Mixture Of CaCl2 Research Articles

Effect of low-temperature plasma treatment of electrospun polycaprolactone fibrous scaffolds on calcium carbonate mineralisation.

This article reports on a study of the mineralisation behaviour of CaCO3 deposited on electrospun poly(ε-caprolactone) (PCL) scaffolds preliminarily treated with low-temperature plasma. This work was aimed at developing an approach that improves the wettability and permeability of PCL scaffolds in order to obtain a superior composite coated with highly porous CaCO3, which is a prerequisite for biomedical scaffolds used for drug delivery. Since PCL is a synthetic polymer that lacks functional groups, plasma processing of PCL scaffolds in O2, NH3, and Ar atmospheres enables introduction of highly reactive chemical groups, which influence the interaction between organic and inorganic phases and govern the nucleation, crystal growth, particle morphology, and phase composition of the CaCO3 coating. Our studies showed that the plasma treatment induced the formation of O- and N-containing polar functional groups on the scaffold surface, which caused an increase in the PCL surface hydrophilicity. Mineralisation of the PCL scaffolds was performed by inducing precipitation of CaCO3 particles on the surface of polymer fibres from a mixture of CaCl2- and Na2CO3-saturated solutions. The presence of highly porous vaterite and nonporous calcite crystal phases in the obtained coating was established. Our findings confirmed that preferential growth of the vaterite phase occurred in the O2-plasma-treated PCL scaffold and that the coating formed on this scaffold was smoother and more homogenous than those formed on the untreated PCL scaffold and the Ar- and NH3-plasma-treated PCL scaffolds. A more detailed three-dimensional assessment of the penetration depth of CaCO3 into the PCL scaffold was performed by high-resolution micro-computed tomography. The assessment revealed that O2-plasma treatment of the PCL scaffold caused CaCO3 to nucleate and precipitate much deeper inside the porous structure. From our findings, we conclude that O2-plasma treatment is preferable for PCL scaffold surface modification from the viewpoint of use of the PCL/CaCO3 composite as a drug delivery platform for tissue engineering.

Vaporization Behavior of Cs, K, and Na in Cs-Containing Incineration Bottom Ash during Thermal Treatment with CaCl2 and CaO

The vaporization behaviors of the alkali metals Cs, K, and Na were investigated at 900, 1000, and 1100 °C in a lab-scale electrical-heating horizontal furnace using a Cs-doped ash with the addition of CaCl2 and/or CaO. Knudsen effusion mass spectrometry was employed to measure the vaporization of the alkali metals in the Cs-doped ash with CaO under a high vacuum. Molecular beam mass spectrometry was used online to measure their vaporization from the Cs-doped ash with either CaCl2 or a mixture of CaCl2 and CaO. The addition of CaO caused some vaporization of these elements, which was probably due to the replacement of the Cs+, K+, and Na+ cations in aluminosilicates with Ca2+ cations during the thermal treatment. The vaporization propensity of the three elements followed the sequence of Cs > K > Na. The vaporization of Cs, K, and Na were observed during a thermal treatment with CaCl2. An increase in the content of CaCl2 or the reaction temperature facilitated the vaporization of Cs, K, and Na. O2 and H2O i...

Gelation of commercially available mineral oils by lecithin and CaCl2 mixture

We describe the gelation of commercially available mineral oils used in cell cultures, food preparations and cosmetics. The addition of lecithin and CaCl2 mixtures (<5wt%) to mineral oils induced the gelation of the mineral oils by controlling the molar ratio of lecithin and CaCl2. The formation of the gels is believed to reflect the entanglement of reverse cylindrical micelles created by interactions between the lecithin and CaCl2. The rheological properties of the gels were studied by analyzing dynamic and steady rheology data, and FTIR techniques were used to clarify the interactions between the headgroups of lecithin and CaCl2. In addition, we showed that mineral oil gels were readily ungelled (liquefied) by the addition of an ungelling agent, such as a small amount of ethanol, or by heating.

