Bromide Hydrate Research Articles

Carbon nanospheres derived from crop residues by acidic lithium bromide hydrate treatment

Exploring an efficient technique for carbon sphere preparation has attracted extensive attention. Herein, acidic lithium bromide hydrate (ALBH) was used in the hydrothermal carbonization (HTC) process to overcome the recalcitrance of lignocellulose, such that nano-carbon spheres were prepared at mild condition: 140 °C for 150 min with 0.8 M of HCl from 20-40 meshed corn stover. That carbon spheres showed decent morphology properties and abundant functional groups, which was better than that from pine and poplar wood. The corn stover derived carbon nanospheres could efficiently adsorb both heavy ions and methyl orange in wastewater. Meanwhile, the ALBH after reaction could be recovered and reused. Specifically, the morphologies and adsorption capability of the prepared carbon nanospheres using recovered ALBH were negligibly affected even after 5 cycles. These results verified the practical production of carbon nanospheres from lignocellulose at mild conditions, which provided more potential for the synthesis of novel biomass-based materials for comprehensive applications.

Hydration of bromide at reverse micelle interfaces studied by X-ray absorption fine structure

Nanoconfined water exhibits various interesting properties, which are not only of fundamental importance but also of practical use. Because reverse micelles (RMs) provide versatile ways to prepare nanoconfined water, the understanding of their physicochemical properties is essential for developing efficient applications. Although the water properties in the RMs could be affected by its interaction with the RM interface, the details have not been well understood. This study focuses on the local structures of Br− in hexadecyltrimethylammonium bromide (HTAB) RMs formed in chloroform and 10% hexanol/heptane. The dependence in Br− hydration on the molar ratio of water to HTAB (w) is investigated using X-ray absorption fine structure (XAFS). These systems cover a wide range of w values (0–30) and allow us to study the impact of this parameter on the local structure of Br− at the RM interface, which comprises water, surfactant headgroups, and organic solvent components. The presence of multiple scattering paths complicates the XAFS spectra and makes it difficult to analyze them using standard fitting methods. The linear combination of the spectra corresponding to the individual scattering paths captures the molecular processes that occur at the RM interface upon increasing w. The maximum hydration number of Br− is found to be 4.5 at w > 15, suggesting that although most of the ions remain at the interface as partly hydrated ions, some of them dissociate as completely hydrated ones.

Immunomodulatory, Antioxidant Activity and Cytotoxic Effect of Sulfated Polysaccharides from Porphyridium cruentum. (S.F.Gray) Nägeli.

Porphyridium cruentum is a unicellular microalga that can synthesize and secrete to the culture medium-high amounts of polysaccharides. In this study, the immunomodulatory, cytotoxic effect and antioxidant activity of the sulfated polysaccharides (PcSPs) were determinate. The PcSPs were precipitated with 2% Cetylpyridinium bromide hydrate and ethanol and purified by dialysis. The extract was lyophilized for its characterization by Fourier transform-Infrared (FT-IR) spectroscopy and gas chromatography–mass spectrometry (GC-MS). The antioxidant activity of PcSPs were examined with assay 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and compared with that of the biomass, observing significant differences between the results obtained from the PcSPs and biomass. To determine their ability to induce cytokine production Tumor Necrosis Factor alpha (TNF-α) and interleukina-6 (IL-6), the immunomodulatory activity of the PcSPs has been evaluated. In the mouse macrophage cell line (RAW 264.7), PcSPs are potent inducers of IL-6 cytokines but mainly of TNF-α. The cytotoxic capacity of PcSPs was measured by the MTT colorimetric assay in colorectal carcinoma (HTC-116), human leukemia (U-937 and HL-60), breast cancer (MCF-7), lung cancer (NCI-H460) and human gingival fibroblasts (HGF-1) cell lines. The IC50 value of 2311.20 µg mL−1, 1676.74 µg mL−1, 1089.63 µg mL−1, 5498.14 µg mL−1 and 2861.49 µg mL−1 respectively in the tumor lines and 5022.55 µg mL−1 in gingival fibroblasts were obtained. Our study suggested that PcSPs from P. cruentum have a moderate immunomodulatory and cytotoxic effect. The results obtained indicate that the polysaccharides from P. cruentum are potent inducers of IL-6 cytokines and, most importantly, of TNF-α. PcSPs showed no evidence of antigenic activity or hypersensitivity when administered intraperitoneally in mice. Furthermore, the in vivo study revealed an improvement of local inflammatory response against stress in the peritoneum. These findings suggest that the PcSPs from P. cruentum might have potential as a valuable ingredient in nutraceutical products.

