D152弱酸性离子交换树脂吸附L-组氨酸

测定25 ℃下D152弱酸性离子交换树脂吸附L-组氨酸的动力学曲线和吸附等温线,考察了溶液中pH值、硫酸铵浓度、L-赖氨酸浓度和L-精氨酸浓度等因素对吸附的影响.结果表明：D152离子交换树脂吸附L-组氨酸约30 min即可达到平衡;Langmuir方程可以较好地描述D152离子交换树脂对L-组氨酸的吸附;在实验pH值范围内,L-组氨酸的吸附率随pH值的减小而减小,当pH降至3.19时,吸附率仍达到82.38%;NH＋^4的存在使L-组氨酸的吸附率明显下降,当硫酸铵浓度达到1.0 mol/L时,吸附率仅为5.10%;L-赖氨酸或L-精氨酸的存在使吸附率略微减小.     

Ion‐Exchange Adsorption of Proteins: Experiments and Molecular Dynamics Simulations

The adsorption of serum albumin and hemoglobin onto Q Sepharose FF was investigated, where the single and binary adsorption were considered. Both experiments and molecular dynamics simulations have been performed to study the adsorption from macroscopic and microscopic points of view. The steric mass‐action model was applied to describe the single adsorption isotherms and to predict the binary isotherms. The results of the experiments and simulations were connected and compared by two parameters of the steric mass‐action model. Both results present a preferential adsorption of serum albumin.     

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。     

Ion‐Exchange Equilibria of Nitrates on a Strongly Basic Resin

Adsorption isotherms of nitrates on the resin Amberlite IRA 410 at various pH values (6.8–12) were experimentally determined by batch tests. Six models involving two or three parameters are discussed. Concerning the Langmuir equation, the linear method had no significant effect on the estimation of isotherm parameters and simulation precision. Irrespective of the pH, the Sips model was found to give the best fit of the adsorption isotherm data. The maximum adsorption capacity decreased with increasing pH values and could be predicted by the correlation equations obtained in this study.     

Adsorption Equilibrium and Adsorption Kinetics: A Unified Approach

Conventional methods for the characterization of adsorption systems (determination of equilibrium and kinetic parameters) have been discussed. It is shown that the kinetic parameters determined by conventional methods are completely inconsistent with the equilibrium parameters. This inconsistency is due to the application of completely different models for equilibrium and kinetic study. In the present study adsorption is viewed as a Langmuir type physico‐chemical reversible process and a three‐parameter model is proposed which describes an adsorption system from both equilibrium and kinetic viewpoints. The model satisfactorily describes the kinetic and the equilibrium data reported by previous authors.     

Adsorption of ethane and ethylene on modified ETS-10

Ethylene and ethane adsorption isotherms were measured for Engelhard Titanosilicate (ETS-10) both as made in the sodium form and ion exchanged with different mono-, di-, and trivalent cations. Isotherms for Na-, K-, and Ag-ETS-10 were found to be nearly rectangular indicating very strong adsorption. In contrast, isotherms for Li-, Ba-, and Cu-ETS-10 show substantial curvature. Isotherms for some mixed cation forms (such as Ba/H and La/H) demonstrate the weakest adsorption with substantial adsorption swing capacity between 1 and 200 kPa. Using the ideal adsorption solution theory (IAST), it was determined that ethylene/ethane adsorption selectivity decreases in the order Na>K>Li>Cu≈Ba>Ba/H>La/H, while the adsorption swing capacity (from 1 to 200 kPa) shows an exactly reversed trend. It is thus probable to find the right balance between selectivity and swing capacity in order to design appropriate pressure swing adsorption (PSA) processes for the separation of ethylene and ethane under a wide range of conditions.     

Adsorption of chromate and molybdate by cetylpyridinium bentonite

Bentonite was modified with cetylpyridinium bromide (CPBr) and investigated by elemental analysis, IR, X-ray diffraction, thermogravimetric analysis, specific surface area (BET) and electrokinetic mobility measurements. The surfactant was adsorbed on the montmorillonite in a bilayer structure. The organo-bentonite removed the oxyanions of Cr(VI) and Mo(VI) from aqueous solutions. The adsorption followed a pseudo-second-order kinetics and adsorption capacities of 0.7 and 1.4 mmol/g for Cr(VI) and Mo(VI) were recorded. E_a = 5.34 and 14.50 kJ/mol for the adsorption of Cr(VI) and Mo(VI) indicated an ion exchange mechanism. The standard free energy values (ΔG°) of − 2.11 and − 3.40 kJ/mol for Cr(VI) and Mo(VI) indicated a spontaneous adsorption process. Column studies showed the suitability of the organo-bentonite for operation in continuous flow systems.     

