吸附密度对蛋白质在离子交换吸附剂中孔扩散系数的影响

通过间歇吸附动力学实验,采用孔扩散模型研究了牛血清白蛋白和γ-球蛋白在阴离子交换剂中的扩散行为,考察了蛋白质初浓度和平均吸附密度对孔扩散系数的影响.结果表明,随蛋白质初浓度和平均吸附密度增大,孔扩散系数均呈指数下降,且蛋白质分子尺寸越大下降趋势越明显.     

蛋白质在离子交换介质中的动态吸附性能

研究了离子交换介质CM－Sepharose FF对几种不同的蛋白质－溶菌酶，木瓜蛋白酶，牛血清蛋白的动态吸附性能，考察了PH值，溶液粘度，初始蛋白浓度及吸附剂量等因素的影响，结果表明，这些参数会对吸附动态吸附性能产生不同程度的影响，而这些蛋白质也都显示了相似的规律，采用两相阻力模型描述了蛋白质在离子交换介质的动态吸附性能，计算得到了蛋白质在吸附剂颗粒中的扩散系数，有助于进一步研究蛋白质吸附过程的传质现象。     

离子强度对吸附有机污染物影响的研究进展

吸附由于其高效、低成本、易操作等特点,是目前国内外应用最广泛、最有效的废水处理方法之一。废水成分复杂,尤其是存在的背景离子会通过改变吸附剂和吸附质的相互作用影响有机物的吸附效果,造成主要吸附机制难以确认、吸附条件难以优化等问题。因此,研究离子强度对废水中有机物吸附性能的影响是提高吸附处理废水效果的重要途径。本文以吸附剂种类进行分类,阐述了在最常见氯化钠盐存在条件下钠离子和氯离子对于各类吸附剂吸附分离废水中有机物的影响,总结了各个研究者对此所做的研究,并以此展望了在离子存在条件下吸附剂在废水处理中的应用发展,指出开发新型、高效、经济、绿色、环保的吸附剂必将成为未来的发展趋势。     

盐种类和浓度对蛋白质疏水性吸附过程有效孔扩散系数的影响

研究了牛血清白蛋白在配基密度不同的两种疏水性吸附剂Phenyl Sepharose FF low sub和Phenyl Sepharose FF high sub上的吸附平衡和孔内传质动力学,重点考察了盐种类和浓度的影响.结果表明,Na2SO4溶液中盐浓度的增加导致蛋白质吸附容量的增大和解离常数的降低比(NH4)2SO4溶液更显著.利用孔扩散模型得到的有效扩散系数随盐浓度及配基密度的增大而提高,表明表面扩散作用对孔内传质的贡献随吸附容量提高而增大.     

固定床吸附过程浓度分布方程在离子交换法去除酒中锰离子的应用

本文将固定床吸附过程浓度分布方程应用于离子交换法去除酒中的锰离子。在给定交换柱利用效率条件下,计算所需离子交换柱树脂层的高度,反之亦然。     

pH和离子强度对海藻吸附Pb2+的影响研究

研究了pH值和离子强度对海带Laminariajaponica、裙带菜Undaria pinnatifida和条斑紫菜Porphyra yezoensis吸附Pb2+的影响.结果表明:海带和裙带菜吸附pb2+的适宜pH值在3～5之间,紫菜吸附Pb2+的最佳pH值为4;溶液中NaNO3的浓度由0 M增加到0.05M,三种...     

蛋白质在膨胀床吸附层析剂的静态和动态吸附性能

以牛血清白蛋白 (BSA)为目标蛋白 ,考察膨胀床用离子交换树脂StreamlineDEAE的静态和动态吸附性能 ,并和离子交换树脂DEAESepharoseFF进行比较 ,实验发现两者的静态吸附性能相似 ,而动态吸附性能差别较大。根据动态吸附数据计算出液膜扩散系数和孔内扩散系数。     

离子交换树脂对有机废水中铜离子的吸附

选用多种大孔强酸型离子交换树脂,用于吸附浓集含有机物废水中的铜离子,通过测定各种树脂对铜离子的去除率、不同铜离子浓度和溶液pH值对去除率的影响,以及各树脂再生性能的比较,表明“争光”、“强酸1号”和PK208树脂性能最为突出,效果明显优于其它几种树脂,可用于吸附处理有机废水中的铜离子。     

一种新型复合材料对氟离子吸附性能的影响

将钛酸丁酯加到多孔球状吸附树脂中，用一水溶液将该醇盐水解，制得由钛的水合氧化物和多孔树脂组成的复合材料，本文研究了这种复合材料对氟离子的吸附性能。     

溶液pH、离子强度和温度对活性炭吸附活性染料的影响（一）

在活性染料的生产过程中,使用活性炭作为吸附剂用来精制原料或半成品或废水处理是经常见。但对于其机理和最佳条件国内研究者十分鲜见。 该文重点介绍国外学者Yahya S．Al-Degs,Musa I．El-barghouthi和Amjad H．El—Sheikh,Gavin M．Walker等近期研究的结果,全面阐述了溶液pH,离子强度和温度对活性炭吸附活性染料的影响,这对提高有关活性染料质量和降低原材料消耗及处理有色污水有很好的参考价值。     