Permeation mechanism and interplay between ions in nanofiltration

Nanofiltration (NF) is widely used today for water purification, however, governing physical mechanisms are still largely unclear and predictive modeling remains a challenge, especially, for mixed ionic solutions. The current study systematically investigates NF of binary mixtures of NaCl and CaCl2 with the purpose to understand the mechanisms and interplay between different ions in the membrane. Using extensive filtration data and the Nernst-Planck relations, the paper concludes that (a) the standard mean-field models based on an average Donnan potential are unsuitable for describing ion permeation in NF; (b) the observed ranking of ion permeabilities (Na+ > Cl- > Ca2+) points to the solvation (Born) energy rather than interaction with fixed charges as the main factor controlling ion permeation; (c) the fixed charges are largely neutralized by pairing with counter-ions, which reduces their role in ion permeation; (d) saturation of Ca2+ uptake and its competition with Na+ for pairing with fixed charges may explain the unusual decrease of Ca2+ permeability with Ca2+ concentration and its strong effect on Na+ permeability. These conclusions, inconsistent with the commonly used mean-field picture, strongly suggest the need to revise the current approach to NF modeling.

Enhancement of Cs vaporization from simulated granular ash through thermal treatment in N2 atmosphere with the addition of a mixture of CaCl2 and CaO

This study aims to clarify the vaporization propensity of Cs in simulated granular ash through thermal treatment in N2 atmosphere at 1100–1500 °C with the addition of a mixture of CaCl2 and CaO. XRD and XPS were employed to specify Cl-bearing species in the treated ash. The results indicated that CaCl2 addition facilitated the vaporization of Cs. The vaporization ratio of Cs as a function of temperature was nonlinear. The ash melt formed at 1400 °C constrained the diffusion of Cs species by blocking the pores and/or decreasing the surface area of the ash particles which, however, was compensated by increasing the temperature to 1500 °C. The addition of the mixture of CaCl2 and CaO highly promoted the vaporization of Cs in the ash compared to that of the addition of CaCl2. Formation of wadalite/igumnovite through chemical reactions among granular ash, CaCl2 and CaO, as well as more liquid produced by additional CaO, were in favor of the reaction of Cs with Cl, thereby synergistically promoting the Cs vaporization. Addition of the mixture of CaCl2 and CaO is highly recommended to remove Cs from Cs-contaminated incineration ash during thermal treatment.

Performance analysis of multi-salt sorbents without sorption hysteresis for low-grade heat recovery

Abstract Three types of consolidated compact composite multi-salt sorbents are studied, which are mixtures of NH4Cl, CaCl2 and MnCl2 with different proportions. The Clapeyron curves under non-equilibrium conditions and isobaric sorption/desorption curves are tested. The multi-salt sorbents show combining properties of NH4Cl, CaCl2 and MnCl2 at different temperatures. One distinguished feature of these three types of multi-salt sorbents is the disappearance of sorption hysteresis. However, there are some differences in cycle sorption quantities, which may influence refrigeration and energy storage performances for different types of multi-salt sorbents. The behaviors of different types of sorption working pairs are analyzed for continuous sorption refrigeration cycle and energy storage system. Results indicate that the multi-salt sorbents are more suitable for variable temperature heat source and low-grade heat recovery than single salt sorbents. The NH4Cl/CaCl2/MnCl2 mixture with the mass ratio of 1:3:2 generates more cooling power than the other two with similar coefficient of performance (COP), while the multi-salt sorbent with the mass ratio of 3:2:1 is optimal for the thermochemical sorption energy storage system. Analysis of exergy efficiency and exergy destruction also shows that the multi-salt sorbents adapt better for low temperature low-grade heat.

The impact of monovalent and divalent ions on wettability alteration in oil/low salinity brine/limestone systems

Waterflooding is applied worldwide to improve oil recovery. Due to the complexity of the crude oil-brine-rock interactions, the mechanism behind the low saline enhanced oil recovery (EOR) process has been debated in the literature for the last decade. Both physical and chemical mechanisms have been proposed, but it appears that none of the suggested mechanisms have got a general acceptance in the scientific literature so far. The main objective of this paper is to investigate the affinity of ions toward the surface during low and high salinity injection by measuring the contact angle (CA) and interfacial tension (IFT) in a carbonate rock substrate/oil/brine system, in different salinity and pH levels. The brines were original sea and formation water, brine solutions containing single component salt such as; MgSO4, KCl, Na2SO4, CaCl2, MgCl2, NaCl, and multicomponent mixtures of them at different concentrations. Three different stock-tank crude oils are utilized in this study. Results showed that the asphaltenic-acidic crude oils have a positive impact to wettability alteration of carbonate rocks during low salinity water injection. Also we observed that the low salinity waterflooding possibly behaving similar to alkaline flooding due to increase in pH. The IFT results show that the lowest IFT value is obtained at 5000ppm smart water containing divalent ions, Mg2+ and SO42−.

