Dibutylamine Research Articles

Pyranine Interaction with Amines in Micelles.

The fluorescence behavior of pyranine in anionic micellar system of sodium dodecyl sulphate was studied in the presence of selected amines. The amines included cyclopropylamine (CPA), ethylenediamine (EDA), benzylamine (BA), dibutylamine (DBA), cyclohexylamine (CHA), and polyethylenediamine (PEDA). All the studied amines quenched the intensity of pyranine. Study was performed in 0.05M and 0.1M SDS. The thermodynamic parameters were determined in order to understand the quenching of pyranine by the studied amines. Change in Gibbs free energy and quenching was found higher in 0.05M SDS concentration and was found lower when SDS concentration was increased to 0.1M SDS. Pyranine quenching by the amines studied were treated with an extended Stern-Volmer equation that produced the Stern-Volmer constant ([Formula: see text]). Binding constant (Kb), number of binding stoichiometry (n) and Gibbs free energy change (ΔGbinding) were found higher for lower surfactant concentration as compare to higher surfactant concentration. More negative (-ve) the Gibbs free energies more will be the quenching, higher will be the sensitivity and vice versa. The Gibbs free energies for all the studied amines were found in the order as cyclopropylamine > ethylenediamine > benzylamine > dibutylamine > cyclohexylamine > polyethylenediamine. Fluorescence quenching of pyranine by amines in aqueous SDS is reproducible and is useful for the determination of amines in environmental samples.

In-syringe homogeneous liquid–liquid microextraction as an economical, convenient, and one-step analytical method for the extraction and preconcentration of five plasticizers and one antioxidant from different city tap water samples

In this study, an analytical method called in-syringe homogeneous liquid–liquid microextraction was developed and applied for the extraction and preconcentration of plasticizers including di ethyl phthalate, di isobutyl phthalate, di-n-butyl phthalate, di(2-ethylhexyl) adipate, and di(2-ethylhexyl) phthalate and one antioxidant, (butylated hydroxytoluene). Only a few microliters of dibutyl amine was used as the extraction solvent. This switchable solvent became miscible in the solution of interest by adding acetic acid at µL-level to extract the analytes. Also, the addition of sodium carbonate (in mg-level) into the solution led to the release of carbon dioxide, which facilitated the extraction of plasticizers into the extractant. Also, sodium carbonate caused to the regeneration of the extractant in the upper narrow bore of the syringe. The enriched analytes were determined by a gas chromatographic equipped with a flame ionization detector. Under the optimum conditions, extraction recoveries and enrichment factors were obtained in the ranges of 39–78 % and 196–394, respectively. Also, the limits of detection and quantification were in the ranges of 1.76–12.51 µg/L and 5.80–41.28 µg/L, respectively, and the r2 values were equal to or better than 0.991. Development of the method as a one-step analysis processed which was electrically independent in extraction and preconcentration stage (no centrifugation or vortexing) and inexpensive. The use of only µL-level of organic solvent, convenient operation, and short extraction time are the other highlights of the method. This method was successfully applied to the extraction, preconcentration, and determination of several plasticizers in eight different city water samples.

Willow catkins-assisted synthesis of ZnFe2O4/ZnO hetero-tubes for chemiresistive dibutylamine sensors operated at 130 °C

The chemiresistive sensors have enabled the sensing of diverse organoamines, but the low-temperature detection of highly carcinogenic and combustible dibutylamine (DBA) has not been achieved to date. Herein, based on the concept of waste reuse and sustainable development, the discarded willow catkins were served as biotemplates and soaked into zinc or iron nitrates and their mixed solution. The above precursors were calcined at 500 °C in the air to controllably synthesize two homo-tubes and two ZnFe2O4/ZnO hetero-tubes, all of which are assembled by uniform nanoparticles. Among, the 1.25 at% ZnFe2O4/ZnO hetero-tubes possess uniform mesoporous distribution, high content of adsorbed oxygen species, and catalytic sites of high-valent Fe4+ Lewis acid, thus realizing the first metal oxide-based sensor with excellent trace DBA sensing at low temperature. The 1.25 at% ZnFe2O4/ZnO sensor exhibits high response of 79–100 ppm DBA at low 133 °C, which is 1.4, 1.8 and 2.3 times higher than those of 3.2 at% ZnFe2O4/ZnO, ZnO and ZnFe2O4 tubes, respectively. Furthermore, it also behaves rapid response kinetics (11 s∼10 ppm), good humidity resistance, reliable long-term stability (60 days), and the ability to actually detect prometryn herbicide. In addition, its response mechanism for the enhanced DBA sensing was investigated.

