表面活性剂对天然胶乳蛋白质含量影响的研究

采用表面活性剂直接处理鲜胶乳离心浓缩法制备浓缩胶乳,先用尿素预处理新鲜胶乳后加入表面活性剂处理,再离心浓缩法制备浓缩胶乳。研究表面活性剂种类、尿素预处理时间和预处理温度及新鲜胶乳的pH值对处理所得浓缩胶乳蛋白质含量的影响。同时用傅立叶红外吸收光谱对2种处理方法制备的浓缩胶乳胶膜进行了表征。实验结果表明,鲜胶乳先经尿素预处理一定时间后加入阴离子表面活性剂处理,再离心浓缩制备浓缩胶乳,蛋白质含量显著降低。适宜条件下,浓缩胶乳的氮含量从质量分数0．430％下降至0．089％。红外光谱分析表明,先用尿素预处理新鲜胶乳,然后加入阴离子表面活性剂处理,再离心浓缩制备浓缩胶乳,胶膜在1546cm。处蛋白质的酰胺Ⅱ谱带几乎消失,在3295cm。处N—H的伸缩振动峰明显减弱。     

氨含量和贮存时间对原产天然胶乳和胶清胶乳凝聚物性能的影响

原产天然胶乳用质量分数分别为0.35%、0.60%和0.80%的氨进行处理,经离心处理后分离成为浓缩天然胶乳(干胶含量60%)和胶清胶乳(干胶含量约5%)。再通过加入质量分数0.65%～0.75%(以胶乳计)的NH;、月桂酸铵和水,将浓缩胶乳调节为高氨型胶乳,在室温下贮存30～120 d,考察了贮存时间和原产胶乳中的氨含量对胶乳碱度、力学性能稳定时间(MST)、挥发性脂肪酸(VFA)值、凝胶含量和磷酸盐含量的影响。结果表明,胶乳的MST、VFA值、凝胶含量和磷酸盐含量随着贮存时间的延长而增加。在原产天然胶乳中加入过量氨后,由于[Zn(NH_3)_n)^(2+)络合物的生成,使浓缩天然胶乳中的凝胶含量增加。当浓缩天然胶乳和胶清胶乳二者中的氨含量增加,且原产胶乳的贮存时间延长时,胶乳的稳定性得到提高,胶清胶乳中不易产生凝聚物。     

以壳聚糖为载体固定化海藻糖合成酶

以壳聚糖为栽体,采用戊二醛为交联剂的方法来固定海藻糖合成酶。研究结果表明：在戊二醛质量分数为0．5％、液态酶与壳聚糖凝胶的配比为1：1、交联pH值为8．0、交联温度为15℃、交联时间为12h条件下,固定化海藻糖合成酶的活性最高,生成的海藻糖量最多,海藻糖的最高含量能达到40％左右。另外,固定化酶转化麦芽糖为海藻糖的最佳反应时间为18h,这时可以获得最高含量的海藻糖。     

三甲胺修饰戊二醛交联壳聚糖树脂的制备及其吸附性能

用水相均匀交联法制备戊二醛交联壳聚糖树脂 ,以三聚氯氰为活化剂 ,合成了三甲胺修饰戊二醛交联壳聚糖树脂 ,研究了该树脂的红外光谱特征及吸附性能。该树脂对铜 (Ⅱ )和牛血清白蛋白 (BSA)的吸附容量分别为 37mg/g和 460mg/g(以折合干重计 ) ,其吸附行为符合Freundlich等温吸附模型。该树脂制备工艺简单 ,可作为蛋白质分离纯化的吸附剂     

壳聚糖制膜研究

甲壳素是广泛存在于自然界的一种天然高分子材料。本文制备了甲壳素的一种重要衍生物壳聚糖，并与戊二醛交联制备了壳聚糖交联膜。用红外光谱和扫描电镜探讨了壳聚糖交联前后的差异。     

AS1.398中性蛋白酶的固定化研究

利用壳聚糖为载体，戊二醛为交联剂，对AS1．398中性蛋白酶进行了固定化研究，固定化反应的最佳条件是采用1％的戊二醛浓度，壳聚糖和戊二醛的交联反应时间为4h，加入酶固定化反应12h，固定化酶的最适温度35℃，最适pH值8．0。得到的固定化酶的活力回收平均为82．5％，固定化酶的稳定性能好于游离酶。     

纤维素/壳聚糖复合微球的制备及对铜(Ⅱ)的吸附性能研究

采用纤维素与壳聚糖复合的方法,以戊二醛为交联剂制备了一种具有Cu2+印迹的纤维素/壳聚糖复合微球,考察了制备过程中纤维素种类,纤维素与壳聚糖质量比、戊二醛用量、交联时间、交联温度及溶液pH对吸附铜(Ⅱ)的影响,并用扫描电镜(SEM)和傅里叶红外光谱(FTIR)对复合微球进行表征.结果表明,当壳聚糖与羧甲基纤维素质量比为...     

