聚酰胺／硅胶吸附剂在茶多酚提取中的应用

介绍了用聚酰胺／硅胶吸附剂提取茶叶中茶多酚,提取率达１２％,茶多酚纯度达８５％￣９０％。     

漆酚树脂吸附纯化茶多酚的研究

本文研究了漆酚树脂对茶多酚的吸附纯化。结果表明,漆酚树脂对茶多酚的吸附容量达１５０ｍｇ／ｇ树脂（干）,８５％的乙醇溶液是良好的洗脱剂,经过漆酚树脂吸附柱吸附纯化后,茶多酚纯度能达到９６％以上,且树脂具有较好的重复使用性。     

茶多酚微胶囊的制备及其性质研究

利用油相分离法以天然高分子材料甲壳糖包裹天然抗氧化剂茶多酚,制备微胶囊,初步探索了原料配比、交联剂用量对茶多酚包含量、释放速率的影响,茶多酚微胶囊化后其瞬时释放量在4h达最大值,随后缓慢释放可持续12h以上,在释放12h时,累积释放量在90％左右,当加工处理过程在0.5h以内不会对茶多酚的性能有太大影响。胶囊化不仅起保护作用,而且延长了抗氧化时间。     

茶多酚提取新工艺

茶多酚是一种新型天然食品添加剂和新兴的医药保健品。医药保健用茶多酚的咖啡因含量要求很低,采用本工艺得到的绿茶提取物茶多酚含量≥95％,儿茶素含量≥70％,咖啡因含量≤0.5％～1％,达到或超过医药保健用茶多酚产品的要求。     

低咖啡因茶多酚提取新工艺研究

茶多酚是一种新型天然食品添加剂和新兴的医药保健品。医药保健用茶多酚对产品质量要求较高，采用本工艺得到的绿茶提取物茶多酚含量≥９５％，儿茶素含量≥７０％，咖啡因含量≤０．５％￣１％，达到或超过医药保健用茶多酚产品的要求。     

离子沉淀法提取揭阳地区绿茶茶多酚的基础研究

茶多酚具有重要的医药及保健价值。本课题采用Zn^2＋沉淀法提取茶多酚,与当前国内外采用的其它在茶叶中提取茶多酚的方法比较,对比探索出最佳的提取工艺参数。在本实验条件下,揭西大北山低档茶叶中茶多酚的提取率达16.5%,茶叶加工过程的下脚料中茶多酚的提取率达8%以上。结论：本课题采用的方法科学性强,工艺简化,投入少,产出高,实用性强,适用范围广,具有很高的社会、经济效益和推广应用价值。     

从莲花绿茶中提取茶多酚

本文报道了从莲花绿茶中提取茶多酚。用85％的乙醇水溶液为溶剂，W茶叶／V溶剂=1：7，80℃，搅拌提取3次，提取率17．5％，茶多酚含量为75％。粗产品用廉价易得的叹附剂＊A代替昂贵的葡聚精疑胶，经柱色谱分离后，纯度达gO你作为食品添加剂，这已经能够满足要求。产物的＊V和IR以‘＊＊HR测定数据与文献报连相符。     

茶叶茶多酚、咖啡碱提取及超滤-吸附综合分离纯化过程研究

介绍了采用三级错流提取茶叶有效成分茶多酚、咖啡碱的优化提取工艺。该工艺提取率高达９０％ 以上,其提取液经醋酸纤维素复合钛微孔体超滤膜初步纯化,可得到茶多酚含量大于４０％ 的部标三级品。并建立了茶叶水提取液超滤过程修正凝胶极化模型。超滤透过液经聚酰胺树脂吸附、８５％ 乙醇洗脱,得到茶多酚含量大于９０％ ,咖啡碱含量低于４％ 的部标茶多酚一级品。该工艺具有不另外添加物质、不使用有毒溶剂、工艺简单等特点。     

绿茶饮料的超声波与微波杀菌及防褐的比较研究

绿茶饮料在存放过程中容易发生褐变,影响产品的质量。经高温灭菌后可使饮用安全．但茶多酚等有效成分又将受到一定程度的破坏。用超声波或微波技术代替高温杀菌,不但可杀灭细菌,而且茶多酚的损失可以降低许多,按高温、微波和超声波的灭菌结果,茶多酚损失依次为30％、25％和15％。     

茶多酚的制备新方法

阐述了茶多酚制备的传统方法及存在的问题，报道了运用超临界CO2萃取技术与溶剂萃取相结合生产茶多酚的方法，实验结果表明：运用超临界CO2萃取技术与溶剂萃取相结合的方法生产的茶多酚，其含量可大于90％，咖啡因含量小于2％，收率大于9％（以茶叶计），残留溶剂为零。     