Sorption of ionic and nonionic organic solutes onto giant Miscanthus-derived biochar from methanol-water mixtures

The sorption of naphthalene (NAP) and 1-naphthoic acid (1-NAPA) onto giant Miscanthus–derived biochar was investigated in methanol volume fractions (fc) of 0–0.6 as a function of ionic composition (5mM CaCl2 and 10mM KCl) and liquid pH (2 and 7). The sorption onto biochar was nonlinear with 0.42≤N≤0.95; thus, a concentration-specific sorption constant (Km) was compared. The Km log linearly decreased with increasing fc, except for 1-NAPA from a CaCl2 mixture at pH7. Isotherm data was fitted with a cosolvency sorption model through which the slope (ασ) of the inverse log linear Km-fc plot and empirical constant (α) were obtained. NAP sorption was well described by the cosolvency model with the α value being 0.41–0.53, indicating a methanol–biochar interaction favoring more sorption than the cosolvency based prediction. In particular, the slope (ασ) of 1-NAPA was lower than that of NAP, indicating less reduction of 1-NAPA sorption (i.e., lower α value) by methanol. In comparison with other sorbents, the α value was approximately intermediate between a humic substance and kaolinite clay. An analysis of FT-IR spectra suggested the transformation of O-containing functional groups by methanol, which will subsequently boost the π–π interaction between an organic solute and biochar. Moreover, Ca2+-induced sorption between anionic 1-NAPA and a negatively charged biochar surface was also fortified in the methanol mixture. The results revealed unexplored cosolvent effects on organic solute sorption onto biochar and identified the hydrophobic and hydrophilic sorption moieties of biochar as affected by the cosolvent.

In-vitro assessment of the effect of dabigatran on thrombosis of adult and neonatal plasma: comparisons using thromboelastography and microscopic visualization of fibrin clot structure.

: Thromboelastography (TEG) is a global assay used for evaluating features of clot formation in vitro. Dabigatran is a reversible direct inhibitor of thrombin that has not been studied in neonates using a sophisticated global assay, such as TEG. Neonatal hemostasis differs from adult hemostasis in both quantitative and qualitative characteristics. Our aim was to compare the TEG clotting profile of neonatal and adult platelet-poor plasma when exposed to different concentrations of dabigatran. We used commercially collected adult pooled plasma and neonatal cord blood collected from placentas of healthy full term newborns. Platelet-poor plasma was isolated, pooled, and frozen. Prior to experiment, plasma was thawed and filtered. A reaction mixture of CaCl2, corn trypsin inhibitor, tissue factor, and dabigatran in imidazole buffer was mixed with plasma in a TEG cup. Time to clot initiation (R-time), speed of clot strengthening (α-angle), and maximum clot strength (maximal amplitude) were measured. Scanning electron microscopy was performed to evaluate fibrin clot structure. Without dabigatran, there was no significant difference in TEG measurements between neonatal and adult samples. However, neonatal plasma clotting with dabigatran had slower onset, slower speed, and weaker clots that were more porous with thicker fibers, compared with adult plasma clotting. Thus, neonatal plasma may be more sensitive to dabigatran as assessed by our in-vitro TEG study.

First-Principles Study of Chemical Mixtures of CaCl2 and MgCl2 Hydrates for Optimized Seasonal Heat Storage.

