玉米纤维素在Pickering乳液制备中的应用研究

由超细固体颗粒取代普通乳化剂制备的Pickering乳液发展迅速。采用淀粉酶、糖化酶以及中性蛋白酶处理玉米麸皮得到了纯度相对较高的玉米纤维素,以大豆油为模式油相,以显微形态、外观和贮藏稳定性为指标,对玉米纤维素制备Pickering乳液的可能性及条件进行了研究。结果表明,玉米纤维素具有稳定大豆油乳液的能力,且最适条件为油水体积比5∶5、分散转速11 000 r/min、分散时间7 min、分散温度10℃、纤维素添加量0.015%(m/V)。在此条件下制备的大豆油Pickering乳液外观均一,贮藏过程中无明显的析油及析乳现象。因此,玉米纤维素在新型Pickering乳液的开发中具有较好的应用潜力。关键字     

基于熊果酸的W/O/W型Pickering乳液制备方法

目的:提高熊果酸的应用范围和生物利用率。方法:以熊果酸为乳化剂,果胶为外水相,采用两步法制备W/O/W型Pickering乳液。通过单因素试验优化W/O乳液制备条件,研究果胶质量浓度对W/O/W型Pickering乳液理化性质、微观结构、流变学特性及长期稳定性的影响。结果:W/O乳液的最佳制备工艺为熊果酸质量浓度4 g/100 mL、水油质量比2∶3、均质转速9 000 r/min、均质时间5 min;以果胶为外水相制备的双层乳液粒径均在30～40μm,果胶质量浓度的增加使乳液的zeta电位绝对值、流变性能以及4℃贮藏稳定性有着显著性的提高。结论:果胶质量浓度为0.3,0.4,0.5 g/100 mL时能够制备稳定的Pickering双层乳液。     

核壳结构Fe3O4纳米催化剂催化降解酸性废水的研究

利用静电自组装法,将羧甲基纤维素(CMC)组装到Fe3O4上得到Fe3O4@CMC,再通过自由基聚合反应将丙烯酸(AA)和丙烯酰胺(AM)接枝交联到Fe3O4@CMC上,制备出F e3O4@CMC-g-p(AA-co-AM)(Fe3O4@hydrogel)微球。利用TEM、XRD、FTIR、TGA、XPS、BET等技术对Fe3O4hydrogel微球进行了表征,并将其作为催化剂应用于类芬顿高级氧化反应中催化降解酸性红73。结果表明:Fe3O4@hydrogel仍为反尖晶石型结构,共聚物CMC-g-p(AA-c o-AM)成功包覆在Fe3O4表面,且含量为17.7%,复合微球平均粒径在10n m左右,饱和磁化强度为44.8 emu/g,BET表面积为73.5m2/g,平均孔直径为8.3nm,为介孔结构。Fe3O4@hydrogel微球对酸性染料废水有良好的催化降解性能,通过调节芬顿反应体系中初始pH值、催化剂用量以及H2O2浓度,得到反应最适条件为pH3.5、H2O210mmol/l、催化剂用量200mg/l。在此条件下3h内能达到对酸性红7399.83%以上的降解。     

辛烯基琥珀酸纳米淀粉酯颗粒的制备及其食品级Pickering乳液的特性

利用醇沉法结合辛烯基琥珀酸酐酯化反应,成功制备能够稳定食品级Pickering乳液的纳米淀粉酯颗粒。以纳米淀粉酯粒径、Zeta电位、光学和荧光显微镜观察为指标,研究颗粒添加量、pH值和离子强度对Pickering乳液稳定性的影响。结果表明,体系pH值和离子强度在一定范围内改变了纳米淀粉酯的电位值,其中在极端pH值或者高离子强度条件下,纳米淀粉酯的电位绝对值最低。研究发现,当纳米淀粉酯添加量为2.0 g/100 mL时,制备的Pickering乳液具有较强的稳定性;此外,在体系pH 6.0并且KCl浓度为0.005 mol/L条件下,Pickering乳液分散相油滴的直径最小并且分布均匀,油滴不容易发生聚结,Pickering乳液的稳定性最高。     

玉米醇溶蛋白/乳清蛋白纤维核复合纳米粒稳定 Pickering乳液的制备与性质

以玉米醇溶蛋白和乳清蛋白为原料,利用反溶剂共沉淀法制备玉米醇溶蛋白/乳清蛋白纤维核复合纳米粒,并与玉米油高速剪切制备Pickering乳液。探究了复合纳米粒在不同pH下的乳化性,以及复合纳米粒添加量对Pickering乳液粒径、微观形貌、储藏稳定性及流变学特性的影响。结果表明：玉米醇溶蛋白与乳清蛋白纤维核复合后乳化性显著提高,制备的Pickering乳液类型为水包油型;随着复合纳米粒添加量的增加,Pickering乳液粒径先减小后稍增大,添加量大于3 g（100 mL玉米油）后无显著性差异;在复合纳米粒添加量为4 g（100 mL玉米油）时,Pickering乳液油滴大小均一,储藏稳定性最好;Pickering乳液为假塑性流体,随复合纳米粒添加量的增加,表观黏度先减小后增大。     

