Preparation of High Concentration Polyaluminum Chloride with High Al_c Content by Membrane Distillation

A direct contact membrane distillation（DCMD）process was applied to prepare high concentration polyaluminum chloride（PACl）with high Alc content.The changes in total Al concentration（AlT）and Al species distribution were investigated.The results showed that AlT increased but the flux decreased with operating time during the DCMD process.The Alc content increased from 65%to 81%while the Alb content decreased from 34% to 18%,and the Ala content was almost 1%in the process.2.1 mol·L 1PACl with 81%Alc was successfully prepared by DCMD method.Thus the DCMD is an effective method for preparing high concentration PACl with high Alc content.

Concentration of Bio-Ethanol through Cellulose Ester Membranes during Temperature-Difference Controlled Evapomeation

To evaluate the high-performance of membrane materials in the concentration of an aqueous solution of dilute bioethanol under temperature-difference controlled evapomeation (TDEV), asymmetric porous cellulose nitrate (CN) and cellulose acetate (CA) membranes were prepared by a phase inversion method. In the concentration of dilute ethanol under TDEV, these membranes showed a high permeation rate and high ethanol/water selectivity. In membranes with almost the similar pore size, the ethanol/water selectivity was considerably higher for the CN membrane than the corresponding CA membrane. This result suggested that the affinity between the membrane material and the permeant is an important factor in the separation selectivity.

Absorption of Low Concentration Sulfur Dioxide Using Liquid-containing Microporous Membrane

The absorption of low concentration SO2 in flue gas by using the module of liquid-containing microporous membrane which is made up of hollow fiber and citric acid-sodium citrate buffer solution was investigated.The absorption efficiency of hydrophilic and hydrophobic membranes by using the concept of dynamic contact angle was mainly studied.The influences on absorption efficiency from absorption time,flowrate of gas phase,SO2 concentration of gas phase,air pressure,citrate concentration,pH value of solution as well as the generation of sulfate radical in absorption solution were examined.The results indicate that the hydrophobic hollow fiber membrane is better than hydrophilic membrane,the absorption efficiency decreases with increasing absorption time,gas phase flowrate,gas phase SO2 concentration and air pressure,the absorption rate and capacity of SO2 can be improved by increasing the citrate concentration,the absorption efficiency can be improved by increasing the pH value of citrate solution,the concentration of SO42-in absorption solution increases linearly with the absorption time at a rate around 0.192 g/(L-h).

Synthesis of ZSM-5 zeolite membranes without organic templates using a varying-concentration technique

Template-free nanosized ZSM-5 seeds with an average size of 15 nm were prepared from a synthesis solution with the composition 12Na2O∶100SiO2∶2Al2O3∶2500H2O. By the use of these seeds, thin ZSM-5 zeolite membranes were prepared on the outer surface of a porous α-alumina tube with a pore size of 2 μm in a gel system by varying-concentration synthesis with organic-free template. The first composition synthesis sol-gel was the same as seeds of molar composition and the second one was 12Na2O∶100SiO2∶2Al2O3∶5000H2O at 180 ℃ for 10 h, respectively. XRD shows that the film consists of well-crystallized ZSM-5 zeolite. SEM investigation indicats that the zeolite films on the supports are defect free and the film thickness is approximately 8 μm. The permeances for H2, N2, CH4 and CO2 are 8.94×10-7, 3.27×10-7, 3.9×10-7, 3.14×10-7 and 0.874×10-7 mol·m2·s-1·Pa-1, respectively. The ideal selectivity of membrane at room temperature for H2/CO2, H2/N2, H2/CH4 are 2.84, 2.73 and 2.29, respectively.

LARGE DEFORMATION OF CIRCULAR MEMBRANE UNDER THE CONCENTRATED FORCE

Making use of basic equation of large deformation of circular membrane under the concentrated force and its boundary conditions and Hencky transformation, the problems of nonlinear boundary condition were solved. The Hencky transformation was extended and a exact solution of large deformation of circular membrane under the concentrated force has been obtained.

Large deflection of circular membrane under concentrated force

The analytical solution to a Foppl-Hencky membrane with a rigidly clamped boundary condition under concentrated force is provided. Stability of a nonlinear circular membrane is investigated.

