selective blocking of base sites by CO2 poisoning and reversal at varying temperatures showed that both aldolization and dehydration are likely driven by the strongest base sites, yielding a site density (0.19 μmol m−2) in agreement with separate propionic acid titration studies. Density functional theory (DFT) simulations of Mg5Al2O8 surfaces were employed to gain microscopic insights into these materials, revealing the importance of Al substitution in creating cation vacancies which can drive aldol condensation through enolate intermediates stabilized in the oxyanion resonance form. High-coverage simulations of the surface show participation of the vacancy in both aldolization and dehydration, rationalizing the coupling of rate trends observed experimentally. Ultimately, this study provides new insights and approaches useful in the design of heterogeneous aldolization catalysts.

Water Uptake of Airborne Cells of P. syringae Measured with a Hygroscopicity Tandem Differential Mobility Analyzer.

Airborne microorganisms impact cloud formation and are involved in disease spreading. The ability of airborne cells to survive and express genes may be limited by reduced water availability in the atmosphere and depend on the ability of the cells to attract water vapor at subsaturated conditions, i.e., their hygroscopicity. We assessed hygroscopic properties of the plant pathogen Pseudomonas syringae, known to participate in cloud formation. We used a hygroscopicity tandem differential mobility analyzer to examine both hydration and dehydration behavior in the relative humidity (RH) range 5-90%. The cells were aerosolized either from Milli-Q water or from a 35 g L-1 NaCl solution, resulting in pure cells or cells associated with NaCl. Pure cells exhibited no deliquescence/efflorescence and a small gradual water uptake reaching a maximum growth factor (GF) of 1.09 ± 0.01 at 90% RH. For cells associated with NaCl, we observed deliquescence and a much larger maximum GF of 1.74 ± 0.03 at 90% RH. Deliquescence RH was comparable to that of pure NaCl, highlighting the major role of the salt associated with the cells. It remains to be investigated how the observed hygroscopic properties relate to survival, metabolic, and ice-nucleation activities of airborne P. syringae.

Investigation of the dehydration and rehydration behavior of osmotic pretreated paneer slices (Indian cottage cheese) and its modeling approach

AbstractThe study aimed to investigate the impact of the osmotic effect on the drying and rehydration of paneer. The paneer slices were pre‐treated with salt at seven different concentrations and surface treatments. The osmotic solution and product ratio was taken as 1:4 and the pretreatment time was fixed as 12 h. Weight loss (WL), solute gain (SG), and weight reduction (WR) of paneer were evaluated during osmotic pretreatment. The pretreated paneer was dried at 50°C in a tray dryer. The equilibrium moisture content of dried slices varied from 14.12% to 15.86% and the moisture diffusivity of the osmotic treated samples had a better result with maximum value of 4.76 × 10−8 m2/s. The osmotic pretreatment minimized the drying time of paneer. The Midilli model revealed the best fit for drying paneer slices with R2 value >.99. Rehydration was carried out at three different temperatures at 4, 28, and 100°C. The samples rehydrated at 28°C showed better results in terms of the rehydration ratio with a maximal value of 1.85. In model investigation, the Peleg, Exponential, and Weibull model was found good fit for samples rehydrated at 4, 28, and 100°C. The osmotic pretreatment impacted positively on the quality matrices such as color retention, drying time, nutritional profile, and rehydration ratio of paneer slices. However, the higher osmotic pretreatments above 12% recorded unacceptable salty flavor.Practical applicationsThe stability of paneer is limited and it requires refrigeration facility to store the paneer which is a frailty factor in supply chain cycle of dairy industries. In current practices, the high‐cost freeze drying technique was used to dry the paneer to make as shelf stable. The conventional drying techniques would not suit for drying the paneer, that alters the characteristics of paneer. The research findings will improve the characteristics of dried paneer in conventional dryer and hence, it is viable to make the shelf stable paneer at low cost. This research would make an alternative approach to manufacture the shelf stable and ready to eat paneer.

