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m-Cresol and p-cresol are widely used in medicine and pesticides as important chemical intermediates. They are generally produced as a mixture in industry and are difficult to separate due to the similarities in both chemical structures and physical properties. The adsorption behaviours of m-cresol and p-cresol on zeolites (NaZSM-5 and HZSM-5) with different Si/Al ratios have been compared by static experiments. Selectivity on NaZSM-5(Si/Al = 80) could be greater than 6.0. Adsorption kinetics and isotherms were investigated in detail. The kinetic data was correlated by PFO, PSO, and ID models, the NRMSE of which were 14.03%, 9.41%, and 21.11%, respectively. In the meanwhile, according to the NRMSE of Langmuir (6.01%), Freundlich (57.80%), D-R (1.1%), and Temkin (0.56%) isotherms, adsorption on NaZSM-5(Si/Al = 80) was mainly a monolayer and chemical adsorption process. It was endothermic for m-cresol and exothermic for p-cresol. The Gibbs free energy, entropy, and enthalpy were calculated accordingly. The adsorption of cresol isomers on NaZSM-5(Si/Al = 80) were both spontaneous, and it was exothermic (ΔH = −37.11kJ/mol) for p-cresol while endothermic (ΔH = 52.30kJ/mol) for m-cresol. Additionally, ΔS were respectively −0.05 and 0.20 kJ·mol−1·K−1for p-cresol and m-cresol, which were both close to zero. The adsorption was mainly driven by enthalpy. The result of breakthrough further demonstrated m-cresol and p-cresol could be separated effectively by NaZSM-5(Si/Al = 80). Additionally, the selectivity increased from 7.53 to 14.72 after four cycles regeneration with 9.95% and 53.96% decreases in the adsorption amounts for m-cresol and p-cresol, respectively. In conclusion, NaZSM-5(Si/Al = 80) could be a feasible adsorbent for the separation of m-cresol and p-cresol. [ABSTRACT FROM AUTHOR]

Liquid − liquid equilibrium (LLE) data for the water + 2,3-butanediol (2,3-BD) + solvent (n-hexanol or iso-pentanol) ternary systems were obtained at different temperatures (298.2, 308.2, and 318.2 K) under 101.3 kPa. Distribution coefficients and separation factors were calculated accordingly. Distribution coefficients and separation factors were greater than 0.2 and 2.5, respectively, for both n-hexanol and iso-pentanol, which indicated that they were feasible to extract 2,3-BD from aqueous solution. Meanwhile, the reliability of the experimental LLE data was confirmed by both Othmer − Tobias equation and Hand equation. Lastly, the LLE data were correlated by both thermodynamic nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) models, and their binary interaction parameters were correlated from the data. In addition, topological analysis related to the Gibbs minor common tangent test was applied to validate the binary interaction parameters. Supplemental data for this article is available online at here. [ABSTRACT FROM AUTHOR]

The isobaric vapor–liquid equilibrium (VLE) data at 101.3kPa for (1,3-propanediol(PG) + 1,3-butanediol(BD)), (1,3-PG+2,3-BD) and (1,3-BD+2,3-BD) and for the ternary system of (1,3-PG+1,3-BD+2,3-BD) have been measured. The thermodynamic properties of the non-ideal vapor phase have been considered with the EOS equation. The liquid activity coefficients have been calculated with Wilson, NRTL and UNIQUAC equations, and the binary interaction parameters were regressed by these models. The vapor composition of VLE data were calculated by the optimum parameter group and generated a good consistency to experimental values. Based on all the preceding results, a two-column distillation process was designed. [ABSTRACT FROM AUTHOR]

The solubility data of N-acetylglucosamine in five pure solvents (water, methanol, ethanol, n-propanol and acetone) and two binary solvents (water + ethanol, water + acetone) were measured by gravimetric method at temperatures from 283.15 to 313.15 K under atmosphere pressure (p = 101 kPa). The solubility data show that the solubility of N-acetylglucosamine in pure solvents increases with the increasing temperature and the solubility in binary solvents is affected by temperature and solvent composition. The solubility data of N-acetylglucosamine in pure solvents were correlated by Van't Hoff model, modified Apelblat model, λh model and the modified Apelblat model has the best performance. Jouyban-Acree model was used to correlate the solubility data of N-acetylglucosamine in binary solvents and the fitting performance was well. The dissolution thermodynamic properties of N-acetylglucosamine in all solvents were also estimated in this work. The experimental data will be helpful for purification process of N-acetylglucosamine in industry. [ABSTRACT FROM AUTHOR]

