Preparation and Characterization of the Modified Polyvinylidene Fluoride (PVDF) Hollow Fibre Microfiltration Membrane

A novel thermally induced graft polymerization technique was used to modify a polyvinylidene fluoride （PVDF） hollow fibre microfiltration membrane. An artificial neural network （ANN） was applied to optimize the prepared condition of the membrane. The optimized dosing of acrylic acid （AA）, acrylamide （AM）, N, N＇- methylenebisacrylamide （NMBA） and potassium persulphate （KSP） designed by ANN was that AA was 40.63 ml/L; AM acted as 6.25 g/L; NMBA was 1.72 g/L and KSP was 1.5 g/L, respectively. The thermal stability of the PVDF modified hollow fibre membrane （PVDF-PAA） was investigated by thermogravimetric （TG） and differential scanning calorimetry （DSC） analysis. The polycrystallinity of the PVDF-PAA membrane was evaluated by X-ray diffraction （XRD） analysis. The complex formation of the modified membrane was ascertained by Fourier transform infrared spectroscopy （FTIR）. The morphology of the PVDF-PAA membrane was studied by environmental scanning electron microscopy （ESEM）. The surface compositions of the membrane were analyzed by X-ray photoelectron spectroscopy （XPS）. The adsorption capacity of Cu^2＋ ion on the PVDF-PAA hollow fibre membrane was also investigated.

Modeling of a SrCe_(0.95)Yb_(0.05)O_3-αHollow Fibre Membrane Reactor for Methane Coupling

Proton-hole mixed conductor, SrCeo.95Yb0.05O3-α(SCYb), has the potential to be used as a membrane for dehydrogenation reactions such as methane coupling due to its high C2-selectivity and its simplicity for fabricating reactor systems. In addition, the mixed conducting membrane in the hollow fibre geometry is capable of providing high surface area per unit volume. In this study, mechanism of methane coupling reaction on the SCYb membrane was proposed and the kinetic parameters were obtained by regression of experimental data. A mathematical model describing the methane coupling in the SCYb hollow fibre membrane reactor was also developed. With this mathematical model, various operating conditions such as the operation mode, operation pressure and feed concentrations affecting performance of the reactor were investigated. The simulation results show that the cocurrent flow in the reactor exhibits higher conversion of methane and higher yield of ethylene compared to the countercurrent flow. In order to achieve the highest C2 yield, especially of ethylene, pure methane should be used as feed and the operating pressure be 300 kPa. Air can be used as the source of oxygen for the reaction and its optimum feed velocity is twice of the methane feed velocity. The air pressure in the lumen side should be kept the same as or slightly lower than the pressure of shell side.

PVDMS-Al2O3 Composite Hollow Fibre Membranes for Chloroform Recovery from Gas Streams

Sorption isotherm of chloroform in polyvinyl dimethylsiloxane (PVDMS) polymer film was measured via the gravimetric method, and this film was confirmed experimentally to be good membrane material to recover chloroform from gas stream with high sorption capacity. A new PVDMS-Al2O3 composite hollow fibre membrane was further prepared by coating a PVDMS film on the outer surface of Al2O3 hollow fibre porpous substrate prepared by a dry/wet phase inversion method. Microstructure of the composite membranes was examined by scanning electron microscopy (SEM), indicating the PVDMS coating layer was uniform, free of defects, and around 15μm thick. Performance of the PVDMS-Al2O3 composite hollow fibre membranes for chloroform recovery was investigated. By comparing the experimental data that derived from a mathematical model, the permeabilities of chloroform and nitrogen in the PVDMS polymer membrane were obtained. The effects of temperature and feed flow rate on the chloroform recovery and permeate concentration were investigated both experimentally and theoretically.

Research of Anti-Cancer Components in Traditional Chinese Medicine on Hollow Fibre Cell Fishing and Hollow Fibre Liquid Phase Microextraction

Hollow fibre cell fishing with HPLC (HFCF-HPLC) based on the human ovarian cancer cell line SKOV-3, human renal tubular cell line ACHN or hepatoma cell line HepG-2 was employed to screen active groups of coumarin and volatile oil in Radix angelicae sinensis, Radix angelicae dahuricae and Fructus citri sarcodactylis. Simultaneously, hollow fibre liquid phase microextraction with HPLC (HFLPME-HPLC) was conducted to enrich and determine the contents of active components in the same sample solution. Before application, for HFCF-HPLC, cells growth states and survival rates on the fibre, effect of ethanol concentration in the extract of samples on cell survival rates, non-specific binding between fibre active centres and the target components, positive and negative controls and repeatabilities were validated;for HFLPME, extraction solvent, sample phase pH, agitation speed, extraction time and sample phase volume were investigated. Many active components were screened from three medicines. Some of them, such as scoparone, psoralen, bergapten, oxypeucedanin, imperatorin, ligustilide, were identified by MS. The target fishing factors of active components and the cell apoptosis rates of three cells under the medicines effect were researched. The binding sites of active groups on HepG-2 cells were preliminarily determined. The results demonstrated that HFCF-HPLC, coupled with HFLPME-HPLC, is a simple and universal approach to find bioactive components at the cellular level, determine their content and research traditional Chinese medicines (TCMs) entirety effect of multi-component and multi-target. The approach may provide us a new and good solution to clarify the material basis of anti-cancer effect and conduct personalized quality control for the components associated with efficacy in TCMs.