Enhanced Li+/Mg2+ separation via Ca2+-supported graphene membranes: Mechanistic insights from molecular dynamics simulations

Achieving the efficient separation of Li+ and Mg2+ ions remains a significant challenge. To address this issue, a Ca2+-supported graphene membrane was engineered and evaluated through molecular dynamics simulations. The separation mechanism of Li+/Mg2+ in the Ca2+-supported graphene membrane was investigated by analyzing the dehydration behavior as well as the interfacial interactions between ions and the graphene membrane. The Ca2+-supported graphene membrane exhibits well separation performance for Li+ and Mg2+ mixtures, and the separation efficiency of the Ca2+-supported graphene membrane for Li+/Mg2+ mixture increases first and then decreases with the increase of Ca2+ ion number inserted into the membrane. Li+ ions display heightened permeability and reduced ion rejection, which can be attributed to their relatively weaker interaction with the graphene sheets compared to Mg2+ ions, facilitating smoother penetration. Furthermore, Li+ ions are intended to form smaller sizes with Cl− ions at the entrances of the Ca2+-supported graphene membrane, mitigating size-related effects. Additionally, their weaker interactions with water molecules, facilitate the dehydration process of Li+ ions.

Dehydration behaviors and properties of anhydrite II prepared by phosphogypsum with low-temperature calcination

Certain concentration H+ can combine with the crystal water to form the H3O+, influencing the stability of the crystal water in dihydrate so that can be completely removed under lower temperature. Therefore, this paper introduces a method wherein sulfuric acid is employed as a medium, facilitating direct dry mixing and low calcination temperatures to produce anhydrite II. Initially, the low and high calcination temperatures were determined as 280°C and 500°C, respectively, through XRD analysis of the phase composition of calcination products under varying conditions. Subsequently, the influence of different sulfuric acid contents and concentrations on the calcination products at 280°C was investigated. Additionally, the impact of sulfuric acid on the dehydration behavior of PG was analyzed using TG-DSC and FTIR. The present work also assessed the physical-mechanical properties of anhydrite II at 280°C and 500°C, along with their hydration activity and microscopic morphology. The results indicated that the optimal sulfuric acid content and concentration were determined as 2 % and 40 wt%, respectively, yielding dehydration temperatures of 86.08°C and 146.95°C. The water requirement (WR) for normal consistency for anhydrite II at 280°C was 0.68, exhibiting higher flexural and compressive strength compared to calcination at 500°C (WR=0.58), and the hydration rate at 28 days reached 78.5 %. At 280°C, the dihydrate crystals formed by anhydrite II at 28 days exhibited a compact microstructure characterized by relatively small crystals with well overlapping.

Sub-nanopores enabling optimized ion storage performance of carbon cathodes for Zn-ion hybrid supercapacitors

Aqueous Zn-ion hybrid supercapacitors (ZHSs) are attracting significant attention as a promising electrochemical energy storage system. However, carbon cathodes of ZHSs exhibit unsatisfactory ion storage performance due to the large size of hydrated Zn-ions (e.g., [Zn(H2O)6]2+), which encumbers compact ion arrangement and rapid ion transport at the carbon-electrolyte interfaces. Herein, a porous carbon material (HMFC) with abundant sub-nanopores is synthesized to optimize the ion storage performance of the carbon cathode in ZHSs, in which the sub-nanopores effectively promote the dehydration of hydrated Zn-ions and thus optimize the ion storage performance of the carbon cathode in ZHSs. A novel strategy is proposed to study the dehydration behaviors of hydrated Zn-ions in carbon cathodes, including quantitatively determining the desolvation activation energy of hydrated Zn-ions and in-situ monitoring active water content at the carbon-electrolyte interface. The sub-nanopores-induced desolvation effect is verified, and its coupling with large specific surface area and hierarchically porous structure endows the HMFC cathode with improved electrochemical performance, including a 53 % capacity increase compared to the carbon cathode counterpart without sub-nanopores, fast charge/discharge ability that can output 46.0 Wh/kg energy within only 4.4 s, and 98.2 % capacity retention over 20,000 charge/discharge cycles. This work provides new insights into the rational design of porous carbon cathode materials toward high-performance ZHSs.

