聚砜酰胺纤维成型工艺的比较与分析

利用自制的湿法纺丝和静电纺丝装置制备了两种在不同作用力成纤系统下的聚砜酰胺纤维。从纤维微观结构、物理性能等方面对两种工艺制备的聚砜酰胺纤维进行综合性能的比较分析。尝试采用COMSOL软件建立湿法纺丝的流体运动模型和静电纺丝的静电场模型,阐明两种作用力下纤维成型的机理。实验结果表明:湿法纺丝制备的聚砜酰胺具有较高的结晶度、较好的力学性能和热稳定性能;而静电纺丝制备的纤维具有更小的纤维直径以及较大的比表面积。     

添加剂对聚砜超滤膜亲水性能及过滤性能的影响分析

采用浸没相转变沉淀法制备聚砜超滤膜,探究添加剂对聚砜超滤膜亲水性能以及过滤性能的影响。以聚砜为原料,以N,N-二甲基乙酰胺(DMAc)为铸膜液溶剂,通过添加不同种类的添加剂聚乙烯吡咯烷酮(PVP)和聚乙二醇PEG,制得不同结构和性能的聚砜超滤膜。应用扫描电子显微镜观察膜的表面微观结构。测试超滤膜的接触角、平衡水含量、水通量、截留率,并通过接触角和平衡水含量结果来表征膜的亲水性能;以水通量和截留率来表征膜的过滤性能。结果表明:对于同一种添加剂,随着PVP-K30质量分数的增加,聚砜膜的亲水性能得到明显改善;水通量上升,过滤性能增加。对于同一质量分数的PEG,随其相对分子质量的增加,其亲水性、过滤性及抗污性显著提高。当PEG相对分子质量为2000,质量分数为6%时,得到的膜具有最佳的亲水性和过滤性能。     

荷电超滤膜制备及对酵母味素超滤应用研究

以自制磺化聚砜为膜材，采用L-S相转化法制备荷电聚砜超滤膜，考察了各因素对酵母味素膜通量和蛋白质截留率的影响显著程度，得到较佳制膜工艺组合：磺化聚砜浓度20％，蒸发时间10s，磺化度为37％，丙酮浓度10％，凝固浴温度20℃。在此条件下制得的荷电超滤膜对酵母液中蛋白的截留率达到70％，与同样条件下制备的聚砜超滤膜相比有较好的分离效果。     

壳聚糖/聚乙烯亚胺改性大豆蛋白膜的 制备与性能

采用环氧氯丙烷和聚乙烯亚胺对壳聚糖进行改性得到改性壳聚糖,并利用聚乙烯亚胺、壳聚糖和改性壳聚糖分别对大豆分离蛋白进行改性处理,共混浇铸制备大豆蛋白膜材料。探讨了不同改性处理对大豆蛋白膜微观结构、疏水性能、力学性能以及热稳定性的影响。结果表明：采用改性壳聚糖处理得到的大豆蛋白膜的结晶度增加,表面疏水性增强,力学性能提高,热稳定性提升。当改性壳聚糖添加量为5%（以大豆分离蛋白质量计）时,整体改性效果最优,此时大豆蛋白膜的表面疏水性增强了23.32%,力学强度提高了36.27%。     

再生纤维素膜在水处理中的应用研究进展

膜分离技术具有分离效率高、易控制、无污染等优点,成为水处理技术的首要选择。商品有机膜主要为聚砜类、聚偏氟乙烯类合成高分子膜和再生纤维素及其衍生物类天然高分子膜。本文在对不同分离膜的优缺点及应用领域概述的基础上,对再生纤维素微滤膜、超滤膜和纳滤膜的制备、化学改性及应用现状进行了综述,进而阐述了分离性能、力学性能及抗污染性能对再生纤维素膜在水处理中的影响与研究进展。     

大豆分离蛋白膜最佳成膜条件研究

本论文采用湿法工艺制备可食性大豆分离蛋白膜(SPI膜),通过L9(34)正交实验,考察了SPI浓度,甘油浓度,pH和温度四个因素对SPI膜性能的影响.结果显示,在SPI浓度为5.0 %(m/m),甘油浓度为2.0 %(m/m),pH为10,温度为90 ℃时得到的膜综合性能最佳.     

