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In this work, a series of microporous aminal-linked polymers (MALPs) are designed and prepared through the polycondensation of 1,4-bis(2,4-diamino-1,3,5-triazine)-benzene and four rigid tetra-aldeh...

A new approach was proposed for grouping separation of 14 lanthanide rare-earth ions from their co-existing mixed aqueous solutions, by performing liquid-column elution using the aqueous solution containing 14 lanthanide rare-earth ions as the stationary phase and the dispersed organic oil droplets containing P507 extractant as the mobile phase. It was revealed that 14 lanthanide rare-earth ions could be separated into four groups, according to the lanthanide tetrad effect, respectively eluting out from the liquid column at different time in a certain order. Various effects including the saponification degree of P507, the concentration of P507 in organic phase, the length and inner diameter of the extraction column on the performance of grouping separation of rare-earth ions were discussed. The changes of the mass transfer coefficients were also investigated. The separation efficiency of the four groups of rare-earth elements (REEs) was evaluated based on the elution resolution, Rs, of the elution peaks of La(III), Gd(III), Ho(III) and Lu(III), the four representative elements respectively from each of the four groups of REEs. Experimental results demonstrated that the separation of REEs by liquid-column elution mainly depended on the competitive adsorption of different rare-earth groups onto the surface of ascending P507 oil droplets. The affinity of different rare-earth groups with P507 extractant and a limited adsorption capacity of P507 molecules at the surface of the oil droplets ascending in liquid column play the important role. The present work highlights a promising technique for grouping separation of multiple lanthanide elements co-existing complex systems.

Waste cellulosic biomass obtains various applications due to low-cost and eco-benign characteristics. A general strategy is proposed for waste cellulosic biomass to be modified with dialdehyde functional groups as intermediates through periodate partial oxidation. Finally, aminothiourea-modified waste cellulosic biomass can be prepared through Schiff reaction. Waste corn stalk, cotton and paper as typical precursors, were used to prepare cellulosic biomass, abbreviated as AT-S, AT-C and AT-P, respectively, and their adsorption behaviors of Au(III) from the hydrochloric acid medium were investigated. The pseudo-second kinetics equation as well as the Langmuir isotherm equation can be used to depict the adsorption process, and the maximum adsorption capacities of Au(III) are 21.4, 19.0 and 3.28 mol/kg for AT-S, AT-C and AT-P at 298 K, respectively. The adsorption capacities of Au(III) on aminothiourea modified corn stalk (AT-S) is almost 357 times greater than that of raw corn stalk. To the best of our knowledge, AT-S has the highest adsorption capacity towards Au(III). AT-S also displays a superior separation selectivity towards Au(III) in the presence of Cu(II), Ni(II), Co(II), Pt(VI), Pd(II) and Rh(III). Furthermore, the characterization analysis of XRD, TG, SEM, TEM and FTIR confirms that AuCl4– has been reduced to elemental Au nanoparticles and deposit onto the surface of the biomass. It shows a prospect for waste corn stalk to be used to adsorb Au(III) from liquid phase and the possible fabrication of gold nanoparticles by a general adsorption process without any reductant.

Hydrodeoxygenation of phenolic components in pyrolysis bio-oil is considered to be a potential strategy for producing renewable aromatic chemicals. The key issue of this process is the establishment of an effective catalytic system that can cleave the CAr–O bonds without affecting the aromatic structure. To achieve this goal, an efficient heterogeneous catalyst with solid acid support (WOx/ZrO2) and active metal (Ru) was prepared in this study. The Ru–WOx/ZrO2 catalyst can effectively convert model phenolic compounds into aromatic hydrocarbons. For a mixed phenolic sample, the conversion to and selectivity for arenes were all around 90%. The good selectivity was proved to be strongly related to the surface adsorption and acid properties of the catalyst as well as the reaction pathway. Moreover, the hydrodeoxygenation of a pretreated bio-oil was also conducted and presented a satisfactory yield of arenes at 240 °C with 1 MPa of H2 reacted for 5 h. The depolymerization of high-molecular-weight phenolic olig...

The upcycling of Polyurethane (PU) degradation products has been gaining tremendous attention and research interest in recent years. In particular, due to the toxicity to microorganisms, the key process is to remove aromatic diamines selectively and efficiently from the bio-hydrolysate which also includes multiple carboxylic diacids and polyols. Herein, a series of super-hydrophobic hypercrosslinked porous polymers (HCPPs) were prepared to selectively remove aromatic diamines in a neutral condition. They were facially fabricated via Friedel-Crafts alkylation reactions with benzene and three types of benzyl bromides. Besides, the surface area, porous structure, and hydrophobic properties of resulting polymers were adjusted by changing the length and connected nodes numbers of crosslinkers. Particularly, HCPP-TBMB knitted by 1,3,5-tris(bromomethyl)-benzene (TBMB) owned a maximum BET surface area of 1048.8 m2 g−1 with hierarchical porosity, as well as high thermal stability and super-hydrophobicity. The adsorption experiments on HCPP-TBMB clarified the large adsorption capacities of 2,4-toluene diamine (TDA, 1.062 mmol g−1) and 4,4′-methylene dianiline (MDA, 1.971 mmol g−1) as well as high selectivity in the model PU hydrolysate. Moreover, thermodynamic experiments and spectral analysis revealed the physical adsorption process for uptake of aromatic diamines on HCPP-TBMB. The main adsorption mechanism contained π-π stacking, hydrophobic interaction, and hole size effect. These findings may provide a promising strategy for highly selective removal of aromatic diamines from the PU bio-hydrolysate.

Herein, a new tetraphenyladamantane-cored triazine-based multiamine (TPADT) was designed and synthesized. Its bulky molecular volume, strong rigidity, and high amine functionality enable it easy to prop up the polymer backbone and form a high hypercrosslinking degree to obtain high microporosity. A series of highly microporous tetraphenyladamantane-based polyaminals (Ad-MALPs) were prepared through the catalyst-free copolymerization of TPADT and commercial aromatic aldehydes. By changing the strut length and functionality of aldehyde monomers, the resulting polymers exhibit tailored BET surface area (1541–1779 m2/g) and narrow ultramicropore size distribution (0.52–0.93 nm). Ad-MALP-2 with the largest microporosity possesses the highest CO2 uptake (21.1 wt %, 273 K/1.0 bar) and CO2/N2 adsorption selectivity (35.2). Interestingly, Ad-MALP-3 shows the highest H2 uptake (2.26 wt%, 77 K/1.0 bar) due to larger total pore volume. In addition, highly microporous Ad-MALPs simultaneously contain aromatic and cycloaliphatic components, and thus show exceptionally large aromatic and cycloaliphatic organic vapor adsorption capacity under low pressure. At P/P0 = 0.1, the benzene and cyclohexane vapor uptakes of Ad-MALPs are up to 44.8 wt% and 39.0 wt %, far exceeding that of most previously reported porous organic polymers. Considering that Ad-MALPs have outstanding gas adsorption performance, simple preparation, good stability, and cycle ability, they are expected to be promising adsorbent materials for CO2 adsorption/separation, H2 storage and low-concentration volatile organic vapors capture.

