介孔Al_2O_3/PVDF复合中空纤维膜的制备及其性能

为了提高PVDF中空纤维膜在处理含油废水过程中的亲水性能、抗压实性能和抗污染性能,实验以介孔Al2O3为无机添加粒子,采用溶液纺丝法制备出介孔Al2O3/PVDF复合中空纤维膜。通过扫描电子显微镜和傅里叶红外光谱观察介孔Al2O3/PVDF复合中空纤维膜的形貌和成分,结果证明介孔Al2O3成功地添加到PVDF中空纤维膜中。通过接触角,纯水和含油废水通量的测试,结果表明介孔Al2O3的添加改善了PVDF膜的亲水性能、抗压实性能和抗污染性能。     

Preparation of PET threads reinforced PVDF hollow fiber membrane

PET threads were incorporated in the support layer of hollow fiber membrane in axial direction as a special reinforcement material for the purpose of improving the mechanical properties of PVDF hollow fiber membranes. It was found that the reinforcement threads had a limited effect on the separation-related properties of the membrane, such as porosity and pore size, but the tensile strength of the reinforced membrane was improved several folds. Also, the criterion of choosing reinforced fiber materials was suggested.     

PVDF-ZrO2复合中空纤维膜在乳化油废水中的应用

针对普通聚偏二氟乙烯(PVDF)中空纤维膜具有疏水性强、易污染的应用缺陷,在制备纳米粒子掺杂改性的PDVF-ZrO2复合中空纤维膜前期工作基础上,表征了其微观结构,并考察了其在油水体系中的分离效果。微观结构检测表明,随着ZrO2含量的增大,复合膜的断面微观结构完成由指状大孔向海绵状结构的转化。PDVF-ZrO2复合膜的接触角和牛血清蛋白(BSA)吸附实验结果显示其亲水性及抗污染性能均得到了提高。进一步考察了PDVF-ZrO2复合中空纤维渗透分离性能,ZrO2纳米粒子质量分数为0.3%时,显示了最佳的渗透性能。在乳化油废水处理过程中,在油质量浓度为1 g/L,操作压力为0.1MPa、搅拌强度为20 r/min条件下,通量为105 L/(m2.h),TOC去除率为95.4%,表明具有较好的废水处理效果。     

聚偏氟乙烯中空纤维膜的耐辐射性能研究

研究了较低剂量的γ辐射对聚偏氟乙烯中空纤维膜的结构与性能的影响。在试验中,选用44.57 Gy/min的剂量率,分别采用2,4,6,10 kGy剂量对浸泡在pH=10的氢氧化钠溶液中的中空纤维膜进行辐照。对辐照前后的样品作相关的性能测试,结果表明:随着辐射剂量的增加,透水通量先增大后减小,最大孔径持续减小,最大幅度至14.9%,分离性能增强。在≤10 kGy的剂量内,断裂强力呈现增大趋势,断裂伸长率呈现下降趋势,爆破强度先增大后减小。工艺优化的剂量为2 kGy。微观形貌和红外分析表明,辐射对膜的外表面化学基团及内表面的形貌产生一定的影响。热分析表明,辐照使膜的结晶度有所提高。     

中空纤维更新液膜处理含镍电镀废水

利用自制疏水聚偏氟乙烯(PVDF)中空纤维膜组件对中空纤维更新液膜处理含镍电镀废水过程中的影响因素进行了研究,考察了液膜两侧液相浓度、流速、萃取剂P204所占油相比例等因素对镍去除率的影响.并把中空纤维更新液膜和中空纤维支撑液膜处理效果进行了对比.     

膜生物反应器中PVDF中空纤维膜亲水性变化特征

为研究膜生物反应器(MBR)中PVDF中空纤维膜的亲水性变化特征,提出以接触角变化速率的绝对值(λ)表征亲水性的方法 ,按轴向长度将膜纤维划分为4个位置,考察过滤和清洗对膜亲水性的影响。结果表明:在MBR运行过程中,膜污染的加剧与膜的亲水性变化有关,膜纤维通量越高的位置,膜的亲水性越差。采用物理反洗和短时间的化学浸泡清洗,膜的亲水性能得到一定恢复,但效果有限。延长化学浸泡清洗时间发现,浸泡3 h膜纤维的亲水性最好。     

Surface modification of polypropylene membrane by low‐temperature plasma treatment

