2-propanol Water Research Articles

Catalytic hydrogen production from 2-propanol in supercritical water: Comparison of some metal catalysts

The gasification of organics in supercritical water is a promising method for the direct production of hydrogen at high pressures, and in order to improve the hydrogen yield or selectivity, activities of various catalysts are evaluated. In this study, hydrogen production from 2-propanol over Ni/Al2O3 and Fe–Cr catalysts was investigated in supercritical water. The experiments were carried out in the temperature range of 400–600°C and in the reaction time range of 10–30s, under a pressure of 25MPa. The hydrogen yields and selectivities of Ni/Al2O3 and Fe–Cr used in this study, and those of Pt/Al2O3 and Ru/Al2O3 used in our previous work were compared. The hydrogen contents of the gaseous products obtained by using Ni/Al2O3 and Fe–Cr were measured as 62mol% and 70mol%, respectively, at low temperatures and reaction times. However, the hydrogen yields remained in low levels when compared with that of Pt/Al2O3 used in previous study. Pt/Al2O3 was established to be the most effective and selective catalyst for hydrogen production. During the catalytic gasification of a 0.5M solution of 2-propanol, hydrogen content up to 96mol% and hydrogen yield of 1.05mol/mol 2-propanol were obtained.

Growth and physical properties of an organic crystal for NLO applications: Guanidinium phenyl arsonate (GPA)

Single crystals of organic material guanidinium phenyl arsonate (GPA) of size 28×14×10mm3 were grown from propanol–water mixed solvent by slow solvent evaporation technique. The crystal belongs to monoclinic system with noncentrosymmetric space group Cc. The lattice parameter values of GPA crystals are a=18.453Å, b=7.609Å, c=12.592Å and β=121.856°. The grown crystal was subjected to X-ray diffraction (XRD) study to identify its morphology and structure. Chemical etching study using propanol–water as etchant reveals the mechanism of growth. The formation of synthesized compound was confirmed by Fourier transform infrared (FT-IR) spectroscopy analysis. Optical transmittance and second harmonic generation (SHG) of the grown crystals were studied by UV–vis–NIR spectrum and Kurtz powder technique respectively. The transmittance of GPA has been used to calculate the refractive index ‘n’ and the extinction coefficient ‘k’. The laser induced surface damage threshold for the grown crystal was determined using Nd:YAG laser. The mechanical behavior of GPA was analyzed using Vickers microhardness test.

Easy Demonstration of the Marangoni Effect by Prolonged and Directional Motion: “Soap Boat 2.0”

So-called “soap boats” have been known for decades and can be used to demonstrate the Marangoni effect. Inspired by recent scientific work, this paper reports an improved demonstration: a “soap boat 2.0”. With this demonstration, a floating object (typically polystyrene foam) can be propelled along the water surface for up to several minutes. The direction of motion (straight, left-handed, or right-handed circles) can be influenced by the boat design. Three easy-to-make and effective boat designs are presented, and fifteen “fuels” have been considered with regard to safety, effectiveness, duration, ease of use, and availability. Some other possible variations of the demonstration are also proposed. The demonstration can be done with any age group, lasts for up to several minutes, and can be turned into a student project of varying length. Readily available materials (e.g., polystyrene foam) and benign household chemicals (e.g., ≥10% 2-propanol (“rubbing alcohol”) in water) can be used.

In vitro angiotensin-converting enzyme inhibition or digestive stability of casein hydrolysates treated by plastein reaction in propanol–water medium