Chloride-based salt hydrates form a promising class of thermochemical materials (TCMs), having high storage capacity and fast kinetics. In the charging cycles of these hydrates however hydrolysis might appear along with dehydration. The HCl produced during the hydrolysis degrades and corrodes the storage system. Our GGA-DFT results show that the enthalpy charge during proton formation (an important step in hydrolysis) is much higher for CaCl2·2H2O (33.75 kcal/mol) than for MgCl2·2H2O (19.55 kcal/mol). This is a strong indicator that hydrolysis can be minimized by appropriate chemical mixing of CaCl2 and Mg Cl2 hydrates, which is also confirmed by recent experimental studies. GGA-DFT calculations were performed to obtain and analyze the optimized structures, charge distributions, bonding indicators and harmonic frequencies of various chemical mixtures hydrates and compared them to their elementary salts hydrates. We have further assessed the equilibrium products concentration of dehydration/hydrolysis of the chemical mixtures under a wide range of operating conditions. We observed that chemical mixing leads to an increase of the onset hydrolysis temperature with a maximum value of 79 K, thus increasing the resistance against hydrolysis with respect to the elementary salt hydrates. We also found that the chemical mixing of CaCl2 and MgCl2 hydrates widens the operating dehydration temperature range by a maximum value of 182 K (CaMg2Cl6·2H2O) and lowers the binding enthalpy with respect to the physical mixture by ≈65 kcal/mol for TCM based heat storage systems.

A calcium chloride hexahydrate/expanded perlite composite with good heat storage and insulation properties for building energy conservation

A porous supporting matrix, expanded perlite (EP) is composited with a salt hydrate mixture of CaCl2·6H2O and SrCl2·6H2O (98:2 in mass ratio), to develop a nonflammable thermal storage material for building use. The salt hydrate is uniformly adsorbed on sheets of EP, and a maximum absorption capacity test shows EP can contain as high as 55 wt% the salt hydrate and keep the stable form. It is shown that the melting temperature of the composite PCM is 27.38 °C, close to that of CaCl2·6H2O, and its latent heat is 87.44 J/g, equivalent to the calculated value based on the mass fraction of CaCl2·6H2O in the composite. EP further reduces the salt hydrate thermal conductivity by over 70% to enhance its thermal insulation, and suppresses the supercooling. A 1000 heating-cooling cycles test verifies the CaCl2·6H2O/EP composite possesses good thermal reliability. The CaCl2·6H2O/EP composite is then fabricated into a board for replacing the foam board employed as the core in a commercial foam insulating brick to obtain a PCM brick. It is found that, when applied as the roof of a test room, the PCM brick has the function of decreasing the indoor peak temperature and causing the hysteresis in the indoor temperature rise, compared with the foam insulation brick. The nonflammability along with good thermal storage and insulation properties makes the CaCl2·6H2O/EP composite PCM show great promises for use in building energy conservation.

The Use of Silicon Wafer Barriers in the Electrochemical Reduction of Solid Silica to Form Silicon in Molten Salts

Nowadays, silicon is the most critical element in solar cells and/or solar chips. Silicon having 98 to 99% Si as being metallurgical grade, requires further refinement/purification processes such as zone refining [1,2] and/or Siemens process [3] to upgrade it for solar applications. A promising method, based on straightforward electrochemical reduction of oxides by FFC Cambridge Process [4], was adopted to form silicon from porous SiO2 pellets in molten CaCl2 and CaCl2-NaCl salt mixture [5]. It was reported that silicon powder contaminated by iron and nickel emanated from stainless steel cathode, consequently disqualified the product from solar applications. SiO2 pellets sintered at 1300oC for 4 hours, were placed in between pure silicon wafer plates to defeat the contamination problem. Encouraging results indicated a reliable alternative method of direct solar grade silicon production for expanding solar energy field.

Silica Polymerization from Supersaturated Dilute Aqueous Solutions in the Presence of Alkaline Earth Salts.

