Junteng Liu

Solvent extraction of phenol with cumene from wastewater

Abstract In this paper, the extraction of phenol from wastewater using cumene as an extractant is investigated. H2SO4 and HCl are used for the pH adjustment of the wastewater. The effects of extraction temperature, pH value, initial concentration, and phase ratio on the extraction performance are studied. The results show that the distribution coefficient D increases with the increase in extraction temperature (from 25 to 55°C) and the decrease in pH value of the aqueous phase (from 13.0 to 0.0). The type of the acids and the initial concentration of phenol show a weak effect on the distribution coefficient. The stripping of loaded organic and the reuse of extractant are also discussed.

The Transport of Copper(II) through Hollow Fiber Renewal Liquid Membrane and Hollow Fiber Supported Liquid Membrane

Abstract In this paper, hollow fiber renewal liquid membrane (HFRLM) and hollow fiber supported liquid membrane (HFSLM) were used to simultaneously remove and recover copper(II) from aqueous solutions, and the transport performance of these two techniques were compared under the similar conditions for the system of CuSO4 +D2EHPA in kerosene +HCl. The results showed that the HFRLM process was more stable than the HFSLM process. The HFRLM process had a higher overall mass transfer coefficient than that of HFSLM process in single-pass experiments. These were because the renewal effect of the liquid membrane layer could reduce the mass transfer resistance of the lumen side and replenish the loss of the membrane liquid in the HFRLM process. The transport results were better in the HFRLM process than that in the HFSLM process with recycling experiments. Therefore, HFRLM technique is a promising method for simultaneous removal and recovery of heavy metal from aqueous solutions.

Melting and β to α transition behavior of β-PBA and the β-PBA/PVPh blend investigated by synchrotron SAXS and WAXD

Synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) are used to monitor the melting and βα transition behavior of β-PBA and the β-PBA/PVPh blend during the heating process. After melt recrystallized at 10 °C, the β crystals are obtained. The lamellar thickness of β crystals in the neat PBA is similar to that in its PBA/PVPh blend and the long period for the former one is shorter than the latter one. At lower heating rate, α crystals start to appear at 39 °C suggesting the βα phase transition occurs. Compared with the neat PBA, the β-PBA in the blend transits to α crystals at a higher rate. At a higher heating rate, β crystals melt directly. Both at the lower and higher heating rate, the crystal structure along the a-axis is much more stable than that along b-axis in the β crystals. Moreover, the heating rate does not play a role in the melting mechanism of the β crystals. The melting of the β crystals in the neat PBA and its PBA/PVPh blend chose different mechanisms. The melting mechanism of the β crystals in the PBA/PVPh blend is attributed to the sequential melting. On the contrary, the melting of the β phase in the neat PBA is complex. Besides the peak of q = 0.54 nm−1, a new peak appears at q = 0.32 nm−1 in the SAXS profiles in the heating process suggesting the appearance of a population with a larger long period. The presence of two peaks is caused by the coexistence of two kinds of lamellar stacks. And the partial melting of thinner β-PBA lamellae occurs firstly in one kind of lamellar stacks.

Immobilization of lipase on porous monodisperse chitosan microspheres

Porous monodisperse chitosan microspheres were synthesized for enzyme immobilization. The microspheres were prepared using microchannels and modified with glutaraldehyde. The microspheres had a mean diameter of 495 µm; the polydispersity indices were less than 0.08, and the specific surface area was between 121 and 173 m2/g. Candida sp. 1619 lipase was selected as a model lipase. Immobilization conditions such as enzyme loading, glutaraldehyde concentration, and immobilization time were optimized. The temperature, pH, and storage stability of the free and immobilized enzymes were also investigated. The immobilized enzyme had broad‐ranging pH and temperature optima as compared with free enzyme. The storage stability of the immobilized enzyme was higher than that of the free enzyme.

High efficiency organosilicon-containing polymer sensors for the detection of trinitrotoluene and dinitrotoluene

Trinitrotoluene (TNT) and dinitrotoluene (DNT) as the most common explosives are considered to be harmful to the environment and humans. Therefore, the detection of these explosives has been attracting more and more attention. And easily prepared polymer materials with high sensing performance are still in demand. In this study, two silicon-containing polymers, PCzSiO and PCzSiPh, are employed to detect the explosives TNT and DNT. PCzSiPh shows a better performance and the quenching efficiency of PCzSiPh films in TNT and DNT vapor can reach 91.0 ± 0.3% and 94.4 ± 0.3%, respectively, due to their loose molecular chain structure. Furthermore, the fluorescence quenching of PCzSiPh in TNT and DNT is little dependent on the thickness of the film. And the PCzSiPh films show good reversibility, good film-forming ability and high thermal and morphological stability, which suggest their potential application in the coating of detection devices.