In-vitro dehydration kinetics coefficient of Kalifilcon A and other contact lens materials

In contact lens (CL) wear, dehydration needs to be tailored to avoid dryness and related symptoms. In this view, this work aims to assess and compare the in-vitro dehydration kinetics of five CL materials, including the newly developed Kalifilcon A CL. At 36 °C and 60% relative humidity, the in-vitro dehydration kinetics of the different CLs were compared using a gravimetric method. CLs were analyzed either after a rinse of a few seconds in preservative-free saline solution or after a 24-h incubation in the same solution. A model based on the Fick diffusion equation was employed to deduce a water kinetics coefficient, providing insights into water diffusion within the polymeric matrix. The study reveals that all materials exhibit a non-Fickian dehydration behavior, with significant differences in dehydration kinetics coefficients and dehydration rate slopes. Etafilcon A and Omafilcon A, both hydrogel CLs, exhibit a similar behavior, different compared to the pattern shown by Senofilcon A and Delefilcon A, silicone-hydrogel CLs. Notably, Kalifilcon A, despite being a silicone-hydrogel, displays a hydration behavior reminiscent of hydrogel CLs.

Sodium acetate-based thermochemical energy storage with low charging temperature and enhanced power density

The electrification of heat necessitates the development of innovative domestic heat batteries to effectively balance energy demand with renewable power supply. Thermochemical heat storage systems show great promise in supporting the electrification of heating, thanks to their high thermal energy storage density and minimal thermal losses. Among these systems, salt hydrate-based thermochemical systems are particularly appealing. However, they do suffer from slow hydration kinetics in the presence of steam, which limits the achievable power density. Additionally, their relatively high dehydration temperature hinders their application in supporting heating systems. Furthermore, there are still challenges regarding the appropriate thermodynamic, physical, kinetic, chemical, and economic requirements for implementing these systems in heating applications. This study analyzes a proposal for thermochemical energy storage based on the direct hydration of sodium acetate with liquid water. The proposed scheme satisfies numerous requirements for heating applications. By directly adding liquid water to the salt, an unprecedented power density of 5.96 W/g is achieved, nearly two orders of magnitude higher than previously reported for other salt-based systems that utilize steam. Albeit the reactivity drops as a consequence of deliquescence and particle aggregation, it has been shown that this deactivation can be effectively mitigated by incorporating 10 % silica, achieving lower but stable energy and power density values. Furthermore, unlike other salts studied previously, sodium acetate can be fully dehydrated at temperatures within the ideal range for electrified heating systems such as heat pumps (40 °C – 60 °C). The performance of the proposed scheme in terms of dehydration, hydration, and multicyclic behavior is determined through experimental analysis.

Dehydration behaviour of some potato cultivars with high content of antioxidants

Dehydration behaviour of some potato cultivars with high content of antioxidants

Molecular insight into the separation mechanism of crown Ether-Based channels for lithium Extraction

The shortage of lithium resources can be effectively improved by using membrane separation technology to extract lithium from salt lake brines that contain rich Li. In this study, GO modified with functionalized crown ether group (2)-hydroxymethyl-15-crown-5,15C) was used as a separation membrane for Li+/Mg2+. The effect of 15C and its content on the separation mechanism of Li+/Mg2+ in membrane was designed and studied by molecular dynamics simulation. Improving water permeability of the membrane can be achieved with the appropriate amount of 15Cs, but an excessive amount of 15C will result in channel obstruction, which is not conducive to the transport of water molecules. In addition, the special recognition of Li+ by 15Cs enhances the transmission of Li+ within the channel. Finally, it is found that the dehydration behavior of Li+ is facilitated by the interaction between 15Cs and Li+. As the diameter of Li+ is smaller than the diameter of the 15C cavity, dehydrated Li+ passes through the 15C cavity with ease under pressure. This means that during the separation process, Li+ enters a “dual transport” mode. The membrane gains higher permeability for Li+ while blocking Mg2+. This study clarifies the rapid transport mechanism of Li+ in GO-15C，which provides a feasible strategy for designing highly selective Li+/Mg2+ separation membranes.

Density Functional Theory and Density Functional Tight Binding Studies of Thiamine Hydrochloride Hydrates.