Microporous polypropylene membranes were low temperature plasma treated with acrylic acid and allylamine. Parameters of plasma treatment were examined and optimized for the enhancement of membrane performance properties. Excess power damaged the membrane surface and excess monomer flow rate increased the reactor pressure to interfere with the glow discharge. Longer plasma treatment time resulted in even more plasma coating and micropore blocking. The contact angle with water decreased and wettabilities increased with the increase of plasma treatment time. Deposition of the plasma polymer on the membrane surface was confirmed by FTIR/ATR spectra of the treated surface. In determining the flux, the hydrophilicity of the surface played a role as important as that of the micropore size. Adequate plasma treatment could enhance both water flux and solute removal efficiency. Results from the BSA (bovine serum albumin) solution test confirmed that fouling was greatly reduced after the plasma treatment. The BSA solution flux through the plasma‐treated membranes depended on pH, whereas pH variation had no serious effects on the untreated membrane. Modification of the surface charge by the plasma treatment should exert a substantial influence on the adsorption and removal of BSA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1555–1566, 2001     

Preparation and properties of PVDF/PVA hollow fiber membranes

On principle of polymer blend phase separation, PVDF/PVA hollow fiber membranes were prepared using phase inversion method. The membrane morphology and performance varied with the blending ratio. The PVDF/PVA blends showed incompatibility by the results of dynamic mechanical analysis (DMA) and infrared attenuated total reflection (FTIR-ATR) sampling technique. Based on bursting pressure and tensile strengths results, we suggest that the mechanical properties of PVDF/PVA blend membranes are worse than that of PVDF membrane. PVA can improve the hydrophilicity of PVDF/PVA hollow fiber membranes, which could be illuminated by the decrease in contact angle, the increase in equilibrium water content (EWC) and the variety in dynamic moisture regain. The pure water flux increases while the rejection ratio decreases with PVA content increasing. Moreover, PVA can improve the anti-fouling property of PVDF/PVA hollow fiber membranes, which could be illuminated by the result of increase coefficient of resistance.     

酚酞型聚醚砜对聚偏氟乙烯中空纤维膜结构及性能的影响

以二苯甲酮和N,N-二甲基乙酰胺为稀释剂,酚酞型聚醚砜(PES-C)为添加剂,通过热致相分离法制备了聚偏氟乙烯(PVDF)中空纤维膜。采用扫描电镜观察了膜的结构,测试了膜的纯水通量。在膜生物反应器(MBR)中测试了膜的污水通量和出水的化学需氧量及氨氮指标。该法制得的膜具有较为致密的皮层结构和疏松的支撑层结构,添加质量分数为2%的PES-C制备的PVDF膜与PVDF膜相比纯水通量增加60%,污水通量增加37.8%,出水COD去除率增加了3.32%,NH4+—N去除率增加了2.2%,且MBR出水达到排放标准。     

中空纤维渗透汽化膜分离研究现状与展望

本文综述了中空纤维渗透汽化膜分离的研究进展,包括中空纤维支撑膜的制备、复合膜的制备方法、中空纤维渗透汽化膜的工业应用和中空纤维渗透汽化膜传质特性等几个方面,对这个方面所存在的问题以及今后发展方向进行了展望.     

Experimental study of CO2 absorption/stripping via PVDF hollow fiber membrane contactor

Gas–liquid hollow fiber membrane contactor can be a promising alternative for the CO₂ absorption/stripping due to the advantages over traditional contacting devices. In this study, the structurally developed hydrophobic polyvinylidene fluoride (PVDF) hollow fiber membranes were prepared via a wet spinning method. The membranes were characterized in terms of morphology, permeability, wetting resistance, overall porosity and mass transfer resistance. From the morphology analysis, the membranes demonstrated a thin outer finger-like layer with ultra thin skin and a thick inner sponge-like layer without skin. The characterization results indicated that the membranes possess a mean pore size of 9.6 nm with high permeability and wetting resistance and low mass transfer resistance (1.2 × 10⁴ s/m). Physical CO₂ absorption/stripping were conducted through the fabricated gas–liquid membrane contactor modules, where distilled water was used as the liquid absorbent. The liquid phase resistance was dominant due to significant change in the absorption/stripping flux with the liquid velocity. The CO₂ absorption flux was approximately 10 times higher than the CO₂ stripping flux at the same operating condition due to high solubility of CO₂ in water as confirmed with the effect of liquid phase pressure and temperature on the absorption/stripping flux.     

