利用膜分离技术回收正丁醇/水混合液的工艺研究

研究了聚乙烯醇（PVA）／聚丙烯腈（PAN）、海藻酸钠（SA）／PAN复合膜及海藻酸钠／醋酸纤维素（CA）共混膜等五种膜的渗透汽化特性,发现它们对正丁醇／水的混合液均表现为水优先透过,其渗透通量与选择分离系数都很高。并初步确定了正丁醇／水混合液渗透汽化分离的工业生产操作条件。     

CA/PAN/DMAc溶液相转变过程的研究

通过二醋酸纤维素（CA）溶液、以丙烯腈为主体二元共聚物（PA）溶液及两者共混溶液凝胶化过程的显微摄影、高聚物／溶剂／沉淀剂的三元相图以及共混体系的玻璃化转变温度的考查，揭示了CA／PAN／DMAC溶液的相转变特性以及影响其混膜结构和性能的内在因素。结果表明，CA和PAN在DMAC溶液中具有相互渗透、相互扩散作用；在沉起剂的作用下，以不同的速度发生相转变，共混膜断面依共混比及温度的改变呈现不对称指状结构和网络结构；共混膜的水通量和平均孔径大于纯组份。     

醋酸纤维素氨基甲酸酯的合成及其膜性能的研究

研究了用甲苯二异氰酸酯对醋酸纤维素进行改性,合成醋酸纤维素氨基甲酸酯,以增强高聚物的物理性能和耐菌性能。探讨了反应时间、原料配比、反应温度、催化剂用量及产物分离用溶剂等因素对此高聚物材料合成的影响。对醋酸纤维素苯基氨基甲酸酯铸成的反渗透膜的水通量、脱盐率、耐水解和耐微生物的稳定性能的测试表明,经改性的醋酸纤维素膜具有较好的上述性能,是一种良好的膜材料。     

不同形貌固体酸的纤维素乙酰化催化性能研究

为了考察不同形貌的固体酸对纤维素乙酰化反应性能的影响,制备了微球状（NSP）、片状（NS）、棒状（NR）及颗粒状（NP）四种不同形貌的钛基硫酸促进型固体超强酸,将其用于纤维素乙酰化反应合成醋酸纤维素中。利用扫描电子显微镜（SEM）、X-射线衍射分析（XRD）、氮气吸脱附测试（BET）、傅里叶变换红外光谱（FT-IR）等技术对催化剂的形貌、晶体结构类型、比表面积及孔容、结构组分进行分析,利用XRD、FT-IR对产物醋酸纤维素（CA）的结构性质进行表征。酸碱滴定结果表明,上述不同形貌的钛基硫酸促进型固体超强酸材料催化合成的醋酸纤维素（CA）的取代度大小顺序为微球>片>棒>颗粒状固体酸,表明微球形貌的固体酸的催化性能最优。进一步考察反应温度及时间对催化合成CA的影响。结果表明,制备CA的最佳工艺为：2 g纤维素,8 mL醋酸酐,1 g固体超强酸催化剂,酯化反应温度65℃,反应时间为2 h。     

纤维素醋酸酯接枝己内酯的合成与表征

以冰醋酸为溶剂,浓硫酸为催化剂,将三醋酸纤维素水解为不同取代度的醋酸纤维素(CA),再用此醋酸纤维素同ε-己内酯(ε-CL)接枝共聚合成醋酸纤维素/聚己内酯接枝共聚物(CA-g-PCL).研究了醋酸纤维素取代度和原料配比对单体转化率(C)、接枝率(G)、接枝效率(EG)的影响,结果表明在醋酸纤维素取代度为0.7时接枝共聚反应C、G、EG可分别达到46%、238.6%、88.5%;m(ε-CL)m(CA)=51时可分别达48.3%、140.553%、58.2%,并对相应的接枝共聚物进行了FTIR和1H-NMR的表征分析.     

混合溶剂制备醋酸纤维素膜及其性能

以醋酸纤维素、丙酮、N-甲基吡咯烷酮(NMP)和聚乙二醇400(PEG-400)为原料,采用相转化法制备醋酸纤维素膜,对其结构和形貌进行了表征;在室温、操作压力0.1 MPa下,用去离子水和500 mg/L PEG-600溶液分别测定膜的水通量和截留率,考察了混合溶剂中丙酮和NMP含量、反应温度和致孔剂PEG-400含量对醋酸纤维素膜性能的影响. 结果表明,NMP含量60%(w)、丙酮含量22.5%(w)、反应温度60℃及PEG-400含量6%(w)条件下,所制醋酸纤维素膜表面光滑,孔径分布均匀,水通量达212.87 L/(m2×h),截留率达87.67%.     

