Exchange Reaction Characteristics of Anion Exchange Resin for Diclofenac Sodium

Aim To study the exchange reaction characteristics of anion exchange resin for diclofenac sodium. Methods The drug-resin complexes were prepared by a batch method with diclofenac sodium as the model drug and the strong anion exchange resin (201 × 7) as the carrier. The effects of different forms (OH~ - and Cl~ - ) of the strong anion exchange resin, the particle size of the resin, and the reaction temperature on the exchange behavior were described. The exchange kinetic profiles were fitted. The related exc...

Theoretical Study on the Mass Transfer of Metal Ions in Ion Exchange Process

The kinetics of ion exchange between Ca2+, Mg2+, Co(Ⅱ), Cu(Ⅱ),Ni(Ⅱ), Fe(Ⅲ), y3+ or Sm3+ , respectively, in 0.50 mol/L HC1 and H+ on macrorecticular sulfonic ion exchange resin and the kinetics of the same reactions (M -H exchange) when Mn(Ⅱ) coexisted in resin phase as accelerating ion were studied. The accelerating effect manifested and its rule are consistent with the accelerating effect theory based on the concept concerned with adsorption electrical double layer which has been suggested in a previous paper published.

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, De, De/Do 〉 1.4）, which was six times greater than the ungrafted resins （De/Do 〈 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 fS, they kept the extremely high level of De values （De/Do 〉 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.

Adsorption behavior of molybdenum onto D314 ion exchange resin

The adsorption behavior of molybdenum onto D314 was studied with the static adsorption method. The adsorption process was analyzed from thermodynamic and kinetic aspects. The experimental results show that the equilibrium adsorption data conform satisfactorily to the Langmuir equation. In the adsorption process of D314 for molybdenum, the enthalpy change ΔH is positive when temperature is in the range of 298-338 K, which indicates that the adsorption is an endothermic process, and the elevated temperature benefits to the adsorption. Kinetic analysis shows that the adsorption rate is controlled by intraparticle diffusion and chemical diffusion at the same time. The adsorption mechanism of molybdenum onto D314 was discussed based on IR spectra.

Analytical solution for concentration distribution in an open channel flow with phase exchange kinetics

This study is about an analytical attempt that explores the two-dimensional concentration distribution of a solute in an open channel flow.The solute undergoes reversible sorption at the channel bed.The method of multiple scales is used to find the two-dimensional concentration distribution,which is important for modem day application in industry,environmental risk assessment,etc.Study deduces an analytic expression of two-dimensional concentration distribution for an open channel flow with sorptive channel bed.Effects of retention parameter,Darnkohler number on the solute dispersion are also discussed in this paper.Results reveal that slow or strong kinetics(small value of Darnkohler number)increases solute dispersion.It is also observed.that for slow phase exchange kinetics between bulk flow and small retentive channel bed,solute concentration distribution will uniform faster than their inert counterpart.

Investigation on Ligand Exchange Kinetics on CdSe/ZnS Quantum Dot Surface Utilizing Pyrene as Flourescent Probe

Direct ligand exchange kinetics between hydrophilic molecules and quantum dots（QDs） was investigated. Meanwhile, pyrene was exploited as probe to detect the efficiency of the ligand exchange reaction between octade- cylamine-coated QDs（ODA-QDs） and different ligands[ligand 1： NH2G3-OH, ligand 2： G4.5-PEG5-FA5, ligand 3： （COOH）2G3-OH or ligand 4： G4.5-PEG1-FAl]. It was indicated that water-soluble QDs exhibit the same fluores- cence and absorption spectra as ODA-QDs when they were dissolved in chloroform. Furthermore, the cellular expe- riments demonstrated that the folic acid（FA） targeting poly（amidoamine）（PAMAM） modified QD conjugates could be used as molecular targeting sensing systems for nanoparticle probes.

Kinetic study on the ligand exchange reactions between bis(alkylxanthato)palladium(II)and bis(N,N-dialkyldithiocarbamato)palladium(II)by high-performance liquid chromatography

The rate constants and equilibrium constants of ligand exchange reactions between his (alkylxanthato)palladium(Ⅱ),Pd(S_2COR)_2(R=Am,n-Hex,Bz),and bis(N,N-dialkyldithiocarbamato) palladium(Ⅱ),Pd(S_2CNR_2)_2(K=Et,n-Pr,n-Bu),in chloroform solution have been determined in a temperature range of 20—50°C by means of high-performance liquid chromatography.It was found that both the forward and reverse reactions are of second order.All of the equilibrium constants K determined are 10.3±1.0,much greater than the value(K=4)calculated statistically which indicates that the ternary complexes are more stable than the binary complexes.The experimental results revealed that the reaction rate decreases with the increase in the size of R and R^1 groups and the latter are more remarkable,consistent with the deduction of steric effect.The activation parameters of the reactions have been calculated.In reaction series(11)and(12)(in the text)the isokinetic tempera- tures B=390±8K and β=346±15 K have been observed respectively.A plausiblemechanism in- volving an eight-membered ring intermediate has been proposed on the basis of experimental results.

Removal of perfluorinated surfactants from wastewater by adsorption and ion exchange--Influence of material properties,sorption mechanism and modeling

Perfluorooctane sulfonate（PFOS） has attracted increasing concern in recent years due to its world-wide distribution, persistence, bioaccumulation and potential toxicity. The influence of sorbent properties on the adsorptive elimination of PFOS from wastewater by activated carbons, polymer adsorbents and anion exchange resins was investigated with regard to their isotherms and kinetics. The batch and column tests were combined with physicochemical characterization methods, e.g., N2 physisorption, mercury porosimetry, infrared spectroscopy, differential scanning calorimetry, titrations, as well as modeling. Sorption kinetics was successfully modelled applying the linear driving force（LDF） approach for surface diffusion after introducing a load dependency of the mass transfer coefficient βs.The big difference in the initial mass transfer coefficient βs,0, when non-functionalized adsorbents and ion-exchange resins are compared, suggests that the presence of functional groups impedes the intraparticle mass transport. The more functional groups a resin possesses and the longer the alkyl moieties are the bigger is the decrease in sorption rate.But the selectivity for PFOS sorption is increasing when the character of the functional groups becomes more hydrophobic. Accordingly, ion exchange and hydrophobic interaction were found to be involved in the sorption processes on resins, while PFOS is only physisorptively bound to activated carbons and polymer adsorbents. In agreement with the different adsorption mechanisms, resins possess higher total sorption capacities than adsorbents. Hence, the latter ones are rendered more effective in PFOS elimination at concentrations in the low μg/L range, due to a less pronounced convex curvature of the sorption isotherm in this concentration range.