Thiamine hydrochloride (THCL), also known as vitamin B1, is an active pharmaceutical ingredient (API), present on the list of essential medicines developed by the WHO, which proves its importance for public health. THCL is highly hygroscopic and can occur in the form of hydrates with varying degrees of hydration, depending on the air humidity. Although experimental characterization of the THCL hydrates has been described in the literature, the questions raised in previously published works suggest that additional research and in-depth analysis of THCL dehydration behavior are still needed. Therefore, the main aim of this study was to characterize, by means of quantum chemical calculations, the behavior of thiamine hydrates and explain the previously obtained results, including changes in the NMR spectra, at the molecular level. To achieve this goal, a series of DFT (CASTEP) and DFTB (DFTB+) calculations under periodic boundary conditions have been performed, including molecular dynamics simulations and GIPAW NMR calculations. The obtained results explain the differences in the relative stability of the studied forms and changes in the spectra observed for the samples of various degrees of hydration. This work highlights the application of periodic DFT calculations in the analysis of various solid forms of APIs.

Mathematical Modelling, Drying Behavior, and Quality Investigation of the Turkey Berry in a Fluidized Bed Dryer

The dehydration behavior of turkey berries was analysed in a fluidized bed dryer at various inlet air velocities (0.8, 2.1, and 3.4 m/s) and temperatures (50, 60, and 70°C). The drying parameters and physiochemical values of fruits were extensively studied, as were the moisture content, rate of drying, moisture diffusivity of the sample, shrinking percentage, color variations, retention of vitamin C, β-carotene, antioxidant capacity, and total phenolic content. The activation energy varies between 36.82 and 45.63 kJ/mol under different bed conditions. According to the experimental results, it has been observed that the maximum moisture diffusion rate was 2.898 × 10−10 m2/s and maximum retention rates of vitamin C, β-carotene, antioxidant capacity, and total phenolic content were 1.91 mg/100 g d.m, 184 μg/100 g d.m, 21.34 mg AAE/100 g d.m, and 513 mg GAE/100 g, during the drying of the sample at 70°C and 3.4 m/s. The minimum shrinkage (49.1%) and color variation (ΔE = 11.08) were detected at 3.4 m/s and 70°C. The Midilli et al. model was fitted, which is the most preferable model for predicting the dehydration characteristics of turkey berries.

Humidity- and temperature-dependent study of YUG type zeolite. A new dehydrated topology

The dehydration and hydration behaviour of a natural zeolite with YUG framework type was investigated as a function of water vapour pressure (PH2O) and temperature (T) by in situ single crystal X-ray diffraction. The chemical composition of the sample is CaAl2Si6O16∙nH2O, with n varying as a function of T and PH2O. Under ambient conditions (T = 302 K and relative humidity RH = 60%) the structure contains 4 H2O per formula unit. After exposure to dry air for 30 min, 1 H2O is released. Prolongation of the exposure time to 60 min does not induce further dehydration. The H2O can easily be up taken by exposing the crystal to ambient conditions for few minutes.The temperature-dependent experiments were conducted under N2 flow from 299 to 673 K, in steps of 50 K. In the investigated T range, the unit-cell volume is reduced by 13% and the space group Pc is maintained. Two main structural changes were observed: i) at 523 K, the release of 2.5 H2O is accompanied by the doubling of one unit-cell parameter (a-axis); ii) at 573 K, the structure becomes anhydrous, the c-axis triples, and two T-O-T connections of the framework break, leading to the formation of an interrupted framework. This topology (called HT-B phase) was never reported before. Moreover, the breaking process takes place by a different mechanism with respect that reported for other zeolites, and it is here described for the first time.

Kinetic Study on the Dehydration Behavior of Titanium Dioxide as a Denitration Catalyst Carrier

The dehydration of titanium dioxide, which is the carrier for denitration catalysts, is a crucial control step in the preparation of functional materials and has an impact on the performance of the product. In this study, the kinetics of the dehydration behavior and reaction mechanism of titanium dioxide were investigated under different atmospheres by measuring the thermal analysis curve of titanium dioxide at different heating rates. The results indicate that the dehydration behavior of the catalyst carrier titanium dioxide is closely related to the calcination atmosphere. The dehydration rate differed for oxygen and no-oxygen atmospheres. Dehydration began quickly in an oxygenated atmosphere and then slowed down towards the end of the reaction, completing slowly in an oxygen-free atmosphere. Kinetic calculations were carried out using modeless and mode function methods. The results show that dehydration of titanium dioxide is consistent with the Avrami–Erofeev equation in an oxygen-containing atmosphere and with the power function rule in an oxygen-free atmosphere, with the process of dehydration being influenced by the formation and growth of crystal nuclei.