LiBr hydrate as reaction medium for preparation of carbon spheres from wood powders via hydrothermal carbonization

In this work, a suitable solvent (Lithium Bromide Hydrate) was selected and used for the efficient dissolution and carbonization of biomass for the preparation of carbon spheres directly from wood powders by hydrothermal carbonization (HTC), which was so far the first successful attempt of making carbon spheres directly from woody biomass. The impacts of the preparation conditions on the yield and morphology of carbon spheres were carefully studied, and it was found that the yield and degree of carbonization of carbon spheres were positively correlated with the temperature and reaction time. The optimal operation conditions were determined as 170 °C, reaction time 5 h and LiBr concentration 65 wt%. And the produced carbon spheres have an average particle size of 603 nm with a yield of 22.4%. The characterization of carbon spheres revealed that the prepared nanoparticles had excellent spherical morphology and multifunctional groups, which led to a better surface reactivity than the raw material itself. Moreover, levulinic acid (LA) and 5-hydroxymethylfurfural (5-HMF) were found in the liquid phase of the reaction products, indicating the furan derivatives were formed in the HTC process, which demonstrated a great potential of biomass valorisation with this innovative process.

Disinfectant and antimicrobial susceptibility studies of the foodborne pathogen Campylobacter jejuni isolated from the litter of broiler chicken houses

Foodborne illness is an ongoing problem worldwide and is caused by bacteria that invade the food chain from the farm, slaughter house, restaurant or grocery, or in the home and can be controlled by strategies using biocides (antiseptics and disinfectants). Susceptibility profiles were determined for 96 Campylobacter jejuni strains obtained in 2011–2012 from broiler chicken house environments to antimicrobials and disinfectants as per the methods of the Clinical and Laboratory Standards Institute and TREK Diagnostics using CAMPY AST Campylobacter plates. Low prevalence of antimicrobial resistance was observed in C. jejuni strains to tetracycline (TET; 21.9%), ciprofloxacin (CIP; 13.5%), and nalidixic acid (NAL; 12.5%). The resistance profiles had a maximum of 3 antimicrobials, CIP-NAL-TET, with TET being the main profile observed. No cross-resistance was observed between antimicrobials and disinfectants. The C. jejuni strains (99%) were resistant to triclosan, 32% were resistant to chlorhexidine, and they all were susceptible to benzalkonium chloride. The strains had low-level minimum inhibitory concentrations (MICs) to the disinfectants P-128, Food Service Sanitizer, F-25 Sanitizer, Final Step 512 Sanitizer, OdoBan, dioctyldimethylammmonium chloride, didecyldimethylammonium chloride (C10AC), benzyldimethyldodecylammonium chloride (C12BAC), and benzyldimethyltetradecylammonium chloride (C14BAC). Intermediate MICs against DC&R, cetylpyridinium bromide hydrate, hexadecylpyridinium chloride, ethylhexadecyldimethylammonium bromide, and hexadecyltrimethylammonium bromide with elevated intermediate MICs against Tek-Trol, benzyldimethylhexadecylammonium chloride, tris(hydroxylmethyl)nitromethane (THN), and formaldehyde. The highest MIC were obtained for povidone-iodine. The components THN and the benzylammonium chlorides C12BAC and C14BAC were responsible for the inhibition by DC&R. The components C10AC and C12BAC may act synergistically causing inhibition of C. jejuni by the disinfectant P-128. The formaldehyde component in DC&R was not effective against C. jejuni compared with the ammonium chloride components. Its use in disinfectants may result in additional unnecessary chemicals in the environment. Didecyldimethylammonium chloride is the most effective ammonium chloride component against C. jejuni.

