BaTiO3颗粒对分散剂PMAA-NH4的吸附机制研究

通过ζ电位测量及PTIR分析，研究了BaTiO3颗粒对阴离子型分散剂PMAA－NH4的吸附机制。结果表明，加入PMAA－NH4后，由于BaTiO3颗粒表面上存在Ba-OH2^ 的正电荷中心，从而吸附了分散剂的阴离子，使BaTiO3表面带电特性改变，等电点由pH＝5.1移至pH=3.5，当pH=10，PMAA－NH4的加入量为0．8wt％时，BaTiO3颗粒表面吸附达到饱和，可以得到稳定性好的BaTiO3悬浮体。     

吸附途径对α-Al2O3-H2O-PAA悬浮液流变性影响

采用两阶段吸附法(两个pH不同的阶段)研究了不同吸附途径制备的浆料的稳定性．结果表明，pH值为6．5的浆料，经过pH值高于粉体等电点阶段的吸附，浆料的稳定性显著提高，第一吸附阶段的pH值对浆料的稳定性有很大的影响，其pH从8．0提高到10．0，浆料的粘度降低，稳定性提高，但当pH值增加到11．0时，浆料的稳定性则下降，增加第一阶段的吸附时间，有利于改善PAA在粒子表面的分布状态和提高浆料的稳定性。     

TiO2纳米管阵列膜对牛血清白蛋白的吸附与脱附

采用电化学阳极氧化法以含氟的乙二醇溶液为电解液阳极氧化纯钛制备出排列规则的高长径比TiO2纳米管阵列膜,并用扫描电镜(SEM)、比表面积仪表征了TiO2纳米管阵列膜的形貌和比表面积。结果表明,所制得的TiO2纳米管阵列的管径约180nm,管长可达230μm,比表面积约59.8m2/g。以牛血清白蛋白(BSA)为药物蛋白分子的模型,并研究了TiO2纳米管阵列膜对BSA的吸附和脱附行为,考察了溶液pH值、BSA初始浓度和溶液离子强度对BSA吸附的影响与吸附态的BSA在不同pH值的PBS溶液中的释放行为。结果表明,BSA分子在其等电点(pH值=4.8)附近较容易吸附到TiO2纳米管上,吸附量随着BSA初始浓度的增加而增加,较高的离子强度会降低BSA的吸附,碱性条件下吸附态的BSA容易从TiO2纳米管上脱附,并由于纳米管的扩散限制效益呈现一定程度的缓释。     

BaTiO3颗粒对分散剂PMAA-NH4的吸附机制研究

通过ζ电位测量及FTIR分析,研究了BaTiO3颗粒对阴离子型分散剂PMAA-NH4的吸附机制.结果表明,加入PMAA-NH4后,由于BaTiO3颗粒表面上存在Ba-OH2+的正电荷中心,从而吸附了分散剂的阴离子,使BaTiO3表面带电特性改变,等电点由pH=5.1移至pH=3.5.当pH=10,PMAA-NH4的加入量为0.8wt%时,BaTiO3颗粒表面吸附达到饱和,可以得到稳定性好的BaTiO3悬浮体.     

pH值敏感介孔纳米复合材料SBA-15/PAA的制备与性能研究

通过浸渍吸附的方法将pH值敏感的功能单体-丙烯酸引入到介孔二氧化硅SBA-15的孔道内,经自由基聚合使丙烯酸(AA)在孔道内聚合,成功合成了pH值敏感的SBA-15/聚丙烯酸(PAA)纳米复合材料,所得纳米复合材料的结构通过XRD、TEM、氮气吸附/脱附、TG、FT-IR等手段进行了表征,并进行了pH敏感性能研究.结果表明,当聚合物(PAA)的量达到20%左右时,复合材料仍然具有较大的孔体积0.5203cm3/g和较高的比表面积334.5m2/g.聚合反应的发生没有破坏SBA-15的有序介孔结构,这种纳米复合材料初步显示出了pH敏感性.这种具有高比表面的pH值响应介孔纳米复合材料,有望在药物缓释领域得到应用.     