橡胶小辞典6条

保存胶乳ｐｒｅｓｅｒｖｅｄｌａｔｅｘ指用保存剂处理后在一定时间内可保持稳定状态的胶乳。包括鲜胶乳和经过浓缩处理直接用作胶乳制品原料的浓缩胶乳。传统的胶乳保存剂是氨和甲醛等。近年来发展了以氨为基础、配合各种杀菌剂和毒酶剂的复合型保存剂,以提高保存胶乳的...     

壳聚糖凝胶注模成型氧化铝瓷的研究

采用生物大分子壳聚糖的凝胶系统，进行了凝胶注模成型氧化铝瓷的研究。傅立叶变换红外光谱(FT—IR)分析表明，在稀醋酸中壳聚糖和戊二醛通过亚胺键交联反应可以形成较高强度的凝胶体，加入氧化铝并不破坏胶体的结构。同时研究探讨了醋酸、壳聚糖、戊二醛含量及Al2O3粉末固相体积分数和反应温度等对凝胶固化反应时间的影响因素。通过改变影响因素有效的控制了凝胶反应时间，最终实现理想的注模成型工艺。     

天然胶乳胶膜干燥过程及交联结构研究

采用失重法、溶胀法及红外光谱,研究了天然胶乳厚胶膜的干燥动力学过程及干燥过程与橡胶分子链交联密度的关系。结果表明,天然胶乳胶膜的干燥温度和厚度显著影响其干燥过程,通过动力学拟合结果,建立了干燥动力学方程;胶膜干燥开始后,橡胶分子交联密度迅速上升,达到最大交联密度后,交联密度随干燥时间的增加而降低,红外光谱的研究结果也证明了这一规律。干燥过程对天然胶膜的交联结构有明显影响。     

交联壳聚糖渗透蒸发膜的制备及其在偏二甲肼/水体系分离中的应用

采用壳聚糖为原料,聚酯无纺布为支撑层,用戊二醛交联制备了高选择性、高通量的交联壳聚糖渗透蒸发复合膜.考察了料液浓度、料液温度、膜厚等对偏二甲肼/水体系分离性能的影响.结果表明:在料液温度为10℃,膜厚度为25 μm,进料液中偏二甲肼的质量分数为50％时,改性复合膜的分离因子最高达到5.25,渗透通量可达167 g/(m...     

Synthesis and characterization of a thiourea derivative of chitosan for platinum recovery

Chitosan is effective at removing platinum from dilute solutions, but sorption properties are significantly affected by the presence of competitor anions, such as chloride and, especially, sulfate anions. Sorption capacities in such complex solutions are enhanced by grafting thiourea through glutaraldehyde linkage. The influence of the amount of glutaraldehyde and thiourea in the impregnation bath was investigated and optimized with special attention to the composition of the solution and the type of acid used for pH control. This modification involves a change in the sorption mechanism: While glutaraldehyde‐crosslinked chitosan adsorbs platinum through an ion‐exchange mechanism, the thiourea derivative of chitosan acts as a chelating resin, less sensitive to ionic strength and competitor anions. Platinum sorption is also less sensitive to pH, and increasing the sulfate anion concentration has a limited effect on platinum sorption in comparison with the crosslinked sorbent. Thiourea grafting seems to increase sorption kinetics, especially in solutions controlled with sulfuric acid. SEM–EDAX techniques as well as FTIR analyses were used to characterize chemical modifications of the sorbent. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 119–134, 2000     

Preparation and characterization of collagen‐based composite conduit for peripheral nerve regeneration

Collagen‐based composite nerve conduit scaffold was prepared by freeze‐drying steam‐extrusion method and modified chemically with glutaraldehyde (GTA) by adding chitosan into collagen. Fourier transform infrared spectroscopy showed that the collagen and chitosan are certainly crosslinked through GTA. It was observed under scanning electron microscope that the modified nerve conduit material is a porous three‐dimensional crosslinked structure and the quantity ratio of the collagen to chitosan has influence on the morphology. The cell proliferation experiment results showed that the collagen‐based composite scaffold prompts the adhesion and proliferation of cells, but as the chitosan increasing, the cell proliferation decreased slightly. The swelling property, the collagenase degradation, and the mechanical property of the scaffold are tested at the quantity ratios of collagen to chitosan 4 : 3, 3 : 1, and 4 : 1 and crosslinking time 0.5 and 1.0 h. The experiments show that the stability of the scaffold is enhanced with decreasing the quantity ratio of collagen to chitosan and increasing crosslinking time. Through the experimental investigations, the modifying technique parameters are discussed and the scaffold exhibits better physical and chemical properties at the quantity ratio of collagen to chitosan 3 : 1 and crosslinking time 0.5 h. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of chitosan membranes for filtration and concentration of compounds under high pressure process