Effect of metal particles on promoting the nucleation of tetra-n-butylammonium semiclathrate hydrate

Abstract The formation of tetra-n-butylammonium bromide (TBAB) hydrate from a TBAB aqueous solution tends to show a supercooling phenomenon, which is non-ideal for the practical use of TBAB hydrate. However, as reported in the literature, the products obtained from the use of metal electrodes for the application of an electric field can accelerate the nucleation of the hydrate. Herein, we investigated the role of metal particles (Ag, AgBr, Zn, and ZnO) and their mixed forms (Ag–AgBr and Zn–ZnO) on promoting the nucleation of TBAB semiclathrate hydrate. The nucleation-promoting effect was most significant for the mixed metal particles when prepared by simultaneous grinding of the metal particle components. The changes in the physicochemical properties of the mixed metal particles as a result of grinding were believed to accelerate the nucleation of TBAB hydrate.

Ionic clathrate hydrates loaded into a cryogel – halloysite clay composite for cold storage

Mixed type phase change material (PCM) based on the tetra-n-butylammonium bromide (TBAB) hydrate loaded in a composite matrix included poly(vinyl alcohol) (PVA) and natural halloysite clay nanotubes can be used for the cold storage. Poly(vinyl alcohol) provides the formation of a cryogel, while the clay nanotubes promote the hydrate nucleation reducing the supercooling of the formed hydrate. At the same time, the cryogel formation ensures the sedimentation stability of halloysite inside the dispersion. The relationship between the concentration of the target compound in the initial solution, the presence/absence of halloysite, and specific enthalpy of the phase transition made it possible to optimize the properties of this material for cold storage. The formation of two hydrates in the systems under study with different water content as well as the possibility of recrystallization of the low content water hydrate into the high content water one and during the melting of ice was experimentally revealed. The obtained PCM melted at a temperature of 9–13 °C and had a melting enthalpy up to 196 J/g. It was shown that the halloysite is a nucleator for TBAB hydrates. Adding 1 mass% of halloysite to the composite increases the temperature of hydrate onset by 2 °C. The best thermal stability in an open system was shown for the 1:50 M ratio. The energy capacity of such material does not decrease during 50 cycles of the reversible melting-crystallization phase transition, which indicates the stability of the TBAB-PVA-halloysite system. As both halloysite clay nanotubes and poly(vinyl alcohol) cryogel are biocompatible, encapsulation of tetra-n-butylammonium bromide hydrate in such material will protect the environment from harmful effects of a quaternary ammonium salt and expand the scope of this cold accumulator. The halloysite as an additive for phase change composites is also low-cost, readily available from natural mineral deposits, and non-toxic.

Experimental study of the drilling process in hydrate-bearing sediments under different circulation rates of drilling fluid

Natural gas hydrate (NGH) is widely considered a potential alternative to traditional energy resources. Some countries are trying to exploit and utilize NGH. However, due to the sensitivity of the hydrate, and a lack of exploitation experience with the NGH, drilling in hydrate reservoirs is considered risky. In order to understand the disturbance effects of drilling fluid with different circulation rates on the hydrate-bearing sediments during the drilling process, a novel hydrate drilling experimental apparatus was used to study the drilling process in the hydrate-bearing sediments. Four drilling experiments were carried out in consolidated sediments containing Tetra-n-butyl ammonium bromide (TBAB) hydrate. The drilling fluid injection rate ranges from 500 to 1800 g/min. The results show that hydrate dissociation can be induced by the circulation of relatively high-temperature drilling fluid when drilling in hydrate-bearing sediments, and that the hydrate dissociation rate is greatly influenced by the circulation rate of the drilling fluid. The drilling fluid invasion area has a maximum as the experiment progresses. Increasing the drilling fluid circulation rate can enhance the sediment temperature rise rate, enlarge the hydrate dissociation region, and increase cumulative TBAB production. Drilling fluid with a relatively low circulation rate is beneficial to wellbore stability. These findings will provide help with drilling design suitable for hydrate-bearing sediments, and provide a scientific basis for achieving safe drilling in hydrate-bearing sediments.

