Phase separation dynamic processes in three-liquid-phase system (TLPS), composed of organic oil (P507 extractant), water-soluble polymer (PEG2000), ammonium sulfate, and water, with the change of mass composition of phase-forming components were investigated. It was found that dynamic separation of three-layered liquid phases in TLPS is in fact a course of dispersive polymer and organic oil droplets aggregated and separated out respectively from continuous salt aqueous bottom phase. Formation rate of organic oil phase was controlled mainly by coalescence rate of dispersed oil droplets; however, the rate-determining process for formation of polymer middle phase may change from drop sedimentation to coalescence or co-determined by both, when mass composition of the TLPS changed along different operation lines. With the formation of organic oil phase, it becomes another continuous phase, from which dispersive polymer droplets separated out and aggregated into a bulk phase gradually. Phase separation equilibrating time of TLPS, tE, depends on formation rate of the polymer middle phase and its equilibrium volume. A quantitative correlation of phase separation rate of TLPS with its physicochemical properties was given. The present work promotes further understanding about influence from change in mass composition of phase-forming components in TLPS on three-phase separation dynamic processes.

A novel redox responsive controlled release system based on the host–guest interaction between ferrocene modified mesoporous silica nanoparticles (MSN-Fc) and β-cyclodextrin modified gold nanoparticles (Au@CD) was developed. FITC was used as the release molecule and it was loaded into the pores of MSN-Fc. With the addition of oxidant (H2O2), oxidized ferrocene leaves the hydrophobic cavity of β-CD, resulting in cargo controlled release. Due to the structural properties of the modified MSN, the continuously slow release behavior showed the prospect to be a sustained drug delivery system. This novel redox responsive system possessed stimuli-responsive controlled release and sustained release properties, and therefore has potential applications in sustained and targeted drug delivery.

Penicillin G is a widely used antibiotic, but the traditional volatile organic solvent extraction causes serious environmental problems. In this work, a hydrophobic ionic liquid ([Bmim]PF6) was developed as a new extraction agent for recovery of penicillin G from aqueous solutions. The extraction efficiency and the partition coefficient of penicillin G were used as the indexes to evaluate the IL extraction ability. Key factors affecting the effectiveness of recovery, such as the pH of the aqueous solution, the initial concentration of penicillin G, and the IL-to-aqueous solution volume ratio, were investigated to determine the optimal conditions. The results showed that the pH of the aqueous phase strongly influenced the success of the extraction. The optimal pH value, phase ratio, and penicillin concentration were 1.5–2.0, 1.5/1 to 2.0/1, and 3.00–5.00 × 104 units/mL, respectively, whereby the partition coefficient and extraction efficiency were more than 30 and 91%, respectively. The extraction mechanism was explored by analyzing the chemical bonds using spectrographic analysis. Preliminary results indicated that penicillin G can be effectively extracted from fermentation broth by [Bmim]PF6 with extraction efficiencies of >87%. In addition, a higher selectivity and a much lower extent of emulsification were achieved by [Bmim]PF6 compared to those of butyl acetate. It demonstrates that the IL-based extraction strategy developed in this work is promising and effective, and as a result, the development of an IL-based extraction process for the recovery of penicillin G is straightforwardly envisaged.Keywords: Ionic liquids; Liquid−liquid extraction; Mechanism; Partition coefficient; Penicillin G;

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.

•Chemically modified magnetic chitosan microspheres were prepared and used for Cr(VI) removal.•Its maximum adsorption capacity was 233.1 mg/g at pH 2.5 and 25 °C.•The adsorbent exhibited strong acid resistance and a magnetic responsive nature.•The adsorbent with 95.6% desorption efficiency had a good reusability.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 °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(VI) removal from acidic wastewater.

•Regulation of adsorption/desorption of protein with different temperature.•Using temperature can affect aggregation and dispersion of gold nanoparticles.•Aptamer provides high affinity and selectivity to corresponding target.•This method could be applied for other targets that have corresponding aptamer.In this paper, we described a temperature responsive nano-system that can regulate activity of enzyme with different temperature. Temperature responsive polymer poly(N-isopropylacrylamide) (PNIPAAm), with low critical solution temperature of 32 °C, was synthesized with thiol modification. PNIPAAm and thrombin aptamer were co-functionalized on the surface of gold nanoparticles for effective regulation of thrombin activity with different temperature. On the one hand, we studied the thermal responsive properties of this inhibitor via UV–visible spectroscopy. On the other hand, we investigated the regulation of thrombin activity by this platform with different temperature. The PNIPAAm chains could extend and shrink with different temperature, which suggested that PNIPAAm on the surface of gold nanoparticles could regulate interaction between thrombin and aptamer according to temperature changing. At 25 °C, PNIPAAm was hydrophilic extended state, which blocked the interaction between thrombin and aptamer on the surface of gold nanoparticles, therefore thrombin activity had no change. On the contrary, at 37 °C, PNIPAAm transformed from hydrophilic extended state to hydrophobic shrank state, allowing the aptamer to capture thrombin, inhibiting the activity of thrombin. More interestingly, this regulation was reverse to normal condition, where 37 °C was always the optimum reaction temperature for most of human enzymes. This system we prepared was opposite, which was capable of inhibiting the thrombin activity at 37 °C. Furthermore, this was the first report of regulation of thrombin activity using this temperature responsive platform.