大豆蛋白在聚砜膜上的吸附行为

结合扫描电镜（SEM）观察,系统研究了溶液化学特性（包括pH、离子强度和给液浓度）对大豆蛋白在疏水聚砜膜上吸附行为的影响．大豆蛋白一膜间的相互作用符合静电作用机理,吸附量在其等电点附近取得最大值．低pH时随pH升高吸附量增加;高pH时随pH升高吸附量降低,离子强度降低,同性电荷物质之间的静电排斥增加吸附,也降低异性电荷物质之间的静电吸引,降低吸附．溶液化学条件同样影响大豆蛋白在聚砜膜上的吸附速率（膜污染速率）．大豆蛋白吸附等温线遵循兰格缪尔方程,通过实验给出了有关的方程参数,由此可预计不同溶液化学条件的膜污染程度和速率．为了确定对流力和静电作用对大豆蛋白吸附行为的影响,进行了静态和动态吸附实验的比较,结果表明,静电作用在大豆蛋白吸附到膜表面的过程中起着关键作用,控制静电作用可以有效减轻大豆蛋白在膜表面的吸附,进而降低膜的长期通量降低．     

赖氨酸修饰磁性Fe3O4纳米粒子的制备及其对Cu（Ⅱ）的吸附性能

采用化学共沉淀法制备磁性Fe3O4纳米粒子,通过在磁性Fe3O4纳米粒子表面接枝赖氨酸,制备一种新型磁性纳米吸附剂。通过TEM、FT-IR、XRD、VSM对其进行表征,着重研究了其对Cu(Ⅱ)离子的吸附性能。结果表明,溶液pH值能显著影响吸附剂对Cu(Ⅱ)的吸附效果,pH为5时其效果最佳。等温吸附数据符合Langmuir模型,T=298K、pH=5、V=5mL时,吸附剂的饱和吸附容量qm=22.42mg/g,吸附常数为0.0346L/mg。     

硫锌双修饰磁性Fe3 O 4的制备及对铀酰离子的吸附

纳米Fe_3O_4作为典型的磁性吸附材料可应用于放射性废水处理,为进一步提高其吸附性能,本文通过Zn和S双修饰Fe_3O_4制备出纳米磁性S-ZnFe_2O_4,并通过SEM、XRD、EDS、FT-IR、Raman等手段对比表征了Fe_3O_4及S-ZnFe_2O_4的结构及形貌,研究了pH对其吸附铀酰离子(UO_2~(2+))效果的影响,并基于变量接触时间及初始浓度探索了其吸附动力学及热力学规律。结果表明:Zn和S的双修饰后,纳米材料对UO_2~(2+)的吸附量显著增加,从27.12 mg/g增加至51.68 mg/g;纳米Fe_3O_4和S-ZnFe_2O_4吸附UO_2~(2+)的最佳pH为6.0,吸附过程均符合伪二阶动力学模型;纳米Fe_3O_4的吸附过程同时符合Langmuir和Freundlich吸附模型,纳米S-ZnFe_2O_4的吸附过程符合Langmuir等温吸附模型。本研究对开发新型高效含铀废水处理用吸附材料具有重要指导意义。     

氧化铝悬浮液的分散行为及其影响因素研究

详细研究了氧化铝悬浮液的分散行为及固含量、pH值和聚丙烯酸(PAA)添加量对分散行为的影响。实验结果表明,固含量、pH值和PAA添加量对氧化铝悬浮液的分散行为有显著影响。粘度法及Zeta电位测试法所反映的悬浮液分散性随pH值和分散剂添加量的变化规律基本一致。当pH=9～10、分散剂添加量的质量分数为2.0%～2.5%时粘度最低、Zeta电位绝对值最大、分散效果最好。分散剂添加量存在最佳范围,且最佳范围不随固含量的变化而改变。随固含量的增加,粘度开始缓慢上升,到达一定程度后迅速增大。     

过量油酸钠加入对磁流体表面包覆结构的影响

通过研究过量油酸钠的加入对磁流体中Fe3O4纳米颗粒表面包覆结构的影响来探讨油酸钠形成牢固双层包覆结构的条件。结果表明，在反应温度为80℃，反应时间为30min，反应pH-5的条件下，过量油酸钠在Fe3O4颗粒表面可以形成双层包覆结构，但第二层物理吸附层与第一层化学吸附层结合力低，极易脱落；Fe3O4颗粒表面包覆结构不随油酸钠加入量的改变而改变；随着油酸钠加入量的增加，油酸钠在Fe3O4颗粒表面的吸附量呈先增加后降低的变化规律。最后提出反应介质水的pH值是控制Fe3O4颗粒表面形成油酸钠双层包覆结构的关键因素。     

ZrB2-SiC陶瓷的注浆成型与无压烧结

研究了以聚乙烯亚胺 (PEI) 为分散剂,ZrB₂粉体在水相中的分散性能. 结果显示ZrB₂的等电点在pH为5.7,加入PEI后的等电点移到pH为11.5. 以PEI为分散剂,在pH为8.0处制备了固含量达45vol%的ZrB₂-20vol%SiC陶瓷浆料. 采用注浆成型方法制备了相对密度为53%的ZrB₂-SiC陶瓷坯体,并对其进行了无压烧结,同时研究了硼粉为烧结助剂对其致密化及性能的影响. 结果表明：硼粉为烧结助剂,实现了ZrB₂-SiC陶瓷的完全致密化的同时,也降低了ZrB₂-SiC陶瓷的烧结温度,2100℃烧结3h后的陶瓷维氏硬度为(17.5±0.5)GPa,弯曲强度为(406±41)MPa,断裂韧性为(4.6±0.4)MPa·m^1/2.     