A theoretical and experimental study of a TBAB salt hydrate based cold thermal energy storage in an air conditioning system

Various phase change materials (PCMs) have been studied in the past decade for cold thermal energy storage (CTES), among which semi-clathrate hydrates of quaternary ammonium salts have aroused great interests. Tetrabutylammonium bromide (TBAB) hydrates can form at temperatures applicable for air conditioning applications. Based on the results of former studies on a TBAB hydrate based PCMs, this paper investigates the influencing factors of a lab-scale CTES tank based on this self-developed PCM in an emulated air conditioning system. The effect of chilled water temperature and flowrate on charge, and the effect of return water flowrate and cooling load on discharge are experimentally studied. A model of the CTES was developed using ε-NTU method, through which its performance are evaluated in terms of charging/discharging rate, charging/discharging capacity and efficiency. In addition, influencing factors such as return water temperature and flowrate, initial PCM liquid fraction, and the number and material of the heat transfer coils are analysed using TRNSYS simulation employing the developed CTES model. According to the results, it is suggested in the actual use of TBAB hydrate based CTES to apply 2.0 °C chilled water for charge with initial solids and 4.0 °C chilled water for charge without initial solids. The optimal chilled water flowrate, 12 g s−1 for charge with initial solids and 18 g s−1 for charge without initial solids, can also be employed. In addition, in the design of a CTES the heat transfer coils are suggested to have a thermal conductivity close to 16 W m–1 K−1 but no need to exceed this value.

2-4-4 低波数Raman分光法を用いたTBA/TBP bromideハイドレートのゲスト分子相互作用の差異

2-4-4 低波数Raman分光法を用いたTBA/TBP bromideハイドレートのゲスト分子相互作用の差異

Syntheses of Four-Coordinate Nickel(II)-Phosphine Compounds and a Rapid Suzuki–Miyaura Cross-Coupling Reaction for Short Laboratory Sessions

[NiBr2(PPh3)2] and [NiBr2(dppe)] are prepared from nickel bromide hydrate and phosphine. These brightly colored coordination compounds are then converted into the related organometallic compounds trans-[NiBr(Mes)(PPh3)2] and [NiBr(Mes)(dppe)] (Mes = 2,4,6-Me3C6H2) by reaction with the Grignard reagent MesMgBr. Characterization of the compounds is accomplished by a combination of UV–vis and multinuclear NMR spectroscopies. [NiBr(Mes)(dppe)] is a highly active precatalyst for the Suzuki–Miyaura cross-coupling of 4′-bromoacetophenone and phenylboronic acid. The catalytic reaction is complete in as little as 15–20 min with only a 1 mol % precatalyst loading, and the reaction can be carried out in air. Results are assessed by 1H NMR spectroscopy, or the solid 4-acetylbiphenyl product can be isolated following aqueous workup and recrystallization. The experiments are flexible and accommodate a variety of laboratory schedules and student skill levels. Each experimental component has been designed to be completed within a 3 h laboratory period.

Thermodynamic properties of tetra-n-butylammonium 2-ethylbutyrate semiclathrate hydrate for latent heat storage

The quaternary onium salt-based semiclathrate hydrates have been investigated in many kinds of fields such as latent heat storage materials and gas separation media. In the present study, equilibrium (temperature−composition) relations in the tetra-n-butylammonium 2-ethylbutyrate (TBA-2 EB) semiclathrate hydrate system have been measured. In addition, thermodynamic and spectroscopic properties of TBA-2 EB semiclathrate hydrate were analyzed. The maximal equilibrium temperature and stoichiometric concentration of TBA-2 EB semiclathrate hydrate was 283.22 ± 0.05 K and x1 = 0.0281 ± 0.0007, respectively. The crystal lattice of TBA-2 EB semiclathrate hydrate, determined by the single crystal X-ray diffraction, was tetragonal. Other properties, not only Raman spectrum but also the maximum allowable degree of supercooling, in the TBA-2 EB semiclathrate hydrate system were similar to those in the tetra-n-butylammonium bromide (TBAB) hydrate. The TBA-2 EB semiclathrate hydrate would be an alternative to TBAB hydrate as a halogen-free semiclathrate hydrate system.

Clinical benefit of two-times-per-day aclidinium bromide compared with once-a-day tiotropium bromide hydrate in COPD: a multicentre, open-label, randomised study

ObjectiveChronic obstructive pulmonary disease (COPD) is mainly treated pharmaceutically with bronchodilators. The purpose of this study was to evaluate the clinical benefits of two-times-per-day aclidinium bromide (Acli-BID) compared with once-a-day...