醋酸纤维素的降解性研究进展

介绍了醋酸纤维素的生物降解、水解、光解的降解机理与研究现状,并对影响醋酸纤维素降解速率的因素进行了探究。从现有研究中可知,影响醋酸纤维素降解速率的主要因素为醋酸纤维素自身的分子结构（如取代度、取代度分布及结晶性等）,物理改性、化学改性及增塑改性会通过改变醋酸纤维素的分子结构,进而影响醋酸纤维素的降解性能。最后,总结了醋酸纤维的应用领域,并做出了展望。     

利用膜分离技术回收正丁醇／水混合液的工艺研究

研究了聚乙烯醇（ＰＶＡ）／聚丙烯腈（ＰＡＮ）、海藻酸钠（ＳＡ）／ＰＡＮ复合膜及海藻酸钠／醋酸纤维素（ＣＡ）共混膜等五种膜的渗透汽化特性,发现它们对正丁醇／水的混合液均表现为水优先透过,其渗透通量与选择分离系整都很高。并初步确定了正丁醇／水混合液渗透汽化分离的工业生产操作条件。     

超滤膜在饮用水处理中临界通量的影响因素研究

超滤膜在临界通量以下过滤可不产生膜污染或产生极轻的膜污染,针对超滤膜在饮用水处理中的临界通量的影响因素,系统考察曝气、过滤方式和混凝沉淀预处理等对浸没式超滤膜处理松花江水临界通量的影响.结果表明,曝气强度达到10 m3/(m2·h),连续曝气可将超滤膜的临界通量提高5 L/(m2·h),曝气强度达到40 m3/(m2·...     

脱乙酰基改性乙酸纤维薄膜对乳化油分离及积垢机理的探究

利用静电纺丝制造乙酸纤维素膜（CA纤维膜）,并利用添加TiO₂及脱乙酰基（d-CA）对CA纤维膜进行改性,后续对膜过滤特性、渗透通量、油水乳化液去除效率、反洗特性及积垢机制进行讨究。结果显示,CA纤维膜通过TiO₂及d-CA改性后可以提高膜的热稳定性及亲水性能,并得到稳定的纯水通量和过滤通量;最佳的比例为TiO₂@d-18.5%CA纤维膜,在40kPa跨膜压差、60min的操作条件下,其纯水通量、过滤通量、1g/L油水乳化液去除效率以及反洗后通量分别为824.8L/(m²·h)、(311.3±12.5)L/(m²·h)、93.6%±1.1%、451.5L/(m²·h);另外,添加TiO₂可能导致油水乳化液在膜表面不可逆阻力比例的增加,脱乙酰基改性CA纤维膜则可以降低膜自身阻力及增加可逆阻力的比例,提高CA纤维膜在油水分离方面的潜力。     

Biodegradation behavior of acid‐containing cellulose acetate film in soil

The biodegradation behavior of various cellulose acetate (CA; degree of substitution = 2.5) films that contain acids was examined by a laboratory soil burial test to clarify the effects of additives on the biodegradability of CA. The biodegradation rate of the CA films containing polyphosphoric acid, phosphoric acid, and p‐toluenesulfonic acid increased compared to that of the nonadditive CA film. CA films containing mandelic acid and maleic acid showed a small tendency to increase. Conversely, CA films containing adipic acid did not affect the biodegradability of CA. A similar experiment was carried out with a sterilization system. The acid‐containing CA film, which showed an accelerated biodegradation rate, was chemically deacetylated by contact with water in the environment and was consequently converted to a lower degree of acetyl group substitution matter that had higher biodegradability. An IR analysis suggested that this deacetylating ability of acids is correlated with the intensity of their interaction with the acetyl group of CA. In the biodegradation process, the contact efficiency of acids to CA was considerably lowered by the elution of internal acids with time. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 466–473, 2005     

甘蔗渣综纤维素膜的制备和性能研究

以甘蔗渣中所提取的综纤维素为原料，ZnCl₂溶液为溶剂，通过相转化法制备综纤维素膜，探究了综纤维素用量（以ZnCl₂溶液质量计，下同）、溶解时间、凝胶化时间和所浸泡甘油质量分数等因素对湿膜的孔隙率、水通量及干膜的力学性能的影响；并通过SEM、XRD、FT-IR、TG等表征方法分析了溶解成膜机理。研究结果证实了从甘蔗渣中提取的综纤维素可直接作为原料来制备综纤维素膜，当综纤维素用量为5%、凝胶化时间3 d、溶解1 h时制得的湿膜有着最小的水通量为17.2L/（m²·h），孔隙率为83.3%，再经10%质量分数的甘油增塑得到的干膜有着最大的拉伸强度，为21.9MPa，此时断裂伸长率为22.2%。根据FT-IR、TG可知以综纤维素为原料制得的膜中未包含半纤维素，半纤维素可能在溶解过程中水解或者在成膜过程中析出。根据SEM可知湿膜状态下膜内部有均匀孔洞，干燥后膜孔洞收缩形成致密结构。XRD结果表明综纤维素成膜后其中的纤维素由纤维素Ⅰ型转变为纤维素Ⅱ型，结晶度由48.8%降至41.5%。     

