Papers by Keyword: Dichloromethane

Abstract: The solubility of L-proline in binary solvents of methanol and dichloromethane were measured by a dynamic method via a laser monitoring technique. In the binary solvent mixtures, the solubility increases with the increasing of temperature and proportion of the methanol. The experimental solubility were fitted to modified Apelblat equation and Van’t Hoff equation in this work can be used as essential data and models in the purification process of L-proline. The dissolving process is endothermic and the dissolution driving force converts from enthalpy-driving to entropy-driving.

Abstract: In the present study, carbon-coated titanium oxide (C-TiO₂) was synthesized by hydrothermal method using dichloromethane as the novel low-cost carbon source. XRD patterns revealed that after purification method, only diffraction peaks of anatase TiO₂ can be observed. On the other hand, the formation of carbon can be suggested from DR UV-visible spectrum and SEM image, which showed the additional of absorption band in the visible region and the successful formation of carbon that grew both on the surface with a unique noodle-like structure and surroundings of the TiO₂ with non-uniform bulk structure, respectively.

Abstract: Electrospinning of polycaprolactone (PCL) in a mixed solvent of dichloromethane (DCM)/dimethylformamide (DMF) with 1:1 volumetic mixing ratio was studied. The effects of solution concentration (5-30 %w/v), applied voltage (10-25 kV), solution flow rate (0.1-2.0 mL/h) and collecting distance (10, 20 cm) on fiber formation and morphology were investigated. The size of PCL fibers obtained were in the range of 10s nm-2.6 μm with either bead on string or smooth fiber morphology. In this study, the solution concentration strongly affected fiber size exponentially. The fiber size also increased with an increase in solution flow rate. The applied voltage and the collecting distance have no or minimal effect on PCL fiber size.

Abstract: Sensor response and pattern recognition of polymer-coated single-walled carbon nanotubes (SWNTs) were investigated. Printed circuit board (PCB) with Cu/Au interdigitated electrode was used as sensor platform. SWNTs network was firstly formed on PCB by drop-casting. For polymer-coated SWNTs preparation, poly(methyl methacrylate) (PMMA) and thiophene were employed as polymers to coat on SWNTs by spin coating; PMMA/SWNTs and thiophene/SWNTs. Raman spectra showed no obvious structure changes of SWNTs after polymer coating. Next, gas sensing test was conducted. Pristine SWNTs, PMMA/SWNTs and thiophene/SWNTs were exposed to vapors of ethanol and dichloromethane at room temperature. From normalized sensor response results, it was found that pristine SWNTs and PMMA/SWNTs showed the highest response to ethanol and dichloromethane vapors, respectively. In order to discriminate vapors between ethanol and dichloromethane, pattern recognition technique was utilized. Principal component analysis (PCA) results showed that pattern recognition of ethanol and dichloromethane vapors can be discriminated by using pristine SWNTs and polymer-coated SWNTs sensors.

Abstract: Silk fibroin (SF) was regenerated for electrospinning. A mixture solvents Trifluoracetic acid (TFA) and dichloromethane (DCM) was selected as the solvent of regenerated SF. Its spinning properties and characteristics of end nanofibers mats were compared with those of the regenerated SF electrospinning solution dissolved in formic acid (FA). From the comparison of SEM images of regenerated SF electrospinning from the two different solvents solutions, it could be found that the spinning concentration range in TFA&DCM was smaller than that in FA for the solution viscosity was bigger than that in FA. Moreover, from the FTIR spectra of electrospun nanofibers obtained from TFA&DCM and FA was both similar with that of regenerated SF. This meant that there was no new group formed when TFA& DCM was selected as solvents. Therefore, TFA&DCM were also a nice option for the electrospinning of regenerated SF.

Abstract: Abstract. To determine the residual organic solvents(methanol, dichloromethane, normal hexane ) in antitumor crude drug di-phenyl-di-(2,4-dichlorobenzohydroxamato)tin(DPDCT), capillary gas chromatography (GC) method was established. The HP-5 (30m×320μm×0.25μm) capillary column and flame ionization detector (FID) detector were adopted. The carrier gas was nitrogen with flow rate 5.08 ml·min-1. The column temperature was 50.0°C and column pressure was 20.00psi. The distributary ratio was 20:1. 1, 2-dichloroethane was used as the internal standard substance while toluene as the solvent to determine the residual organic solvents. The calibration curves for methanol, dichloromethane and normal hexane are linear in the rang of 180.6～481.5μg·ml-1(r2 = 0.9974), 35.78～95.40μg·ml-1(r2 = 0.9950), 17.82～47.52μg·ml-1(r2 = 0.9995), respectively. The average recoveries of methanol, dichloromethane and normal hexane are 100.4 %( RSD=1.8%), 100.3 %( RSD=1.7%), 99.6 %( RSD=1.5%), respectively. The method is a simple and accurate method with high sensitivity and repeatability. It is suitable for the residual solvent determination of antitumor DPDCT.

Abstract: Dichloromethane (DCM) is a toxic pollutant with prolonged persistence in air and water. The work focused on the cultivation of Methylobacterium rhodesiaum H13 which could utilize DCM as the sole carbon source. By comparison and analysis, R2A was chosen as the suitable culture medium for large-scale cultivation. Furthermore, the optimized composition of medium was established on the basis of biomass obtained and the DCM degradation activity of M. rhodesiaum H13, which contained yeast extract 1.5 g/L, peptone 1.5 g/L, glucose 1.5 g/L, sodium pyruvate 0.9 g/L, K2HPO4 0.9 g/L and MgSO4•H2O 0.15 g/L.

Abstract: Base on the geological, hydrogeological condition survey of petroleum contaminated site, we choose benzene, dichloromethane, chloroform as target pollutants, and research the adsorption characteristics of target pollutant on the site soil media. Mainly design adsorption kinetics experiment and isothermal adsorption experiment of target pollutant on sandy silt, silt and fine sand. The result of the experiments show that the finer media the adsorption equilibrium time is shorter, the equilibrium time is sandy silt chloroform >dichloromethane, Migration is dichloromethane > chloroform > benzene. To same pollutant, the maximum adsorption of target pollutant is sandy silt >silt >fine sand.

Abstract: After the 9∙11 terrorism and America-Iraq war, apprehension of mass destruction weapons such as bio-chemical agents calls for much more sensitive sensors which can detect toxic gases. In this study, semiconductor gas sensors based on tin oxide were examined to detect chemical agent simulants: dimethyl-methyl-phosponate (DMMP), di(propylene glycol) methyl ether (DPGME), acetonitrile, and dichloromethane. DMMP((CH3O)3), DPGME(C7H16O3), acetonitrile(CH3CN), and dichloromethane(CH2Cl2) gases are the simulants of nerve agent-sarin, vesicant agent-HN(N(CH2CH2Cl)3), blood agent-AC(HCN), and choking agent-CG(COCl2) gases, repectively. The SnO2 powder was prepared by a coprecipitation method from the mixture of tin chloride and zinc acetate dihydrate. Zinc oxide was doped into SnO2 from 1 wt% to 4 wt% to improve its reliability and sensitivity. To fabricate a thick film, powders were made into paste with organic binder of ethyl cellulose and screen-printed on the alumina substrate. The phase development and morphology of ZnO-doped SnO2 film were investigated by XRD (X-ray diffraction analysis), BET (surface and pore size analyzer), and SEM (scanning electron microscope). The gas sensing characteristics for target gases were examined with a flow-type measurement system. The concentrations of simulants were controlled from 500 ppb to 1500 ppb, and working temperatures were regulated from 250  to 400 .