A novel biosorbent, corn stalk gels with double carboxylic groups synthesized by two oxidation steps (the double carboxylic groups modified adsorbent is abbreviated as DCCS-2), was prepared, characterized, and applied for the recovery of rare earths (III) from the nitric media. For the whole lanthanides, it exhibits a distinct “tetrad effect” with the increase of atomic numbers. Taking Nd(III) as a representative element, the adsorption capacity, kinetics, selectivity and mechanism were investigated. Thermodynamics and kinetic fittings were found to abide by Langmuir and pseudo-second-order rate equations and the corresponding parameters were calculated. The maximum adsorption capacity was calculated to be 2.44 mol/kg at 298 K for DCCS-2. Results showed that the double carboxylic groups played an important role for improving the adsorption capacity, e.g. the adsorption capacity of Nd(III) by DCCS-2 increased to 53.5 times compared to the raw corn stalk. Furthermore, DCCS-2 also shows a good selectivity between Nd(III) and many non-rare earth metal ions. The cation exchange is proposed to be the possible adsorption mechanism.

A series of ethanediamine (EDA) – modified magnetic poly-(glycidyl methacrylate) (m-PGMA-EDA)microspheres with different amine density were synthesized and their cadmium saturation adsorption capacities were examined. The results showed that the cadmium saturation adsorption capacity increased with the immobilized amine density. However, they did not show strong positive linear correlation in the whole range of amine density examined. The molar ratio of amine groups to the adsorbed cadmium decreased with the increase of amine density and eventually reached a minimum value about 4. It suggested that low immobilized amine density led to low coordination efficiency of the amine. It is hypothesized that the immobilized amine groups needed to be physically close enough to form stable amine-metal complex. When the amine density reached to a critical value 1.25 m mol m −2 , stable amine-cadmium complex (4:1 N/Cd) was proposed to form. To illustrate the coordination mechanism (structure and number) of amine and Cd, FT-IR spectra of m-PGMA-EDA and m-PGMA-EDA-Cd , and X-ray photoelectron spectroscopy (XPS) of PGMA–EDA and PGMA-EDA-Cd were examined and analyzed.

In this work, two hypercrosslinked hydroxyl-rich polymers (HCP-P and HCP-R) were facilely prepared through a one-pot Friedel-Crafts polymerization of phenol, resorcinol and formaldehyde dimethyl acetal, respectively. HCP-P and HCP-R were investigated for their ability to separate Cs+ from the salt lake brine via ion-exchange reaction between Cs+ and O−Na+. The Cs+ adsorption isotherms of HCP-P and HCP-R follow the Langmuir model, and their adsorption capacities reach 249.64 mg g−1 and 259.97 mg g−1, surpassing most of commercial materials like AMP-PAN (81 mg g−1) and TAM-5 (191.8 mg g−1). The Cs+/K+ separation factors (S.F.) of HCPs can reach 12.4 even in the presence of high concentrations of K+ (C(K+)/C(Cs+) = 712.5). Notably, HCPs could retain more than 90% of the adsorption capacities after 5 successive adsorption-desorption cycles. Besides, X-ray photoelectron spectroscopy (XPS), FT-IR spectra and TEM-EDS analysis revealed the ion exchange mechanism of the Cs+ adsorption process. This work demonstrated the excellent application potential of hypercrosslinked hydroxyl-rich polymer adsorbents in separating Cs+ from the salt lake brine.

In this paper, the separation and purification of nattokinase have been reviewed by primarily focusing on solvent precipitation, adsorption column chromatography, magnetic microspheres, expanded bed, reverse micelle, and three-phase separation methods. The different methods for determination of the enzyme activity have been discussed and compared. Finally, the feasibility that the nucleic acid-based identification techniques can be used for nattokinase purification and enzyme activity assay has been proposed.

Understanding the fundamentals of confined chemical reaction was an important subject in various heterogeneous physicochemical processes. Here, we investigated the orientation behavior of an amphiphilic ligand, the tri- n-octylphosphine oxide (TOPO), in a compressed monolayer at the air/water interface and its impact on the complexation reactivity of TOPO molecules with chromate ions at the interface. The analysis of sum frequency generation and polarization modulation infrared reflection absorption spectroscopy experiments combined with surface pressure measurements reveals a significant dependence of the adsorption rate and saturated concentration of chromate ions on the orientation of TOPO molecules during the increase of the surface pressure. In parallel, the analysis of molecular dynamics simulations indicates that the interaction energy between TOPO molecules and chromate ions is strongly sensitive to the orientation of TOPO molecules confined at the water/air interface. The present work provides a novel insight into the unique chemical reactivity of molecules in a confined microenvironment, and it provides a basis for further progresses in improving chemical reactivity and selectivity of molecules in a confined environment by regulating confinement of molecules.

Novel porous coordination polymers (PCPs) modified with sulfonic acid/phosphotungstic acid (PTA) were prepared by hydrothermal method via one-pot self-assembly. The materials were characterized by FTIR, XRD, TEM, SEM-EDS, N 2 adsorption/desorption, TG, NH 3 -TPD, etc., and have been used as solid acid catalysts for reproducible glucose transformation to 5-hydroxymethylfurfural (HMF) in environmentally friendly solvents. With PCP(Cr)-SO 3 H·Cr(III) as catalyst, over 99.9% glucose conversion and an excellent HMF yield of 80.7% were obtained at 180 °C for 4 h in water, with THF as the online extraction agent for HMF. In this system, the staple glucose material could successfully substitute the expensive fructose (HMF yield = 85.3%). A possible mechanism of glucose conversion and the formation procedure of byproduct were deduced and analyzed. The catalyst could be easily reused with good reproducibility and low wastage of active metal, showing a good prospect for high value applications of glucose.