Crystal Structures and Physicochemical Properties of 3-Chloro-4-hydroxyphenylacetic Acid Salts with Amines.

3-chloro-4-hydroxyphenylacetic acid (CHPAA) is a fungal metabolite. It is a small molecule that is useful in crystal engineering studies due to the functional groups present. Six amines were selected to form salts with CHPAA. Linear derivatives included diethylamine (DEA) and di-N-butylamine (DBM). The aromatic compounds chosen were 2-aminopyridine (A2MP), 2-amino-4-methylpyridine (A24MP), 2-amino-6-methylpyridine (A26MP) and 4-dimethylaminopyridine (DMAP). The salts were characterised using single-crystal X-ray diffraction, thermal analysis, FTIR spectroscopy and Hirshfeld surface analysis. For all the crystal structures, N-H···O and C-H···Cl contacts were present. O-H···O contacts were found in all the crystal structures except for (CHPAA2-)2DEA+, which was also the only structure that displayed a Cl···Cl contact. Furthermore, C-H···O contacts were found in all the crystal structures except for (CHPAA-)(DBM+). The thermal stability trend showed that the DBM salt was more stable than the DEA salt. For the aromatic co-formers, the thermal stability trend showed the following: CHPAA-(DMAP+) > (CHPAA-)(A2MP+)>2CHPAA-2A26MP+>(CHPAA-)(A24MP+).

Effects of Aluminum Source with Different Properties on the Properties of Pd/SAPO-41 and its Catalytic Hydroisomerization Reaction

Aluminium source is one of the main factors affecting the physicochemical properties of SAPO-41.Silicoaluminophosphate molecular sieves-SAPO-41 were prepared via hydrothermal synthesis using di-n-butylamine (DBA) as templating agent, pseudo-boehmites, phosphoric acid and silica sol as aluminum, phosphorus and silicon sources respectively. Using XRD, N2 physical adsorption, SEM and Py-IR analysis media, the effects of aluminum sources on the crystal and pore structure, morphology, B-acid center strength of the prepared SAPO-41 molecular sieves. The catalytic hydroisomerization performance over Pd/SAPO-41 bifunctional catalysts were investigated. Pseudo-boehmite type has little effect on the crystal structure and chemical composition of SAPO-41 molecular sieve, but has different effects on its morphology, pore structure, B-acid strength of SAPO-41, and Pd dispersion on Pd/SAPO-41. The hydroisomerization conversion of n-decane over 0.5Pd/S41-A1 can reach 88.56 %, and the selectivity of isoparaffin can reach 90.88%.This work provides a reference for selecting an ideal aluminum source for the synthesis of SAPO-41.

The hydroisomerization of n-hexadecane over Pd/SAPOs bifunctional catalysts with different opening size: Features of the diffusion properties in pore channels and the metal-acid synergistic catalysis

In this work, SAPO-11, SAPO-31 and SAPO-41 with one-dimensional channels are synthesized hydrothermally by employing a di-n-butylamine (DBA) template, industrial silicon and aluminum sources, and the corresponding Pd/SAPOs bifunctional catalysts are prepared by loading 0.5 wt% Pd via the wet impregnation method. The diffusivity of n-hexadecane and 2-methylpentadecane in the micropores of different SAPOs is determined by molecular dynamics (MD) simulation, which indicates that the opening size has strong effects on the diffusion property of reactants and intermediates in the micropore channels. The calculated self-diffusion coefficients (Ds) of both n-hexadecane and 2-methylpentadecane based on MD simulation of three SAPOs decrease as SAPO-31 > SAPO-41 > SAPO-11, which is consistent with their minor axis size of micropores. The results of n-hexadecane hydroisomerization test indicate that the Pd/SAPO-31 catalyst shows the highest activity and iso‐hexadecane yield of 85.0% due to the significantly improved diffusion and favorable metal-acid balance. Different from Pd/SAPO-11 and Pd/SAPO-41, hydroisomerization over Pd/SAPO-31 occurs via the key lock mechanism, which leads to an increased multi-branched iso‐hexadecane proportion of 66.3% at the n-hexadecane conversion of 95.3%. The Pd/SAPO-31 catalyst is proven to be a highly effective bifunctional catalyst for the industrial production of bio-diesel with excellent low-temperature fluidity.

