聚天冬氨酸衍生物的合成及性能

利用聚天冬氨酸热缩聚产物聚琥珀酰亚胺(PSI)和天冬氨酸(ASP)合成了一种聚天冬氨酸衍生物.研究了聚天冬氨酸衍生物的阻垢性能、分散性能和污垢热阻.实验结果表明:当Ca~(2+)质量浓度为400mg/L、HCO_3~-质量浓度为800mg/L、聚天冬氨酸衍生物用量为6mg/L时,阻垢率达到100%,比聚天冬氨酸的阻垢率最大提高4%以上;聚天冬氨酸衍生物对Fe_2O_3有一定的分散作用;聚天冬氨酸衍生物的污垢热阻小于聚天冬氨酸的污垢热阻.     

我国聚天冬氨酸(钠)技术进展与发展建议

聚天冬氨酸(钠)是一种新型的可生物降解并具有生物相容性的高分子材料。介绍了聚天冬氨酸(钠)的生产与技术进展,着重介绍了聚天冬氨酸(钠)的应用领域和市场前景,并提出了聚天冬氨酸(钠)的发展建议。     

聚天冬氨酸共聚物阻磷酸钙垢性能研究

以天冬氨酸(ASP)、2-氨基乙磺酸(AESA)、氢氧化钠等为原料制备了一种无磷环保型阻垢剂聚天冬氨酸共聚物(PASP-AESA-ASP),采取静态阻垢法考察了其阻磷酸钙垢性能,用扫描电子显微镜观察了加入聚天冬氨酸共聚物后形成的磷酸钙形貌。实验结果表明,聚天冬氨酸共聚物阻磷酸钙垢的性能明显高于聚天冬氨酸,在加药量为6 mg/L时,比聚天冬氨酸的阻垢率提高了86%;对不同磷酸钙离子浓度的阻垢率也均有很好的效果,在加药量为14 mg/L时,聚天冬氨酸共聚物的阻垢率均达到了91%以上,当PO43-为10 mg/L时其阻垢率达到了95.2%。     

聚天冬氨酸共聚物的合成、表征及性能研究

利用天冬氨酸热缩聚产物聚琥珀酰亚胺(PSI)和2-氨基乙磺酸(SEA)、天冬氨酸(ASP)合成了一种聚天冬氨酸共聚物。红外光谱法和元素分析法表征了聚天冬氨酸共聚物的结构,研究了聚琥珀酰亚胺与2-氨基乙磺酸、天冬氨酸不同比例时的接枝率;考查了聚天冬氨酸共聚物的阻垢和分散性能;利用扫描电子显微镜对CaCO3晶形进行了观察和分析。实验结果表明:当PSI:SEA:ASP=1:0.6:0.4时,其阻垢和分散的综合性能较好;当Ca2+质量浓度400mg·L-1、HCO3-量浓度800mg·L-1、聚天冬氨酸共聚物用量4mg·L-1时,阻垢率为59%;聚天冬氨酸共聚物用量10mg·L-1,分散氧化铁时上清液最小透光率为53%。聚天冬氨酸共聚物对CaCO3有晶格扭曲和分散作用。     

聚天冬氨酸的合成及其阻垢性能研究

聚天冬氨酸作为无磷、可生物降解的环保型阻垢剂,目前已经成为研究热点。研究了聚天冬氨酸的合成及其阻垢性能,实验结果表明,合成的聚天冬氨酸(PASP)具有良好的阻垢性能,阻垢率可达73.69%。     

聚天冬氨酸的改性对阻垢分散性能的影响

将聚琥珀酰亚胺(PSI)与天冬氨酸(ASP)、2-氨基乙磺酸(SEA)分别进行反应,对聚天冬氨酸进行改性,并对改性聚天冬氨酸的阻CaCO3垢、分散Fe2O3和缓蚀性能进行了评定。实验结果表明:在PASP分子结构中引入羧基可以提高其阻垢率,而磺酸基的引入则会降低其阻垢率,当引入羧基的改性聚天冬氨酸质量浓度为6mg/L时,阻垢率达到了100%;磺酸基的引入可以大大提高聚天冬氨酸的分散性能,加药质量浓度为10mg/L,分散Fe2O3时上清液最小透光率为40.3%;羧基的引入有助于缓蚀性能的提高,加药质量浓度为100mg/L时,比PASP的缓蚀率提高35%以上。     

聚天冬氨酸及衍生物的结构对性能的影响研究进展

聚天冬氨酸(PASP)是具有优良的阻垢缓蚀性能和可生物降解性新型绿色水处理药剂,但其性能在某些应用领域存在一定局限性,为加速水处理药剂的绿色化进程,以提高聚天冬氨酸的阻垢性能为目标的多种改性研究相继出现,以聚天冬氨酸及衍生物的现有研究文献为材料,分别研究聚天冬氨酸及衍生物的结构及相应结构产品的性能,总结它们的结构对性能的影响,为今后聚天冬氨酸改性和新型环境友好水处理剂的发展提供理论依据。     

聚天冬氨酸合成及性能研究

本文对L-天冬氨酸合成聚天冬氨酸方法进行了研究,探索了聚天冬氨酸聚合条件与产率的关系.用正交实验对热缩聚法制聚天冬氨酸进行了讨论,找到了合成聚天冬氨酸产率高的较佳的工艺.     