超声处理对大豆蛋白膜性能和微观结构的影响

研究了超声处理对大豆分离蛋白膜性能和微观结构的影响。结果表明,大豆分离蛋白膜液经超声功率20W、10min的处理,可显著地增加膜的抗拉强度及阻湿性能;红外和扫描电镜结果显示,超声处理改变了膜的空间结构,使膜表面平滑、均匀。     

聚砜复合膜的制备及其空气过滤性能研究

以聚砜(PSF)为原材料,聚乙烯吡咯烷酮(PVP)为添加剂,N,N-二甲基乙酰胺(DMAc)为溶剂,熔喷非织造布为支撑材料制备出聚砜复合膜。在凝固浴温度95℃条件下,改变聚砜固含量以及添加剂PVP的配比,制备不同性能的聚砜复合膜材料。测试复合膜的透气性、过滤性能、断裂强力,采用扫描电镜观察膜材料结构。结果表明,PSF的固含量对复合膜的过滤性能有直接影响。随着固含量的降低,聚砜复合膜的透气性能明显增强,截留率呈下降趋势;随着PVP的配比量的增加,透气量基本呈现增加趋势;截留率大体呈现先增后减的趋势。     

乙醇发酵膜生物反应器PDMS膜性能衰减问题

对乙醇发酵膜生物反应器中的PDMS-PA膜性能衰减进行了研究,在35 d的发酵过程中,膜对乙醇的分离能力逐渐下降,分离因子从峰值11.02降至1.417,均值为6.01,平均渗透通量为431.5 g/m~2·h。发酵结束后,对膜微观结构进行了分析,发现膜对水的接触角变小,疏水性能降低;通过扫描电镜发现,发酵前后膜支撑层无明显变化,但PDMS分离层略有减薄。并依据发酵前后膜性能衰减问题,讨论了膜寿命评估方法。     

可食性花生蛋白膜研究进展

花生蛋白膜是一种以花生分离蛋白为原料的天然高分子材料,具有可食用、可降解、可再生、原料价格低廉等优点。对可食性花生蛋白膜的制备(湿法、干法)、蛋白膜性能(机械性能、热性质和耐水性)、花生蛋白改性(物理、化学、酶法)对蛋白膜性能的影响、蛋白膜结构(化学键、微观表面结构)以及应用进行综述,同时指出目前该研究领域中存在的问题,并对未来的研究重点进行展望,为可食性花生蛋白膜的进一步开发利用提供参考。     

基于纳滤技术的质检萃取液脱色预处理方法

为提高纺织品及皮革甲醛检测效率和准确性,通过界面聚合法,将采用St?ber方法制备的无机颗粒与聚酰胺复合制备有机-无机杂化纳滤膜,用于纺织品和皮革萃取液脱色预处理。分别采用扫描电子显微镜、X射线光电子能谱仪和接触角仪,对颗粒形貌、纳滤膜表面元素及分离层接触角进行分析;通过纯水通量、无机盐和染料截留等对纳滤膜分离性能进行考察;并分析了纳滤脱色预处理法纺织品和皮革甲醛检测的加标回收率。结果表明:粒径分布均匀的球形二氧化硅及银离子修饰的二氧化硅颗粒成功地负载于亲水性良好的纳滤膜分离层;适量颗粒的添加有利于提高纳滤膜的纯水通量;银离子修饰的二氧化硅颗粒改善了纳滤膜对二价阳离子盐及阳离子染料的截留性能,回收率满足纺织品和皮革甲醛检测的要求。     

冷却温度对聚偏氟乙烯/超高分子量聚乙烯共混中空纤维膜结构与性能的影响

针对聚偏氟乙烯(PVDF)膜强度与渗透性能难以同步提高的问题,以矿物油和邻苯二甲酸二丁酯为复合稀释剂,通过热致相分离法制备了PVDF/超高分子量聚乙烯(UHMWPE)共混中空纤维膜,探究不同冷却温度对膜形貌及孔结构的影响,并通过气通量、水通量及拉伸强力测试表征了中空纤维膜的渗透性能与力学性能。结果表明:原纤状UHMWPE增加了PVDF球晶聚集体的连接性;冷却温度对共混中空纤维膜的结构与性能影响显著;随着冷却温度的升高,PVDF/邻苯二甲酸二丁酯和UHMWPE/矿物油的相分离与结晶时间均延长,纤维膜的平均孔径和孔隙率增加,渗透性能改善,但大孔的出现和UHMWPE原纤数量的减少使纤维膜的力学性能下降。     

