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.

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 benzenesulfonic acid by novel weakly basic anion exchange resins

Two novel weakly basic anion exchange resins（SZ-1 and SZ-2） were prepared via the reaction of macroporous chloromethylated polystyrene-divinylbenzene（Cl-PS-DVB） beads with dicyclohexylamine and piperidine, respectively. The physicochemical structures of the resulting resins were characterized using Fourier Transform Infrared Spectroscopy and pore size distribution analysis. The adsorption behavior of SZ-1 and SZ-2 for benzenesulfonic acid（BA） was evaluated, and the common commercial weakly basic anion exchanger D301 was also employed for comparison purpose. Adsorption isotherms and influence of solution p H, temperature and coexisting competitive inorganic salts（Na2SO4and Na Cl） on adsorption behavior were investigated and the optimum desorption agent was obtained.Adsorption isotherms of BA were found to be well represented by the Langmuir model.Thermodynamic parameters involving ΔH, ΔG and ΔS were also calculated and the results indicate that adsorption is an exothermic and spontaneous process. Enhanced selectivity of BA sorption over sulfate on the two novel resins was observed by comparison with the commercial anion exchanger D301. The fact that the tested resins loaded with BA can be efficiently regenerated by Na Cl solution indicates the reversible sorption process. From a mechanistic viewpoint, this observation clearly suggests that electrostatic interaction is the predominant adsorption mechanism. Furthermore, results of column tests show that SZ-1possesses a better adsorption property than D301, which reinforces the feasibility of SZ-1for potential industrial application.

Simultaneous removal of dissolved organic matter and bromide from drinking water source by anion exchange resins for controlling disinfection by-products

Anion exchange resins （AERs） with different properties were evaluated for their ability to remove dissolved organic matter （DOM） and bromide, and to reduce disinfection by-product （DBP） formation potentials of water collected from a eutrophic surface water source in Japan. DOM and bromide were simultaneously removed by all selected AERs in batch adsorption experiments. A polyacrylic magnetic ion exchange resin （MIEX） showed faster dissolved organic carbon （DOC） removal than other AERs because it had the smallest resin bead size. Aromatic DOM fractions with molecular weight larger than 1600 Da and fluorescent organic fractions of fulvic acid- and humic acid-like compounds were efficiently removed by all AERs. Polystyrene AERs were more effective in bromide removal than polyacrylic AERs. This result implied that the properties of AERs, i.e. material and resin size, influenced not only DOM removal but also bromide removal efficiency, MIEX showed significant chlorinated DBP removal because it had the highest DOC removal within 30 rain, whereas polystyrene AERs efficiently removed brominated DBPs, especially brominated trihalomethane species. The results suggested that, depending on source water DOM and bromide concentration, selecting a suitable AER is a key factor in effective control of chlorinated and brominated DBPs in drinking water.

Preparation of a novel magnetic resin for effective removal of both natural organic matter and organic micropollutants

A novel, bifunctional, hypercrosslinked, magnetic resin W2 was prepared using divinylbenzene （DVB） and glycidyl methacrylate （GMA） as comonomers in three steps （i.e., suspension polymerization, amination and post-crosslinking reactions）. To evaluate the adsorption of natural organic matter （NOM） and organic micropollutants （OMPs） on the obtained resin W2, two magnetic resins W1 （the precursor of W2 before post-crosslinking） and W0 （the precursor of W1 before amination） were chosen for comparison. The results indicated that W2 would be a promising material for the removal of both NOM and OMPs from aquatic environments.