Chiral liquid membrane for enantioselective separation of racemic ibuprofen by L-tartaric acid derivatives

The chirality of drugs plays a significant role in most chemical and biochemical process. In this paper, a chiral liquid membrane using L-tartaric ester dissolved in n-octane as liquid membrane phase and polyvinylidene fluoride hollow fibers as membrane support was investigated to separate racemic ibuprofen. For L-dipentyl tartaric ester, the separation factor was 1.18. The favorable L-dipentyl tartaric ester concentration was 0.20 mol L−1. With an increase of flow rates on two sides, a flux change of mass transfer in stripping phase was not observed. The same trend is obtained in feed phase. The concentration of both R-ibuprofen and S-ibuprofen in stripping phase increased with an increase of pH value. The best pH in stripping phase was 2.5 and the separation factor was about 1.2. The best separation factor was up to 1.38 after a six-level experiment.

Preparation and application of a novel ethanol permselective poly(vinyltriethoxysilane) membrane

A novel thin poly(vinyltriethoxysilane) membrane with hydrophobic Si–O–Si backbone and vinyl groups is proposed to recover ethanol by pervaporation. It exhibits high flux (>10000 g m−2 h−1), which is about ten times higher than that of PDMS, demonstrating that this membrane would facilitate the ethanol industrial production by pervaporation–fermentation process.

Structure evolution of poly(3-hexylthiophene) on Si wafer and poly(vinylphenol) sublayer.

The structure evolution of P3HT thin films on Si wafer and PVPh covered Si wafer during heating, thermal annealing, and melt recrystallization processes has been studied in detail using X-ray analysis techniques. The effect of substrate on the crystallization behavior and interface structure of P3HT films was explored. For the P3HT films deposited on the Si substrate, it was found that the stability of P3HT crystals is orientation dependent. The crystals oriented with b-axis normal to the substrate, that is, a face-on molecular orientation, are less stable than those with the a-axis arranged normal to the substrate (side-on molecular orientation). Thermal annealing temperature plays an important role in the molecular structure of P3HT including crystal structure, film thickness, and surface roughness. After annealing at relatively high temperature, new crystals form during the cooling process accompanied by the shrinking of a-axis. Moreover, the melt recrystallization favors the formation of more stable P3HT crystals with side-on molecular orientation. The PVPh substrate does not affect the crystallization behavior of solution cast P3HT significantly but inhibits the formation of P3HT crystal with face-on molecular orientation. However, the interfacial morphology of P3HT and PVPh changes by annealing at elevated temperature. The P3HT/PVPh interface changes from a sharply defined one into a diffused one at around 160 °C. The PVPh sublayer inhibits the melt recrystallization of P3HT to some extent, leading to a slight expansion of the a-axis.

Extraction separation of toluene/cyclohexane with hollow fiber supported ionic liquid membrane

A supported liquid membrane with ionic liquid was used for the separation of toluene/cyclohexane. The interactions of ionic liquid with toluene and cyclohexane were calculated and experimentally studied by quantum chemical calculation and liquid-liquid extraction process. The results showed [BPy][BF4] have stronger interaction with toluene than that with cyclohexane. The selectivity of SILM processes was larger than 10 at the temperature of 323 K and the flow rate of 13.5 mL·min−1 on both shell side and lumen side. Due to the higher viscosity of IL, SILM process had good long-term stability. As the effects of mass transfer driving force of SILM process, the flux and removal efficiency increased with increase of initial toluene concentration, while the selectivity decreased because of the competitive transport. Base on the resistance in-series model and experimental results, the mass transfer resistance was mainly lay liquid membrane phase. The influence of flow rates on both sides was slight. The higher temperature could enhance the mass transfer performance significantly. The removal efficiency increased from 28.2% to 45.1% with the increasing of operation temperature from 298 K to 323 K.

Synthesis and Charge-Transporting Properties of Dibenzothiphene Dioxide-Based Polysiloxanes

We designed and synthesized a dibenzothiphene dioxide-based homopolysiloxane, PDBTSi, and a carbazole-dibenzothiophene dioxide alternating copolysiloxane, PCzSi-alt-PDBTSi, respectively. Both PDBTSi and PCzSi-alt-PDBTSi possess an improved solubility, good film-forming ability and extremely high thermal stability due to introduction of polysiloxane main chains. Meanwhile, PDBTSi and PCzSi-alt-PDBTSi exhibit high triplet energy levels of 2.95 eV and 3.05 eV, respectively. Furthermore, PDBTSi possesses good electron-transporting property with an electron mobility of 1.02×10-4  cm2  V-1  s-1 and a relatively balanced hole mobility of 8.76×10-5  cm2  V-1  s-1 . In contrast, PCzSi-alt-PDBTSi exhibits an electron mobility of 4.65×10-5  cm2  V-1  s-1 and a hole mobility of 1.17×10-4  cm2  V-1  s-1 . Therefore, our results here provide a feasible strategy to obtain solution-processed polysiloxane materials with high and balanced electron- and hole-transporting properties.