An Efficient Processing Strategy to Improve the Flavor Profile of Egg Yolk: Ozone-Mediated Oxidation.

This study investigated the effect of ozone treatment on egg yolk volatiles and fatty acids. The composition and content of volatile substances and the fatty acid content of the egg yolk were changed significantly after ozonation. With proper ozone treatment (30 min), the aldehyde content in the egg yolk increased from 78.08% to 94.63%, and the relative content of dibutyl amine decreased from 1.50% to 0.00%. There were no significant differences among the types of fatty acids in the egg yolks after being treated with ozone, but there were differences in their relative contents. The results of SDS-PAGE showed no significant difference in yolk protein composition and contents among the groups. SEM results showed that moderate ozone treatment (20 min and 30 min) led to a regular and dense network structure of egg yolk. These results provided a theoretical basis for expanding the application of ozone technology in the egg yolk processing industry.

A Multi-Analyte LC-MS/MS Method for Determination and Quantification of Six Nitrosamine Impurities in Sartans like Azilsartan, Valsartan, Telmisartan, Olmesartan, Losartan and Irbesartan.

A sensitive and robust method for determination and quantification of potential genotoxic impurities in sartans has been developed. These impurities need to be controlled at trace levels during quantification in drug substances and drug products for safe consumption. Recent regulatory requirements also suggested the need to have highly sensitive analytical method for trace level quantification of nitrosamine impurities. In this paper, we have described a simple, rapid and sensitive liquid chromatography-mass spectrometry method for six potential genotoxic nitrosamine impurities: N-Nitroso dimethyl amine (NDMA), N-Nitroso diethyl amine (NDEA), N-Nitroso Ethyl Iso propylamine (NIPEA), N-Nitroso-Nmethyl-4-aminobutyric acid (NMBA) N-Nitroso diisopropylamino (NDIPA) and N-Nitroso dibutyl amine (NDBA) in Azilsartan (AZL), Valsartan (VAL), Telmisartan (TEL), Olmesartan (OLM), Losartan (LOS) and Irbesartan (IRB) with a limit of quantification of less than 0.003ppm. Chromatographic separation is achieved using Poroshell HPH- C18, 150 × 4.6mm, 2.7μm column with 0.1% formic acid in water as mobile phase A and 0.1% formic acid in methanol as mobile phase B at a flow rate of 0.5mL/min using gradient mode of elution at a total run time of 20min. Six nitrosamine impurities are ionized and quantified in positive mode of atmospheric pressure chemical ionization using multiple reaction monitoring. As per ICH guidelines, method validation is performed and evaluated the limit of quantification and detection and found to give good S/N ratios with good linearity range of 0.003-0.045ppm with regression coefficient > 0.999 for all the six nitrosamine impurities. Method recoveries are also established using three-step sample preparation and are found to be satisfactory within 80-120%. The single method can be used routinely applied for the detection of nitrosamines in AZL, VAL, TEL, OLM, LOS and IRB.

