Structure and Properties of PSf Hollow Fiber Membranes with Different Molecular Weight Hyperbranched Polyester Using Pentaerythritol as Core.

A homologous series of hyperbranched polyesters (HBPEs) was successfully synthesized via an esterification reaction of 2,2-bis(methylol)propionic acid (bis-MPA) with pentaerythritol. The molecular weights of the HBPEs were 2160, 2660, 4150 and 5840 g/mol, respectively. These HBPEs were used as additives to prepare polysulfone (PSf) hollow fiber membranes via non-solvent induced phase separation. The characteristic behaviors of the casting solution were investigated, as well as the morphologies, hydrophilicity and mechanical properties of the PSf membranes. The results showed that the initial viscosities of the casting solutions were increased, and the shear-thinning phenomenon became increasingly obvious. The demixing rate first increased and then decreased when increasing the HBPE molecular weight, and the turning point was 2660 g/mol. The PSf hollow fiber membranes with different molecular weights of HBPEs had a co-existing morphology of double finger-like and sponge-like structures. The starting pure water contact angle decreased obviously, and the mechanical properties improved.

A polyethersulfone-bisphenol sulfuric acid hollow fiber ultrafiltration membrane fabricated by a reverse thermally induced phase separation process.

A novel antifouling polyethersulfone (PES) hollow fiber membrane was modified by the addition of bisphenol sulfuric acid (BPA-PS) using a reverse thermally induced phase separation (RTIPS) process. BPA-PS was synthesized by click chemistry and was blended to improve the hydrophilicity of PES hollow fiber membranes. The performance of PES/BPA-PS hollow fiber membranes, prepared with different contents of BPA-PS and at different temperatures of the coagulation water bath, was characterized by scanning electron microscopy (SEM), pure water flux (J w), BSA rejection rate (R), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and water contact angle measurements. SEM morphologies revealed that a finger-like cross-section emerged in the hollow fiber membrane by a non-solvent induced phase separation (NIPS) mechanism while a sponge-like cross-section appeared in the hollow fiber membrane via the RTIPS method. Both FTIR and XPS analysis indicated that the sulfate group in BPA-PS was successfully blended with the PES membranes. The results from AFM and water contact angle measurements showed that the surface roughness increased and the hydrophilicity of the PES/BPA-PS hollow fiber membrane was improved with the addition of BPA-PS. The results demonstrated that the PES/BPA-PS membrane with 1 wt% BPA-PS via RTIPS exhibited optimal properties.

[Hyperspectral Detection Model for Soil Dispersion in Zhouqu Debris Flow Source Region].

Sensitive band positions, models and the principles of soil dispersion detected by hyperspectral remote sensing were firstly discussed according to the results of soil dispersive hyperspectral remote sensing experiment. Results showed that, (1) signals and noises could be separated by Fourier transformation. A finely mineral identification system was developed to remove spectral noises and provide highly accurate data for establishing soil dispersive model; (2) Soil dispersive hyperspectral remote sensing model established by the multiple linear regression method was good at soil dispersion forecasting for the high correlation between sensitive bands and the soil dispersions. (3) According to mineral spectra, soil minerals and their absorbed irons were reflected by sensitive bands which revealed reasons causing soils to be dispersive. Sodium was the closest iron correlated with soil dispersion. The secondary was calcite, montmorillonite and illite. However, the correlation between soil dispersion and chlorite, kaolinite, PH value, quartz, potassium feldspar, plagioclase was weak. The main reason was probably that sodium was low in ionic valence, small ionic radius and strong hydration forces; calcite was high water soluble and illite was weak binding forces between two layers under high pH value.

FAS Grafted Electrospun Poly(vinyl alcohol) Nanofiber Membranes with Robust Superhydrophobicity for Membrane Distillation.

This study develops a novel type of electrospun nanofiber membranes (ENMs) with high permeability and robust superhydrophobicity for membrane distillation (MD) process by mimicking the unique unitary microstructures of ramee leaves. The superhydrophobic ENMs were fabricated by the eletrospinning of poly(vinyl alcohol) (PVA), followed by chemical cross-linking with glutaraldehyde and surface modification via low surface energy fluoroalkylsilane (FAS). The resultant FAS grafted PVA (F-PVA) nanofiber membranes were endowed with self-cleaning properties with water contact angles of 158° and sliding angles of 4° via the modification process, while retaining their high porosities and interconnected open structures. For the first time, the robust superhydrophobicity of the ENMs for MD was confirmed by testing the F-PVA nanofiber membranes under violent ultrasonic treatment and harsh chemical conditions. Furthermore, vacuum membrane distillation experiments illustrated that the F-PVA membranes presented a high and stable permeate flux of 25.2 kg/m2 h, 70% higher than those of the commercial PTFE membranes, with satisfied permeate conductivity (<5 µm/cm) during a continuous test of 16 h (3.5 wt % NaCl as the feed solution, and feed temperature and permeate pressure were set as 333 K and 9 kPa, respectively), suggesting their great potentials in myriad MD processes such as high salinity water desalination and volatile organiccompounds removal.