A bioadsorbent composed of magnetic silica nanoparticles encapsulated by chitosan microspheres was prepared by the emulsion cross-linking method, and it was then modified with quaternary ammonium groups by reaction with ethylenediamine and glycidyl trimethylammonium chloride. Characterization of the bioadsorbent indicated that it was highly acid resistant and magnetically responsive. The bioadsorbent was then used to remove Cr(VI) from acidic aqueous solution. The results of batch experiments indicated that the optimal pH value was 2.5, and the adsorbent exhibited low pH dependence. The maximum adsorption capacity was 233.1 mg/g at pH 2.5 and 25 degrees C, and the equilibrium time was determined to be 40-120 min depending on the initial Cr(VI) concentration. The adsorbent could be effectively regenerated using a mixture of 0.3 mol/L NaOH and 0.3 mol/L NaCl with a desorption efficiency of 95.6%, indicating high reusability. In conclusion, the bioadsorbent shows potential for Cr(Vl) removal from acidic wastewater. (C) 2016 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Extraction and recovery of gold(I) with extremely low concentration in cyanide wastewater were conducted as an example aimed to develop a feasible method based upon the experimental kinetic data for calculating the required mass transfer height of a new bubbling organic liquid membrane extraction tower. The kinetic extraction equation based on curve fitting the experimental c(t) ∼ t data from single column extraction could be established to describe the quantitative relationship of the concentration change of gold(I) in flowing-out aqueous solution from the tower with the reaction time in the tower, so that the required tower height involved in the axial gas mixing effect could be calculated from the residence time of the aqueous solution passing through the tower to achieve a target equilibrating concentration. The influence of organic phase recycling on the calculation was discussed. Double column extraction experiments confirmed that the suggested calculation method obtained from single column extracti...

In this paper, gas-assisted magnetic separation (GAMS), a technique that combines magnetic separation with flotation, was investigated for the potential large-scale separation of proteins. The GAMS process includes adsorption of target proteins and magnetic separation to recover protein-loaded magnetic particles from the dilute biosuspension with the assistance of bubbles. Microsized ethylenediamine-functionalized poly(glycidyl methacrylate) superparamagnetic microspheres (MPMs) and bovine serum albumin (BSA) were used as a model system. The feasibility of GAMS for capturing BSA-loaded MPMs from an appropriate medium was shown. High recovery of BSA-loaded MPMs was obtained by simple adjustment of the initial solution pH without extra detergents and antifoaming agents. The GAMS conditions were consistent with the adsorption conditions, and no proteins were desorbed from the MPMs during this process. Under the optimal conditions, the separation rate and recovery percentage reached 410 mL/min and 98% in 0.61 min, respectively. Conformational changes of BSA during the GAMS process were investigated by fluorescence spectroscopy and circular dichroism spectrometry. (C) 2015 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Three triphenylamine-based polyaminal networks (TMPs) with monodispersed ultramicropore (about 0.54 nm) and abundant doped-nitrogen (up to 42.88 wt%) are successfully prepared through the direct polycondensation of triphenylamine-based aldehydes with melamine. The synergistic effects of uniform ultramicropore and rich CO2-philic polar sites endow TMPs with exceptional CO2 sorption capacity and selectivity over N2 and CH4. For example, the CO2 uptakes of TMPs can reach 15.7 wt% (273 K) and 11.2 wt% (298 K) at 1 bar. Especially, at a low pressure of 0.15 bar, TMP-3 simultaneously exhibits excellent CO2 sorption capacity of 4.16 wt% (∼1 mmol g−1, 298 K), high adsorption selectivities of CO2/N2 (61.9, 298 K) and CO2/CH4 (7.8, 298 K) and good cycle reusability, which are superior to most of the microporous polymers. In addition, the porous properties of TMPs could be effectively tuned by varying the amount of substitution formyl. This facile preparation method and excellent CO2 adsorption properties enable TMPs to possess promising application potential in CO2 capture and separation from low-concentration gas mixtures.

Adsorption, especially competitive adsorption of ions at the interfaces, governs a wealth of physicochemical processes. Understanding the mechanism behind these interfacial behaviors is crucial for developing novel strategies to intensify reactions or transfer processes. Herein, as an example, we found that in the case of liquid-liquid transport of V(V) and Cr(VI) ions, the competitive adsorption of V(V) and Cr(VI) ions against coexisting SO42- ions at the oil-water interface exhibits a significant impact on the selective separation behaviors of V(V) and Cr(VI) ions. The transport of Cr(VI) ions would be hindered by adding Na2SO4 into the aqueous solutions because of the competitive adsorption of SO42- ions at the interface being stronger than that of Cr(VI) ions, whereas the transport of V(V) ions would not be affected because of the stronger affinity of V(V) ions to the interfaces compared to that of SO42- ions. The present work provides new inspirations for developing efficient strategies to improve the separation efficiency of target ions with similar physic-chemical properties by regulating their adsorption behaviors at the interface. It is beneficial to get a deeper understanding into the microscopic nature of competitive adsorption behaviors of ions at interfaces from the interface-molecular level.

Two novel strongly basic magnetic adsorbents, quaternary ammonium-modified polystyrene and chitosan magnetic microspheres (Pst-MIMCl and CTS-GTMAC), were prepared using the in situ coprecipitation and emulsion cross-linking methods under mild conditions, with features of strong magnetic responsiveness and high quaternary ammonium group contents. The Cr(VI) adsorption/desorption properties and mechanisms of strongly and weakly basic magnetic adsorbents were compared through simulated wastewater. The strongly basic adsorbent exhibited low pH dependence, and the main adsorption mechanism was ion exchange. The weakly basic adsorbent exhibited high pH dependence, and the major adsorption mechanism was electrostatic attraction. Besides, the strongly basic adsorbent required higher desorption conditions than the weakly basic adsorbent owing to the difference of the desorption mechanisms. Furthermore, the removal selectivity of the strongly and weakly basic magnetic adsorbents was estimated by the chromium plating wastewater. The results demonstrated that the strongly basic magnetic adsorbents exhibited higher selectivity than the weakly basic magnetic adsorbents. In addition, the Pst-MIMCl was selected as the optimal magnetic adsorbent for Cr(VI) recovery from wastewater, with the advantages of strongly magnetic responsiveness, wide pH applicable range, high removal efficiency, high adsorption selectivity and good reusability.