Fe3O4-壳聚糖磁性微球的制备及对Cu2+的吸附性能

用壳聚糖包覆羧基化Fe3O4磁性纳米粒子制备了Fe3O4-壳聚糖磁性微球,分别用X-射线衍射、扫描电镜、热重分析等方法和手段对所制备的样品进行了结构表征.利用原子吸收光谱,探讨了时间、pH值、Cu2+浓度等对Fe3O4-壳聚糖磁性微球吸附溶液中Cu2+量的影响.结果表明:Fe3O4-壳聚糖磁性微球粒径分布较均匀,平均粒径约为110 nm;Fe3O4-壳聚糖磁性微球能够吸附Cu2+,最大吸附量可达21.3 mg/g.随着吸附剂用量的增加、温度的升高,单位吸附量减小,室温下吸附较佳;Cu2+初始浓度、pH对吸附的影响很大,Cu2+初始浓度在120 mg/L,5.0相似文献   

β-环糊精稳定柠檬醛Pickering乳液的制备及其稳定性研究

制备由β-环糊精稳定的高比例柠檬醛相Pickering乳液并研究乳液的稳定特性。利用β-环糊精与柠檬醛的包合物微粒作为乳化稳定剂、通过高速均质法制备柠檬醛的Pickering乳液,观察乳液的微观结构、测定其粒度和Zeta电位,研究体系pH值及添加黄原胶对乳液稳定性的影响,并对其稳定性进行了初步测定。结果表明,柠檬醛-水体系经β-环糊精稳定乳化后可形成稳定的水包油型Pickering乳液,油滴呈标准球形,粒径在数百纳米;偏酸或偏碱性环境条件及添加黄原胶有利于乳液的稳定。进一步研究表明,乳液具有较好的耐热稳定性,但耐冻能力较差,黄原胶的加入(5 g/L)可显著提高乳液的耐冻性。该研究为柠檬醛乳液的绿色制备提供一种新的途径。     

磁性壳聚糖复合纳米材料的制备

 采用静电纺丝技术制备了壳聚糖复合纳米纤维膜,利用纳米纤维大的表面能,通过表面吸附纳米Fe3O4微粒的方法制得了磁性壳聚糖复合纳米材料,并采用扫描电镜(SEM)、红外光谱(FT-IR)、X射线衍射(XRD)、磁性测试等一系列方法对磁性壳聚糖复合纳米材料进行了分析与表征。结果表明：采用表面吸附法制备出了具有良好形貌的磁性壳聚糖复合纳米材料,复合纳米材料呈现出超顺磁性的特征,其饱和磁化强度可达15.4emu/g。     

纤维素/壳聚糖磁性气凝胶的冻融法制备及其对染料吸附性能

为开发一种高效可再生的磁性生物质基吸附剂,以微晶纤维素(MCC)和壳聚糖(CS)为凝胶网络框架、纳米Fe3 O4为掺杂剂,通过悬浮液滴和冻融结合法制备MCC/CS磁性气凝胶.借助扫描电子显微镜、傅里叶红外光谱、X射线衍射等表征其微观形貌及化学结构,并探讨了对染料刚果红的去除效果.结果 表明:在加入1.0 g纳米Fe3 ...     

明胶纳米颗粒稳定的Pickering乳液的制备及表征

以B型明胶和京尼平为原材料,通过2次去溶剂结合京尼平交联固化明胶法制备得到明胶纳米颗粒。然后以明胶纳米颗粒为乳化剂,玉米油为油相,采用均质乳化法制备得到水包油型Pickering乳液。研究了明胶纳米颗粒的浓度、乳化时间、转速、水相pH值和盐离子浓度对Pickering乳液的影响。结果表明,明胶纳米颗粒呈表面光滑的球形颗粒,粒径约为186.7 nm,等电点约为6,三相接触角为76.6°。综合考察制备的Pickering乳液液滴的微观形貌和粒径,明胶纳米颗粒稳定的Pickering乳液的最佳制备工艺参数为：明胶纳米颗粒的浓度为20.0 mg/mL,乳化时间为90 s,乳化转速为13 000 r/min,水相pH为8.0,NaCl浓度为50 mmol/L。最佳工艺下制备的Pickering乳液能够承受高于40%的剪切应变,表现出良好的稳定性。     