Adsorption behavior of radioiodides in hexadecylpyridinium–humate complexes

The adsorption and desorption of the radionuclides iodide (¹²⁵I⁻) and cesium (¹³⁴Cs⁺) to and from humates with different hexadecylpyridinium (HDPy⁺) loadings were studied with the batch technique using bidistilled water and synthetic ground water (SGW) as equilibrium solutions.Furthermore, original humates, HDPyCl molecules, and the organo-humate samples were characterized by X-ray diffraction (XRD) and thermogravimetric (TG) measurements, differential thermo-analysis (DTA), and FT-IR spectroscopy.In HDPy⁺-modified humates, iodide ions exhibited increased adsorption (characterized by the distribution coefficient, K_d), while the adsorption of the cationic cesium was negligible. Higher distribution coefficients were obtained for the desorption than for the adsorption steps indicating that part of the iodide ions were bound irreversibly (hysteresis).In a log–log plot, adsorption and desorption isotherms for iodide exhibited non-linearity over wide concentration ranges of the carrier ions investigated, suggesting that besides ion exchange other types of adsorption mechanism also exist. The diffraction measurements revealed a distinct crystalline character of the HDPy-humate samples in contrast to the amorphous state of the original humic substances. These implications were confirmed by the thermal data and from the results of the FT-IR spectroscopy.     

Adsorption thermodynamics and kinetics of Cr(VI) on KIP210 resin

Series of resin selection experiments were carried out and the KIP210 strong base anion exchange resin was confirmed to have the maximum equilibrium adsorption capacity to remove Cr(VI) from wastewater. The adsorption thermodynamics and kinetics of Cr(VI) on KIP210 resin were investigated completely and systematically. The static experiments were performed to study the effects of various parameters, such as shaking speed, resin dosage and pH during the adsorption process. The results indicate that the effect of external diffusion is eliminated at 160 rpm, the best pH value is 3.0 and the removal percentage of Cr(VI) increases with the increase of the resin dosage. The adsorption of Cr(VI) on KIP210 agrees well with the Langmuir isotherm and the adsorption parameters of thermodynamics are ΔH = 26.5 kJ mol⁻¹, ΔS = 126.7 J mol⁻¹ K⁻¹ and ΔG < 0. It demonstrates that the adsorption of Cr(VI) on KIP210 is a spontaneously endothermic physisorption process. Moreover, the adsorption process can be described well by a pseudo-second-order kinetic model and the activation energy is 30.9 kJ mol⁻¹. The kinetic analysis showed that the adsorption rate is controlled by intraparticle diffusion. The resin is successfully regenerated using the NaOH solutions.     

Ion-Exchange Equilibrium of Ca2+, Mg2+, K+, Na+, and H+ Ions on Amberlite IR-120: Experimental Determination and Theoretical Prediction of the Ternary and Quaternary Equilibrium Data

Abstract

A study of the cation-exchange equilibria between Amberlite IR-120 resin and aqueous solutions of calcium, magnesium, potassium, and sodium chlorides and hydrochloric acid has been made. Experiments were carried out at 283, 303, and 323 K with solutions having total cation concentrations of approximately 0.1, 0.3, and 0.5 N. Experimental data for the ion-exchange equilibria of the ternary and quaternary systems are reported. These systems exhibit nonideal characteristics in both phases. The predictions have been based on the reaction equilibrium constants and correlations for the activity coefficients in both phases. A model which allows the prediction of multicomponent ion-exchange equilibria from binary data has been developed. Predictions of ternary and quaternary systems based solely on the binary data are in good agreement with the experimental results.     

药物偶联亲和高分子微球对牛血蛋白吸附性能研究

在制备亲和高分子乳液微球基础上,对其进行空间臂改性和药物分子偶联制得PSGN-MTA亲和高分子微球药物。为研究亲和高分子微球生物相容性,考察了高分子微球药物在缓冲液中药物释放行为及对BSA蛋白吸附能力。结果表明,亲和微球表面化学键合MTA药物浓度较高且分布均匀时,对BSA蛋白的吸附过程较符合一级动力学方程。还考察了pH值对BSA蛋白吸附的影响,中性条件时PSGN-MTA微球对于BSA吸附效果较好。     

Adsorption of Organic Solutes on Membrane Filters during Aqueous Phase Filtration. I. Basic Rate and Equilibrium Studies Using Toluidine Blue

Abstract

Membrane filters are made from a wide variety of polymeric materials, in a wide range of pore sizes, and are used in large numbers (several hundred million per year) to filter particulates from many types of solutions. However, during filtration, organic solutes are adsorbed by these membranes, often quite extensively. Thus, the composition of the filtrate can be very different from that of the original solution. A systematic study has been initiated to quantify and explain the adsorption of organic solutes during membrane filtration as affected by membrane type (material, pore size, presence/absence of wetting agents), solute type, pH, ionic strength, and filtration flow rate. Our first studies have employed a dye (toluidine blue) as the dissolved organic solute, and 11 membrane filters made of mixed cellulose esters, polyvinylidene difluoride, polytetrafluoroethylene, and polycarbonate. The results of these studies, which are both equilibrium and kinetic in nature, are presented. These results indicate how adsorption effects may be minimized.     