减电荷聚甲基丙烯酸钠接枝介质的制备及蛋白质吸附性能

离子交换容量（IC）为320mmol/L的聚甲基丙烯酸钠（pMA）接枝型介质（FF-pMA-320）对溶菌酶和γ-球蛋白具有较高的吸附容量,但其传质速率较低。在保持聚合物链长度的前提下,通过乙醇胺与接枝链上的羧基进行电荷中和反应,降低pMA接枝型介质的电荷密度,提升介质的蛋白质传质速率。将FF-pMA-320进行部分电荷中和修饰,制备得到离子交换容量分别为230mmol/L和170mmol/L的减电荷阳离子交换介质,分别命名为pMA-320-R230和pMA-320-R170。采用吸附平衡、吸附动力学和柱穿透实验,研究了溶菌酶和γ-球蛋白在这两种新型介质上的吸附行为,并与初始介质FF-pMA-320进行了比较。结果表明：随着介质的IC值（电荷密度）从320mmol/L降低到170mmol/L,介质对两种蛋白质吸附容量随之减少,这与电荷中和修饰降低蛋白质吸附位点有关。随着接枝聚合物电荷密度的降低,相邻聚合物链之间的静电排斥作用减弱,蛋白质吸附容量降低,造成接枝链的灵活性增加以及蛋白质排阻效应减弱。因此,溶菌酶和γ-球蛋白在pMA-320-R170上的传质速率分别是FF-pMA-320的1...     

Effect of ionic strength on bubble coalescence in inorganic salt and seawater solutions

Bubble size is of fundamental importance in the flotation process, as it provides the surface area for particle collection. Typically, weak surfactants (frothers) are added to process water to reduce bubble coalescence. Certain inorganic electrolytes, which occur naturally in some flotation process water, have been shown to mimic the role of frothers. The concentration at which bubble coalescence is inhibited, the critical coalescence concentration, was determined in a 5.5‐L mechanical flotation cell for a series of coalescence inhibiting inorganic salts. To mimic some industrial flotation process water, a synthetic sea salt solution was also tested. It was found that when the multicomponent sea salt solution was broken down into its constituent parts, the addition of the ionic strength of each ion correlated well with the overall ionic strength curve of all the salts tested. The critical coalescence ionic strength ranged from 0.22 to 0.35, with sea salt being 0.26. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2489–2496, 2015     

Effect of assembly pH and ionic strength of chitosan/casein multilayers on benzydamine hydrochloride release

Abstract

Multilayer biopolyelectrolyte films are built from chitosan and casein by layer-by-layer deposition onto corona precharged poly(DL-lactic acid) substrate. Such structure allows optimization with respect to the morphology and ability of drug immobilization and release by changing the assembly conditions. Variation of chitosan and casein solutions ionic strength and chitosan solution pH at constant casein solution pH, effects significantly the polyelectrolyte multilayer structure and drug release. pH and ionic strength increase change the morphology from dense to loose, and the ionic strength increase let to screening effect and complexation of the drug, resulting in slow drug release.     

尿素变性对大豆分离蛋白粘接强度和分子结构的影响

大豆分离蛋白基胶粘剂由于具有环境友好性、生物降解性和可再生性而受到人们的关注。研究了尿素变性对大豆分离蛋白粘接强度及对蛋白分子结构的影响。结果表明,蛋白质经过尿素变性后,随着尿素浓度的增加,蛋白质分子展开的程度过大反而对粘接强度有不利的影响。在对榉木进行粘接时,1mol/L尿素变性获得的粘接强度最大。     

The effects of ionic strength and pH on antibacterial activity of hybrid biosurfactant-biopolymer nanoparticles

The physicochemical properties of nanoparticles (NPs) directly influence the colloidal stability and bio-nano interface, which makes the study of these factors extremely important for NPs applicability. Here, we report the influence of pH and ionic strength in the size, surface charge, and antimicrobial activity of chitosan/rhamnolipid nanoparticles (C/RL-NPs), synthesized by mixing C and RL in the proportion of 1:1, with the dropwise addition of TPP (sodium tripolyphosphate) in the molar ratio of 1:2.5:1.3, respectively. The obtained NPs were resuspended in different solvents to investigate the ionic strength effect on their stability and antimicrobial activity. By decreasing pH and ionic strength, NPs size was reduced while their surface charge increased. Chitosan nanoparticles (C-NPs) remained stable in the presence of TPP at acidic pH and low ionic strength, indicating that the modulation of physicochemical conditions for the crosslinking between the two ionic components was an efficient approach to enhance C/RL-NPs colloidal stability. Thermogravimetric analysis confirmed the interaction between rhamnolipid and chitosan in C/RL-NPs. The antibacterial activity of C/RL-NPs against Staphylococcus aureus increased significantly, demonstrating the importance of investigating size and surface charge to dictate the bioactivity properties of such hybrid natural-based nanomaterial.     