Casein hydrolysate with in vitro angiotensin-I-converting enzyme (ACE)-inhibitory activity of 48.2% was prepared from caseinate by Alcalase and modified by plastein reaction in propanol–water medium with extrinsic tyrosine or phenylalanine. By applying response surface methodology, suitable reaction temperature, Alcalase addition, substrate and propanol concentration were optimized as 46.8°C, 8.36 kU/g peptide, 56.8% (w/v) and 58.5% (v/v), respectively. A reaction time of 1 h conferred two modified hydrolysates the highest inhibitory activity (61.6–68.5%), while longer time (e.g. 6 h) brought them greater reaction extent but lower inhibitory activity (41.4–54.7%). Pepsic- and trypsic-digestion of the modified hydrolysates of the highest inhibitory activity (or of greater reaction extent) totally resulted in damaged (or enhanced) inhibitory activity. Twelve out of the obtained 16 digests had residual inhibitory activity about 48–70%, close or larger than casein hydrolysate. It is thus concluded that plastein reaction can enhance ACE inhibition and digestive stability of casein hydrolysate.

Hollow mesoporous silica spheres supported Ag and Ag–Au catalyzed reduction of 4-nitrobenzo-15-crown

Hollow mesoporous silica (HMS) spheres of size within the range 120–220nm have been prepared using propanol–water solvent as template and cetyltrimethylammonium bromide (CTAB) as stabilizer. HMS supported silver and silver–gold catalysts were prepared by impregnating metal nanoparticles on HMS and were characterized by ultraviolet–visible spectroscopy (UV–vis), dynamic light scattering (DLS), optical microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), inductive coupled plasma optical emission spectroscopy (ICP-OES) and N2 adsorption–desorption. The reduction of 4-nitrobenzo-15-crown (4-NB-15-C) was compared using HMS supported silver and silver–gold nanocatalysts varying experimental parameters. Bimetallic Ag–Au/HMS nanocatalysts was found to be more active than monometallic Ag/HMS nanocatalyst.

Photocatalytic reductive dechlorination of chlorobenzene in alkali-free aqueous alcoholic suspensions of palladium-loaded titanium(iv) oxide particles in the absence or presence of oxygen

Photocatalytic reductive dechlorination of chlorobenzene in aqueous 2-propanol suspensions of palladium-loaded titanium(IV) oxide (Pd–TiO2) particles was examined in a wide range of aerated and deaerated solutions with different water and NaOH contents. In water-free 2-propanol, the presence of dissolved NaOH and removal of oxygen (O2) were critical for the dechlorination of chlorobenzene at a sufficient reaction rate and a redox balance (stoichiometry with the oxidation of 2-propanol) close to unity. In 50 vol% water–2-propanol solvent, the yield of benzene under aerated conditions was the same as that under deaerated conditions and was very close to the yield of acetone under aerated conditions, indicating that photogenerated electrons were selectively used for the reduction of chlorobenzene in the water–2-propanol solvent even in the presence of O2. The low solubility of O2 in the water–2-propanol solvents was attributed to the high selectivity of photocatalytic dechlorination. In 50 vol% water–2-propanol solvent, NaOH was unnecessary when the reaction was performed under deaerated conditions, suggesting that water played a role in removing chloride ions from the reaction site (surface of TiO2) and in suppressing the consumption of chloride ions by another side-reaction even in the absence of NaOH. Under ideal conditions, i.e., reaction in the absence of NaOH under aerated conditions, benzene was obtained in a 71% yield and a high material balance of benzene and chlorobenzene was recovered.

Physicochemical properties and controlled drug release of microcapsules prepared by simple coacervation

Ternary phase diagrams of gelatin–water–methanol, gelatin–water–ethanol, and gelatin–water–propanol systems were prepared to evaluate optimal coacervation. The results of their evaluation suggested that the optimal coacervation region expands with the hydrophobicity of the added poor solvent (methanol, ethanol, 1-propanol, and 2-propanol).Microcapsules prepared based on the optimal coacervation region differed in controlled drug release among poor solvents used even when the concentration of gelatin, a membrane component, is the same. Compared with microcapsules prepared using the gelatin–water–ethanol system, those prepared using the gelatin–water–propanol system showed a 34% decrease in the drug release rate 24h after the initiation of the drug release test. These results suggested that microcapsules prepared using gelatin–water–various lower alcohol systems can readily control drug release and can be a useful drug delivery system (DDS).