Performance of forward (direct) osmosis process: membrane structure and transport phenomenon

The performance of a forward (direct) osmosis (FO) process was investigated using a laboratory-scale unit to elucidate the effect of membrane structure and orientation on waterflux. Two types of RO membrane and a FO membrane were tested using ammonium bicarbonate, glucose, and fructose as the draw solution to extract water from a saline feed solution. The FO membrane was able to achieve higher water flux than the RO membranes under the same experimental conditions while maintaining high salt rejection of greater than 97%. Increasing operating temperature increased the water flux in FO process. To investigate the effect of membrane orientation on water flux, the FO membrane was tested normally (dense selective layer facing draw solution) and reversely (dense selective layer facing feed solution). Explanations on transport phenomenon in FO process were proposed which explain the observation that the FO membrane, when used in the normal orientation, performed better due to lesser internal concentration polarization. This study suggests that an ideal FO membrane should consist of a thin dense selective layer without any loose fabric support layer.     

Application of tailor-made membranes in a multi-stage process for the purification of sweeteners from Stevia rebaudiana

In this paper the performance of a three stage process with commercial as well as tailor-made polyethersulphone (PES) membranes for the purification of sweeteners from Stevia rebaudiana Bertoni was evaluated. Retentions of the sweeteners for a synthetic mixture and plant extract in combination with flux decline measurements indicated that, in contrast with the laboratory-made membranes, on most commercial membranes a foulant layer was formed that influenced the separation performance negatively. For the plant extract, the best commercial membrane (PW010) had a selectivity and flux similar to the best laboratory-made membrane (27% PES), but the laboratory-made membrane was preferred because it showed a slightly lower retention of the sweeteners, as desired. Starting from an extract purity of 11% with the overall process (microfiltration, ultrafiltration, nanofiltration) a purity of 37% and a yield of 30% could be reached.     

鸡蛋壳、壳下膜分离工艺优化

为了开发利用鸡蛋壳和蛋壳膜,首先必须使二者分离。本文采用机械粉碎、水浮选和稀酸处理相结合的方法进行壳膜分离,筛选了鸡蛋壳、壳下膜分离的条件;通过单因素实验考察盐酸体积、反应时间、盐酸浓度对蛋壳膜脱钙率的影响,并采用响应面分析方法,对稀盐酸除蛋壳膜中残留蛋壳的工艺条件进行优化。结果表明：鸡蛋壳在粉碎机运行5 s/次、粉碎3次的条件下壳膜分离效果最佳,出粉率58.72%,脱膜率87.91%,综合得分72.91;用盐酸去除蛋壳膜中残留蛋壳的最佳工艺条件为粗蛋壳膜1 g时,使用盐酸体积20 mL、反应时间19 min、盐酸浓度0.5 mol/L,此时脱钙率可达89.21%。该工艺为鸡蛋壳的精深加工提供技术支撑。     

Microscopic observation of multispecies biofilm of various structures on whey concentration membranes

The objective of this study was to evaluate biofilm formation on polyamide reverse osmosis (RO) whey concentration membranes. Biofilms were observed with scanning electron and fluorescence microscopy. For scanning electron microscopy, pieces of 6-, 12-, and 14-mo-old membranes were allowed to air dry at room temperature (22°C) for 24 h followed by sputter coating with a 5-nm layer of gold and microscopic observations. Scanning electron microscopy images revealed that the hydrophilic layer, used to prevent membrane plugging, was not evenly distributed on the surface. Although this hydrophilic layer seemed to prevent the attachment of proteins, it supported biofilm formation. Three different structures of multispecies biofilm were observed on the retentate side of the membrane: 1) a mono layer, 2) a 3-dimensional structure of a dense matrix of extracellular polymeric substances where different types of bacterial cells were embedded, and 3) cell aggregates. In some of the biofilms, a smooth layer (shell) covered cell aggregates. In the 6-mo-old membranes, part of the shell layer was broken off. Biofilms as observed on the RO membrane were described as having a hill-and-valley type of structure, with hills showing a mushroom-like appearance and valleys comprising dense matrices of extracellular polymers with embedded bacterial cells. Fluorescence microscopy showed live cells on the surface of the biofilm. It is concluded that both cells in the deep layers of biofilm and surface cells may resist cleaning and sanitation. The extent of biofilm formation and the presence of live cells on RO membranes after regular clean in place cycles indicate the need for a more effective cleaning regimen customized for dairy separation systems.     