Design and synthesis of multi-stimuli responsive π-extended phenothiazine aldehydes: Solvatochromism, acidochromism, moisture detection and fluorochromic sensing of amine vapors

A series of phenothiazine-based A-π-D-A type ‘push-pull’ molecules containing sites sensitive to external stimuli was designed and synthesized by phase transfer Heck coupling reaction. A positive solvatochromism was observed with an increase in solvent polarity resulting in an enhanced intramolecular charge transfer (ICT). The existence of TICT was prominent in highly polar media such as methanol and water. Single crystal X-ray diffraction revealed the existence of two structures of VPTZ, with torsional angles of 145.92⁰ and −161.04⁰, respectively along C–N–S–C plane of the phenothiazine rings. These compounds were used as probes for quantitative measurement of moisture present in three organic solvents, namely CH3CN, THF, and DMSO. The probes could detect moisture as low as 0.0034% (v/v) in CH3CN. Further, these compounds displayed reversible acidochromism in both solution and solid-state. VPTZ, containing pyridine ring as the receptor, displayed excellent sensing of trifluoroacetic acid (TFA) with a detection limit of 91.4 nM. A detailed mechanism involved in reversible acid sensing was studied by 1H NMR. Finally, silica-coated TLC plates were used to fabricate test strips by coating them with VPTZ and then were used as a portable device for selective turn-on sensing of triethyl amine (TEA) and n-dibutyl amine (DBA). TEA and DBA exhibited exceptional fluorochromic turn-on response from purplish-pink to yellow-green and mustard yellow, respectively.

Influence of meteorological parameters and oxidizing capacity on characteristics of airborne particulate amines in an urban area of the Pearl River Delta, China

Nine amine species in atmospheric particles during haze and low-pollution days with low and high relative humidity (RH) were analyzed in urban Guangzhou, China. The mean concentrations of total measured amines (Ʃamines) in fine particles were 208 ± 127, 63.7 ± 21.3, and 120 ± 20.1 ng m−3 during haze, low pollution-low RH (LP-LRH), and low pollution-high RH (LP-HRH) episodes, respectively. The dominant amine species were methylamine (MA), dimethylamine (DMA), diethylamine (DEA) and dibutylamine (DBA), which in total accounted for 82–91% of the Ʃamines during different pollution episodes. The contributions of Ʃamines-C to water-soluble organic carbon (WSOC) and Ʃamines-N to water-soluble organic nitrogen (WSON) were 1.52% and 2.49% during haze, 1.24% and 1.96% during LP-LRH, and 2.00 and 2.98% during LP-HRH days, respectively. The mass proportion of Ʃamines in fine particles was higher during LP-HRH periods (0.19%) than during haze and LP-LRH periods (0.16%). The mass proportion of DBA in Ʃamines increased from 7% during haze and LP-LRH episodes to 25% during LP-HRH episodes. Compared with other amines, DBA showed a stronger linear relationship with RH (r = 0.867, p < 0.01), which demonstrates its high sensitivity to high RH conditions. Meteorological parameters (including RH, the mixed layer depth, wind speed and temperature), the oxidizing capacity (ozone concentration), and gaseous pollutants (NOx and SO2) correlated with amines under different pollution conditions. Under high RH, acid-base reactions were the dominant pathway for the gas-to-particle distribution of amines in urban areas, while direct dissolution dominated in the background site. To our knowledge, this study is the first attempt to conduct in situ measurements of particulate amines during different pollution conditions in China, and further research is needed to in-depth understanding of the influence of amines on haze formation.

Types and Distribution of Organic Amines in Organic Nitrogen Deposition in Strategic Water Sources.

Organic nitrogen (ON) is an important part of atmospheric nitrogen deposition, but the content and distribution of components other than urea and amino acids are the blind area of current research. The deposition of organic amines (OA) in strategic water sources poses a great public health risk to unspecified populations. In order to further reveal the composition of about 50% soluble organic nitrogen, besides urea and amino acids, five functional sampling points (such as industrial area, agricultural area, urban area, tourism area and forest area) were set in the reservoir area to detect dissolved total nitrogen (DTN), dissolved organic nitrogen (DON) and OA components. The results show that the total nitrogen concentration was 6.42–10.82 mg/m3 and the DON concentration was 2.77–4.99 mg/m3. Ten kinds of OA were detected: dimethylamine (DMA), diethylamine (DEA), propylamine (PA), butylamine (BA), pyrrolidine (PYR), dibutylamine (DBA), N-methylaniline (NMA), 2-ethylaniline (2-ELA), benzylamine (BMA), and 4-ethylaniline (4-ELA). The average concentrations were 7.64, 26.35, 14.51, 14.10, 18.55, 7.92, 10.56, 12.84, 13.46 and 21.00 ng/m3, respectively. The total concentration of ten OA accounted for 2.28–9.81% of DON in the current month, of which the content of DEA was the highest, reaching 0.71%, the content of 4-ELA, PYR, PA and BA was 0.4–0.56%, and the content of DMA, DBA and NMA was 0.2–0.36%. The sources of OA in the reservoir area have significant seasonal differences. The content is the highest in spring, followed by autumn, and lower in summer and winter. The rainfall in spring and autumn is small, the source of road dust is relatively high, and the rainfall in summer is large. After the particles in the air are washed by rain, the concentration of OA in the sample is the lowest. On account of spring and autumn being the time of frequent agricultural activities, the concentration of OA is significantly higher than that in winter and summer.