Performance of a novel cold thermal storage material in an emulated air conditioning system using different storage strategies

With the increasing use of thermal energy storage in space cooling systems, various phase change materials have been explored. Semi-clathrate hydrates of quaternary ammonium salts can form under atmosphere pressure at applicable temperature ranges of air conditioning systems, among which tetrabutylammonium bromide (TBAB) hydrate has aroused most intensive interests in the past decade. This paper presents an experimental study to modify the phase equilibrium point of a novel TBAB hydrate based cold storage material, and investigates the material's performance in an emulate cold storage air conditioning system at various operation modes. Single charging and discharging operations, tank charging with chiller delivering load, and tank discharging with chiller delivering load operations with or without using bypass, are implemented to achieve full-storage and partial-storage strategies. The temperature distribution, charging and discharging rate and capacity are studied as key indexes to evaluate the cold storage performance. It was during a tank charging-chiller delivering load operation, using bypass is unfavourable for thermal storage effectiveness. During a tank discharging-chiller delivering load operation, chiller starting at a later stage with bypass is favourable for the system efficiency.

Development and validation of RP-HPLC method for simultaneous estimation of teneliglipt in hydro bromide hydrate and glimepiride in bulk and tablet dosage form

A novel RP-HPLC and HPTLC method were developed and validated for the simultaneous estimation of Teneligliptin hydrobromide hydrate and Glimepiride. RP-HPLC method was developed in reverse phase mode using acetonitrile and phosphate buffer (pH 3 adjusted with orthophosphoric acid) as mobile phase in the ratio of 65:35 (v/v) at a flow rate 1ml/min and. Quantitation was achieved with ultraviolet detection at 246nm and retention time was found to be 5.8 min and 9.41 min for Teneligliptin hydrobromide hydrate and Glimepiride respectively. The linearity was found to be in the range of 5 – 25 ng/ml and 0.25 – 1.25 ng/ml and recovery were found to be 98.80 and 99.68 % for Teneligliptin hydrobromide hydrate and Glimepiride respectively. The developed method is co-friendly and the peaks were more resolved when compared to the previous literatures with reduced flow rate. HPTLC method wasdeveloped on Merck TLC aluminium sheets of silica gel 60 F₂₂₂ using Toluene: Methanol: Triethylamine (1: 3: 1 v/v/v) as mobile phase. Quantitation was achieved with ultraviolet detection a 246 nm and Rf value was found to be 0.48 and 0.60 for Glimepiride and Teneligliptin hydrobromide hydrate respectively. The linearity was found to be in the range of 2000 – 20000 ng/spot and 100 – 1000 ng/spot and mean recovery was found to be 99.64 and 99.28 % of Glimepiride and Teneligliptin hydrobromide hydrate respectively. Both HPLC and HPTLC were found to be specific since there was no co-eluting peak with drug.

Investigation of the Growth Kinetics of Tetra-n-butylammonium Bromide Hydrate Formation in Small Spaces

The kinetics of tetra-n-butylammonium bromide (TBAB) hydrate formation orientated within the space of a small dimensional tube is investigated through microscopic experiments in the temperature range of −5.5 to −9.7 °C. Based on the experimental data, a kinetic model in a small dimensional space is proposed to describe the formation process. Hydrate crystals are observed uniformly growing in the small dimensional space. The experimental results show that the nucleation time of TBAB hydrate increases from 9 to 25 min and the linear growth rate decreases from 16.36 to 9.66 μm/s with the increasing temperature. Crystal morphologies show that the tube wall has less effect on the inner crystal growth when the temperature is lower. Furthermore, the number of nucleation sites increases under even lower temperatures. The varying degree of brightness of the crystals indicates that there is a variation of facets of hydrate crystals formed at different temperatures. Hydrate crystals under lower temperatures exhibit ...