Design of TiO2-zeolite composites with enhanced photocatalytic performances under irradiation of UV and visible light

Design of TiO2 and FAU zeolite composite photocatalysts was performed by using Y-zeolite with different SiO2/Al2O3 ratio and two different kinds of TiO2 precursors, i.e., titanium ammonium oxalate and ammonium hexafluorotitanate. The SiO2/Al2O3 ratio of Y-zeolite and kinds of TiO2 precursors strongly affect the photocatalytic performances of composites in the degradation of 2-propanol in water due to the different adsorption properties of organics and crystallinity of TiO2. The usages of fluorine containing TiO2 precursor were quite effective for enhancement of photocatalytic performances of composites due to the improvement of hydrophobicity of Y-zeolite as a support, achievement of good crystallinity of TiO2, and the contribution of visible light sensitivity after calcination at suitable temperatures.

Impact of cationic surfactant chain length during SAPO-11 molecular sieve synthesis on structure, acidity, and n-octane isomerization to di-methyl hexanes

The structure, acidity, and n-octane di-branched isomerization of SAPO-11 synthesized with surfactants of different chain lengths in water–propanol system were investigated. The results showed that with the increasing chain length of surfactants, the crystallite size of SAPO-11 firstly decreased and then increased, but the external surface area and the active B acid sites of SAPO-11 firstly increased and then decreased. The smallest crystallite, the highest external surface area, and the most B acid sites were obtained simultaneously with the surfactant of 12 carbon atoms. The isomerization results of n-octane indicated that among the series Pt/SAPO-11 catalysts, the catalyst with DoTAB-directed SAPO-11 as support had the highest selectivity to di-branched isomers and the lowest cracking selectivity due to the largest external surface area that created more active sites to promote the formation of di-branched isomers by the key-lock mechanism and improve the diffusion of intermediates and products for reducing cracking reactions.

Erratum to: Efficient synthesis of optically pure alcohols by asymmetric hydrogen-transfer biocatalysis: application of engineered enzymes in a 2-propanol–water medium

Erratum to: Efficient synthesis of optically pure alcohols by asymmetric hydrogen-transfer biocatalysis: application of engineered enzymes in a 2-propanol–water medium

Photoinduced Electron Transfer in an Imidazolium Ionic Liquid and in Its Binary Mixtures with Water, Methanol, and 2-Propanol: Appearance of Marcus-Type of Inversion

The photoinduced electron transfer (PET) reaction has been investigated in a room temperature imidazolium ionic liquid (RTIL), 1-ethyl-3-methylimidazolium ethyl sulfate ([Emim][EtSO(4)]) and also in [Emim][EtSO(4)]-co-solvents mixtures from N,N-dimethyl aniline (DMA) to different Coumarin dyes using steady state and time-resolved fluorescence quenching measurements. We have used water and methanol and 2-propanol as the cosolvents of RTILs for the PET study. On going from neat ionic liquid to the RTIL-co-solvents mixtures the electron transfer rate has been largely enhanced. In neat RTIL as well as in [Emim][EtSO(4)]-co-solvents mixtures, a Marcus type of inversion in the PET rate have been observed.

Visible-light photoactivity of hierarchical porous carbon supported N-doped TiO2

Hierarchical porous carbon fabricated from biomass provides an effective support for catalysts. Nitrogen doped TiO2 particles (50 nm in size) synthesized from titanium tetraethoxide were loaded uniformly on the porous carbons carbonized from Zizania latifolia leaves by a sol–gel method. X-Ray diffraction and Auger Electronic Spectrometer analysis indicated that nitrogen atoms were doped into anatase TiO2 lattices. The bandgap of the nitrogen doped TiO2 derived from the light absorption spectrum was about 3.05 eV. The nitrogen doped TiO2 on the hierarchical porous carbon hybrid photocatalysts showed a high degradation rate of 2-propanol in water with visible light irradiation.