In this study, a method combined low-field magnetic separation (MS) with flotation, named as gas-assisted magnetic separation (GAMS), was applied for the removal of cadmium from wastewater. With bubbles' assistance, the speed of magnetic separation can be greatly improved and the limitation of magnetic force on the capture distance can be overcome. Thus, GAMS is much more efficient and easily scalable than MS. In this work, ethanediamine-modified magnetic poly-(glycidyl methacrylate) microspheres (EMPs) were synthesized as the adsorbent for cadmium. And GAMS was used to separate the EMPs and Cd-loaded EMPs. The effects of pH, gas flow rate, concentration of Cd-loaded EMPs, loading volume, and ionic strength on GAMS were investigated. The results indicated that the EMPs and Cd-loaded EMPs could be rapidly and remotely removed from the solution with GAMS. And the separation time decreased with the increase of gas flow rate and NaCl concentration, but grew with the rise of pH value, loading volume, and concentration of the EMPs. This work showed the great potential of GAMS in the area of water treatment. (C) 2015 Elsevier B.V. All rights reserved.

In the protein separation, adsorption and desorption of target protein have been using different buffer condition. Different buffer will change the structure and activity of target protein in some cases. This work describes the use of different wavelength light for remote regulation of adsorption and desorption of target protein in the same buffer solutions. A dynamic system that captured and released protein in response to light is reported. Matrix gold nanoparticles and light-responsive affinity ligand comprising thrombin aptamer (APT15), polyethylene glycol linker, and azobenzene-modified complementary sequence were used. UV light induced a trans-cis isomerization of the azobenzene that destabilized the duplex of aptamer and azobenzene-modified complementary sequence, resulting in thrombin binding to aptamer sequence. Visible light irradiation resulted in DNA duplex rehybridization and thrombin released. Our work demonstrates that different light wavelengths effectively regulated the adsorption and desorption of thrombin in the same buffer, and this system also can capture and release prothrombin from plasma with different wavelength light. Furthermore, this method can be widely applied to a variety of different protein separation process. (C) 2015 Elsevier B.V. All rights reserved.

A novel adsorbent, polyethylenimine-functionalized poly(vinyl alcohol) (PVA-PEI) magnetic microspheres, was prepared by a process involving: (1) synthesis of magnetic poly(vinyl acetate) microspheres (PVAc) using modified suspension polymerization, (2) preparation of PVA magnetic microspheres by methanolysis of PVAc and (3) two-step reaction with epichlorohydrin and polyethylenimine to yield amino groups. Magnetic measurement illustrated that the PVA-PEI microspheres were superparamagnetic, with a high saturated magnetization of 36.7 emu/g. Once generated, the PVA-PEI microspheres were used as adsorbent to remove Cr(VI) from an aqueous solution. The results demonstrated that the optimized pH value was observed at 2.0. The adsorption rate was extremely fast and the equilibrium was reached within 8 min. The adsorption isotherms of the adsorbent were preferably fitted to the Langmuir model, with the maximum adsorption capacity of 88.4 mg/g at 25 degrees C. Thermodynamic parameters indicated the spontaneous and exothermic nature of adsorption. In addition, the Cr(VI) ions were successfully eluted by a 0.1 mol/L NaOH solution, with the desorption efficiency of over 99%, and the adsorbent exhibited a good reusability. These results implied that the PVA-PEI microspheres should be considered as a potential adsorbent to remove Cr(VI) from wastewater. (C) 2014 Elsevier B.V. All rights reserved.

Hydrothermal carbon spherules (HCSs) can be loaded with a variety of metal nanoparticles for various applications. In this work, three types of HCSs were prepared from saccharides (mono-, di- and poly-saccharides) by a modified hydrothermal method using glucose, sucrose and starch as sources. Au nanoparticles can be deposited onto the HCSs through a regular adsorption process. For comparison, the HCSs made from mono-saccharide glucose (HCSs-M) have a higher adsorption capacity for Au(III) from aqueous acidic chloride media. The adsorption behaviors for AuCl4- by HCSs-M were systematically investigated. HCSs-M shows a high selectivity for Au(III) towards Pd(II), Pt(VI), Rh(III) and some relevant base metals such as Fe(III), Co(II), Cu(II) and Ni(II). An extra reductant glycine can not only significantly improve the adsorption capacities and selectivity, but also accelerate the adsorption rate. The Langmuir isotherm model and the 2nd-order kinetics model can properly describe the adsorption behaviors of AuCl4-. The adsorption mechanism of Au(III) by HCSs has been confirmed by XPS, XRD, TG, FTIR, SEM and TEM techniques, which demonstrate that AuCl4- deposited onto the HCSs has been reduced to Au-0. On the basis of this phenomenon, a reductiondeposition coupled mechanism has been proposed. The current research illustrates the prospect for HCSs to be used as effective adsorbents for the selective adsorption separation of Au(III) from chloride media. It also demonstrates the possibility to integrate the selective recovery of gold from complex industrial waste streams and the fabrication of functional carbon materials through loading with gold nanoparticles.

Rapid and sensitive detection of thrombin has very important significance in clinical diagnosis. In this work, bare magnetic iron oxide nanoparticles (magnetic nanoparticles) without any modification were used as fluorescence quenchers. In the absence of thrombin, a fluorescent dye (CY3) labeled thrombin aptamer (named CY3-aptamer) was adsorbed on the surface of magnetic nanoparticles through interaction between a phosphate backbone of the CY3-aptamer and hydroxyl groups on the bare magnetic nanoparticles in binding solution, leading to fluorescence quenching. Once thrombin was introduced, the CY3-aptamer formed a G-quartet structure and combined with thrombin, which resulted in the CY3-aptamer being separated from the magnetic nanoparticles and restoration of fluorescence. This proposed assay took advantage of binding affinity between the CY3-aptamer and thrombin for specificity, and bare magnetic nanoparticles for fluorescence quenching. The fluorescence signal had a good linear relationship with thrombin concentration in the range of 1-60 nM, and the limit of detection for thrombin was estimated as low as 0.5 nM. Furthermore, this method could be applied for other target detection using the corresponding fluorescence labeled aptamer.