Summary Chitosan membranes of three types: i) dried in ammonia atmosphere (CSA); ii) double layer crosslinked with glutaraldehyde (CSG); and iii) prepared from aqueous-ethanolic solution and dried in the presence of ammonia vapor (CSE) were developed by casting chitosan solutions onto a glossy paper used as a support in the process of filtration under high pressures. All the membranes were characterized by infrared spectroscopy, scanning electron microscopy and by permeation experiments. Addition of ethanol to the chitosan solution decreased the time of membrane preparation and of the filtration process. The performance (solute rejection) of these membranes was found to be efficient with organic compounds such as methylene blue, truncated hemoglobin and bovine serum albumin (BSA) with molecular weights of 319.8 Da 17.7 kDa and 66.4 kDa respectively, since it retained practically 100% of the sample.     

壳聚糖-透明质酸复合凝胶的制备

合成了壳聚糖-透明质酸复合凝胶（壳聚糖15g/L,透明质酸1g/L,交联剂戊二醛用量为壳聚糖-透明质酸质量的30%,即4.8g/L,室温下放置24h）,以改善单纯壳聚糖凝胶脆性较大、黏弹性及持水能力较弱等性能。壳聚糖与透明质酸在复合水凝胶中未发生微相分离,具有良好的相容性。与单纯的壳聚糖凝胶相比,含有透明质酸的复合凝胶具有较好的弹性及持水性能等。复合凝胶水分保持能力随凝胶中透明质酸含量的增大而增大,高温条件下复合凝胶持水能力更显著优于单纯壳聚糖凝胶。复合凝胶随温度、pH值等外界条件的改变会出现规律性的溶胀或收缩,具有作为智能材料使用的前景。     

丙烯酸接枝改性壳聚糖纤维的制备及性能

在引发剂过硫酸铵(APS)的作用下,采用丙烯酸(AA)接枝改性壳聚糖(CS),制备出CS-AA接枝共聚物,经湿法纺丝将其纺制成纤维,再用戊二醛对纤维进行一定程度的交联,可得到较好力学性能的改性CS纤维。结果表明:CS质量分数(相对AA)为14.3%,APS(相对AA)的摩尔分数为1.0%,反应温度65℃,反应时间6 h,凝固浴中无水乙醇和质量分数为10%氢氧化钠水溶液的体积比为50/50。在此条件下制得的纤维的断裂强度为0.55 cN/dtex,断裂伸长率为367%,经交联处理后纤维的断裂强度达2.03 cN/dtex。     

交联壳聚糖树脂对Au(Ⅲ)的等温吸附特性和吸附动力学

以戊二醛为交联剂、用硫脲进行接枝改性合成了交联壳聚糖树脂,研究其对Au(Ⅲ)的吸附特性,考察了pH值、吸附温度、吸附时间等因素对吸附过程的影响。结果表明:溶液pH值对吸附影响较大,最佳pH值在5.0左右;在实验浓度和温度范围内,树脂对Au(Ⅲ)的等温吸附数据与Freundlich模型拟合较好;吸附过程宏观表现为吸热过程;吸附动力学符合准二级动力学方程,表观活化能为41.12kJ/mol,吸附过程主要为化学吸附控制。     

交联壳聚糖对废水中Cu2+的吸附性能

以壳聚糖为原料制备交联壳聚糖吸附剂,并将其用于吸附废水中的Cu2+,考察了交联剂的用量、溶液中Cu2+初始浓度、pH、温度和时间等对交联壳聚糖吸附性能的影响。结果表明,壳聚糖与交联剂的用量比为m(壳聚糖)∶V(甲醛)∶V(戊二醛)=1.5g∶6mL∶4.5mL、溶液pH为6,溶液中Cu2+初始浓度为5mmol/L时吸附效果最佳,且吸附量随着温度升高而增加,吸附表现为吸热过程。     

Microwave preparation and copper ions adsorption properties of crosslinked chitosan/ZSM molecular sieve composites

A novel chitosan‐based composite (CTS/ZSM) made of chitosan and ZSM molecular sieve was prepared under microwave irradiation and was used for the removal of Cu (II) ions from aqueous solution. The composites were characterized by FTIR spectra, XRD spectra, and thermogravimetric analysis. The effects of the ZSM content, amount of glutaraldehyde and pH value on adsorption properties of Cu (II) ions by CTS/ZSM were discussed in detail. Contrast with crosslinked chitosan (CCTS), the CTS/ZSM had higher adsorption capacity for Cu (II). Kinetic studies showed that the adsorption of Cu (II) onto CTS/ZSM composite had low correlation coefficients for the pseudo‐first and ‐second order model and intraparticle diffusion model. The equilibrium process was better described by the Langmuir than Freundlich isotherm model. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013