Adsorption of BSA on passivated chromium studied by a flow-cell EQCM and XPS

The adsorption of bovine serum albumin (BSA) on a passivated chromium surface in deaerated pH 4 sulphate solution was studied in situ using a switch-flow cell in combination with an electrochemical quartz crystal microbalance (EQCM) and ex situ by X-ray photoelectron spectroscopy (XPS). EQCM measurements showed that the kinetics of BSA adsorption was fast, and that a steady-state was reached about 10 min after introducing the protein. They also showed that BSA adsorption was an irreversible process, or that the kinetics of desorption was very slow. The equivalent thicknesses of the adsorbed BSA layer estimated in situ by EQCM and ex situ by XPS are in excellent agreement, and are equal to 3.5 ± 0.7 nm, which corresponds to one horizontally orientated monolayer.     

Adsorption equilibrium of solvent vapors on activated carbons

Adsorption amounts of solvent vapors such as n-hexane, toluene, and MEK on two commercial activated carbons (SLG-2PS and X-7000) were measured experimentally using a quartz spring balance connected with a high vacuum system. Single-species equilibrium data show typical type II isotherms, which are most frequently encountered in separation processes. Equilibrium data obtained at relative vapor pressures less than 0.3 were fitted to four well-known isotherms such as Langmuir, Freundlich, Sips, and Dubinin-Astakov (D-A) equations. All isotherm equations were found to describe experimental equilibrium data satisfactorily. Only the Langmuir equation was not proper to fit the equilibrium data of solvent vapors on SLG-2PS. In order to evaluate the adsorption energy distribution of the solvent vapors on activated carbons, a simple model based on the condensation approximation (CA) approach was applied. According to the result, it was proven that two carbons have energetically heterogeneous surfaces.     

Adsorption equilibrium of heavy metals on natural zeolites

Prior to equilibrium experiments, a clinoptilolite-type Korean natural zeolite was pretreated with HCl, NaOH, and NaCl to improve the ion-exchange capacity for heavy metals. Singleand multi-species equilibrium data of heavy metals such as copper, cadmium, cesium, and lead on treated and untreated natural zeolites were measured experimentally. For single-species equilibrium data, one of the conventional adsorption isotherms, the Sips equation, was used to fit them and then multi-species equilibrium data were predicted by using the loading ratio correlation (LRC), the ideal adsorbed solution (IAS) theory, and the real adsorbed solution (RAS) theory based on the Sips equation. In applying the RAS theory, we used the Wilson equation for fitting activity coefficients of metal ions in the ion-exchanger phase. It was proven that basic adsorption models except the LRC model could describe multi-species ion-exchange equilibrium for heavy metals/natural zeolite systems well.     

Adsorption equilibria of chloropentafluoroethane on activated carbon powder

An equilibrium study was conducted on the adsorption of chloropentafluoroethane (CFC-115, CF₃CF₂Cl) on activated carbon powder between 298.15 K and 373.15 K. Experimental data were fitted with several isotherm equations. Among the twoparameter equations, the BET equation showed the best results over the entire relative pressure range studied. When the pressure range was divided into two regions, a better result was obtained by applying the Langmuir equation in the lower pressure range and the BET equation in the higher relative pressure region. Among the threeparameter equations, the Langmuir-Freundlich equation gave better results than the RedrichPeterson equation. The isosteric heat of adsorption of CFC-115 on the activated carbon powder was estimated. It was found to have the same order of magnitude with the heat of condensation, which indicates that the adsorption was primarily due to physical forces.     

Adsorption of carbon dioxide, ethane, and methane on titanosilicate type molecular sieves

The separation of carbon dioxide from light hydrocarbons is a vital step in multiple industrial processes that could be achieved by pressure swing adsorption (PSA), if appropriate adsorbents could be identified. To compare candidate PSA adsorbents, carbon dioxide, methane, and ethane adsorption isotherms were measured for cation exchanged forms of the titanosilicate molecular sieves ETS-10, ETS-4, and RPZ. Mixed cation forms, such as Ba/H-ETS-10, may offer appropriate stability, selectivity, and swing capacity to be utilized as adsorbents in CO₂/CH₄ PSA processes. Certain cation exchanged forms of ETS-4 were found to partially or completely exclude ethane by size, and equivalent RPZ materials were observed to exclude both methane and ethane, while allowing carbon dioxide to be substantially adsorbed. Adsorbents such as Ca/H-ETS-4 and Ca/H-RPZ are strong candidates for use in PSA separation processes for both CO₂/C₂H₆ and CO₂/CH₄, potentially replacing current amine scrubber systems.     

Extended Elution by Characteristic Point Method for Characterization of Protein Ion‐Exchange Adsorption

An adequate characterization of adsorption isotherms is mandatory for chromatographic process development. Here, the elution by characteristic point (ECP) is a suitable method with low consumption of material and time. However, the ECP method requires a highly ideal behavior of the measured system. An innovative extended ECP approach is presented to characterize a non‐ideal system by the example of protein ion‐exchange adsorption. A marker, here bovine hemoglobin, is used to quantify all non‐idealities, e.g., convection, dispersion, or low number of theoretical plates. The system signal of the marker is used to compensate the system signal of the interesting solute, here bovine serum albumin. The resulting isotherm agrees well with the control results of a validated static approach.