结晶母液回收D-对羟基苯甘氨酸的工艺优化研究

D-对羟基苯甘氨酸（D-HPG）是合成甜味剂、药物的重要中间体，为降低工艺成本，提高产品质量，提出了一种结晶母液回收D-HPG的连续色谱新工艺。优选纳滤膜进行前处理，增浓结晶母液，筛选Applexion NF200纳滤膜增浓D-HPG效果较好。通过单柱实验筛选连续色谱系统填料树脂，其中Applexion XA945树脂对D-HPG和硫酸铵分离度可达16。进一步对色谱系统的分离效果进行研究，结果表明，经连续色谱分离后，进料液中D-HPG平均纯度由42.2%提高至96.3%，平均收率达91%。利用连续色谱系统从结晶母液中回收D-HPG，是较有前途的工艺。与传统工艺相比，新工艺既保证了D-HPG总收率，又降低其工艺成本，提高了产品质量。     

再生纤维素纳米纤维膜的制备及其蛋白质分离性能

为将纳米纤维膜应用于蛋白质分离处理,用静电纺丝和化学改性方法制备聚丙烯腈/再生纤维素（PAN∕ RC）复合纳米纤维膜,通过扫描电镜、红外光谱、比表面积及孔径分析等对制备的复合纳米纤维膜进行了表征,并将制备的再生纤维素复合纳米纤维膜作为分离层,构建膜分离系统并分离纯化血清白蛋白,通过调节操作压力和过滤时间等影响因素,确定其分离纯化过程的最佳条件。研究结果表明：在操作压力为0.10 MPa、过滤时间为1.5h条件下,再生纤维素复合纳米纤维膜对蛋白质的截留率达到80.04%,膜通量达到1.85L ∕ （m²?min）,与商用聚醚砜超滤膜相比,在截留率差异不大的情况下,膜通量有了数倍的提升;同时再生纤维素复合纳米纤维膜具有优异的重复使用能力,并在使用的过程中保持良好的纳米纤维形态结构。     

Recovery and purification of potato proteins from potato starch wastewater by hollow fiber separation membrane integrated process

Potato starch wastewater contains high-concentration potato proteins which have great potential in the fields of food and health care. Most researches on potato protein recovery by membrane separation technique are focused on flat sheet or tubular ultrafiltration (UF) and reverse osmosis (RO) membranes and lack the further protein purification and the in-depth discussions on the fouling behavior. In this laboratory-scale study, potato proteins were recovered and purified from the simulated potato starch wastewater by the self-made hollow fiber (HF) UF and nanofiltration (NF) separation membrane integrated process. 85.62% potato proteins with high molecular weight in the potato starch wastewater could be retained by UF membrane and 92.1% potato proteins with low molecular weight were rejected by NF membrane. The concentrated solution after UF and NF filtration was desalinated and purified by diluting the solution eight times and filtering the diluted solution with UF membrane. Both types of HF membranes, UF and NF, suffered the inevitable membrane fouling. After the traditional physical washing and chemical cleaning, water flux of UF and NF membranes can be effectively recovered. The corresponding recovery rates of UF and NF membranes can reach 93.5% and 84.7%, respectively. The hollow fiber UF-NF separation membrane integrated process was proved to be a promising technique of high-purity potato protein recovery from potato starch wastewater.     

超支化季铵盐诱导制备树枝状纳米纤维膜及其性能

为开发具有高效过滤性能的膜材料,以超支化季铵盐(HBP-HTC)为枝化促进剂,利用静电纺丝技术一步法制备了聚偏氟乙烯(PVDF)树枝状纳米纤维膜,探讨了纺丝工艺对纤维膜成形结构的影响,分析了树枝状纳米纤维膜的力学性能及其空气过滤性能。结果表明:由于HBP-HTC表面丰富的季铵基团具有对电荷的稳定富集作用,可获得比用小分子季铵盐制成膜更多的树枝状纳米纤维结构,当PVDF质量分数为12%,季铵基团添加量为 0.10 mol/L, 纺丝电压为25 kV时,制得的纤维膜树枝状覆盖率高达78.32%,且具有较好的力学性能;所制备的纳米纤维膜厚度为40 μm时,其过滤效率高达99.995%,而压降为122.4 Pa。