Gas-assisted three-liquid-phase extraction(GATE), which has the advantages of both three-liquid-phase extraction and solvent sublation, is a novel separation technique for separation and concentration of two organic compounds into different phases in one step. This highly effective and economically applicable method has been developed for separating emodin and rhein from herbal extract. In a GATE system composed of butyl acetate/PEG4000/ammonium sulfate aqueous solution, influence of various parameters including gas flow rate, flotation time, salt concentration, initial volume of PEG and butyl acetate was investigated. Within 50 min of 30 ml·min-1nitrogen flow, removal ratio of emodin and rhein from aqueous phase could be over 99% and 97%, respectively.Mass fraction of emodin in the BA phase and rhein in the PEG phase could reach 97% and 95%, respectively. It is demonstrated that gas bubbling is effective for partitioning of emodin and rhein into butyl acetate and PEG phase respectively, and dispersed PEG and butyl acetate could be captured from the aqueous solution. Experimental results show that GATE could be an effective and economical technology for concentration and separation of co-existed products in medicinal plants.
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 bioadsor- bent 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 233.1mg/g at pH 2.5 and 25 ℃, and the equilibrium time was deter- mined 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 NaCI with a desorption efficiency of 95.6%, indicating high reusability. In conclusion, the bioadsorbent shows potential for Cr（VI） removal from acidic
A novel Heck reaction catalyst consisting of a palladium（ll） complex of meso-tetra（p- hydroxyphenyl）porphyrin （MTP） and cross-linked chloromethylated polystyrene microspheres （PMs） was successfully prepared via covalent ether bonds between the chloride groups in the PMs and the hydroxyl groups in MTP. The catalyst was characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and inductively coupled plasma atomic emission spectroscopy （ICP-AES）. This polystyrene-supported palladium-complex was an efficient heterogeneous catalyst for cross-coupling of aryl iodides with ethyl acrylate. The reaction of iodobenzene and ethyl acrylate under N2 at 100 °C and a catalyst concentration of 0.1% gave a gas chromatography product yield of 99.8%, which is much higher than that achieved using a free palladium（II） complex of MTP as the catalyst （41.3%）. The catalyst was recycled up to six times without significant loss of catalytic activity. These results suggest that the immobilized palladium（II） MTP catalyst has potential applications in synthetic and industrial chemistry.
Abstract 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 polym erization 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 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-l）. The polymer microspheres with grafted tentacle polymer chains have potenial application in large-scale removal of Cr（VI） in aqueous solution.