We demonstrate that a series of high-performance cathode materials, sodium vanadium polyanionic compounds, Na3(VO1−xPO4)2F1+2x (x = 0, 0.5 and 1), can be synthesized by a phase-transfer assisted solvo-thermal strategy at a rather low temperature (80–140 °C) in one simple step, exhibiting a high Na storage capacity of ca. 120 mA h g−1 and excellent cycling performance. This study makes a significant step to extend this strategy to the synthesis of functional materials from simple binary to complex multicomponent compounds.

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.

Single crystals of three polymorphous compounds were synthesized started from two building blocks, [Fe(CN)6]3− and [Co(LN3O2)]2+ (L is a Schiff-base macrocyclic ligand derived from the condensation of 2,6-diacetylpyridine with 3,6-dioxaoctane-1,8-diamine) using a crystallization condition control. All three compounds consist of electroneutral skeletons made up of Fe6Co6 twelve-metal ring units, which is the smallest enclosed circle in their structures: 1 is comprised of 1D nanometer-diameter tubes possessing nanometer-sized tunnels (0.58 nm × 0.74 nm); 2 and 3 are based on piled-up 2D lamellar layers in the (6, 3) and (4, 4) networks, respectively. Magnetic studies indicate ferromagnetic interactions between cyanide-bridged cobalt(II) and iron(III) in each compound.

•Regulation of adsorption/desorption of protein with different wavelength light.•Different wavelength light cannot affect structure and activity of target protein.•Aptamer provides high affinity and selectivity to corresponding target.•This method could be applied for other targets that have corresponding aptamer.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.

In the present work, three-liquid-phase extraction and separation of rare earths and Fe, Al, and Si by a novel mixer–settler–mixer three-chamber integrated extractor was investigated. Various three-liquid-phase systems (TLPSs) involving different organic extractants were employed to conduct continuous three-liquid-phase separation of rare earths and Fe, Al, and Si. In the TLPS of PC-88A/PEG 2000/(NH4)2SO4–H2O, light, middle, and heavy rare-earth ions had different distribution behaviors selectively into the organic top phase and salt-rich bottom phase, while most of Fe, Al, and Si were enriched into the poly(ethylene glycol) (PEG)-rich middle phase. Influences from aqueous pH values, agitation speeds, and flow ratios on three-liquid-phase partition behaviors of rare earths and Fe, Al, Si were evaluated. Experimental results indicated that an increase of the aqueous pH value facilitated the extraction of rare earths into the organic top phase and enrichment of Fe, Al, and Si into the PEG-rich middle phase. An increase of the agitation speed in three-phase mixer resulted in a change in the disappearance time of the dispersion band in a three-phase settler. The agitation speeds in a two-phase mixer and flow ratios of the organic phase to an aqueous biphasic mixture resulted in a change in the phase volumes of three-layered liquid flows in a three-phase settler so as to affect the partition behaviors of rare earths and Fe, Al, and Si. On the basis of analysis of the phase-forming behaviors of TLPSs and partition behaviors of rare earths and Fe, Al, and Si, the novel mixer–settler–mixer extractor is recommended for future application of continuous and countercurrent TLPE processes.