The solubility data of N-acetyl-L-glutamine in aqueous solution with different proportions of methanol and ethanol were determined with a static analytical method from 293.15 to 318.15 K. The data were then correlated by five models including the modified Apelblat equation, Van't Hoff equation, local composition model (NRTL model), CNIBS/Redlich-Kister model, and Jouyban-Acree model. The results show that Van't Hoff equation agrees well with the experimental data. When the ratio of methanol or ethanol in aqueous solution is in the range of 0.2-0.4, the solubility of N-acetyl-L-glutamine reaches its maximum. Besides, the melting temperature and fusion enthalpy of N-acetyl-L-glutamine were measured by the differential scanning calorimetry (DSC) and no polymorphism was found in the systems studied. The thermodynamic properties including enthalpy, entropy and Gibbs free energy during dissolution were calculated accordingly in this work. [ABSTRACT FROM AUTHOR]

A study on separation of system (1,2-ethanediol (1,2-EG) + 1,3-butanediol (1,3-BD) + 1,3-propanediol (1,3-PG)) was conducted in the article. Vapor-liquid equilibria (VLE) behaviors of systems (1,2-EG + 1,3-BD), (1,2-EG +1,3-PG), (1,2-EG + 1,3-BD + 1,3-PG) were studied at 101.3 kPa. A two-column (column C1 and column C2) sequence distillation process at normal pressure was designed and optimized to separate the ternary mixture. The results have shown Wilson model is the most appropriate one to describe the ternary system; product amounts of 1,2-EG, 1,3-BD, and 1,3-PG can be up to 0.970, 0.945, and 0.980, respectively, under optimized conditions. [ABSTRACT FROM AUTHOR]

Thermodynamic behaviors of ternary system (1,2-propanediol (1,2-PG) + 1,3-butanediol (1,3-BD) + 1,4-butanediol (1,4-BD)) were studied in this paper. Vapor-liquid equilibria (VLE) data of systems (1,2-PG + 1,3-BD), (1,2-PG + 1,4-BD), (1,3-BD + 1,4-BD), and (1,2-PG + 1,3-BD + 1,4-BD) were measured at 101.3 kPa. The binary interactive parameters were obtained by regressed the binary VLE data with different models. The results have shown that the Wilson model, the NRTL model and the UNIQUAC model are suitable to describe the ternary system, but the UNIFAC model is not appropriate; the residue curve map of the ternary system was obtained on the basis of the binary interactive parameters. Finally, the design and optimization of the two-column sequence distillation process were completed for separation of the ternary system. Under the optimized conditions, product amounts of 1,2-PG, 1,3-BD, and 1,4-BD can be up to 0.98, 0.90, and 0.98, respectively, after separation. [ABSTRACT FROM AUTHOR]

A polymer–salt aqueous two-phase system based on polyethylene glycol and sulfates was applied to explore the partition behavior of spiramycin. Binodal curves were measured by the turbidimetric titration method. The influence of temperature, salt concentration, and pH on the distribution behavior was investigated in detail by determining the partition coefficient and extraction efficiency. As pH and salt concentration increase, the partition coefficients increase accordingly. It was found that pH displays a significant influence on the partition behavior. The partition coefficient and extraction efficiency can reach 42.46 and 97.8%, respectively, at pH 9.0 and 15.80% (w/w) salt concentration. [ABSTRACT FROM AUTHOR]

The crystal transformation of ammonium polyphosphate crystalline form V (APPv) was studied. The effects of heating time and water content in the reactor were explored. The results showed that APPv underwent complete conversion to crystalline form II (APPii) when heated at 200°C. The pure and water-insoluble APPii was obtained under the alternate wet ammonia and dry ammonia atmosphere. Then, the thermal behavior of APPv and APPii was investigated. The TG analysis showed APPv had high thermal stability over the range of 300°C to 580°C, which was possibly due to its highly cross-linked structures. [ABSTRACT FROM AUTHOR]