聚偏氟乙烯/聚氯乙烯/聚甲基丙烯酸甲酯共混多孔中空纤维膜的制备与性能测试

采用干-湿法纺丝工艺,制备聚偏氟乙烯/聚氯乙烯/聚甲基丙烯酸甲酯共混五孔中空纤维膜,分别以聚乙烯吡咯烷酮(PVP)、聚乙二醇1000(PEG1000)和吐温-80为添加剂,改善成膜性能。通过水通量超滤试验、牛血清白蛋白截留试验、拉伸试验以及扫描电子显微镜表征膜的截面分析得出,铸膜液中溶质的质量分数为17%,添加6%PVP时制备的膜综合性能最佳。试验制得的中空纤维膜最大水通量为515.42L/(m2·h),截留率为87.25%。     

Effect of coating and surface modification on water and organic solvent nanofiltration using ceramic hollow fiber membrane

Nanofiltration ceramic hollow fiber membranes were developed to simplify the manufacturing process and improve water and organic solvent permeation performance. The alumina hollow fiber support was prepared by a phase-inversion/sintering method, and a γ-Al₂O₃ sol was coated thereon as a selective layer. Polyvinyl alcohol and ethanol were used as the drying control chemical additive in the coating solution, so that a coating layer could be formed without defects in only one coating step. The coating layer thickness could be adjusted to 0.6–2 μm depending on the coating drawing speed. A sintering temperature of 350 °C was selected to provide both reasonable water permeability (6.91 LMH/bar) and rejection (a molecular weight cutoff of 1000 Da or less) and to form a stable γ-Al₂O₃ phase. In the case of a membrane that was surface-modified with (3-chloropropyl)-trimethoxysilane, the permeability of toluene and hexane was 2.3 and 4.3 LMH/bar, respectively. The newly developed ceramic membrane showed excellent permeability and separation properties, as well as potential effectiveness for organic solvent nanofiltration applications.     

低温水等离子体活化和表面接枝DMAE聚氯乙烯中空纤维膜研究

采用低温水等离子体技术,在三通道聚氯乙烯(PVC)膜表面接枝了甲基丙烯氧基苄基二甲基氯化铵(DMAE)单体,增强了膜亲水和抗菌性能。通过红外分析,表明DMAE成功接枝到了PVC膜上,水通量提高两倍,PVC-ir-H₂O膜(通过水等离子体处理的膜)对牛血清蛋白(BSA)的吸附能力下降67%,对BSA溶液的通量从7.7提高至40 kg·m^-2·h^-1,并且对BSA的截留能力不变。通过静态及动态抗菌实验,接枝后的PVC膜(PVCg-PMAE膜)抗菌率达到100%,膜组件运行中的抗菌率也达到82%以上。在保证细菌截留率100%的同时,其渗透通量提高三倍。该膜表面修饰工程技术能实现膜表面的均一化改性,且绿色环保、操作简便、成本低,改性膜在饮用水处理领域,尤其是家用净水器中展现了很好的应用前景。     

液膜技术原理及中空纤维更新液膜

液膜技术可以实现萃取和反萃的耦合,具有独特的分离优势。因为具有非平衡传质的特性,液膜技术传质推动力大,萃取相用量很少。回顾了液膜技术的原理,指出液膜技术的关键在于形成一层厚度薄且相当稳定的液膜相。分析介绍了近年来发展起来的各种液膜技术的优缺点,提出了一种中空纤维更新液膜技术,其体积传质系数比传统萃取塔的大530倍。     

聚偏氟乙烯(PVDF)超滤膜生物反应器处理小区生活污水的试验研究

利用CASS与PVDF中空纤维超滤膜组件组合工艺进行模拟小区生活污水处理的试验研究,试验结果表明:当水力停留时间为12h ,CODCr浓度在2 15～6 77mg·L-1之间时,该工艺出水CODCr稳定在30mg·L-1左右;氨氮浓度为2 2 .2～4 1.2mg·L-1时,出水NH3 -N最低可达0 .2mg·L-1,去除率达到90 %以上;出水pH值在7.2 6～7.89之间;出水浊度小于0 .5 ,出水水质优于回用水标准,可直接回用。而且随着膜的污染,出水水质并没有受到任何影响。     

Surface modification of ceramic coating for enhanced hydrophobicity and wear properties

In this paper, a micro–nano structural ceramic coating with good hydrophobicity and wear resistance was successfully prepared by sol–gel method, which is assisted by pore-forming agent and nanoparticles 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane modified. The surface morphology, hardness, roughness, wettability, and tribological properties of three different surface coatings were characterized. With the complication of the surface structure, the roughness of the coating increases from 1.30 to 2.05 μm. Under the combined effect of roughness and long hydrophobic chains, the contact angles of the coatings before and after modification under saline conditions increased from 56.31 to 140.59° (pH4); from 55.58 to 134.40° (pH7); from 53.80 to 132.26° (pH10). Through the comparison of wear rate and wear morphology, it is found that the micro–nano structure coating has the lowest wear rate (0.705 × 10^–6 mm³·N^–1·s^–1) and the smallest plastic deformation. This means that in addition to the good hydrophobicity and chemical stability, the micro–nano structure on the surface also improves the wear resistance of the coating.