•A three-liquid-phase extraction approach for removal of Al, Fe, Si from rare earths.•Al, Fe and Si enriched in PEG middle phase and rare earths in bottom phase of TLPS.•Rare earths concentrated in bottom aqueous phase can be group separation by TLPS.•A new strategy for group separation of multiple target metals by TLPS.A new strategy was suggested to remove Fe, Al and Si impurities from rare-earth leach solution by controlling partitioning and selective enrichment of those impurities and rare earths in three-liquid-phase systems. Experimental results indicated that aqueous pH value and addition of water-soluble complexing agents or their mixtures into initial aqueous solution have significant influence on three-liquid-phase partitioning of Fe, Al, Si and rare earths. When only 1,10-phenanthroline was added, Fe and Si can be “filtered” into PEG-rich middle phase of three-liquid-phase system (Cyanex 272/PEG 2000/(NH4)2SO4–H2O) without affecting separation of heavy and light rare-earth ions in top organic and bottom salt-rich phase, respectively. Al remained in bottom phase. However, addition of EDTA and 1,10-phenanthroline promoted enrichment of Fe, Al and Si into PEG-rich middle phase, and almost all of rare earths were concentrated in salt-rich bottom phase. Those rare earths in salt-rich phase after removal of impurities can be further separated by another three-liquid-phase system of Cyanex 272/PEG 600/(NH4)2SO4–H2O. Heavy, middle and light rare earths, Yb, Eu and La, can be selectively enriched into different liquid phases. Therefore, separation of non-rare-earth impurities from rare earths, and then between light, middle and heavy rare earths can be achieved by two stages of three-liquid-phase partitioning. The present work highlights three-liquid-phase system can be a potential separation media for removal of Fe, Al, Si from complex rare-earth leach solution and group separation of different target metals into different liquid phases.Graphical abstractThree-liquid-phase systems for removal of Al, Fe, Si and separation from rare earths (HREs-heavy rare earths, MREs-middle rare earths, LREs-light rare earths).

Many papers have reported that salt ions can exert a great influence on the self-assembly behavior of PEO-PPO copolymers in the aqueous solution. Whereas the mechanism through which salt ions influence the self-assembly behavior of PEO-PPO copolymers is unclear and the dispute is mainly focused on whether the salt ions have a direct interaction with PEO-PPO copolymers. In this paper, the interaction of sodium and potassium ions with PEO-PPO copolymer was investigated by using FTIR, Raman and 23Na NMR spectroscopy. Experimental results reveal that direct interactions between salt cations and PEO-PPO macromolecular chains indeed occur in appropriate conditions. The present work highlights the role of cations in the self-assembly process of PEO-PPO copolymer.

The present study prepared a size-controllable, uniform, and surfactant-free emulsification to investigate the ζ potential of the solvent effect. The results showed that the ratio of electrophoretic mobility changed with droplet diameter, and the correct factor of the ζ potential was determined. The effect of functional groups on the ζ potential was further studied in the presence of an organic hydrophilic solvent. The study characterized the effects of pH, ionic strength, and ionic type on the ζ potential and indicated that the solvents were able to modulate the local electrochemical environment, thus leading to the redistribution of interface charges.

•Hydrolytic kinetic of piceid was investigated under various conditions.•Solvent species have significant effect on the rate constant.•Solvent effect was explained by LESR and its mode of action was proposed.•The rate constant was increased with elevated acidity and temperature.•Hydrolytic kinetics could be effectively described by first-order reaction model.In this work, the hydrolytic kinetic of piceid was systematically investigated not only in different solvents, but under different conditions of pH and temperature as well. Results showed that the solvents have a significant effect on rate constant. In general, piceid was more readily hydrolyzed in pure organic solvents in which the rate constant was over 10 times of that in conventional aqueous methanol. The solvent effect was analyzed using LSER and it demonstrated that hydrolysis of piceid is accelerated by solvents with larger value of dipolarity/polarizability, being inhibited by hydrogen bond donor solvents. Furthermore, the rate constant increased with elevated acidity and temperature, resulting in shorter time for hydrolysis of piceid and avoiding degradation of resveratrol. The hydrolysis of piceid obeyed first-order kinetics. The new information obtained herein could be helpful to enhanced production of resveratrol via hydrolysis of piceid.Download high-res image (123KB)Download full-size image

•A series of magnetic poly-(glycidyl methacrylate) (m-PGMA-EDA)microspheres with different amine density were synthesized and their cadmium saturation adsorption capacities were examined.•The molar ratio of amine groups to adsorbed cadmium decreased with the increase of amine density and eventually reached a minimum value about 4.•when the amine density reached high enough, 4:1 N/Cd complex was proposed to form, and the hydroxyl also participated in the chelating with Cd.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.

We demonstrate that a series of high-performance cathode materials, sodium vanadium polyanionic compounds, Na3(VO1−xPO4)2F1+2x (x = 0, 0.5 and 1), can be synthesized by a phase-transfer assisted solvo-thermal strategy at a rather low temperature (80–140 °C) in one simple step, exhibiting a high Na storage capacity of ca. 120 mA h g−1 and excellent cycling performance. This study makes a significant step to extend this strategy to the synthesis of functional materials from simple binary to complex multicomponent compounds.