Polyethylenimine-grafted poly(glycidyl methacrylate) (PGMA-PEI) microspheres were prepared using the dispersion polymerization method and a two-step reaction with ethylenediamine (EDA) and polyethylenimine (PEI). The PGMA-PEI microspheres were then characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) and tested for their ability to remove hexavalent chromium (Cr(VI)) from an aqueous solution in batch tests. The results demonstrated that Cr(VI) adsorption depended significantly on pH. The optimized pH value for the Cr(VI) adsorption was 2.0. The adsorption isotherms of PGMA-PEI microspheres with Cr(VI) fit the Langmuir model. The maximum adsorption capacities were 460.83, 485.44 and 505.05 mg g(-1) for PGMA-PEI600, PGMA-PEI1800 and PGMA-PEI10,(172) microspheres, respectively. The adsorption reached equilibrium within 10min and the experimental data fit the pseudo-second-order model. The obtained thermodynamic parameters (Delta G(0), Delta H-0 and Delta S-0) showed that the adsorption of Cr(VI) was an endothermic and spontaneous process. Competition from coexisting ions of K+, Na+, Ca2+, Cu2+, Cl-, NO3-, H2PO4-, and HPO42- was insignificant except SO42-. The regeneration study revealed that PGMA-PEI microspheres could be repeatedly used with no significant loss of adsorption efficiency. (C) 2014 Elsevier B.V. All rights reserved.

The bifunctional coating with antithrombotic and antimicrobial activity was developed using nattokinase (NK) and nanosilver (AgNPs). Firstly, the adsorption interactions between NK and AgNPs were confirmed, and the composite particles of NK-AgNPs were prepared by adsorption of NK with AgNPs. At 5 FU/mL of NK concentration, the saturation adsorption capacity reached 24.35 FU/mg AgNPs with a high activity recovery of 97%, and adsorption by AgNPs also enhanced the heat stability and anticoagulant effect of NK. Based on the electrostatic force driven layer-by-layer self-assembly, the NK-AgNPs were further assembled with polyethylenimine (PEI) to form coating. UV-vis analysis showed that the self-assembly process was regular, and atom force microscopy analysis indicated that NK-AgNPs were uniformly embedded into the coating. The NK-AgNPs-PEI composite coating showed potent antithrombotic activity and antibacterial activity. This study developed a novel strategy to construct the bifunctional coating with antithrombotic and antimicrobial properties, and the coating material showed promising potential to be applied in the medical device. (C) 2014 Elsevier B.V. All rights reserved.

A novel amino-functionalized magnetic cellulose composite was prepared by a process involving: (1) synthesis of magnetic silica nanoparticles using the co-precipitation method followed by the hydrolysis of sodium silicate, (2) coating with cellulose through the regeneration of cellulose dissolved in 7 wt% NaOH/12 wt% urea aqueous solvent, (3) grafting of glycidyl methacrylate using cerium initiated polymerization and (4) ring-opening reaction of epoxy groups with ethylenediamine to yield amino groups. Once generated, the resulting composite was tested for its ability to remove Cr(VI) from an aqueous solution in batch experiments. The results demonstrated that Cr(VI) adsorption was highly pH dependent. The optimized pH value was 2.0. The adsorption isotherms of the adsorbent fit the Langmuir model, with the maximum adsorption capacity of 171.5 mg/g at 25 degrees C. The adsorption rate was considerably fast, and the adsorption reached equilibrium within 10 min. The obtained thermodynamic parameters showed that the adsorption of Cr(VI) onto the adsorbent was an exothermic and spontaneous process. In addition, the Cr(VI) ions could be effectively desorbed using a 0.1 mol/L NaOH solution and the adsorbent exhibited a good reusability. The composite material should be a promising adsorbent for Cr(VI) removal, with the advantages of high adsorption capacity, rapid adsorption rate and convenient recovery under magnetic field. (C) 2013 Elsevier B.V. All rights reserved.

Micron-sized polyethylenimine-functionalized poly(glycidyl methacrylate) superparamagnetic microspheres (m-PGMA-PEI) were prepared by a process involving: (1) synthesis of PGMA microspheres using the dispersion polymerization method; (2) ring-opening reaction of epoxy groups on PGMA microspheres with ethylenediamine (EDA) to yield amino groups; (3) in situ coprecipitation of Fe3O4 nanoparticles into the pores of microspheres; (4) Michael addition of amino groups with methyl acrylate (MA) to yield ester groups; and (5) amidation of the terminal ester groups with polyethylenimine (PEI). Once generated, the resulting m-PGMA-PEI microspheres were tested for their ability to remove Cr(VI) from an aqueous solution in batch experiments. The results demonstrated that Cr(VI) adsorption was significantly pH dependent. The optimized pH value was 2.0. The adsorption isotherm of the adsorbent fit the Langmuir model, with the maximum adsorption capacity of 492.61 mg/g. The Cr(VI) adsorption rate was rapid, and the adsorption reached equilibrium within 15 min. The thermodynamic parameters (Delta G(0), Delta H-0, Delta S-0) demonstrated that the adsorption process was endothermic and spontaneous in nature. The presence of the coexisting anions involving Cl-, NO3-, H2PO4- and HPO42- had no remarkable influence on Cr(VI) adsorption except SO42-. The regeneration study proved that the m-PGMA-PEI microspheres could be repeatedly utilized with no significant loss of adsorption efficiency. (C) 2013 Elsevier B.V. All rights reserved.

In this study, gas-assisted superparamagnetic extraction (GASE) with potential large-scale application was proposed for selective separation of multicomponent proteins. Magnetic poly(glycidyl metha...

A novel separation technology at room temperature for traditional Chinese medicines was proposed in this work by adding magnetic molecularly imprinted polymers (M-MIPs) into extraction solution and sample matrix. The M-MIPs show a more adsorption capacities and higher selectivity for the template than magnetic non-molecularly imprinted polymers (M-NMIPs) without the specific binding sites. Addition of the M-MIPs to the extraction solution provides one-step extraction and cleanup, the improvement of extraction rate and extraction yields of three tanshinones (from 0.40, 0.23 and 0.12 mg g(-1) in 240 min by solvent extraction to 0.52, 0.27 and 0.19 mg g(-1) in 5 min by 200 mg sorbent), and reusability of extraction solvent. The extraction yields of three tanshinones by this technology at room temperature in 5 min were higher than those by ultrasonic extraction in 30 min, by heat reflux extraction in 45 min and by solvent extraction at room temperature in 4 h. The integrated technology has the advantages of one-step extraction and cleanup, high extraction efficiency, low solvent consumption and room temperature. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.