TiO2 photocatalyst for degradation of organic compounds in water and air supported on highly hydrophobic FAU zeolite: Structural, sorptive, and photocatalytic studies

Preparation of highly hydrophobic FAU zeolite has been achieved by a two-step preparation method that comprises predealumination treatment using concentrated mineral acids and subsequent calcination treatment. The hydrophilic/hydrophobic character of the zeolites was estimated by detailed adsorption measurements using water and toluene molecules as adsorbates, which showed the strict hydrophobic nature of the prepared FAU zeolites. By means of TG, FT-IR, and 29Si MAS NMR analyses, it was concluded that the enhancement in hydrophobicity originates from the healing of silanol defect sites and the formation of a refined silica surface with fewer adsorption sites. Thus-prepared FAU zeolite, with high crystallinity, structural and thermal stability, and hydrophobicity, significantly improved the photocatalytic degradation rates of 2-propanol in water and acetaldehyde in air on TiO2 when it was used as a catalyst support. A distinct correlation was found between the hydrophobicity of zeolites and photocatalytic activity of the supported TiO2.

Simultaneous preconcentration of cadmium, cobalt and nickel in water samples by cationic micellar precipitation and their determination by inductively coupled plasma-optical emission spectrometry

In the present study an easy micellar precipitation process at ambient temperature using cationic surfactant cetyl-trimethyl ammonium bromide (CTAB) was applied to the simultaneous extraction of cadmium, cobalt and nickel from aqueous samples. The analytical procedure involved the complex formation of these cations with 1,8-dihydroxyanthrone as a chelating agent in buffer media of pH 7.0. After the phase separation, the precipitated complexes were first dissolved in 0.25mL of 80:20 propanol–water mixture containing 0.03mL HNO3 and then subjected to the inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The concentration of 1,8-dihydroxyanthrone, pH, amount of CTAB and centrifuge time was optimized. Under the optimum conditions, the preconcentration factor was 40 and the improvement factors of 11.6, 9.5 and 14.4 with detection limits of 0.008, 0.009 and 0.004 (ngmL−1) were obtained for Cd, Co and Ni respectively. Under the presence of foreign ions no significant interference was observed. Finally, the proposed extraction method was successfully applied to the determination of these elements in various water and geological CRM samples with recovery percentages of 97–104% and RSD values of 1.87–2.36%.

Efficient synthesis of optically pure alcohols by asymmetric hydrogen-transfer biocatalysis: application of engineered enzymes in a 2-propanol–water medium

We describe an efficient method for producing both enantiomers of chiral alcohols by asymmetric hydrogen-transfer bioreduction of ketones in a 2-propanol (IPA)-water medium with E. coli biocatalysts expressing phenylacetaldehyde reductase (PAR: wild-type and mutant enzymes) from Rhodococcus sp. ST-10 and alcohol dehydrogenase from Leifsonia sp. S749 (LSADH). We also describe the detailed properties of mutant PARs, Sar268, and HAR1, which were engineered to have high activity and productivity in media composed of polar organic solvent and water, and the construction of three-dimensional structure of PAR by homology modeling. The K(m) and V(max) values for some substrates and the substrate specificity of mutant PARs were quite different from those of wild-type PAR. The results well explained the increased productivity of engineered PARs in IPA-water medium.

Impedance analysis for lateral field excited acoustic wave sensors

Lateral field excitation (LFE) acoustic wave devices have been recently investigated for liquid sensing applications. In the present study, the impedance characteristic of the LFE devices working in three operational modes was analyzed. The impedance of the pure-LFE coupling device at resonance can be equivalent to that of a Butterworth–Van Dyke circuit (BVD). It is found that the ( yxl)-16.51° LiTaO 3 LFE device has a much smaller resonance impedance in air due to the large LFE coupling factor and high dielectric constant. For the AT-cut quartz LFE device, there is no significant resonance peak observed in air due to the large resonance impedance. An equivalent circuit was present and used to analyze the impedance of the pseudo-LFE coupling device operating in liquids. It was well explained why the common used AT-cut LFE device is super sensitive to liquid electric property changes compared to a thickness-field-excited (LFE) device. The impedance changes in a single LFE-configuration device, working in a quasi-LFE mode, were also analyzed. And, the experiment results show that the impedance change at the resonance excited by the TFE is much larger than by the LFE in different concentrations of NaCl and 2-propanol water solutions.