The early stages of silica polymerization in aqueous solution proceed according to a mechanism based on three steps: nucleation, particle growth, and agglomeration of the particles. Application of time-resolved static and dynamic light scattering as a powerful in situ technique in combination with spectrophotometric analysis of the monomer consumption based on the molybdenum blue method was carried out to further investigate this 3-step process. Experiments were carried out at four different initial silicic acid contents covering a range between 350 and 750 ppm in the presence of either 10 mM NaCl or 5 mM of a mixture of CaCl2 and MgCl2. The process in all cases was initiated with a drop of pH to 7. Addition of the salts made possible an analysis of the impact of an electrolyte on the process. Independent of the presence or absence of salt, particle growth in step two proceeded as a monomer-addition process without being interfered significantly by Ostwald-ripening. The growing particles were compact with a homogeneous density. The size of the particles approached final values between 5 and 20 nm with the actual value increasing with decreasing initial silicic acid content. Above a certain concentration of initial silica content, which depends on the level of added salt, particle-particle interactions caused agglomeration. The presence of electrolyte shifted this level from ∼2000 ppm to a range between 500 and 750 ppm. The resulting agglomerates had a fractal dimension of 2. Independent of the conditions, particle growth could be described with a simple nucleation and growth model.

Electrochemical Reduction of Solid Silica to Form Silicon in Molten Salts

Nowadays, Silicon is the most critical element in solar cells and/or solar chips. Silicon having 98 to 99% Si as being metallurgical grade, requires further refinement/purification processes such as zone refining [1,2] and/or Siemens process [3] to upgrade it for solar applications. A promising method, based on straightforward electrochemical reduction of oxides by FFC Cambridge Process [4], was adopted to form silicon from porous SiO2 pellets in molten CaCl2 and CaCl2-NaCl salt mixture [5]. It was reported that silicon powder contaminated by iron and nickel emanated from stainless steel cathode, consequently disqualified the product from solar applications. SiO2 pellets sintered at 1300oC for 4 hours, were placed in between pure silicon wafer plates to defeat the contamination problem. Encouraging results indicated a reliable alternative method of direct solar grade silicon production for expanding solar energy field.[1] P.R. Mei, S.P.Moreira, E.Cardoso, A.D.S.Cortes, F.C.Marques, “Purification of metallurgical silicon by horizontal zone melting”, Sol. Energ. Mat. Sol., 98 (2012), 233-239. [2] P. Siffert, E.F. Krimmel, eds. Silicon: Evolution and future of a technology. Berlin,Springer (2004). [3] Siemens & Halske: BRD Patents 1.102.117 and 1.140.1594 filed 1954, issued 1956 [4] G.Z. Chen, D. J. Fray, T. W. Farthing, “Direct Electrochemical Reduction of Titanium Dioxide to Titanium in Molten Calcium Chloride”, Nature, 407 (2000), 361-364. [5] E. Ergül, İ. Karakaya, M. Erdoğan, “Electrochemical decomposition of SiO2 pellets to form silicon in molten salts” Journal of Alloys and Compounds, 509 (2011), 899-903.

Taurine Reverses Atrial Structural Remodeling in Ach-Cacl2 Induced Atrial Fibrillation Rats.

Taurine has been reported to have anti-arrhythmia effects, but the anti-atrial fibrillation (AF) effects and its mechanism remain incompletely understood. In the present study, the therapy effects and partly mechanisms were investigated. AF animal model was established by intravenous administered with the mixture of acetylcholine (Ach) and CaCl2 (66 μg/mL + 10 mg/mL) (i.v.) for 7 days. The actions of taurine (99 mg/kg∙d, introgastric administration) on the levels of Hs-CRP, IL-6, TNF-α, MMP-9, AngII, the extent of the fibrosis and ultrastructural changes in left atrial were studied. The data showed that the serum levels of TNF-α, IL-6, AngII and the plasma levels of Hs-CRP and MMP-9 were significantly elevated in automatic recovery group relative to the control group (p < 0.01), which were all decreased by taurine administration (p < 0.01) similar to Verapamil treatment. Masson's trichrome staining of the left atrial tissue showed an obvious interstitial fibrosis in rats of automatic recovery group. The alteration could be reversed by additional taurine. Electron microscopy revealed that taurine administration could significantly alleviate the ultrastructural damage of atrial cells, and the effects were similar to the Verapamil treatment. In conclusion, the results suggested that taurine could inhibit the structural remodeling of AF in rats partly by decreasing the levels of inflammatory factors and profibrotic molecules, attenuating the extent of myocardial fibrosis and protecting the integrity of myocardial ultrastructure.