BACKGROUND Adsorption is believed to be an effective and green technology for the removal and recovery of rare earths (III) from dilute solution. RESULTS A novel hybrid gel, abbreviated as ALG-PGA, has been prepared through crosslinking calcium alginate (ALG) and γ-poly glutamic acid (PGA), and its adsorption behavior towards whole rare earths (III) has been examined. Taking Nd(III) as a representative element, the adsorption capacity, kinetics, reusability, selectivity and mechanism have been investigated. Cation exchange is proposed as a possible adsorption mechanism. Doping PGA molecules into calcium alginate beads can significantly enhance the adsorption capacity and the selectivity of rare earths from non-rare earths. The maximum adsorption capacity obtained for Nd(III) was 1.65 mmol g−1. Reutilization of ALG-PGA gel was confirmed for up to eight consecutive sorption–desorption cycles with no damage to the gel. CONCLUSION The prepared biosorbent, ALG-PGA, was biocompatible and cost effective with a good adsorption ability for Nd(III), and provides a new approach to the recovery of rare earths (III) from rare earths-containing wastewater. © 2013 Society of Chemical Industry

In this study, gas-assisted superparamagnetic extraction (GASE), a novel technology that combined superparamagnetic extraction technology with flotation technology, was proposed for potential large-scale separation of proteins. GASE includes adsorption for trapping proteins, and flotation and high gradient magnetic separator (HGMS) for recovering proteins-loaded magnetic particles from the dilute biosuspension. Citrate-modified superparamagnetic nanoparticles (CMNs) and bovine serum albumin (BSA) were used as a model. The feasibility of flotation for these particles enrichment was demonstrated. The results indicated that the BSA-loaded CMNs could be well concentrated in either foaming flotation or nonfoaming flotation by simple adjustment of the initial solution pH, without extra detergents and operations. The flotation conditions were consistent with the adsorption ones, and no proteins were desorbed from CMNs in the GASE process. Under the optimal conditions, the enrichment ratio and recovery percentage reached 31 and 99% in 1.5 min, respectively.

Novel alginate hybrid beads were prepared by doping with silica (abbreviated as ALG/SiO2), and their adsorption behavior toward rare earths(III) had been investigated. For the whole lanthanides, it exhibits a distinct “tetrad effect” with increasing atomic number. Taking Nd as an example, the effects of the pH, adsorption kinetics, isotherms, and regeneration of adsorbents had been studied systematically. Doped SiO2 can enhance the mechanical strength of the beads, and the hybrid adsorbents show no observable swelling during the adsorption process. It is interesting to note that NdIII adsorption can be improved about 0.1 mmol/g after the first cycle and shows no apparent decline until the 12th cycle. Finally, it can be concluded that ALG/SiO2 is superior to the other hybrid alginate adsorbents for the adsorption of rare earths.

Pure calcium alginate (CA), CA composite beads containing 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (CA-P507), core–shell structural calcium silicate-alginate (CS-A) and CS-A containing P507 (CS-A-P507) have been synthesized and their adsorption properties towards rare earths (III) have been investigated. The order of their adsorption capacities is as follows: CA-P507 > CS-A-P507 > CA > CS-A. The effect of ionic radii of rare earths on the adsorption distribution ratio has also been examined. Adsorption mechanism could mainly be proposed to be cation exchange. The pseudo-second-order kinetics model and Langmuir isotherm equation are used to describe the adsorption process very well. The adsorption capacity, selectivity and reusability have been improved owing to the introduction of P507 ionophore and CaSiO3 crust, respectively. As far as adsorption properties are concerned, CS-A-P507 is generally superior to the other three kinds of beads and shows its potential industrial application for the separation and recovery of rare earths. Schematic illustration for in situ preparation of core–shell structural calcium silicate-alginate containing 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (CS-A-P507). Core: Calcium alginate (CA); Shell: Calcium silicate (CS).

BACKGROUND: The recovery of neodymium from dilute solutions has become important because of its wide application in industry. This work reports the preparation of novel carboxymethyl chitosan adsorbents entrapped by silica (SiO2/CMCH) and their application for adsorption of neodymium(III) ions from aqueous solution. RESULTS: The effect of the CMCH content, equilibrium pH (pHe), contact time, initial concentrations of Nd(III) and temperature on the adsorption was investigated. The amount of Nd(III) adsorption increases with increasing pHe, which can be explained by the pH-titration curve of CMCH. Temperature has a positive effect on Nd(III) adsorption, and the amount adsorbed is 53.04 mg g-1 dry adsorbent or 434.75 mg g-1 CMCH at 328 K. Adsorption kinetics and isotherm can be described by the pseudo-second-order model and Langmuir equation. Both complexation and ion exchange mechanisms are believed to play an important role in Nd(III) adsorption, and possible coordination between CMCH and Nd(III) is speculated. Complete desorption can be reached when the concentration of HCl is more than 0.1 mol L-1. CONCLUSION: A novel method was developed to prepare SiO2/CMCH adsorbents through a one-step sol-gel strategy. The prepared adsorbents were biocompatible and non-toxic with a good adsorption ability for Nd(III), and could be used for adsorptive recovery of Nd(III) from aqueous solutions. (c) 2012 Society of Chemical Industry

With the aim of improving the stability of penicillin G acylase (PGA), functional ionic liquids (ILs) were used to modify the surface chemistry of the supports on which they were physically adsorbed. Four kinds of ILs—specifically, 1-methyl-3-(triethoxysilylpropyl)-imidazolium salts, with Cl–, BF4–, PF6–, and Tf2N– as the anions (IL-Cl–, BF4–, PF6–, and Tf2N–, respectively)—were used to tune the hydrophilic or hydrophobic properties of the ILs. The synthesized ILs were first immobilized on magnetic silica nanoparticles (Fe3O4/SiO2), and the composite material (Fe3O4/SiO2–IL) was then applied to immobilize PGA via physical adsorption. The amount of protein loading, the specific activity, the immobilization yield, and the stability of immobilized PGA were investigated to evaluate the effects of the ILs on the PGA immobilization. The results showed that PGA immobilized on Fe3O4/SiO2–ILs was more stable than that immobilized on Fe3O4/SiO2 with no IL modification. Among the four kinds of ILs tested, the hydrop...