沉淀法制备氟羟基磷灰石的影响因素

采用沉淀法制备了纳米氟羟基磷灰石(FHA), 研究了合成温度、初始氟离子浓度和 pH 值对氟替代的影响. 用 X 射线衍射和红外光谱表征了FHA粉体的物相组成和晶体结构变化, 用透射电镜观察了FHA的形貌. 结果表明: 氟替代会导致晶格参数和键能的变化, 随着合成温度或原料中氟浓度的升高, FHA 晶粒尺寸和长径比增大; 相组成主要受pH值控制, 考虑到OH^–和F ^–对羟基空位的竞争, 高pH值不利于氟替代.     

Microfluidic high-resolution free-flow isoelectric focusing

A microfluidic free-flow isoelectric focusing glass chip for separation of proteins is described. Free-flow isoelectric focusing is demonstrated with a set of fluorescent standards covering a wide range of isoelectric points from pH 3 to 10 as well as the protein HSA. With respect to an earlier developed device, an improved microfluidic FFE chip was developed. The improvements included the usage of multiple sheath flows and the introduction of preseparated ampholytes. Preseparated ampholytes are commonly used in large-scale conventional free-flow isoelectric focusing instruments but have not been used in micromachined devices yet. Furthermore, the channel depth was further decreased. These adaptations led to a higher separation resolution and peak capacity, which were not achieved with previously published free-flow isoelectric focusing chips. An almost linear pH gradient ranging from pH 2.5 to 11.5 between 1.2 and 2 mm wide was generated. Seven isoelectric focusing markers were successfully and clearly separated within a residence time of 2.5 s and an electrical field of 20 V mm-1. Experiments with pI markers proved that the device is fully capable of separating analytes with a minimum difference in isoelectric point of Delta(pI) = 0.4. Furthermore, the results indicate that even a better resolution can be achieved. The theoretical minimum difference in isoelectric point is Delta(pI) = 0.23 resulting in a peak capacity of 29 peaks within 1.8 mm. This is an 8-fold increase in peak capacity to previously published results. The focusing of pI markers led to an increase in concentration by factor 20 and higher. Further improvement in terms of resolution seems possible, for which we envisage that the influence of electroosmotic flow has to be further reduced. The performance of the microfluidic free-flow isoelectric focusing device will enable new applications, as this device might be used in clinical analysis where often low sample volumes are available and fast separation times are essential.     

Myoglobin adsorption onto poly(glycidyl methacrylate) microbeads with surface functionalized iminodiacetic acid

In this study, poly(glycidyl methacrylate) [PGMA] microbeads with surface modified iminodiacetic acid (IDA) were used for myoglobin (Mb) adsorption from buffer solutions at different pHs and ionic strengths in a packed-bed column. Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) measurements before and after the adsorption process confirmed the structural stability of adsorbed Mb. The effects of initial concentration, flow-rate, pH and ionic strength on the adsorption were investigated. The results showed that the maximum amount of protein was adsorbed at a pH 7.0, which is the protein isoelectric point. The adsorption is rationalized in terms of local electrostatic forces acting between the protein and the IDA modified PGMA surface as well as hydrophobic interactions close to the protein isoelectric point, whereas at low pH the global changes give rise to protein–protein repulsion and at high pH protein-support material repulsion.     

纳滤膜在乳清脱盐中的应用研究

实验通过调节乳清的pH值,利用TFC-SR2卷式纳滤膜对乳清进行脱盐研究,对在不同pH值状态下的乳清浓缩液干物进行灰分的测定.实验结果表明,当调整pH值为乳清蛋白的等电点4.6时,浓缩液干物灰分含量最少,脱盐效果最好.在乳清液pH值为4.6,操作压力为1.3 MPa时,进行了渗透循环操作,得到了更好的脱盐效果.     