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.

Electrochemical Removal of Chlorophenol Pollutants by Reactive Electrode Membranes: Scale-Up Strategy for Engineered Applications

Chlorophenols(CPs)are significant refractory pollutants that are highly toxic to humans and other organ-isms.Reactive electrode membranes(REMs)show considerable potential in the electrochemical removal of refractory pollutants by allowing flow-through operations with convection-enhanced mass transfer.However,relevant studies are commonly performed on the laboratory scale,and there is no straightfor-ward method that guarantees success in scaling up engineered REM reactors.In this study,we demon-strated that a tubular concentric electrode(TCE)configuration with a titanium suboxide ceramic anode and a stainless-steel cathode is suitable for large-scale CPs removal.Both theoretical and experi-mental results showed that the TCE configuration not only allows the electrode surface to be orthogonal to electric field lines everywhere,but also has an ohmic resistance that is inversely proportional to the length of the electrode.In addition,the TCE configuration can be operated in either the anode-to-cathode(AC)or the cathode-to-anode(CA)mode based on the flow direction,creating adjustable condi-tions for selective degradation of CPs.This was confirmed by 98%removal of 2,4-dichlorophenol(2,4-DCP)and 72.5%removal of chemical oxygen demand(COD)in the CA mode,in which the kinetic constant was one order of magnitude higher than that for the AC mode under flow-through single-pass operations.This can be explained by the lower activation energy and free energy in the CA mode,as revealed by the-oretical calculations and experimental measurements.The TCE configuration is also suitable for a numbering-up strategy to scale up the electrochemical reactor without increasing the ohmic resistance or decreasing the specific electrode area,achieving 99.4%removal of 2,4-DCP with an energy consump-tion of 1.5 kW·h·m^(-3) when three TCE modules were employed.This study presents a suitable electrode design configuration for the REM reactor,offering effective strategies to bridge the“Valley of Death”encountered when scaling up the electrochemical removal of CP pollutants.

Numerical Studies of Convective Mass Transfer Enhancement in a Membrane Channel by Rectangular Winglets

Numerical calculations were conducted to simulate the flow and mass transfer in narrow membrane channels with and without flow disturbers. The channel consists of an impermeable solid wall and a membrane surface with a spacing of 2.0 mm. The flow disturbers studied include rectangular winglets, which are often used as longitudinal vortex generators to enhance heat transfer in heat exchanger applications, as well as square prism, triangular prism, and circular cylinder, which are used here to mimic the traditional spacer filaments for comparison of their abilities in enhancing the convective mass transfer near the membrane surface to alleviate the concentration polarization. The disturber performance was evaluated in terms of concentration polarization factor versus consumed pumping power, with a larger factor meaning a more serious concentration polarization.Calculations were carried out for Na Cl solution flow with Reynolds numbers ranging from 400 to 1000. The results show that the traditional flow disturbers can considerably reduce the concentration polarization but cause a substantial pressure drop, while the rectangular winglets can effectively reduce the concentration polarization with a much less pressure drop penalty. The rectangular winglets were optimized in geometry under equal pumping power condition.

Effects of oxygen enriched tent by a new oxygen concentration machine on blood oxygen saturation and heart rate in tibet