Protein adsorption onto diethylaminoethyl dextran modified anion exchanger: Effect of ionic strength and column behavior

Our previous studies on bovine serum albumin(BSA) adsorption to diethylaminoethyl dextran(DEAE dextran,DexD, grafting-ligand) and DEAE(D, surface-ligand) modified Sepharose FF resins found that all the grafted resins(FF-DexD and FF-D-DexD) exhibited extremely fast uptake rate(effective diffusivity, D_e, D_e/D_O 1.4),which was six times greater than the ungrafted resins(D_e/D_O 0.3). In this work, the influence of ionic strength(IS) on 6 typical DEAE dextran-grafted resins was investigated. Bath adsorption equilibria and kinetics, breakthrough, and linear gradient elution experiments were conducted. Commercial DEAE Sepharose FF was used for comparison. It is found that protein adsorption capacities on DEAE dextran-FF resins and the commercial resin decreased with increasing IS, but DEAE dextran-FF resins exhibited much higher capacity sensitivity to salt concentration. Besides, steeper decrease of adsorption capacities could be obtained at higher graftingligand or surface-ligand density. It is worth noting that the facilitating role of surface-ligand to the "chain delivery" effect was weakened after adding salt, leading to the less improvement in uptake rate by increasing surface-ligand density at higher IS. Although the uptake rates of the DEAE dextran-FF resins increased first and then decreased with increasing IS, they kept the extremely high level of De values(D_e/D_O 1.1) at the their working/binding IS range. Moreover, the DEAE dextran-FF resin displayed much higher adsorption capacities and De values than commercial ungrafted resin in their working condition. Furthermore, the column results of DEAE dextran-FF resins presented higher dynamic binding capacities than and similar elution ISs with DEAE Sepharose FF to achieve similar(or even higher) recoveries suggest the excellent chromatographic column performance of the DEAE dextran-FF resins. Finally, both high recovery and purity of BSA and γ-globulin could be easily achieved using the typical DEAE dextran-FF column, FF-D60-DexD160, to separate their binary mixtures,by step gradient elution. The research has provided new insights into the practical application of the series of DEAE-dextran grafted resins in protein chromatography and proved their superiority.     

Effects of ionic strength and pH on the diffusion coefficients and conformation of chitosans molecule in solution

The effects of ionic strength and pH on the diffusion coefficients and gross conformation of chitosan molecules in solution were studied. Chitosan with 83% degree of deacetylation (DD) was prepared from red shrimp (Solemocera prominenitis) processing waste. Ten different molecular weight chitosans were prepared by ultrasonic degradation, and their molecular weights were determined by static light scattering. The weight-average molecular weight (M_w) were between 78 to 914 kilo dalton (KDa). Solution of different ionic strengths (I = 0.01, 0.10, and 0.20) but the same pH (2.18) and different pHs (2.37, 3.10, and 4.14) but the same ionic strength (I = 0.05) were prepared to measure their mutual diffusion coefficient (D_m). The diffusion coefficients for standard condition (D_20,w) were derived from D_m. Intrinsic viscosities ([η]) were determined by a capillary viscometer in different pH solutions. The Mark–Houwink exponents a and ε were obtained from plots of Log [η] and Log D_20,w versus Log M_w, respectively. The results show that diffusion coefficients increased with increasing ionic strength or with increasing pH or with decreasing M_w. Value of ε and a were between 0.503 to 0.571 and ranged from 0.543 to 0.632, respectively. The results indicates that chitosans conformation were in random coil in solutions in the ranges of ionic strength and pH studied. The values of a*, ε* and a**, ε**, Mark–Houwink exponents of smaller and higher than 223 KDa chitosans, respectively, were between 0.752 to 0.988 and 0.585 to 0.777 for smaller M_w chitosans and 0.406 to 0.428 and 0.430 to 0.518 for larger M_w chitosans, respectively. Molecular-weight-induced conformational transition occurred because smaller M_w chitosans was more extended than higher M_w chitosans. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2041–2050, 1999     

反离子对牛血清白蛋白在荷电葡聚糖接枝介质中色谱行为的影响

从前期开发的具有极高的吸附容量及传质速率的二乙氨乙基葡聚糖接枝离子交换介质中选取FF-D50-DexD100和FF-DexD100为典型代表,利用Cl^-、SCN^-、SO₄^2-、HPO₄^2-为模型反离子,以牛血清白蛋白（BSA）为模型蛋白,以商品化介质（Q Sepharose FF、Q Sepharose XL、DEAE Sepharose FF）为对照,在离子强度为0.06mol/L下,系统研究反离子对二乙氨乙基葡聚糖接枝介质的蛋白质吸附与洗脱行为的影响。结果表明,二乙氨乙基葡聚糖接枝介质对不同反离子的偏好性存在差异,且该偏好性差异与基团所处位置（接枝链配基或表面配基）无关。同时,介质偏好性弱的反离子会通过促进二乙氨乙基葡聚糖接枝介质的“链传递”效应加快蛋白质的传质速率,从而提高动态吸附容量。因此,在使用二乙氨乙基葡聚糖接枝介质进行蛋白质色谱柱分离过程中,可在吸附操作中使用HPO₄^2-,在洗脱操作中使用SCN^-来优化分离效果。