A Multiscale Approach for Estimating Permeability and Migration of Large Permeants through Poly(Phenylene Ether)

AbstractMultiscale‐computational‐chemistry (MSCC) simulations are employed—bridging quantum chemistry, coarse‐grained dissipative particle dynamics (DPD), and molecular dynamics (MD)—to derive solubility and diffusivity of dibutylamine (DBA)—a residual moiety in commercially available poly(phenylene ether) (PPE) resins—in PPE and food simulants. Coarse‐grained DPD simulations are used for computationally inexpensive and faster equilibration of high‐molecular‐weight PPE chains, with a final MD step to estimate mean squared displacement (diffusivity) of DBA in PPE. State‐of‐the‐art algorithms involving quasichemical methods and thermodynamic‐integration in DPD are employed to estimate solubility of DBA in various mediums. Such approaches are not hitherto widely employed for polymers. The constants derived using MSCC approaches, implemented in CULGI, a commercially available tool, are used as inputs for estimating migration of DBA from PPE into food simulants using a commercial migration‐estimation software AKTS‐SML. The migration estimates from AKTS‐SML simulations, using parameters derived from MSCC, as well as those derived from in‐built thermodynamic models (Piringer, Brandsch) are compared with experimentally measured migration.

Investigation of the surface properties of dibutyl amine modified poly(styrene) based polymer by inverse gas chromatography method

In the present study, poly(vinyl benzyl chloride) (PVBC) was prepared by the radical polymerization method. Then, PVBC was reacted with dibutyl amine to obtain tertiary amine-modified poly(styrene) based polymer (PVBC-Dibutyl amine) and the resulting polymer was characterized. Surface properties of the polymer were investigated by inverse gas chromatography method at infinite dilution region. For this purpose, the retention diagrams of carefully selected polar and non-polar solvents (probes) on PVBC-Dibutyl amine were obtained over a temperature range from 30 to 50 $$^\circ{\rm C}$$ . By using the diagrams, the dispersive component of the surface free energy of the polymer surface was calculated for the studied temperatures by two different methods. The specific enthalpy of adsorption and the specific component of the adsorption free energy of solvents on PVBC-Dibutyl amine which are adsorption thermodynamic parameters were determined for each solvent used. Using the adsorption data, Lewis acid and Lewis base parameters of PVBC-Dibutyl amine surface were calculated. The obtained parameters reflected that surface of PVBC-Dibutyl amine exhibited a basic behavior. Considering the values in the literature, the effect of dibutyl amine moieties in the structure of poly(styrene) based polymer PVBC-Dibutyl amine on the dispersive surface free energy and acid–base parameters of poly(styrene) was discussed.

Optical Properties, Excess Volume Prediction from Refractive Index and Intermolecular Interactions in Dibutylamine + Isomeric Butanol

The alkyl or alkanol amines are widely used as absorbent for CO2 capture owing to interaction between amines and CO2. In order to increase the CO2 loading in amine based absorbents, blending of amine with alkanol may be one option. As thermophysical properties of of utmost importance in designing, in present work, the refractive index of dibutylamine (DBA) and isomeric butanol as well as their binary mixtures at 298.15 K to 308.15 K were measured. The Δn are found positive for DBA + isomeric butanol mixtures. The Δn values were correlated with Redlich-Kister polynomial. The refractive index data were also predicted by various correlations and results were expressed in terms of standard deviation. The Δn values were also employed to calculate the excess molar volume of the present binary mixtures. Further Δn data analysed in terms of intermolecular interaction among DBA (1) + isomeric butanol (2) mixtures.