Nucleation and growth kinetics estimation for l-phenylalanine hydrate and anhydrate crystallization

A process model for the crystallization of L-phenylalanine crystals from mixed propanol–water solution, an enantiotropic system, is developed with nucleation and growth kinetics estimated for the anhydrate and monohydrate forms using in situATR-FTIR spectroscopy and laser backscattering. A challenging aspect of estimating kinetics for this system is the formation of large numbers of small crystals under certain conditions, which result in biases in the data collected from in situATR-FTIR and FBRM probes. Batch experiments were designed to follow particular trajectories in the phase diagram so that some kinetic phenomena are suppressed in some runs, which enabled the estimation of sets of kinetic parameters in stages, reducing the number of parameters to be estimated simultaneously. The model was validated by comparison of model predictions and experiments for the product crystals and metastable limits obtained from independent characterization and experiments. This combination of experimental design and process modeling may be emulated to facilitate process modeling and development for crystallizations involving multiple crystal structures.

Graphene Coating of TiO2 Nanoparticles Loaded on Mesoporous Silica for Enhancement of Photocatalytic Activity

TiO2 nanoparticles supported on a mesoporous silica surface (TiO2/MCM-41) were selectively coated with graphene through the formation of surface complexes between TiO2 nanoparticles and 2,3-dihydroxynaphthalene and following carbonization under N2 flow. The pore structure as well as the high surface area of MCM-41 was retained even after carbonization at 1073 K. The selective graphene coating led to the enhancement of photocatalytic activities of TiO2/MCM-41 for the decomposition of 2-propanol in water compared with unmodified samples due to the appropriate adsorption properties of organics to transfer to the surface of TiO2 nanoparticles.

Thermochemistry of CuCl2 dissolution in a water—2-propanol—NaCl mixture at 298.15 K

The enthalpies of solution of CuCl2 (m < 0.07 mol per kg of the solvent) in a water—2-propanol—NaCl mixture at a NaCl content from 0 to 5 mol % and a 2-propanol content from 0 to 40 mol % were determined by calorimetry at 298.15 K. The effect of the electrolyte and organic component on the solvation of CuCl2 is discussed.

Direct Chiral Resolution of Metalaxyl and Metabolite Metalaxyl Acid in Aged Mobile Phases: The Role of Trace Water

The separation of chiral transformation products greatly complements the understanding of the stereochemistry of chiral pollutants. In this study, direct enantiomeric resolution of metalaxyl and its main degradation product metalaxyl acid, often co-occurring in the environment, was carried out in normal-phase high-performance liquid chromatography with a Chiralcel OJ-H column. (R)-Metalaxyl acid and (S)-metalaxyl, which were almost parallel bonding to the chiral stationary phase, tended to separate, started to overlap, coeluted, and separated again with subtle changes of the mobile phase consisting of n-hexane, 2-propanol, acetic acid, and trace water. Their competition above hampered an acceptable direct separation in fresh mobile phases. Aged mobile phases with a storage period of 3-5 days, however, significantly improved their separation, in which trace water from moisture air diffusion was found to play a major role. Trace water differentially affected peak width and retention times and then induced enhanced peak separation, confirmed by deliberate addition of water to fresh mobile phases. Furthermore, none of the studied factors, involving temperature, concomitant analytes, and trace water, could cause changes of the configuration of the chiral stationary phase. Simultaneous enantiomeric separation of both compounds was achieved in aged or fresh mobile phases with adventitious or added water and gave satisfactory peak separation, all with Rs values of more than 1.20 in environmental samples.