Many people who live in the low altitude areas are often suffered from hypoxia when they entered the high plateau. This problem may seriously influence the physical and mental state and work efficacy for the travelers and workers. Oxygen enrichment of a small space air at high altitude is considered as a simple way to provide lowlanders enriched oxygen for sleeping and resting, improving work efficiency, so we developed an oxygen concentration machine based on the technology of oxygen enrichment membrane. This paper tested 8 healthy male lowlanders (age 21.63±1.77 yr) who have never exposed to plateau performed an incremental exercise on cycle ergometer at sea-level in order to be used as sea-level controls. Two days later, the same subjects were taken to Lhasa (3700 m) by air and exposed to the plateau, performed the same exercise as they did at sea-level. The next day, all subjects were asked to enter the experimental tent which was enriched with oxygen (higher than 24%) by the oxygen concentration machine and sleep for 10 hours at night, then exposed to plateau and performed the same exercise twice at different time (2 hours and 10 hours after oxygen enrichment). During the tests, subjects must cycled continuously at 60 rpm beginning with a 3 min exercise intensity of 0 W followed by incremental increases of 25 W every 3 min until 150 W, pulse oxygen saturation (SpO2) and heart rate (HR) were recorded. After sleeping in an oxygen enrichment of tent air, 2 hours later, the subjects’ load capacity had no difference compared with control group, but significant difference than before (higher SpO2 and lower HR), which indicated that oxygen concentration machine is effective in increasing the oxygen concentration of the air for the tent and sleeping in the oxygen enrichment tent for l0 h might be effective in improving exercise performance during high-altitude hypoxia. At the same time, 10 hours later, when work-load exceeded 125 W, the same effects were also found. The results indicated the effects of oxygen enrichment of tent air could last a certain period of time.

Application of High-pressure Flat Membranes in Coal Chemical Wastewater Treatment

In the process of using high-pressure flat membranes to treat coal chemical wastewater,the effects of high-pressure flat membranes on the concentration of salt ions and the removal of pollutants were studied under the conditions of different concentrations of influent TDS,COD and silicon dioxide.The results showed that when the concentration of influent TDS was 35 000-55 000 mg/L,the economic benefit of high-pressure flat membrane operation was the best,and the concentration ratio of high-pressure flat membranes was stable,varying from 3.3 to 3.6.As the concentration of influent organic matter ranged from 100 to 1 800 mg/L,the removal rate of organic matter ranged from 60% to 79%.In addition,the retention rate of high-pressure flat membranes to silicon dioxide was more than 90%.

Treatment of stable oil/water emulsion by novel felt-metal supported PVA composite hydrophilic membrane using cross flow ultrafiltration

The novel felt-metal supported PVA composite hydrophilic ultrafiltration membrane was used for the treatment of oil/water(O/W) emulsion. The effects of transmembrane pressure(TMP), cross flow velocity, feed concentration on membrane performance were investigated, and ultrasonic cleaning of the fouled membrane was also investigated. The results show the flux increases with the increase of cross-flow velocity and TMP within the given TMP range from 0.20 MPa to 0.40 MPa. With increase of initial oil concentration increases, the oil rejection increases while the permeate flux decreases. The composite membrane shows more than 90% oil rejection within the initial oil concentration range from 0.05% to 0.50% (mass fraction) at TMP of 0.30 MPa. The fouling of the composite membrane increases rapidly during the initial 20 min at given TMP range from 0.20 MPa to 0.40 MPa, and it increases slowly after 30 min. The results also show that ultrasound is very effective in removing oil fouling of the fouled membrane, and the properties of the composite ultrafiltration membrane can be completely recovered by 10 min of sonication.

Enrichment and immobilization of macromolecular analytes on a porous membrane utilizing permeation drag

Enrichment and immobilization of analytes by chemical bonding or physical adsorption is typically the first step in many commonly used analytical techniques. In this paper, we discuss a permeation drag based technique as an alternative approach for carrying out location-specific immobilization of macro- molecular analytes. Fluorescein isothiocyanate （FITC） labeled macromolecules and their complexes were enriched near the surface of ultrafiltration membranes and detected by direct visual observation and fluorescence imaging. The level of macromolecule enrichment at the immobilization sites could be controlled by manipulating the filtration rate and thereby the magnitude of permeation drag. Higher enrichment as indicated by higher fluorescence intensity was observed at higher filtration rates. Also, larger macromolecules were more easily enriched. The feasibility of using this technique for detecting immunocomplexes was demonstrated by carrying out experiments with FITC labeled bovine serum al- bumin （FITC-BSA） and its corresponding antibody. This permeation drag based enrichment technique could potentially be developed further to suit a range of analytical applications involving more sophis- ticated detection methods.