Preparation of C/M−S−H cementitious materials from phosphate tailings and their dehydration and hydration mechanism

Aiming to reduce the CO2 emission of the cement materials preparation, a novel strategy to fabricate C/M-S-H cementitious materials from phosphate tailings has been proposed. To reveal the dehydration and hydration behavior of C/M-S-H, an experimental program combining TG, XRD, SEM, and corresponding strength evaluation was performed. The agglomerate-shaped C-S-H and flake-shaped M-S-H were synthesized from phosphate tailings. The experimental results showed that the rehydration capacity of C-S-H increased and then decreased with the rise in temperature (200–600 °C). The basic structural framework of M-S-H was maintained below 400 °C and disrupted at 600 °C, where the rehydration capacity decreased sharply. The dehydrated M-S-H showed a structural recovery after rehydration. However, dehydrated C-S-H formed dense C-S-H particles on the surface after rehydration, increasing the accumulation volume in this region and improving early strength. Ultimately, appropriate dehydration temperatures and additions could increase early hydration reactivity, thereby enhancing the concrete.

Alterations promoted by acid straightening and/or bleaching in hair microstructures.

Human hair is a biopolymer constituted mainly of keratin intermediate filaments, lipids, pigments and water. Cosmetic treatments usually interact with the hair at the molecular level, inducing changes in its components and modifying the physicochemical and mechanical properties of the fibers. Here, the effect of acid straightening on the morphology and ultrastructure of Caucasian hair was investigated by a group of complementary experimental methods: wide-, small- and ultra-small-angle X-ray scattering; high-resolution 3D X-ray microscopy; quasi-elastic neutron scattering and inelastic neutron scattering; thermogravimetry-mass spectrometry; and differential scanning calorimetry (DSC). X-ray diffraction patterns showed that acid straightening associated with a flat iron (∼180°C) changed the cortex of the fiber, shown by denaturation of the intermediate filaments (measured by DSC). The increase in the spacing of the lipid layers and the observation of the dehydration behavior of the fiber provided indications that water may be confined between these layers, while neutron spectroscopy showed alterations in the vibration mode of the CH2 groups of the lipids and an increase of the proton (H+) mobility in the hair structure. The latter may be associated with the extremely low pH of the formulation (pH ≃ 1). Additionally, this investigation showed that bleached hair (one-time bleached) is more damaged by the action of acid straightening than virgin hair, which was shown by a threefold increase in the percentage of total porosity of the tresses. The obtained results demonstrate that the investigation approach proposed here can provide very important thermodynamic and structural information on induced changes of hair structure, and certainly can be applied for the evaluation of the action mode and efficiency of cosmetic treatments.

Hydration and dehydration behaviors of poly(N-isopropylacrylamide)-grafted silica beads

The use of poly(N-isopropyl acrylamide) (PNIPAAm) in thermoresponsive interfaces for biomedical applications has been extensively investigated. Understanding the hydration and dehydration characteristics of PNIPAAm-grafted interfaces is crucial for the development of highly functional thermoresponsive interfaces. In this study, four PNIPAAm-grafted silica beads were prepared using atom transfer radical polymerization and radical polymerization techniques, with varying amounts of PNIPAAm grafted onto the beads. These PNIPAAm-grafted silica beads were used as samples, and their hydration and dehydration behaviors were analyzed using FTIR spectroscopy. Through the analysis of FTIR spectra obtained from the PNIPAAm-grafted silica beads prepared in this study, distinct observations were made under varying relative humidity and temperature conditions. Specifically, an elevation in the peak intensity of the broad peak at 3700–3000 cm−1, associated with the O-H group of hydrated water on PNIPAAm, was noted at higher humidity levels at 10°C. This increase in humidity resulted in an amplified peak intensity at 3700–3000 cm−1, indicative of the presence of the hydrated water molecules bonded to the PNIPAAm. Concurrently, shifts in the amide I and II peaks were observed with increasing relative humidity, signifying enhanced hydration and increased hydrogen bonding to C=O and N-H groups. Conversely, increasing the temperature at relatively high humidity led to a decreased in the intensity of the broad peak at 3700–3000 cm−1; this was attributed to the dehydration of the grafted PNIPAAm and subsequent water loss. The dehydration of PNIPAAm resulted in significant peak shifts for the amide I and II peaks, indicating a decrease in hydrogen bonding with the amide group. A significant change in peak intensity and shifts were evident, underscoring PNIPAAm brush's heightened propensity for hydration. These findings confirm the effectiveness of FTIR spectroscopy as a valuable approach for studying the hydration and dehydration behaviors of thinly grafted PNIPAAm layers on substrates.