丙烯酸-丙烯酸酯共聚物对钛酸铋水悬浮液性质的影响

研究了丙烯酸－丙烯酸酯共聚物对钛酸铋（Bi4Ti3O12)悬浮液表面化学性质及流变性的影响。结果表明，共聚物的加入使Bi4Ti3O12的等电点向低pH值方向偏移。共聚物在粉体表面的吸附属于物理吸附，其含量的变化可以引起共聚物在粉体表面吸附构型的变化，当共聚物含量＞1．5wt%时，部分高分子脱附。共聚物的加入可以显著改善悬浮液的稳定性，在低共聚物含量和高共聚物含量均可制备稳定的悬浮液，共聚物含量≤1．5wt%时，浆料的稳定通过静电位阻稳定机理来实现，共聚物含量≥2.0wt%时，可能通过空位稳定机理来实现。     

Tailor-made pH-sensitive polyacrylic acid functionalized mesoporous silica nanoparticles for efficient and controlled delivery of anti-cancer drug Etoposide

A multifaceted therapeutic platform has been proposed for controlled delivery of Etoposide (ETS) leading to a synergistic advantage of maximum therapeutic efficacy and diminished toxicity. A state of the art pH responsive nanoparticles (NPs) MSNs-PAA consisting of mesoporous silica nanoparticles core and polymeric shell layers, were developed for controlled release of model anti-cancer drug ETS. Graft onto strategy was employed and amination served as an interim step, laying a vital foundation for functionalization of the MSN core with hydrophilic and pH responsive polyacrylic acid (PAA). MCM-41-PAA were investigated as carriers for loading and regulated release of ETS at different pH for the first time. The PAA-MSNs contained 20.19% grafted PAA as exhibited by thermogravimetric analysis (TGA), which enormously improved the solubility of ETS in aqueous media. The synthesized PAA-MSNs were characterized by various techniques viz, SEM-EDS, TEM, BET, FT-IR and powder XRD. ETS was effectively loaded into the channels of PAA-MSN via electrostatic interactions. The cumulative release was much rapid at extracellular tumor (6.8) and endosomal pH (5.5) than that of blood pH (7.4). Hemolysis study was done for the prepared NPs. MTT assay results showed that the drug-loaded ETS-MCM-41-PAA NPs were more cytotoxic to both prostate cancer cells namely PC-3 and LNCaP than free ETS, which was attributed to their slow and sustained release behavior. The above results confirmed that PAA-MSN hold a great potential as pH responsive carriers with promising future in the field of cancer therapy.     

Investigation of CaLa2S4 powder prepared by sulphurization of coprecipitated carbonates

Factors, including pH, coprecipitating medium, and temperature, for preparing CaLa₂S₄ powder were investigated. The precursors obtained by rapid precipitation in an aqueous solution at 25 °C had a homogeneous morphology of minute dentrites, and showed little or no CaS in the X-ray diffraction (XRD) patterns after sulphurization at 950 °C for 24 h. The particle size of the precursors or sulphides obtained in the vicinity of isoelectric point of pH=7.8 had a broad distribution, while that obtained at pH>9.24 had a narrow distribution. The precursors obtained in hydrous ethanol were a mixture of spherical, flaky and acicular particles in morphology, but all showed calcium deficiency. Interconnected particles were obtained in anhydrous ethanol at pH=6.81 and 25 °C with a highly homogeneous composition. No CaS phase was determined by XRD after sulphurization at 950 °C for 24 h. The CaLa₂S₄ powders obtained in both aqueous and anhydrous ethanol solutions were sintered, and a translucent pellet was obtained.     

盐离子对纳米氧化锆浆料流变性能的影响

通过测定浆料的Ｚｅｔａ电位和粘度曲线,研究了含高浓度盐溶液电解质对纳米氧化锆浆料电动性能和流变性能的影响。研究结果表明,盐离子的加入可显著改变浆料的悬浮特性,增加盐离子的浓度,氧化锆浆料的Ｚｅｔａ电位降低,粘度增大,对同一种电解质而言,浆料的等电点并不随离子浓度的改变而改变,说明氧化锆浆料对这些盐离子无特性吸附,从浆料 的粘度贡线可以看出,盐离子的加入均对浆料产生絮凝作用,使颗粒间产生一种相互相吸     

聚丙烯酸铵在纳米Y-TZP上的定量吸附研究

利用紫外－可见分光光度计研究了聚丙烯酸铵在纳米Ｙ－ＹＺＰ上的定量吸附情况。测定波长为２６０ｎｍ。分散剂的吸附量受球磨时间、溶液的酸碱性以及分散剂加入量的影响。当ｐＨ＝１．０２时,吸附属于高度亲和型吸附,最高吸附百分数达９８％,加入分散剂后,除强酸条件下,整个体系为ｐＨ趋近８．３,Ｚｅｔａ电势在－３５～４０ｍＶ之间,在较宽的ｐＨ范围里,体系初始的ｐＨ值对吸附情况影响较小。分析产生这种现象的原因是由于