Sifat Fisis dan Mekanis Papan Semen dari Serat Tandan Kosong Kelapa Sawit (The Physical and Mechanical Properties of Cement Board Made from Oil Palm Empty Fruit Bunches Fibers)

Oil palm empty fruit bunches (OPEFB) fiber were industrial waste that has not been widely used by the community, only stacked and cause odors that interfere with the surrounding environment. This research studied the utilization of OPEFB fiber for cement board products using cement as resin and CaCl2 as accelerator. Laboratory scale cement board made from OPEFB fiber were mixed with cement, and CaCl2. The composition of fiber and cement were 1:1, 1:1.5, 1:2, and CaCl2 variations were 0%, 1% and 3%. A mixture of fibers, cement and CaCl2 was compressed at the pressure of 4 ton for 24 hours. The cement boards were tested for physical and mechanical properties according to JIS A 5417-1992, and the results were compared to the requirements of the cement board JIS A 5417-1992. Cement board made from fiber and cement composition 1:1.5 and CaCl2 content 3% produced moisture content, thickness swelling, water absorption, density, modulus of rupture/MOR, modulus of elasticity/MOE and screw withdrawal strength that met the requirement of JIS A 5417-1992. The composition of fiber and cement and the variations of CaCl2 content produced significant effect on water content, water absorption, thickness swelling, modulus of rupture/MOR, modulus of elasticity/MOE and screw withdrawal strength on cement boards.Keywords : oil palm empty fruit bunches fiber, cement boards, physical and mechanical properties

Optical and Scintillation Properties of CsCaCl3-Based Crystals

A scintillation detector is composed of a scintillator, which converts absorbed ionizing radiation into multiple low energy (~eV) photons, and a photomultiplier tube (PMT), avalanche photodiode, or Si-PMT, which can convert the photons into an electrical signal. The performance of the scintillation detector depends greatly on the characteristics of the scintillator. Inorganic scintillators are widely used for detecting high-energy photons such as X-rays and gamma-rays. Eu-doped CsCaCl3 has been reported to display excellent properties because of the 4f65d1–4f7 transitions of Eu2+ [1]. CsCaCl3:Eu exhibits a 4f65d1–4f7 luminescence peak at 450 nm , with a high light yield (18,000 photons/MeV). Further, undoped CsCaCl3 is known to have a small scintillation decay time constant because of their Auger-free luminescence [2]. In this study, CsCaCl3 is used as the host material and luminescence and scintillation properties of CsCaCl3 crystals doped with impurity ions such as Yb and Tl are investigated. Photoluminescence spectra, X-ray-excited radioluminescence spectra, scintillation temporal profiles, and pulse-height spectra (with 662 keV gamma-ray excitation from 137Cs) of the crystals are analyzed. Single crystals of Yb- and Tl-doped CsCaCl3 were prepared with the vertical Bridgman–Stockbarger method using a sealed quartz tube. Before crystal growth, stoichiometric mixtures of CsCl and CaCl2 were dried by heating overnight ~500 K in a vacuum. After growth, the crystals were cut and polished. The Figure shows the X-ray-excited radioluminescence spectra, measured at 300 K, for Yb- and Tl-doped CsCaCl3 crystals. In the spectrum of CsCaCl3:Yb, an intense emission band was observed at 437 nm with a shoulder at 409 nm. The emission band in the radioluminescence spectrum is consistent with that at 439 nm, with a shoulder at 409 nm, in the photoluminescence spectrum. As these emission bands have similarities with emission bands of a SrI2:Yb2+ crystal, the emission bands of the CsCaCl3:Yb crystal are attributed to spin-allowed and spin-forbidden Yb2+ 4f135d–4f14 transitions. In the spectrum of CsCaCl3:Tl, an emission band observed at 327 nm is similar to that at 336 nm in the photoluminescence spectrum. In a previous study of CsCl:Tl, an emission band at 340 nm is attributed to the triplet relaxed excited state of a Tl+ ion [3]. Thus, the emission band at 327 nm can be attributed to the same state. The pulse- height spectra of these crystals were measured with 662 keV gamma-ray excitation from 137Cs. Assuming a light yield of 40,000 photons/MeV for NaI:Tl [4], the light yield is estimated to be 3,800 and 4,300 photons/MeV for CsCaCl3:Yb and CsCaCl3:Tl, respectively. The lower light yields for these crystals can be attributed to the lower concentration of impurity ions. Thus, the light yields of these crystals can be improved by increasing the concentration of impurity ions.[1] M. Zhuravleva, B. Blalock, K. Yang, M. Koschan, and C. L. Melcher, J. Cryst. Growth 352, 115 (2012).[2] M. Koshimizu, N. Yahaba, R. Haruki, F. Nishikido, S. Kishimoto, and K. Asai, Opt. Mater. 36, 1930 (2014).[3] V. Nagirnyi S. Zazubovich, and N. Jaanson, Phys. Stat. sol. 175, (1993) 155. Figure 1