To separate spiramycin from the crude sample of bitespiramycin, the optimal extraction conditions in single stage extraction had been obtained as follows: the temperature was 30-40°C, the concentration of phosphate solution was 0.3-0.4 wt.%, and the volumetric ratio of ester/aqueous was 2-3. A three-stage counter-current extraction technique had been utilized to improve extraction efficiency. The removal rate of spiramycin and the retention rate of bitespiramycin were as high as 79.14% and 92.41%, respectively. A theoretical model of three-stage counter-current extraction was introduced to calculate the results of the extraction and fitted the experimental data with satisfactory accuracy. [ABSTRACT FROM PUBLISHER]

The isobaric vapor-liquid equilibrium data for distillation have been measured for three binary systems of (1,2-butanediol(BD)+1,4-BD), (1,2-BD+2,3-BD), and (1,4-BD+2,3-BD) and for the ternary system of (1,2+BD+1,4-BD+2,3-BD) at 101.3 kPa. The thermodynamic properties of the vapor phase have been calculated with the Hayden-O’Connell equation in consideration of nonideality. The liquid activity coefficients have been satisfactorily correlated with the Wilson, NRTL and UNIQUAC models. The corresponding binary interaction parameters of the three models were calculated. Based on all the preceding results, a two-column distillation process was designed to obtain the required products with purity of 98% for industrial use. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to fabricate a novel nano-bioceramics incorporated lysozyme poly ( d, l-lactide- co-glycolide) (PLGA) microsphere. Methods: The nano-bioceramics was used as a biodegradable and sustained-release antacid to stabilize the lysozyme in the drug release process. First, the nano-bioceramics were prepared by sol-gel method, and then were characterized by energy dispersive X-ray analysis, dynamic light scattering and in vitro degradation test. Second, the lysozyme PLGA microsphere incorporated with nano-bioceramic was fabricated by the S/W/O/W emulsion solvent evaporation method. The microsphere was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and UV circular dichroism (UV CD). Finally the in vitro drug release and bioactivity test was carried out. Results: The composition of the nano-bioceramics was 58% SiO2, 36% CaO, 6% P2O5, and the average particle size was 295 nm. The nano-bioceramics incorporated lysozyme PLGA microspheres were prepared by the multi-emulsion method. The SEM results showed that the bioceramics was uniformly distributed in the PLGA microsphere. Results from in vitro lysozyme release test exhibited a prolonged release time for 1month. The FTIR and UVCD results suggested that the lysozyme in the drug release process had a similar secondary structure conformation to the native one. The Micrococcus lysodeikticus test showed that the microspheres incorporated with bioceramics provided long-term protein stability against the acidic environment resulted from PLGA's degradates and more than 90% of the lysozyme released over the 1 month period was preserved in a bioactive form. Conclusion: A novel bioceramics incorporated lysozyme PLGA microsphere was prepared with potentials for sustained protein release formulation. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to prepare a novel gastric mucoadhesive sustained-release acyclovir (AV)-resinate microsphere. Methods: First, AV absorption ratio was quantified in a rat gastrointestinal (GI) tract model. AV-resinate was prepared by bath method and used as cores to prepare microspheres by an emulsion solvent diffusion technique with carbopol 934 as coating material. GI transit test of the prepared microspheres was carried out in rats and beagle dogs, followed by the in vivo bioavailability evaluation of the microspheres in beagle dogs. Results: The AV absorption ratio in different segments of rat's GI track for 3 hours was as following: stomach 9.46 ± 0.62%, duodenum 20.22 ± 1.50%, jejunum 15.7 ± 1.33%, ileum 9.15 ± 1.01%, and colon 4.59 ± 0.48%. These results showed that AV was mainly absorbed in the stomach and upper intestine. The average diameter of the microspheres was 115.3 μm. The microspheres had a drug content of 33.3 ± 0.7% (w/w) and a sustained-release profile for 12 hours in vitro. The mucoadhesive test in rats and beagle dogs showed that most of the microspheres were retained in the stomach 6 hours after oral administration. The in vivo pharmacokinetics test revealed that the microsphere and reference (AV tablets) preparations have no significant difference for Cmax. The tmax has increased from 2.33 hours (reference) to 5 hours (test). Meanwhile, the relative bioavailability of AV microspheres was 145%. Conclusion: A novel AV-resinate microsphere was prepared. The microspheres were proved to be gastric mucoadhesive and sustained-release with higher bioavailability. [ABSTRACT FROM AUTHOR]