Construction of magnetic switchable Pickering interfacial catalysis system and its application in the hydrolysis of crude rice bran oil

The high refining cost of traditional rice bran oil with high acid value and its large environmental impact have limited its further application. In this study, a lipase-catalysed hydrolysis reaction of crude rice bran oil at the oil–water interface was performed using a Pickering emulsion system stabilised by modified magnetic microcrystalline cellulose (MMC) particles. The results revealed that the modified MMC particles exhibited a rod-like structure, and a contact angle of 84.8°. In addition, the stability of the Pickering emulsion can be enhanced when the modified MMC was used as an emulsifier, and at an optimal addition amount of 2.0wt.%. The saturation magnetisation value of the emulsifier decreased from 38.8 to 8.9 emu g⁻¹ after 12 reuses. Furthermore, the hydrolysis rates of crude rice bran oil in the Pickering emulsion system and a two-phase system at a Candida antarctica lipase B (CALB) content of 2mg mL⁻¹ were 92.8% and 58.8%, respectively. In addition, the relative activity of CALB after 10 reuses was 71.8%. These findings provide a sustainable interface biocatalysis method and provide ideas for the rational development of high acid value oils.     

海藻酸钠/微晶纤维素复合壁材的性能及对精油微胶囊缓释性的影响

将微晶纤维素与海藻酸钠混合,形成复合壁材用于制备精油微胶囊。通过探讨微晶纤维素的添加对壁材溶液流变性以及壁材膜机械性能、透油性、吸湿性和透水性的影响,研究海藻酸钠/微晶纤维素复合壁材对柠檬精油微胶囊包埋效率及精油释放速率的影响。结果表明,复合溶液表观黏度随微晶纤维素含量的增加而增加,随温度的升高而逐渐下降,且都比海藻酸钠的表观黏度高。红外光谱结果表明海藻酸钠和微晶纤维素相容性很好,通过氢键形成复合体系。微晶纤维素较大程度增强壁材复合膜的机械性能,膜的透油性、吸湿性和透水性随微晶纤维素的增加而降低。4%微晶纤维素含量的复合壁材对柠檬精油微胶囊包埋效率比未添加的效率提高了9.2%,并且微晶纤维素的添加能有效延缓微胶囊精油在高温和高湿环境下的释放。     

Coating Fe3O4 magnetic nanoparticles with humic acid for high efficient removal of heavy metals in water

Humic acid (HA) coated Fe3O4 nanoparticles (Fe3O4/HA) were developed for the removal of toxic Hg(II), Pb(II), Cd(II), and Cu(II) from water. Fe3O4/HA were prepared by a coprecipitation procedure with cheap and environmentally friendly iron salts and HA. TOC and XPS analysis showed the as-prepared Fe3O4/HA contains approximately 11% (w/w) of HA which are fractions abundant in O and N-based functional groups. TEM images and laser particle size analysis revealed the Fe3O4/HA (with approximately 10 nm Fe3O4 cores) aggregated in aqueous suspensions to form aggregates with an average hydrodynamic size of approximately 140 nm. With a saturation magnetization of 79.6 emu/g, the Fe3O4/HA can be simply recovered from water with magnetic separations at low magnetic field gradients within a few minutes. Sorption of the heavy metals to Fe3O4/HA reached equilibrium in less than 15 min, and agreed well to the Langmuir adsorption model with maximum adsorption capacities from 46.3 to 97.7 mg/g. The Fe3O4/HA was stable in tap water, natural waters, and acidic/ basic solutions ranging from 0.1 M HCl to 2 M NaOH with low leaching of Fe (< or = 3.7%) and HA (< or = 5.3%). The Fe3O4/HA was able to remove over 99% of Hg(ll) and Pb(ll) and over 95% of Cu(II) and Cd(II) in natural and tap water at optimized pH. Leaching back of the Fe3O4/HA sorbed heavy metals in water was found to be negligible.     

PERCEPTION OF GRITTINESS IN AN OIL-IN-WATER EMULSION

Microcrystalline cellulose was dispersed as a gritty substance in an emulsion, and sensory evaluation was conducted to examine the effect of the presence of oil on grittiness felt in the mouth. Samples were prepared with three types of microcrystalline cellulose of average particle size 14, 38, and 76 μm and with a concentration in water of 0.03–2.7%, with three types of emulsion with an oil-volume fraction of 0.2–0.7, and with three rates of homogenization of 500–15,000 rpm. The flow behavior and loss modulus of each sample were measured and sensory evaluation was made of the perceived grittiness. A multiple regression analysis of the data shows that the proportion of people who could perceive grittiness was influenced by the following factors and in that order: concentration of microcrystalline cellulose, oil droplet size, loss modulus, and particle size of microcrystalline cellulose. The proportion of people who perceived grittiness also increased with increasing oil droplet size. This was conceivably caused by the uneven distribution of microcrystalline cellulose particles promoted by large oil droplets. An equation was developed relating the proportion of people perceiving grittiness to the physical properties of the sample. The result indicates that factors effecting grittiness perception are identical for emulsions, aqueous suspensions, viscous suspensions and gels, studied previously.     