A DFT based equilibrium study of a chemical mixture Tachyhydrite and their lower hydrates for long term heat storage

Chloride based salt hydrates are promising materials for seasonal heat storage. However, hydrolysis, a side reaction, deteriorates, their cycle stability. To improve the kinetics and durability, we have investigated the optimum operating conditions of a chemical mixture of CaCl2 and MgCl2 hydrates. In this study, we apply a GGA-DFT to gain insight into the various hydrates of CaMg2Cl6. We have obtained the structural properties, atomic charges and vibrational frequencies of CaMg2Cl6 hydrates. The entropic contribution and the enthalpy change are quantified from ground state energy and harmonic frequencies. Subsequently, the change in the Gibbs free energy of thermolysis was obtained under a wide range of temperature and pressure. The equilibrium product concentration of thermolysis can be used to design the seasonal heat storage system under different operating conditions.

Thermochemical heat storage materials – Performance of mixed salt hydrates

Thermochemical heat storage is highly promising, in particularly with a view to long-term heat storage. For the implementation of heat storage in households, thermochemical reactions in the low temperature range below 120°C are important. Especially salt hydrates such as MgCl2, CaCl2 or MgSO4 were tested with micro gravimetric methods for their suitability. However, the cycle stability of consecutive charging (dehydration) and discharging (hydration) reactions of these materials was low and could be improved only by control of the water uptake (i.e. discharging time) to prevent overhydration. In contrast, mixtures of these salt hydrates showed significant improvements in cycle stability, mass and enthalpy balances. The experiments also showed that the cycleability of all investigated materials increased if hydration and dehydration reactions were performed under constant vapor pressure of 21mbar. Contrary to other materials, the mixture of CaCl2 and MgCl2 showed good cycleability under all tested conditions. In addition, the mixture showed superior kinetic properties. Additionally, there is evidence of tachyhydrite (CaMg2Cl6⋅12H2O) formation during cycling of the mixture by the use of XRD after the thermal analysis. Further investigations will be performed to identify further synergies, ideal mixing ratios and formed phases.

Lithium-free processing of silk fibroin

Silk fibroin protein was purified from Bombyx mori silkworm cocoons using a novel dialysis strategy to avoid fibroin aggregation and pre-mature formation of β-sheets. The degummed silk fibers were dissolved in Ajisawa's reagent, a mixture of CaCl2-EtOH-H2O, that is less expensive than lithium bromide. The dissolved solutions were dialyzed against either water or urea solution with a stepwise decrease in concentration. When the steps of 4 M-2 M-1 M-0 M urea (referred to as silk-TS-4210) were adopted, the purified silk fibroin had smaller aggregates (<10 nm), similar average molecular weight (225 kDa) and a lower content of β-sheet (∼15%) compared to the sample processing methods (silk-TS-210, 10, 0) studied here. This outcome was close to the fibroin purified by the lithium bromide (silk-Li-0) method. Polyvinyl alcohol-emulsified silk microspheres generated using the purified solution had a similar size distribution and morphology when compared to lithium bromide dissolved solutions, while glycerol-blended silk films showed different mechanical properties. The silk-Li-0 generated films with the highest breaking strength (5.7 MPa ± 0.3) while the silk-TS-4210 had the highest extension at break (215.1% ± 12.5). The films prepared from silk-TS-4210 were cytocompatible to support the adhesion and proliferation of human mesenchymal stem cells, with improvements compared to the other samples likely due to the porous morphology of these films.