Processing-structure-property correlations of polyethersulfone/perfluorosulfonic acid nanofibers fabricated via electrospinning from polymer-nanoparticle suspensions.

Polyethersulfone (PES)/perfluorosulfonic acid (PFSA) nanofiber membranes were successfully fabricated via electrospinning method from polymer solutions containing dispersed calcium carbonate (CaCO(3)) nanoparticles. ATR-FTIR spectra indicated that the nanoparticles mainly existed on the external surface of the nanofibers and could be removed completely by acid treatment. Surface roughness of both the nanofibers and the nanofiber membranes increased with the CaCO(3) loading. Although FTIR spectra showed no special interaction between sulfonic acid (-SO(3)) groups and CaCO(3) nanoparticles, XPS measurement demonstrated that the content of -SO(3) groups on external surface of the acid-treated nanofibers was enhanced by increasing CaCO(3) loading in solution. Besides, the acid-treated nanofiber membranes were performed in esterification reactions, and exhibited acceptable catalytic performance due to the activity of -SO(3)H groups on the nanofiber surface. More importantly, this type of membrane was very easy to separate and recover, which made it a potential substitution for traditional liquid acid catalysts.

[A rapid quantificational identification model of minerals and its applications].

Rapid identification of minerals is the key point for enhancing the efficiency of mineral exploration by remote sensing, mineral mapping by remote sensing and many geological investigations. Because of the limitation of technology and other aspects, the amount of models and software concerning rapid identification of minerals is very small. Since 1990s the development in spectrometers and computers has made it possible to apply near infrared spectrum technology to identify minerals. Two models have emerged. Model I is based on analyzing the position of absorption bands, while Model II is founded on waveform matching. In the present paper, characteristic spectrum linear inversion modeling was built. Validated by the data gained from end-members of USGS mineral spectrum library by mixing randomly, this model with the accuracy being approximately 100% is much better than Model I and II. Used to analyze the 23 samples selected in Baogutu area in Xinjiang, the model we built with the accuracy of 64.6% is superior to Model I (the accuracy is 33.8%) and Model II (the accuracy is 8.1%). Though the accuracy of our model is not as high as that of identification by microscope at present, using our model is much more effective and convenient, and there also will be less artificial error and smaller workload. The good performance of our model in the mineral exploration work by remote sensing in Baogutu area in Xinjiang shows wide popularizing prospects.

[Alteration mineral mapping method based on statistical analysis of field measured spectra].

The present paper presents a new alteration mineral mapping method based on statistical analysis of field measured spectra. First of all, this method processes a cluster of measurement data of spectra of field samples, in order to distinguish different sample area from the overall types. Second, the results of the clustering of different mineral alterations established their respective discriminant functions. Thus, mapping major alteration type accords with the clustered reference spectra by given remote sensing images. Finally mapping further alteration types was based on the discriminant function of second step, which leads to final alteration map. This method takes full account of the different combination of alteration types, as well as the regional differences of alterations, and the establishment of the discriminant function for alteration minerals is more scientific. Moreover, the authors accessed the reliability of mapping to a certain extent. The method was applied to a study area of Baogutu in Xinjiang Province, which represents a good result.

[An algorithm for highlightling structure in multispectral remote sensing].

Based on the principle of mineral generation, structures could provide not only passage ways for ore-forming fluid, but also space for them to aggregate. So, it was very important to study the feature of structures in study area before mineral exploration. In order to highlight structures using multispectral remote sensing data, an algorithm integrating principle component analysis (PCA), maximum noise fraction transformation (MNF) and original image data was proposed here. In the algorithm, the original image was firstly transformed by PCA and MNF; then all bands were normalized to reduce errors caused by different band dimensions, and three bands containing detailed structure information were selected to form the false color image in which structures in study area were highlighted. Results of transformation on enhanced thematic mapper (ETM) data acquired on June 27th 2000 in Hatu area, Xinjiang province, China showed that (1) the transformed image was not only more colorful than the original data, but also more gradational than the original data. (2) The color difference among objects was enhanced by the algorithm. (3) Structrues were highlighted by the algorithm. Therefore, the algorithm's effect of highlighting structures in study area was noticeable.