Hot-air drying behavior of lignite and quantitative characterization for its surface damage

Cracking and fragmentation problems that occur during lignite drying limit its utilization value. In this study, the dehydration, surface damage, and pulverization behaviors of lignite were investigated under hot-air drying conditions, and the effect of the dewatering process on shrinkage cracking was analyzed. Cracks first appear at the edges of the lignite, then gradually extend inward until they spread over the entire surface of the lignite, before beginning to shrink, and eventually stabilize. The crack rate exhibited three stages: rapid development, shrinkage, and stabilization. The crack rate and shrinkage percentage increased significantly with increase in the drying temperature. The moisture content had a greater influence on the crack rate and shrinkage percentage of the samples than the surface temperature. A uniaxial compression test revealed that lignite with different degrees of dryness exhibited different degrees of breakage. The drying process drives the lignite toward finer grain sizes and, with moisture content below 0.8 g/g, the degree of breakage increases significantly. Thus, the main factor affecting the shrinkage and cracking of lignite was the moisture content. Cracks occurred when the tensile strain caused by shrinkage was greater than the tensile strength of the lignite.

Experimental and numerical studies of Ca(OH)2/CaO dehydration process in a fixed-bed reactor for thermochemical energy storage

The Ca(OH)2/CaO thermochemical energy storage (TCES) system based on calcium looping has received extensive attention owing to its high energy storage density, prolonged energy storage time, and environmental friendliness. The heat storage process of the Ca(OH)2/CaO TCES system in a mixed heating reactor was evaluated in this study, by employing a combination of direct and indirect heating modes. The dehydration process was studied experimentally, and a numerical model was established and verified based on the experimental results. The dehydration behavior of 500 g of Ca(OH)2 powder was investigated in a fixed-bed reactor with mixed heating. The experimental and simulation results indicated that mixed heating causes combined centripetal and horizontal propulsion. Heat input is the main limiting factor in the heat storage process, because the radial advance of the reaction is hindered by the low thermal conductivity of the solid reactant particles. Heat transmission partitions were added to enhance the performance of the reactor. The performance of the modified reactor was compared with that of a conventional reactor. The radial heat transmission partitions in the modified reactor effectively enhance the energy storage rate and reduce the reaction time by 59.5% compared with the reactor without partitions.

Drug Phase Transformation and Water Redistribution during Continuous Tablet Manufacturing: A Case Study of Carbamazepine Dihydrate.

In recent years, continuous tablet manufacturing technology has been used to obtain regulatory approval of several new drug products. While a significant fraction of active pharmaceutical ingredients exists as hydrates (wherein water is incorporated stoichiometrically in the crystal lattice), the impact of processing conditions and formulation composition on the dehydration behavior of hydrates during continuous manufacturing has not been investigated. Using powder X-ray diffractometry, we monitored the dehydration kinetics of carbamazepine dihydrate in formulations containing dibasic calcium phosphate, anhydrous (DCPA), mannitol, or microcrystalline cellulose. The combined effect of nitrogen flow and vigorous mixing during the continuous mixing stage of tablet manufacture facilitated API dehydration. Dehydration was rapid and most pronounced in the presence of DCPA. The dehydration product, amorphous anhydrous carbamazepine, sorbed a significant fraction of the water released by dehydration. Thus, the dehydration process resulted in a redistribution of water in the powder blend. The unintended formation of an amorphous dehydrated phase, which tends to be much more reactive than its crystalline counterparts, is of concern and warrants further investigation.