A novel polyglycidylmethacrylate (PGMA) microspheres with high adsorption capacity of Cr(VI) was prepared by cerium(IV) initiated graft polymerization of tentacle-type polymer chains with amino group on polymer microspheres with hydroxyl groups. The micron-sized PGMA microspheres were prepared by a dispersion polymerization method and subsequently modified by ring-opening reaction to introduce functional hydroxyl groups. The polymer microspheres were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results indicated that the polymer microspheres had an average diameter of 5 mu m with uniform size distribution. The free amino group content was determined to be 5.13 mmol.g(-1) for g-PGMA-NH2 microspheres by potentiometric and conductometric titration methods. The Cr(VI) adsorption results indicated that the graft polymerization of tentacle-type polymer chains on the polymer microspheres could produce adsorbents with high adsorption capacity (500 mg.g(-1)). The polymer microsphcres with grafted tentacle polymer chains have potential application in large-scale removal of Cr(VI) in aqueous solution.

Mesoporous aluminosilicates (MAS) showed advantages over zeolites and mesoporous molecular sieves in adsorption desulfurization of diesel fuels. However, the adsorptive capacity still has great space to improve. The equilibrium adsorption data were modeled by Langmuir and Freundlich isotherms. Langmuir model can well describe the adsorption on ion-exchanged MAS. Infer from the hypothesis conditions of Langmuir model, the temperature and the active sites are two key factors to determine the adsorptive capacity. Adsorption experiments were carried out with both model oils and diesel fuels on fixed-bed. The results showed that pi-complexation adsorbents were more efficient to remove sulfur compounds at higher temperature and that the saturated adsorption capacity had a linear relationship with the silver ions loaded on the adsorbents. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

Fe3O4 hollow nanospheres were prepared via a simple one-pot template-free hydrothermal method and were fully characterized. These magnetic spheres have been investigated for application as an adsorbant for the removal of dye contaminants from water. Because of the high specific surface area, nano-scale particle size, and hollow porous material, Fe3O4 hollow spheres showed favorable adsorption behavior for Neutral red. Factors affecting adsorption, such as, initial dye concentration, pH and contact time were evaluated. Langmuir and the Freundlich adsorption isotherms were selected to explicate the interaction of the dye and magnetic adsorbant. The characteristic parameters for each isotherm have been determined. The overall trend followed an increase of the sorption capacity with increasing dye concentration with a maximum of 90% dye removal. The monolayer adsorption capacity of magnetic hollow spheres (0.05 g) for NR in the concentration range studied, as calculated from the Langmuir isotherm model at 25 degrees C and pH 6, was found to be 105 mg g(-1). Adsorption kinetic followed pseudo-second-order reaction kinetics. Thermodynamic study showed that the adsorption processes are spontaneous and endothermic. The combination of the superior adsorption and the magnetic properties of Fe3O4 nanospheres can be useful as a powerful separation tool to deal with environmental pollution. (C) 2010 Elsevier B.V. All rights reserved.

Biodesulfurization activity can be enhanced by assembling nano-γ-Al2O3 particles on the magnetic immobilized Rhodococcus erythropolis LSSE8-1-vgb. The cells can be collected and reused conveniently by an external magnetic field. Firstly, cells were magnetic immobilized by coating with Fe3O4 nano-particles. The optimal ratio of cells to magnetic Fe3O4 nano-particles was determined to be 50:1 (g/g). Then nano-γ-Al2O3 adsorbents were assembled onto the cells to enhance the desulfurization activity. The nano-γ-Al2O3 adsorbent had the largest pore volume as well as specific surface area, and the strongest electrostatics interaction with microbial cell, and cells assembled with this nano-adsorbent performed the highest desulfurization activity. The activity of magnetic immobilized cells assembled with adsorbents was tested in desulfurization of model oil. The desulfurization rate was raised by nearly 20% when the amount ratio of magnetic particles to adsorbents was 1:5 (g/g). These cells can be reused. The activity decreased less than 10% through out three desulfurization-activation-reuse recycles.

Aiming for the deep desulfurization of diesel, a novel adsorption–bioregeneration system was constructed by combining adsorption and biodesulfurization processes. The sequence of adsorption capacity of DBT (dibenzothiophene) is AC (activated carbon) > NiY > AgY > alumina > 13X. The sequence of selectivity of DBT toward naphthalene is NiY > AgY > alumina ≈ 13X > AC. For hydrotreated diesel, MAS (mesoporous aluminosilicates) showed high adsorption capacity, while MCM-41 and NaY showed low adsorption capacity. The bioregeneration process of these adsorbents was also carried out with P. delafieldii R-8 cells. Adding P. delafieldii R-8 cells can improve DBT desorption from adsorbents. The desorption of DBT from adsorbents by bioregeneration follows the sequence: 13X > alumina > AgY > NiY > AC. Ag-MAS can be completely regenerated in in situ adsorption–bioregeneration system.

Mesoporous aluminosilicates (MAS) bearing microporous zeolite units and mesoporous structures were synthesized by the hydrothermal method. Adsorptive desulfurization ability of model oil and hydrotreated diesel was studied. The effects of template concentration, crystalization time and calcination time were investigated. The desulfurization ability of adsorbents was improved by transitional metal ion-exchanging. The adsorptive desulfurization of diesel was carried out on a fixed-bed system. The results show that the adsorptive capacity is MAS>MCM-41>NaY. The improvement of desulfurization ability of MAS by Cu+ is more significant than that of Ag+.

A pH-sensitive magnetic ion exchanger was synthesized by binding carboxymethylated chitosan (CMCH) covalently on the surface of Fe3O4 nanoparticles. The diameter for magnetic particles observed at 25 °C was 15 nm. The ion exchanger was superparamagnetic with a saturation magnetization of 64.21 emu/g and an isoelectric point (pI) of 5.75. In a model system, the laccase adsorption capacity reached equilibrium within 15 min (pH 5). The adsorption process followed the Langmuir adsorption isotherm, and the maximum equilibrium adsorption capacity was calculated to be 198.81 mg/g. The laccase can be completely desorbed at pH 8. About 97% laccase can be effectively desorbed from the surface of particles within 15 min. Moreover, the specific activity of the laccase remained constant during the adsorption and desorption process. Finally, the pH-sensitive magnetic ion exchanger was used for separation of laccase directly from culture supernatant, and nearly pure laccase was isolated by a single step with an activity...