Ultra-Sensitive LC-MS/MS Method for the Trace Level Quantification of Six Potential Genotoxic Nitrosamine Impurities in Telmisartan

Nitrosamine impurities are potentially genotoxic which are considered under cohort of concern as per ICH M7 guidelines and need to be controlled at trace levels during quantification in drug substances and drug products for safe human consumption. Recent regulatory requirements also suggest the need to have highly sensitive analytical methods for the accurate quantification of Nitrosamine impurities. In this paper we have presented simple, rapid and ultra-sensitive LC-MS/MS method for six potential genotoxic nitrosamine impurities: N-Nitroso dimethyl amine (NDMA), N-Nitroso diethyl amine (NDEA), N-Nitroso Ethyl Iso propylamine (NEIPA), N-Nitroso-N-methyl-4-aminobutyric acid (NMBA) N-Nitroso diisopropylamino (NDIPA) and N-Nitroso dibutyl amine (NDBA) with a LOQ of 0.004 ppm. Chromatographic separation is achieved using Zorbax SB C18 150 × 3.0 mm, 3.5 μ column with 0.1% formic acid in water as mobile phase A and 0.1% formic acid in methanol as mobile phase B at a flow rate of 0.3 ml/min using gradient mode of elution at a total run time of 18 minutes. Six nitrosamine impurities are successfully ionized and quantified in positive mode of atmospheric pressure chemical ionization (APCI) using multiple reaction monitoring (MRM). Method validation is performed as per ICH guidelines evaluating the limit of quantification and detection and found to give good S/N ratios with good linearity range of 0.002 - 2 ppm with regression coefficient >0.99 for all the six nitrosamine impurities. Method recoveries are established using three-step sample preparation protocol and are found to be satisfactory within 80% - 120%. The method can be used routinely applied for the detection of Nitrosamines in Telmisartan at a concentration of 1.5 ng/ml (0.03 ppm with respect to telmisartan concentration of 50 mg/ml).

Thermodynamic studies on tert-amine modified polystyrene based polymer/solvent systems by inverse gas chromatography method

In the present work, vinyl benzyl chloride (VBC) was polymerized by using free radical polymerization. The obtained PVBC was reacted with dibutyl amine to obtain tertiary amine modified polystyrene based polymer (PVBC-Dibutyl amine). The inverse gas chromatography (IGC) method was used to examine the thermodynamic properties of the polymer. Firstly, the retention diagrams of some polar and non-polar solvents on PVBC-Dibutyl amine were obtained over a temperature range from 135 to 160° C. Then, the thermodynamic parameters, including Flory–Huggins interaction parameter, weight fraction activity coefficient, partial molar heat of sorption, and partial molar heat of mixing were determined via interactions between the polymer and selected solvents at infinite dilution. The results reveal that the alkanes are poor solvents for the polymer whereas n-butyl acetate, i-butyl acetate, ethyl acetate, n-propylbenzene, i-propylbenzene, and ethylbenzene are moderately solvents in the studied temperature range.

Volumetric, acoustic, transport and FTIR studies of binary di-butylamine + isomeric butanol mixtures as potential CO2 absorbents

Due to application of dibutylamine as absorbent for CO2, densities (ρ), speed of sound (u) and viscosities (η) of binary liquid mixtures containing di-butylamine (DBA) + 1-butanol or + 2-butanol or + 2-methylpropan-1-ol or + 2-methylpropan-2-ol were determined in the temperature range 298.15 to 308.15 K as a function of mole fraction of DBA. Experimental data were used to calculate excess molar volume,VmE, deviation in speed of sound, Δu, excess isentropic compressibility, κSE, deviation in viscosities, Δη. These calculated properties were correlated by Redlich-Kister polynomial equation. Negative sign of VmEand κSE indicated the formation of strong associative interactions between unlike components, DBA and isomeric butanols. Negative values of Δη also is in support with the analysis made on the basis of VmEand κSE. VmEand κSEdata were analyzed theoretically in terms of PFP and Graph theoretical approach. Both theories predict sign as well as magnitude and both the theoretical results well supported the experimental data. The speeds of sound data were examined in terms of free length theory and various related correlations like Nomoto, van Dael, Impedance and collision factor theory (CFT). Δη values were analyzed in terms of Bloomfield and Devan's (BFD) model and theoretical results assisted the experimental results.