介孔硅胶负载次氯酸脱除柴油中的硫化物

采取介孔硅胶负载次氯酸脱除硫含量为150μg·g-1的4,6-二甲基二苯并噻吩模型柴油中的硫化物,考察孔结构和脱硫条件对介孔硅胶负载次氯酸脱除模型柴油硫化物的影响,研究再生条件对脱硫剂再生效果的影响。通过红外光谱和N2等温吸附对硅胶进行表征,N2等温吸附分析结果表明,实验选用的3种硅胶均为介孔硅胶;红外光谱分析结果表明,不同孔结构的介孔硅胶均可以负载次氯酸并将模型柴油中4,6-二甲基二苯并噻吩氧化为砜并吸附在介孔硅胶上。SGA型硅胶脱硫率较低;而在反应温度35℃和剂油质量比0.050条件下,使用次氯酸负载质量分数为90.7%的SGB型硅胶,脱硫率达97.3%,使用次氯酸负载质量分数为79%的SGC型硅胶,脱硫率达99.0%。在反应温度30℃和剂液质量比0.19条件下,分别清洗10次,清洗时间5 min,SGC型硅胶的脱硫率下降幅度很小,而SGB型硅胶的脱硫率明显下降。大孔径有利于介孔硅胶负载次氯酸脱除柴油中的硫化物,而且有利于脱硫剂的再生。     

十六烷基三甲基溴化铵在硅胶基HPLC介孔分离介质制备中的应用

在阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)存在下,以3-氨丙基三乙氧基硅烷(APTES)和正硅酸乙酯(TEOS)为硅源,氨水调节溶液pH,制得了硅胶基HPLC介孔分离介质,并通过FTIR,SEM和氮气物理吸附-脱附等手段对所得产物进行了表征,考察了表面活性剂用量对材料结构的影响。结果表明,制备的材料在硅胶骨架中引入了氨基,粒径为0.5～2μm,孔径为3.8～6.7 nm;以制备的分离材料装柱,用于混合后的4种有机化合物的分离,液相色谱分离结果表明,在6 min内实现了样品中各组分的基线分离,有较好的识别能力。     

介孔分子硅剂改善茶浓缩膜结构特性应用研究

为有效提高功能性茶浓缩反渗透膜的回收效率和抗污性能,探究了3种介孔分子硅材料(MCM-41、SBA-15和MCFs)对浓缩膜面聚酰胺层聚合形成过程的结构影响。结果表明,添加质量分数0.02%经磺化预处理的MCM-41于间苯二胺水相可接枝酰氯基团,形成的聚酰胺结构层峰谷粗糙跨度仅为220 nm且交联紧致,膜抗拉伸强度增加37.8%;SBA-15和MCFs相膜面峰谷跨度达500~780 nm,横向褶皱和团聚,结构存在孔道塌陷;改性膜在3 h内对茶多酚、茶多糖、茶蛋白即可达到最大浓缩度,减少50%浓缩时间;MCM-41和SBA-15膜长时间运行的浓缩降率仅为2.8%~6.1%,48 h下降率比显示改性膜达标使用时长增加112.5%~137.5%,亲水性和抗污堵能力均大幅提升,可有效满足功能化茶浓缩精度。     

复合吸附剂的基质选择与动态吸附性能测试

用不同类型的粗孔硅胶与氯化锂盐复合制备了一系列复合吸附剂。测量了它们的含盐量,并观察其腐蚀性。对纯硅胶与复合吸附剂的孔结构进行分析。测试了纯硅胶和复合吸附剂吸附水蒸气的性能等。实验证明,作为复合吸附剂的基质,不同类型的硅胶对复合的吸附剂影响很大。纯硅胶中,粗孔粒度为0.5～1.5 mm的硅胶吸附性能相对最好,但吸附量很小;复合吸附剂中,微球粗孔硅胶以及片状大孔硅胶虽然吸附量得到了大大的提高,但不易液解表面的氯化盐,将导致复合吸附剂膨胀结块影响传质通道,并腐蚀吸附床。大于2 mm的粗孔硅胶复合了氯化盐后,吸水产生毛细力将撑破硅胶骨架。因此,最适合复合吸附应用的硅胶基质为小颗粒耐水硅胶。在复合氯化盐后,吸水性能有了很大提高。同时,长时间循环吸附不会造成硅胶粉碎。     

钛改性硅胶块体吸附剂除湿性能研究

采用浸渍沉积法制得钛改性硅胶块体吸附剂.对块体吸附剂的孔结构进行表征;考察了改性硅胶吸附剂动、静态除湿性能以及在吸附/脱附过程中湿度场、温度场的变化.结果表明,改性后的硅胶,其微孔、中孔孔径有所减少,而孔容和比表面显著增大;钛改性硅胶的吸附性能好于硅胶,而脱附能力劣于硅胶;由于钛改性硅胶产生更多的吸附热,吸附时出口气流温度略高于硅胶,而脱附时正好相反.     