Catalyst Systems Based on a Metal Halide and a Quaternary Ammonium Salt in the 1,2-Epoxycyclopentane Carboxylation Reaction

Results of a study of 1,2-epoxycyclopentane carboxylation to cyclopentene carbonate (CPC) in the presence of various catalyst systems have been described. It has been found that the reaction occurs most efficiently in the presence of cobalt (nickel) chloride (bromide) hydrate and a quaternary ammonium salt (TEAB, TBAB). It has been recommended that CPC should be synthesized under a CO2 pressure of no less than 3.5 MPa at a temperature of 140–150°С without any solvent or in the medium of a solvent, such as target CPC, DMF, or N-MP, at a 1,2-epoxycyclopentane weight fraction in the feed mixture of no less than 25%. These conditions provide the formation of CPC with a selectivity of 97–99% and almost complete epoxide conversion within 2–4 h. It has been shown that the developed catalyst system can be recycled.

Structural, optical and piezoelectric investigation on brucinium bromide hydrate non linear optical single crystal for optical parametric oscillators, high-power laser, piezo-sensors and transducers applications

In the present work, a good transparent semi-organic brucinium bromide hydrate (BBH) single crystal was grown from the saturated solution by slow evaporation method. The single crystal XRD study reveals that, BBH crystallize in Triclinic crystal system with non-centrosymmetric space group P1. Presences of chemical elements such as Carbon, Hydrogen and Nitrogen are C = 38.79%, H = 44.10% and N = 3.48% respectively. The morphological study concludes that, the growth rate along ‘c’ direction is more expeditious than that of a & b. The UV–Visible spectrum confirms the good transparency of the crystal and diverse optical parameters such as cut-off wavelength, band gap, UV-resonance energy and refractive index values were calculated and relation between the different optical parameters were also discussed in detail. Chemical bonding nature of BBH crystal was identified with the aid of optical electro-negativity value. The Urbach energy value was found to be 0.1238 eV. LDT value of BBH crystal was found to be 6.43 GW/cm2 and it is compared with other standard materials such as KTP, KDP and Urea. To find the suitability of crystal in the field of nonlinear optical application, the second harmonic generation value was determined using Kurtz-Perry powder technique. The spectroscopic investigations were done by vibrational analysis in order to identify the different functional groups in BBH compound. The value of piezo-electric charge co-efficient (d33) was quantified by PM-300 piezometer. Fluorescence spectral study provides the knowledge about electron excitation and also life time of the molecules. Title crystal does not contain any internal structural grain boundaries which are confirmed by HRXRD analysis.

Study on TBAB hydrate nucleating activity of electrode products due to DC voltage application

The effect of the products obtained by applying a direct current (DC) voltage to electrodes on the nucleation of tetra-n‑butyl ammonium bromide (TBAB) hydrate was investigated experimentally. Six kinds of materials were used as electrodes and the products were generated by applying a DC voltage to the electrodes in a TBAB aqueous solution at a normal temperature. The nucleating activities of the products were estimated by measuring the freezing probability of the TBAB aqueous solution containing the products. High probabilities of freezing were obtained for the Zn, Cu, and Ag electrodes. Moreover, the insoluble products were separated from the TBAB solution after a DC voltage was applied to the Zu, Cu, and Ag electrodes. The products were placed in a clear TBAB aqueous solution and the freezing probability of the TBAB solution was measured. The products had a high nucleating activity for TBAB hydrate.

Anti-Agglomerator of Tetra-n-Butyl Ammonium Bromide Hydrate and Its Effect on Hydrate-Based CO2 Capture

Tetra-n-butyl ammonium bromide (TBAB) was widely used in the research fields of cold storage and CO2 hydrate separation due to its high phase change latent heat and thermodynamic promotion for hydrate formation. Agglomeration always occurred in the process of TBAB hydrate generation, which led to the blockage in the pipeline and the separation apparatus. In this work, we screened out a kind of anti-agglomerant that can effectively solve the problem of TBAB hydrate agglomeration. The anti-agglomerant (AA) is composed of 90% cocamidopropyl dimethylamine and 10% glycerol, which can keep TBAB hydrate of 19.3–29.0 wt. % in a stable state of slurry over 72 h. The microscopic observation of the morphology of the TBAB hydrate particles showed that the addition of AA can greatly reduce the size of the TBAB hydrate particles. CO2 gas separation experiments found that the addition of AA led to great improvement on gas storage capacity, CO2 split fraction and separation factor, due to the increasing of contact area between gas phase and hydrate particles. The CO2 split fraction and separation factor with AA addition reached up to 70.3% and 42.8%, respectively.