聚天冬氨酸及其复配物对硫酸钙的阻垢性能

以L-天冬氨酸为原料，热聚合成聚天冬氨酸酐，水解得到聚天冬氨酸的钠盐。采用凝胶色谱法(GPC)测定了聚天冬氨酸的相对分子质量。研究了聚天冬氨酸及其复配物的阻CaSO4垢性能。实验表明：聚天冬氨酸在投加质量浓度为4mg／L时，阻垢率达到90％，优于常用的阻垢剂聚马来酸和聚丙烯酸。聚天冬氨酸与三聚磷酸钠的复配物在投加质量浓度为5mg／L时，阻垢率达到90％，与柠檬酸三钠的复配物的阻垢率达到88％。聚天冬氨酸及其复配物均具有一定的耐温性能，且聚天冬氨酸优于其复配物。     

聚天冬氨酸的合成与表征

介绍了以L -天冬氨酸为原料 ,热缩合成聚天冬氨酸酐 ,水解得到聚天冬氨酸的合成工艺。采用凝胶色谱法测定了聚天冬氨酸的分子量 ,并用核磁共振对其进行了表征。     

聚天冬氨酸及其衍生物的合成研究进展

聚天冬氨酸能够被生物降解,在工业,医学,农药方面都有广泛的应用,将会逐步取代正在使用的不可以生物降解的聚合物。系统的介绍了聚天冬氨酸及其衍生物的不同的合成方法,指出了各种方法的优点和缺陷,并且预测了未来的研究方向。     

聚天冬氨酸合成工艺研究

聚天冬氨酸是氨基酸的一种聚合物,它的生物可降解性好,是一种环境友好型产品,被广泛应用于工业水处理、表面活性剂、日用化学品等领域。在单因素实验的基础上,采用均匀设计法对影响反应收率的原料配比、反应温度和反应时间进行了研究,建立了回归方程数学模型。结果表明,回归模型很好地反映了各因素水平与响应值之间的关系,最佳制备工艺条件为:n(顺丁烯二酸)∶n(尿素)=1∶1,反应时间2.3h,反应温度92℃,产品得率达86.51%。并通过红外吸收谱图对产品进行了表征。     

天冬甜精中间体的合成优化

用均匀设计法优化了天冬甜精中间体———N 乙氧硫羰基天冬氨酸的合成反应条件。优化工艺条件为 :反应温度 72℃ ,n(甲基乙基黄原酸酯 )∶n(天冬氨酸 ) =1 5 0∶1 0 0 ,m(天冬氨酸 )∶m(氢氧化钠 ) =0 5 0∶1 0 0 ,m(水 )∶m(天冬氨酸 ) =4 0 0∶1 0 0 ,m(甲醇 )∶m(水 ) =0 15∶1 0 0。N 乙氧硫羰基天冬氨酸的收率为 88 92 %。     

双酶连续催化生物合成D-丙氨酸

建立了天冬氨酸消旋酶和D-氨基酸转氨酶双酶连续催化制备D-丙氨酸的方法。利用天冬氨酸消旋酶全细胞催化L-天冬氨酸消旋得到DL-天冬氨酸,离心去除天冬氨酸消旋酶全细胞后升温灭活残留的游离天冬氨酸消旋酶,再加入经镍柱亲和纯化的D-氨基酸转氨酶酶液,催化D-天冬氨酸(D-Asp)和丙酮酸(PA)经转氨反应生成D-丙氨酸。经单因素实验得到天冬氨酸消旋酶最佳催化条件为:反应温度40℃,0.2 mol/L磷酸钾缓冲溶液(pH=7.0),底物L-天冬氨酸质量浓度为100 g/L。D-氨基酸转氨酶最佳催化条件为:反应温度42℃,0.2 mol/L磷酸钾缓冲液(pH=7.0),4 mmol/L磷酸吡哆醛,DL-天冬氨酸质量浓度为50 g/L,底物n(PA)∶n(D-Asp)=1∶10。转化产物经等电点结晶和阳离子树脂分离得到D-丙氨酸。在该条件下,D-天冬氨酸转化率达94%,D-丙氨酸收率为84%,对映体过量值(ee值)=98%。     