With the aim of improving the microstructures and properties of TiO2 pillared montmorillonite (MMT), a long-chain polymer (polyoxypropylenediamine, PPO-D 2000) was used as a template to synthesize composite pillared MMT. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometer, Fourier Raman (FT-Raman) spectrophotometer, thermo-gravimeter/differential thermogravimeter (TG/DSC), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) methods. The results show that as compared to low-molecular weight surfactant, this polymer significantly expanded the interlayer spacing and thus more TiO2 could be intercalated into MMT. The specific surface area of polymer/TiO2 pillared MMT was increased by 13% with comparison to TiO2 pillared MMT and rose to 241.52 m2/g. Both the pore diameter and volume are doubled, and thus the pore structure is optimized markedly. The investigation on the photo-catalytic degradation of methyl orange in aqueous solution show that the modulation of polymer molecules raise the adsorption content of montmorillonite and improve the photo-catalytic activity. Therefore, this process provides a novel alternative to design and prepare the advanced eco-catalytic materials with high adsorption capacity and photo-catalytic activity.

Superparamagnetic Fe3O4 nanoparticles are prepared with coprecipitation method followed by modification with ammonia oleate. Magnetic P. delafieldii R-8 cells can be prepared by mixing the cells with magnetite nanoparticles. Saturated magnetization of magnetic cells is about 7.41 emu/g. The pH value of magnetic suspension has significant influence on the desulfurization activity of magnetic cells. Desulfurization of the magnetic cells prepared with pH 7.0 magnetic suspension has similar activity with free cells. When the magnetic cells were used in the bioregeneration of desulfurization adsorbents Ag-Y, the concentration of dibenzothiophene (DBT) and 2-hydroxybiphenyl (2-HBP) with free cells is a little higher that that with magnetic cells. Adsorption capacity of the regenerated adsorbent is 93% that of the fresh one after being desorbed with magnetic P. delafieldii R-8, dried at 100 degrees C for 24 h and calcined in the air at 500 degrees C for 4 h. (c) 2007 Elsevier B.V. All rights reserved.

In-situ coupling of adsorptive desulfurization and biodesulfurization is a new desulfurization technology for fossil oil. It has the merits of high-selectivity of biodesulfurization and high-rate of adsorptive desulfurization. It is carried out by assembling nano-adsorbents onto surfaces of microbial cells. In this work, In-situ coupling desulfurization technology of widely used desulfurization adsorbents of gamma-Al2O3, Na-Y molecular sieves, and active carbon with Pseudomonas delafieldii R-8 were studied. Results show that Na-Y molecular sieves restrain the activity of R-8 cells and active carbon cannot desorb the substrate dibenzothiophene (DBT). Thus, they are not applicable to in-situ coupling desulfurization technology. Gamma-Al2O3 can adsorb DBT from oil phase quickly, and then desorb it and transfer it to R-8 cells for biodegradation, thus increasing desulfurization rate. It is also found that nano-sized gamma-Al2O3 increases desulfurization rate more than regular-sized gamma-Al2O3. Therefore, nano-gamma-Al2O3 is regarded as the better adsorbent for this in-situ coupling desulfurization technology.

Adsorption properties of different adsorbents such as reduced NiY, AgY, alumina, 13X, and activated carbon were studied with dibenzothiophene (DBT) and naphthalene as model compounds. The desorption of DBT was carried on thermo gravimetric-differential thermal analysis (TG-DTA). The interaction of DBT with different adsorbents follows the sequence: activated carbon > reduced NiY > AgY > activated alumina > 13X. The bio-regeneration of these adsorbents was studied with P. delafieldii R-8 as desulfurization strains. Adding P. delafieldii R-8 cells can improve DBT desorption from adsorbent AgY. The desorption of DBT from adsorbents by bioregeneration of adsorbents follows the sequence: 13X > alumina > AgY > reduced NiY > activated carbon. The presence of naphthalene can decrease the desorption of sulfur compounds. The adsorption capacity of AgY decreases for the first time recycling and then changes little. The decrease of the adsorption capacity is due to the loss of Ag+ ions.

An attempt has been made to extract glycyrrhizic acid (GA) from licorice root by surfactant mediated cloud point extraction (CPE) using non-ionic surfactant (Triton X-100). Almost all of the GA molecules were concentrated in the surfactant-rich phase (also called coacervate phase) after phase separation. The pH is the most critical factor regulating the distribution of GA in the micelle which related to the ionization form. The other effects of the concentration of GA and the surfactant, the temperature, and the salt concentration on the extraction efficiency of GA in the coacervate phase and aqueous phase have been studied. The mechanism of CPE of GA was explored with transmitting electron microscopy. It was deduced that aggregate GA molecules were adsorbed on micelles' outer poler mantle and inner cross-linked micelles at high GA concentrations in coacervate phase.

Magnetic Cu2+-chelated particles, prepared by cerium initiated graft polymerization of tentacle-type polymer chains with iminodiacetic acid (IDA) as chelating ligand, were employed for glucoamylase immobilization. The particles had an obvious high adsorption capacity of glucoamylase with a great activity recovery of 84.0% after immobilization. The immobilized glucoamylase exhibited improved stability in reaction conditions over a wide pH region (pH 3.5-6.0) and a broad temperature range (45-75 degrees C). The value of the Michaelis constant (K-m) of the immobilized glucoamylase (1.77 mg/ml) was higher than that of the free one (1.07 mg/ml), whereas the maximum velocity (V-max) was lower for the adsorbed glucoamylase. Storage stability and temperature endurance of the immobilized glucoamylase were found to increase greatly, and the immobilized glucoamylase retained 75.7% of its initial activity after 30 successive batch reactions. The magnetic Cu2+-chelated particles also exhibited excellent reusability, indicating the advantage of the magnetic metal-chelated particles in biocatalytic applications. (c) 2007 Elsevier B.V. All rights reserved.

A micron-sized monodisperse superparamagnetic polyglycidyl methacrylate (PGMA) particles coupled with heparin (PGMA-heparin) was synthesized by the polymerization, and then was evaluated as a method for purifying lactoferrin (LF) from bovine whey. The content of heparin groups at the surface of PGMA particles was 0.92 mg/g. Magnetic PGMA-heparin particles were highly effective in recovering LF directly from acid whey by a single step, whose purity was higher than that of commercial standard proteins, using NaCl solutions as eluent. The maximum LF binding capacity was 164 mg/g. The competitive adsorption tests verified that the magnetic approach offered a fast process and potential at a large scale. The practical use of magnetic PGMA-heparin particles for production of high purified LF from whey is a realistic prospect. (c) 2007 Elsevier B.V. All rights reserved.