金磁微粒模拟酶检测食品中的葡萄糖

采用水热法制备Fe3O4纳米粒子,并通过对其表面氨基化与金纳米粒子自组装方法构建金磁微粒（Fe3O4@Au）,并表征其性能。在其具有模拟过氧化物酶活性的基础上结合葡萄糖在葡萄糖氧化酶作用下产生H2O2,并与过氧化物酶底物二胺盐产生显色反应的原理,建立可视化检测葡萄糖含量的简便方法,并优化葡萄糖检测体系,并对其选择性和回收率进行分析。结果表明,氨基化的Fe3O4纳米粒子可以有效固载金纳米粒子,Fe3O4@Au饱和磁化强度为43 emu/g。检测体系最优工艺组合为：Fe3O4@Au混悬液质量浓度0.15 g/mL、温度70 ℃、时间50 min。在优化条件下,葡萄糖在1～20 mmol/L范围内具有良好的线性关系,线性相关系数R2为0.992 5,检出限为2.45 μmol/L,加标回收率在96%～104%之间,并具有良好的选择性和稳定性。本研究将拓宽纳米材料模拟酶在食品检测的应用并为葡萄糖检测方法的改进提供一种新的思路。     

磁性MOF制备及对阳离子翠蓝X-GB的吸附和光催化降解

选用Cu(NO_3)_2·3H_2O、双(3,5-二羧基苯基)对苯二甲酰胺(H_4L_1)以及纳米Fe_3O_4,采用混合法制备了一种磁性有机骨架材料Fe_3O_4/Cu-H_4L_1,并将其用于阳离子翠蓝X-GB的吸附和可见光催化降解。结果表明:30 mg的吸附材料在180 min内对10 mL质量浓度为15 mg/L的阳离子翠蓝X-GB吸附率可达到85.25%,吸附速率为4.08×10~(-2)mg/(g·min);在可见光照射下,150 min内5 mg的材料对40 mL质量浓度为15 mg/L的阳离子翠蓝X-GB的光降解效率高达99.44%;分别经过5次循环吸附和光催化降解,Fe_3O_4/Cu-H_4L_1不仅保留了较高的染料去除率和光催化降解效率,而且还保留了其优良的磁性;使用后的Fe_3O_4/Cu-H_4L_1能通过外加磁场简易收集和重复使用。     

复合空心纳米粒子PAA@Fe_3O_4的制备及药物控释研究

在反尖晶石型空心磁性Fe3O4纳米粒子表面修饰上APTES,然后通过化学交联法包覆上聚丙烯酸(PAA)制备了p H敏感性PAA@Fe3O4复合空心纳米粒子。用透射电子显微镜(TEM)、振动样品磁强计(VSM)、纳米粒度仪、傅里叶变换红外光谱仪和紫外分光光度计对包覆前后的形貌、结构、磁性和包覆率进行表征。并用罗丹明6G(R6G)作为模拟药物进行药物负载和释放性能进行体外实验研究。结果表明,所制备的PAA@Fe3O4复合粒子具有良好的磁学性能,负载药物为1011 mg/g。复合磁粒上的R6G药物释放的最大释放比达到93.0%,这种药物控释属于一级释放曲线,同时探讨了基于分子溶解度的可能机理。这种基于磁性纳米粒子和高分子材料的复合药物负载体系,有助于提高药物的靶向递送性能并改善诊疗效率。     

Fe_3O_4/海藻酸盐微胶囊固定化细胞生长特性

采用脉冲电场液滴制备工艺,以海藻酸钠、壳聚糖为载体材料,纳米Fe3O4粉末为磁性材料,地衣芽孢杆菌为细胞模型,制备具有超顺磁性的微尺度载细胞微胶囊。以地衣芽孢杆菌的生长量为考察指标,考察不同磁含量、磁场引力、粒径和初始菌浓等因素的影响。实验结果表明,磁性材料Fe3O4的引入对地衣芽孢杆菌的生长没有影响。制备磁性固定化地衣芽孢杆菌微胶囊的最适条件为:Fe3O4含量0.003g/mL,初始接种密度为1.5倍菌浓(6.25×106个/mL),微囊的平均粒径为350μm,磁场环境的引入对地衣芽孢杆菌的生长无明显影响。论证了磁性壳聚糖/海藻酸钙微胶囊固定化细胞工艺进行在线分离,连续化操作的可行性。