Controlling degradation and physical properties of chemical sand fixing agent‐poly(aspartic acid) by crosslinking density and composites

Poly(aspartic acid) (PASP) hydrogel crosslinked with 1,6‐ hexamethylene diamine was applied as sand fixing agent. The effect of crosslinking density of sand fixing agent on sand fixing property was studied. The relations between the degradation time and crosslinking density, sand fixing property, molecular weight, and mass loss were measured. It was found that the sand fixing property relied on the PASP crosslinking density and degradation time. The crust attained the maximal mechanical strength when the PASP crosslinking agent concentration was 0.0325 mol/L and the PASP hydrogel mass loss was 97.9% after 18 days. The composites added into PASP could increase mechanical property and prolong the degradation time when compared with the control. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

DL-天冬氨酸合成工艺的改进研究

在一钛材高压釜中 ,对顺丁烯二酸酐 (马来酸酐 )进行氨化反应合成了DL 天冬氨酸。通过实验研究对原有合成工艺作出了改进 ,使产品收率提高到 70 %以上 ,并且对产品的分离提纯采用顺丁烯二酸 (马来酸 )代替盐酸进行酸化结晶从而提高了反应物的利用和减少反应剩余物的污染。     

Enhanced Production of Polyhydroxybutyrate Using Enterococcus faecium KT722772 Isolated from Cattle Rumen Fluid by Substrates Optimization

Poly(3-hydroxybutyrate)-producing Enterococcus faecium KT722772 was isolated from cattle rumen fluid by Sudan black staining. It was found to be gram-positive cocci. Poly(3-hydroxybutyrate) production using E. faecium KT722772 was optimized at different pH ranging from 2 to 7 and with different substrates such as glucose, butyric acid, propionic acid, sodium acetate, and glycerol as a sole carbon source at a concentration ranging from 0 to 4%. Maximum poly 3-hydroxy butyrate production (1.8?g/L) was achieved with 1% butyric acid at pH 7. Poly 3-hydroxy butyrate produced by E. faecium was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction analysis.     

Extraction equilibria and separation of phenylalanine and aspartic acid from water with di(2‐ethylhexyl)phosphoric acid

The distribution equilibria of single and binary L ‐phenylalanine and L ‐aspartic acid between water and a kerosene solution of di(2‐ethylhexyl)phosphoric acid (D2EHPA) were studied. It was shown that the distribution ratios of phenylalanine generally increased with increasing aqueous pH (2–5) in the D2EHPA concentration range 0.1–0.5 mol dm^?3, but those of aspartic acid decreased with increasing solution pH. Different reaction stoichiometries were proposed for the extraction of phenylalanine and aspartic acid under the conditions studied. The extraction equilibrium constants were obtained. Competitive extraction in binary systems was more apparent in the pH range where the cationic form of amino acids was not predominant. The present results indicated that selective separation of phenylalanine to aspartic acid was possible with this cationic extractant when they were extracted at higher pH and stripped using higher acidity of HCl solution. Copyright © 2006 Society of Chemical Industry     

Kinetics of dehydration–polymerization of aspartic acid and synthesis of polyaspartate catalyzed by potassium bisulfate

The dehydration–polymerization kinetics of DL ‐ and L ‐aspartic acid, either in the absence or presence of KHSO₄, from 323 to 573 K, was studied by thermogravimetric analysis (TGA), and the synthesis of polyaspartate through the polymerization of L ‐aspartic acid was investigated by a thin‐layer polymerization method. The TGA results revealed that the dehydration–polymerization of both type of aspartic acids proceeds in two steps: first, the loss of one water molecule through the reaction of an amino group of one aspartic acid molecule and a hydroxyl group of another aspartic acid molecule, forming amide bonds, and secondly, the loss of another water molecule through the amide hydrogen and another hydroxyl group, leading to the formation of a succinimide ring. The kinetic parameters of the extrapolated onset temperatures of dehydration—the first and the second maxima—were obtained by a method similar to that of Ozawa–Flynn–Wall. The kinetic results indicate that the dehydration of L ‐aspartic acid is slightly more difficult than for DL ‐aspartic acid, and that the presence of potassium bisulfate effectively catalyzes the dehydration–polymerization of aspartic acid. In the synthesis of polyaspartate, the product with a weight‐average molecular mass (M_w) of 5000 g mol^?1 was obtained in the absence of catalyst. However, in the presence of potassium bisulfate, the products obtained had M_ws of up to 7000 g mol^?1 Copyright © 2003 Society of Chemical Industry