Concentration of mixed acid by electrodialysis for the intensification of absorption process in acrylic acid production

The absorption process in acrylic acid production was water-intensive.The concentration of acrylic acid before distillation process was low,which induced to large amount of wastewater and enormous energy consumption.In this work,a new method was proposed to concentrate the side stream of absorption column and thus increase the concentration in bottom product by electrodialysis.The influence of operating conditions on concentration rate and specific energy consumption were investigated by a laboratory-scale device.When the voltage drop was 1 V·cP^(-1)(1 cP=10^(-3) Pa·s),flow velocity was 3 cm·s^(-1) and the temperature was 35℃,the concentration rates of acrylic acid and acetic acid could be 203.3%and 156.6%in the continual-ED process.Based on the experimental data,the absorption process combined with ED was simulated,in which the diluted solution from ED process was used as spray water and the concentrated solution was feed back to the absorption column.The results shown that the flow rate of spray water was decreased by 37.1%,and the acrylic acid concentration at the bottom of the tower was increased by 4.56%.The ions exchange membranes before and after use 1200 h were tested by membrane surface morphology(scanning electron microscope),membrane chemical groups(infrared spectra),ion exchange capacity,and membrane area resistance,which indicated the membrane were stable in the acid system.This method provides new method for energy conservation and emission reduction in the traditional chemical industry.

Simple Models for Diffusion in Thin Plates or Membranes

Two simplified models, linear and nonlinear, were used in a cementation process on a homogeneous thin carbon steel plate. The parameters for these models, as obtained by the least squares’ method the first one in a global way while the other parameters refer to the second model—were estimated by a set of local minimums. To compare the performance of these models we used theoretical data, for the same diffusion problem obtained by a one-dimensional transient model considering the concentrations in the mean plane of the plate. The results for carbon concentrations in weight percentage in the plate (%pC) as a time-only dependent function with these simplified models to represent the analyzed diffusion process were in good agreement with those from a stricter model. The diffusion flows of these models were determined and a reasonable agreement can be seen in relation to the flow obtained by the theoretical model on the surface of the plate. This study shows that it is possible to use this methodology with the given restrictions adopted here to describe the concentration and the diffusion flow of other solutes in thin membranes.

Research on Distribution Regularities of Dust Concentration and Granularity in Large Mining Height Working Face

The key for dust control of coal mine is to clarify the dust concentration distribution and sedimentation in different areas. Both similarity experiment and numerical simulation method have certain restrictions and are quite different from the actual situation on site. In order to study the dust sedimentation regularity of coal mine in large mining height, “filter membrane method” is adopted in this paper, i.e., to dry and weigh the filter membrane before and after sampling, collect the dust of respirable zone on mining face and calculate the dust concentration based on a main airway of 100 m. The result shows that: A large amount of dust will be produced during coal mining, wherein the maximum dust concentration from 6 m upstream to 100 m downstream of coal cutter is 121 mg/m3, while the minimum dust concentration is 61 mg/m3;The dust concentration in return airway is reduced with the distance increases, while the dust concentration at the entrance is 91 mg/m3;A large amount of dust may fall from roof during section advancing and improves the dust concentration of hydraulic support in walking area obviously;The dust granularity of mining face and return airway is 0 - 100 μm, but the amount of respirable dust is higher than 80%, the larger the dust particle size, the higher the dust concentration. Besides, dust in small particle size can be suspended in air flow for longer, but that in large particle size may subside under the action of gravity;To reduce dust exposure, the mining position shall be located in the windward direction of advancing or coal cutter. This research can provide guidance for taking dust prevention measures of working face in large mining height.

Neuroprotective effects of low-concentration alpha-tocopherol Confocal laser microscopy observations