Study on the Effect of Operating Parameters on Water Yield of Hollow Fibre Vacuum Membrane Distillation Using CFD Simulation and Response Surface Methodology

Coal chemical bases in Northwest China are suffering from geographical water scarcity and a large amount of highly saline wastewater that needs to be treated during the production process, resulting in water and energy consumption becoming a key issue in the process of confined zero discharge. Membrane distillation is a thermally driven water treatment technology that can achieve higher water production efficiency and lower energy consumption by using hollow fibre membrane distillation in combination with a vacuum permeation side. In this study, CFD simulation calculations and response surface method analysis of hollow fibre membrane modules were carried out to further reveal the effects of different process operating parameters on water yield and the interactions between the operating parameters. It was found that the influence of the parameters on the membrane flux was as follows: feed inlet temperature > vacuum pressure ≈ feed inlet flow rate > feed inlet sanility, and the optimal operating parameters were predicted to be vacuum pressure of 38.88 kPa, feed solution temperature of 353.15 K, feed solution concentration of 4.13%, and inlet velocity of 0.60 m/s, which achieve membrane flux of 38.90 kg∙m−2∙h−1 according to the response surface method. This study provides more in-depth theoretical guidance for the application of hollow fibre vacuum membrane distillation technology in the treatment of coal chemical high salt wastewater.

Fabrication and characterization of affordable hydrophobic ceramic hollow fibre membrane for contacting processes

Affordable hydrophobic hollow fibre membranes were prepared using kaolin and alumina based ceramic powders via a combined phase inversion and sintering technique,followed by a grafting with fluoroalkylsilane(FAS).The crux of the matter in this paper is to study the changes in the properties of the hollow fibre membranes(gas permeation,mechanical strength,pore size,porosity,tortuosity,morphology,and contact angle)by the addition of alumina(Al2O3)to the pure kaolin with mono or multiparticle sizes.By varying the overall loading and particle size of alumina addition,different morphologies of the membranes were obtained due to the differences in the path lengths during phase inversion process for each solvent and nonsolvent exchange.The successful grafting with FAS was evidenced by the increase in contact angle from nearly equal to zero degree before grafting to 140°after grafting.Kaolin-alumina-4,one of the hollow fibres fabricated in this work,achieved a mean pore size of 0.25μm with the bending strength of 96.4 MPa and high nitrogen permeance of 2.3×10^(-5) mol·m^(-2)·Pa^(-1)·s^(-1),which makes the hollow fibre most suitable for the membrane contactor application.

Preparation and properties of hollow fibre nanofiltration membrane with continuous coffee-ring structure

Polyamide(PA)hollow fibre composite nanofiltration(NF)membranes with a coffee-ring structure and beneficial properties were prepared by adding graphene oxide(GO)into the interfacial polymerization process.The presentation of the coffee-ring structure was attributed to the heterogeneous,finely dispersed multiphase reaction system and the“coffee-stain”effect of the GO solution.When the piperazine concentration was 0.4 wt-%,the trimesoyl chloride concentration was 0.3 wt-%,and the GO concentration was 0.025 wt-%,the prepared NF membranes showed the best separation properties.The permeate flux was 76 L·m^(−2)·h^(−1),and the rejection rate for MgSO4 was 98.6%at 0.4 MPa.Scanning electron microscopy,atomic force microscopy,and attenuated total reflectance-Fourier transform infrared spectroscopy were used to characterize the chemical structure and morphology of the PA/GO NF membrane.The results showed that GO was successfully entrapped into the PA functional layer.Under neutral operating conditions,the PA/GO membrane showed typical negatively charged NF membrane separation characteristics,and the rejection rate decreased in the order of Na2SO_(4)>MgSO_(4)>MgCl_(2)>NaCl.The PA/GO NF membrane showed better antifouling performance than the PA membrane.

Analysis of Temperature and Concentration Polarizations to Improve the Performance of Vacuum Membrane Distillation

Vacuum membrane distillation technology shows considerable promise for the treatment of mine water. Nevertheless, the current vacuum membrane distillation technology’s significant reliance on a heat source presents a challenging equilibrium between its energy consumption and thermal efficiency. Consequently, the present study employed computational fluid dynamics (CFD) calculations and analyses to examine the phenomena of temperature-differential polarisation and concentration-differential polarisation generated during the membrane distillation process, and to ascertain the extent to which the operating parameters affect them. Furthermore, it was observed that CPC and TPC exhibited a notable decline with the elevation of feed inlet temperature, while the polarisation phenomenon was diminished with the augmentation of feed inlet flow rate. The optimal equilibrium between membrane flux and thermal efficiency is intimately associated with the operating parameters. Additionally, this study offers a theoretical rationale for the enhancement of vacuum membrane distillation performance.

Fully automated sample treatment method for high throughput proteome analysis

The bottom-up strategy for proteome analysis typically employs a multistep sample preparation workflow that suffers from being time-consuming and sample loss or contamination caused by the off-line manual operation.Herein,we developed a hollow fibre membrane(HFM)-aided fully automated sample treatment(FAST)method.Due to the confinement effects of HFMs and the immobilized enzymatic reactor,the proteome samples could be denatured,reduced,desalted and digested within 8–20 min via the one-stop service.This method also showed superiority in trace sample analysis.In one and half hours,we could identify about 1,600 protein groups for 500 HeLa cells as the starting materials,1.5–8 times more than those obtained by previously reported methods.Through the on-line combination of FAST with nano-liquid chromatography-electrospray ionization tandem mass spectrometry(nanoLC-ESI-MS/MS),we further established a fully integrated platform for label-free quantification of proteome with high reproducibility and precision.Collectively,FAST presented here represents a major advance in the high throughput sample treatment and quantitative analysis of proteomes.