Elucidation of the desalination mechanism of solvent extraction method through molecular modeling studies

Desalination by solvent extraction is a simple and cost-effective technology to replace current ones. Although desalination solvents are continually developed, there is still a lack of understanding of the mechanism. In this study, we elucidate the solvent extraction desalination mechanism at the atomic level using molecular dynamics(MD) simulations. Three organic solvents octylamine(8A), dibutylamine(DBA), and 2-ethylhexylamine(EHA), which all have the same chemical composition but the amine group at different positions, were used. We simulated the desalination process from the brine-and-organic-solvents-mixing step to the brine-separation step. The MD simulations showed that DBA and EHA formed planar clusters while 8A formed gel clusters. By analyzing MD trajectories, we identified two types of water recovery mechanism, in which DBA and EHA clusters selectively absorb water and 8A traps brine by forming a gel structure. The polar interactions between water molecules and solvents are important driving forces for the absorption of water. To explain the desalination performances of DBA and EHA, morphological characteristics and surface polarity of the clusters were measured. It was found that a higher surface polarity facilitates more water absorption. Partial recovery of the salt ions was attributed to the surface polarity of the organic solvent clusters.

Studies on the interactional behaviour of binary liquid mixtures of tripropylene glycol monomethyl ether and butyl amines at different temperatures

In the present study densities, ρ, and speeds of sound u, have been measured for the binary mixtures of tripropylene glycol monomethyl ether with butyl amine, dibutyl amine, and tributyl amine across the entire composition range at temperatures T = (288.15, 293.15, 298.15, 303.15, 308.15) K and experimental pressure p = 0.1 MPa. Experimental densities and speeds of sound data has been used to determine excess molar volumes, isentropic compressibility, molar isentropic compressibility KS,m and its excess counterpart excess molar isentropic compressibility. Deviations in intermolecular free length and deviations in acoustic impedance have also been determined. Further we have also calculated the partial molar volumes for binary mixtures at different temperatures. The variation of these determined parameters with temperature and composition has been discussed with a view to understand molecular interactions present in the binary liquid mixtures of alkoxypropanol and butyl amines. The experimental data has also been fitted with Jouyban-Acree model.

A novel analytical method for simple and low-cost detection of isocyanates in ambient air.

In this study, we developed a novel method for the collection of gaseous and particulate isocyanates in the air using di-n-butylamine (DBA)-coated glass fiber filters and a cation-exchange column (GFF_SCX-DBA) sampler. Our method showed acceptable linearity, accuracy, and precision in the analysis of eleven kinds of isocyanates (ICA, MIC, EIC, PIC, PHI, 1,6-HDI, 2,4-TDI, 2,6-TDI, trans-IPDI, cis-IPDI, and 4,4'-MDI). And, some of them were detected in the air at the plant manufacturing isocyanates and spray polyurethane foam. Actually, 2,4-TDI and 2,6-TDI (11,000 ± 6600 and 5800 ± 3500 ng/m3, respectively) were detected at much higher levels than others at the plant manufacturing isocyanates, and the levels of these isocyanates were comparable with those obtained by using the commercial sampler. Furthermore, PHI and 4,4'-MDI (5800 ± 470 and 3500 ± 1100 ng/m3, respectively) were detected at a relatively higher concentration than the others in the place of spray polyurethane foam. Through this study, we realized that the concentration of isocyanates in various working places could be analyzed using our GFF_SCX-DBA sampler. This method makes it possible to perform a rapid and simplified extraction operation in a shorter time than in the commercial sampler by combining the GFF and SCX samplers.