接枝硅胶热稳定性红外分析技术

硅胶通过接枝可引入某些有机官能团,接枝后硅胶的表面特性稳定,可用作液相色谱固定相或催化剂载体,在实验中,用薄层硅胶为原料,其孔径约为12—15nm,比表面积大于250m2·g^-1。3-氯丙基-三甲氧基硅烷或3-氨丙基-三甲氧基硅烷为桥联试剂,为了在硅胶结构上引入苯环官能团,键合桥联基的硅胶再与苯胺、茴香胺、苄胺或3-苯丙氯反应,产物用红外吸收光谱表征苯环的存在,在高真空度下,将样品加热到一定的温度,通过判断某些区域中红外光谱吸收峰的强弱变化,评估改性硅胶的热稳定性能。     

Synthesis of an affinity adsorbent based on silica gel and its application in endotoxin removal

An affinity media for endotoxin removal based on silica gel was prepared by activation with silane coupling agent and subsequent conjugation with histidine (His) as a ligand. The influence of pore size and particle dimension of the silica gel and the grafting conditions such as reaction temperature and concentration of His in solution on the grafting yield of His were studied by means of IR, thermogravimetric analysis and elemental analysis. The results show that the silica gel with a particle size of 200 μm and a pore size of about 12 nm was a good carrier material for the preparation of the affinity adsorbent. Under the optimal conditions, histidine was covalently immobilized on silica gel at about 20 mg/g, with a corresponding maximum endotoxin adsorption capacity q_m in contaminated water of about 1.2 mg/g and an apparent dissociation constant K_d of about 1350 μg/L. The adsorbent had little nonspecific adsorption from a protein-containing solution.     

The effect of nanospheres on the permeability of PA6/SiO2 nanocomposites

The permeation of O₂, N₂ and H₂O through polyamide‐6 nanocomposites, prepared with silica nanospheres of different diameters, is reported in this contribution. The mechanical and thermal properties were also evaluated. The nanocomposites were produced by melt mixing the polyamide‐6 with silica nanospheres 12–150 nm in diameter, prepared using standard sol‐gel methods; it was found that the addition of 3 wt% of silica nanospheres to the polyamide‐6 matrix results in an increase in the O₂ and N₂ permeability. This increase was inversely correlated with the nanosphere diameter but directly correlated with the number of spheres added to the matrix, using the same percentage by weight. The same behaviour was found for the water vapour transmission rate. The increase in permeability is probably due to the formation of voids around the particles, which increases the free volume of the polymer. The addition of the nanospheres, regardless of the sphere diameter, generated an increase of 6% in the Young's modulus, a decrease of 65% in the elongation at break and a 24% decrease in the percentage of crystallinity. Copyright © 2011 Society of Chemical Industry     

Modified silica gel with 5-amino-1,3,4-thiadiazole-2-thiol for heavy metal ions removal

A two sorbents was to synthesize for heavy metals removal: silica gel modified with 5-amino-1,3,4-thiadiazole-2-thiol (S5A) and pure silica gel. Modification of silica gel is achieved by tetraethyl orthosilicate (TEOS) preliminary hydrolyzed at room temperature. 5-Amino-1,3,4-thiadiazole-2-thiol is added, with continuous stirring with a magnetic stirrer, to the hydrolyzed TEOS. Pure silica gel (sample SG) is obtained by the classical sol–gel method using the same conditions and initial component ratios. The sorbents have been characterized as to their surface area, pore volumes, content of the functional groups, IR spectra, sulfur and nitrogen content. Their sorption properties to heavy (Cu(II), Co(II), Ni(II), Cd(II), Pb(II) and Hg(II) metals are investigated. The investigations indicate that modified silica gel is characterized by a relatively higher sorption capacity than is the unmodified one. The highest sorption capacity belongs to Hg(II) in presence of unmodified silica gel due to which this sorbent can be used for selective extraction of mercury ions from aqueous solutions.