BACKGROUND： Alpha-tocopherol （ α-tocopherol） can effectively relieve neuronal damage induced by oxygen-centered free radicals. However, the effective dose remains controversial. OBJECTIVE： To evaluate the protective effects of low-concentration α-tocopherol on neuronal membranes. DESIGN, TIME AND SETTING： Contrast observation and in vitro study, performed at Laboratory of Neurosurgery, Tianjin Huanhu Hospital between April and September 2006. MATERIALS： Fetal cortical neurons were derived from two 14-day pregnant SD rats, and α-tocopherol was provided by Sigma, USA. METHODS： The neurons were randomly assigned to six groups： （1） normal： neurons were cultured under normal conditions; （2） oxidative damage： oxidative free radicals was damaged using the Fenton reaction; （3） α-tocopherol： neurons were cultured in different concentrations of -tocopherol 10, 20, 40, and 80 mg/L for 2 hours, respectively. MAIN OUTCOME MEASURES： Neuronal membrane damage was observed using a confocal laser microscope, and malonaldehyde production was detected using the thiobarbituric acid method. RESULTS： At normal, biological concentrations （10 mg/L）, α-tocopherol induced no change in the damaged neurons （P 〉 0.05）. However, at a concentration of 80 mg/L, the number of damaged neurons was significantly reduced, compared with the damage group （P 〈 0.05）. Malonaldehyde levels following 80 mg/L α-tocopherol treatment were less than the oxygen free radical damage group （P 〈 0.05）, but greater than the control group （P 〈 0.01）. CONCLUSION： A concentration of 80 mg/L α-tocopherol can effectively protect the neuronal cell membrane from oxidative damage

Bipolar membrane electrodialysis integrated with in-situ CO_(2)absorption for simulated seawater concentrate utilization,carbon storage and production of sodium carbonate

In the context of carbon capture,utilization,and storage,the high-value utilization of carbon storage presents a significant challenge.To address this challenge,this study employed the bipolar membrane electrodialysis integrated with carbon utilization technology to prepare Na_(2)CO_(3)products using simulated seawater concentrate,achieving simultaneous saline wastewater utilization,carbon storage and high-value production of Na_(2)CO_(3).The effects of various factors,including concentration of simulated seawater concentrate,current density,CO_(2)aeration rate,and circulating flow rate of alkali chamber,on the quality of Na_(2)CO_(3)product,carbon sequestration rate,and energy consumption were investigated.Under the optimal condition,the CO_(3)^(2-)concentration in the alkaline chamber reached a maximum of 0.817 mol/L with 98 mol%purity.The resulting carbon fixation rate was 70.50%,with energy consumption for carbon sequestration and product production of 5.7 k Whr/m^(3)CO_(2)and1237.8 k Whr/ton Na_(2)CO_(3),respectively.This coupling design provides a triple-win outcome promoting waste reduction and efficient utilization of resources.

Respective and interactive effects of doubled CO2 and O3 concentration on membrane lipid peroxidation and antioxidative ability of soybean

Effects of doubled CO2 and O3 concentration on Soybean were studied in open-top chambers (OTC). Under doubled CO2 concentration, grain yield and biomass increased, the SOD activity, vitamin C (Vc) and carotenoid (Car) content also increased; Superoxide (O2-.) generating rate decreased, relative conductivity and malondialdehyde (MDA) content significantly declined.But under doubled O3 concentration, the SOD activity, Vc and Car contents declined, resulting in imbalance of activated-oxygen production, enhanced O2-. generating rate and accelerated process of lipid peroxidation and increase in MDA content and ion leakage of leaves. The final result was decreased grain yield and plant biomass. Interactive effects of doubled CO2 and O3 concentrations on soybean were mostly counteractive. However, the beneficial effects of concentration-doubled CO2 are more than compensate the negative effects imposed by doubled O3, and the latter in its turn partly counteracted the positive effects of the former.

Effects of nitrogen ion implantation on Ca^(2+) concentration and membrane potential of pollen cell

The effects of low energy nitrogen ion implantation on Ca2+ concentration and membrane potential of illy (Mum davidii Duch) pollen cell have been studied. The results showed that the Ca2+ concentration was increased when pollen grain was implanted by nitrogen ion with energy 100 keV and dose 1013 ions/cm2. However, the increase of Ca2+ concentration was partly inhibited by the addition of Ca2+ channel inhibitor depending on dose. And nitrogen ion implantation caused depolarization of pollen cell membrane potential. In other words, membrane potential was increased, but the effect decreased by adding Ca2+ channel inhibitor. However, it was still significantly higher than the membrane potential of control cells. It was indicated that the depolarization of cell membrane potential opened the calcium channel on the membrane that caused the increasing of intracel-lular calcium concentration. This might be an earlier step of the effect of low energy nitrogen ion implantation on pollen germination.