醋酸纤维素/壳聚糖复合膜制备与性能优化

为拓展醋酸纤维素(CA)在可降解包装材料中的应用,采用溶液共混法制备了醋酸纤维素(CA)和壳聚糖(CS)复合膜,研究了CS含量对CA/CS二元复合膜性能的影响。通过观察并分析复合膜的形貌、断面结构、化学键发现,CS能够充分结合膜内外的孔隙结构,两者之间强烈的相互作用增强了复合膜的各项性能。性能测试结果表明,当CS含量为10%时,复合膜的力学性能达到最大,断裂伸长率及抗拉强度分别增加12.37%和38.62 MPa,降解损失率提高了50.14%。同时,抑制了大肠杆菌及金黄色葡萄球菌的生长,抗菌率最高能够达到73.9%和54.6%。因此,CS在提高CA膜的力学性能和降解性能的同时,还赋予了复合膜优异的抗菌性。     

Effect of cellulose acetate/cellulose triacetate ratio on reverse osmosis blend membrane performance

Surface functionalization and modification including the grafting process are effective approaches to improve and enhance the reverse osmosis (RO) membrane performance. This work is aimed to synthesize grafted/crosslinked cellulose acetate (CA)/cellulose triacetate (CTA) blend RO membranes using N-isopropylacrylamide (N-IPAAm) as a monomer and N,N-methylene bisacrylamide (MBAAm) as a crosslinker. The morphology of these membranes was analyzed by scanning electron microscopy and their surface roughness was characterized by atomic force microscopy. The performance of these membranes was evaluated through measuring two major parameters of salt rejection and water flux using RO unit at variable operating pressures. It was noted that the surface average roughness obviously decreased from 148 nm for the pure CA/CTA blend membrane with 2.5% CTA to 110 nm and 87 nm for the grafted N-IPAAm and grafted/crosslinked N-IPAAM/MBAAm/CA/CTA-RO membranes, respectively. Moreover, the contact angle decreased from 51.98° to 47.6° and 43.8° after the grafting and crosslinking process. The salt rejection of the grafted CA/CTA-RO membrane by 0.1% N-IPAAm produced the highest value of 98.12% and the water flux was 3.29 L/m²h at 10 bar.     

醋酸丙酸纤维素的合成与表征

采用非均相催化酯化法合成醋酸丙酸纤维素(CAP),研究了反应时间、温度和催化剂用量对CAP乙酰和丙酰取代度、特性粘度的影响,发现反应温度、反应时间和催化剂浓度增加虽可使产物的取代度增大,但粘度降低,得到优化的反应条件为:催化剂用量1%(wt,相对于纤维素),反应温度60℃,反应时间2 h。酯化反应使纤维素的结晶度降低。     

醋酸纤维素取代基分布与性质的关系

分析了以吡啶为溶剂的醋酸纤维素的13C-NMR核磁共振谱,得出了三种不同位置羟基的取代度。结合X—射线和DSC分析,初步说明具有相同取代度但未经水解和经过水解的醋酸纤维素(CA) 性质上的差异是由于三个羟基上的取代度分布不同及消晶程度差异所致。     

Fabrication of cellulose acetate ultrafiltration membrane with diphenyl ketone via thermally induced phase separation

With diphenyl ketone as diluent, cellulose acetate (CA) ultrafiltration (UF) membrane with a bicontinuous structure was prepared via thermally induced phase separation (TIPS) method. The liquid–liquid phase separation region of CA/diphenyl ketone system was measured and the maximum corresponding polymer concentration was approximately 53 wt %. The effects of polymer concentration, coarsening time and coarsening temperature on the morphologies, and mechanical properties of CA membranes were investigated systematically. As the polymer concentration increased from 15 to 30 wt %, the bicontinuous structure could be obtained and the tensile strength of CA membranes increased from 3.92 to 30.17 MPa. With the increase of coarsening time, the thickness of dense skin layer and the asymmetry of cross‐section reduced. However, excess coarsening rendered the membrane morphology evolved from a bicontinuous structure to a cellular structure. When the coarsening time was 5 min, the bicontinuous structure in cross‐section showed good interconnectivity and the dense skin layer exhibited a thin thickness of 2 μm. The fabricated CA hollow fiber UF membrane exhibited a high tensile strength of 31.00 MPa and rejection of 96.10% for dextran 20 kDa. It is indicated that diphenyl ketone is a competitive diluent to prepare CA membranes with excellent performance via TIPS. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42669.