In this study, a facile method was developed for the preparation of a new conducting polymer composite with core-shell structure. The surfaces of layered titanate (K2Ti4O9) particles were first modified with 3-aminopropyltriethoxysilane, and then a polyaniline/titanate (PANI/K2Ti4O9) composite was synthesized via chemical oxidative polymerization. The resulting composites were characterized by SEM, XRD, FTIR and TG measurements. The results indicated that the PANI deposited on the surface of K2Ti4O9 particles resulted in the formation of the composite with a core-shell structure. TG analysis showed that the composite containing 28.7 wt% PANI had better thermal stability than that of pure PANI. Further, the PANI/K2Ti4O9 composite particles were adopted as a dispersed phase in silicone oil for electrorheological (ER) investigation. Suspension of the composite particles exhibited typical ER behavior subjected to an external electric field under steady and dynamic oscillatory shear. [ABSTRACT FROM AUTHOR]

CVD-grown multiwall carbon nanotubes are dispersed in styrene monomer. During the polymerization of styrene, an AC electric field is applied to induce the CNTs to align along the electric field line to form a macroscopic nanotube network in polystyrene matrix. The dielectrophoresis force and the electric field redistribution at the CNTs apexes are responsible for alignment of the CNTs as well as bonding between the CNTs. Parameters such as field strength and nanotube weight fraction are varied. The results indicate that the macroscopic CNTs alignment along electric field direction can be observed only if the AC voltage reaches or is higher than certain values, and the higher the electric field frequency is, the more uniformly the CNTs align along electric field direction. In addition, nanotube concentration also affects the alignment of CNTs. According to the results of this study, the CNTs will align into a developed network in polystyrene matrix under a proper combination of three parameters of the electric field voltage, frequency, and the CNTs concentration. [ABSTRACT FROM AUTHOR]

AbstractThe solubility of nicotinohydrazide in two binary solvents were determined by a static weight method from 293.15 to 318.15 K. It found that the solubility of nicotinohydrazide was influenced by temperature, solvent polarity, and solvent composition. Meanwhile, the TG-DSC analysis was used to obtain the weight change and thermal effect of nicotinohydrazide. The XRD analysis indicated that the crystal morphology of nicotinohydrazide was coincident in five different solvents. Furthermore, the models including modified Apelblat equation, Van’t Hoff equation, Jouyban-Acree model, and CNIBS/R-K model were used to fit the experimental data. It was concluded that the four models were reliable in fitting the experimental data. Then the dissolution apparent thermodynamic was obtained, which explained well the dissolution of nicotinohydrazide. This study could help optimize and control the industrial crystallization of nicotinohydrazide. [ABSTRACT FROM AUTHOR]

AbstractGlycylglycine (Gly–Gly) is a crucial biochemical reagent widely used in cosmetics, food additives, and medicine. Using the equilibrium method, the solubility data of Gly–Gly in four binary solvents (ethanol/isopropanol/ethanediol/acetone + water) were investigated at temperatures over a range of 288.15–328.15 K under 101.3 kPa, as well as in the binary solvent of acetic acid + water from 293.15 to 333.15 K. The solubility data were correlated by Apelblat-Jouyban Acree, Van’t Hoff-Jouyban Acree, and CNIBS/Redlich-Kister models. Additionally, the radial distribution function was obtained through molecular dynamic simulation. It presented the unusual dissolution behavior of Gly–Gly in acetic acid and water mixture. The apparent thermodynamic properties, including standard enthalpy, Gibbs free energy, and entropy change of dissolution, were obtained accordingly. This article could help the industrial crystallization of Gly–Gly. [ABSTRACT FROM AUTHOR]