Performance evaluation of interfacial polymerisation-fabricated aquaporin-based biomimetic membranes in forward osmosis.

Aquaporins play a promising role in the fabrication of high-performance biomimetic membranes. Interfacial polymerisation is a promising strategy for synthesizing aquaporin-based membranes. In this study, robust and high-performance aquaporin-based biomimetic membranes were successfully fabricated by interfacial polymerisation, and the membrane separation performance and interfacial polymerisation method were systematically evaluated. The effects of modification methods on the performance of aquaporins-based biomimetic membranes, including sodium hypochlorite and thermal post-treatment, protein-to-lipid ratio, liposome concentration and the addition arrangement of aquaporins were also investigated. Morphological observation suggested that the introduced proteoliposomes were completely embedded in the polyamide layer and that their spherical shape was preserved. Sodium hypochlorite post-treatment and thermal treatment were beneficial in improving the water flux and salt rejection of the resultant membrane without sacrificing the aquaporin activity. The biomimetic membranes had a high water flux and salt rejection, which were almost twice that of the control membranes, after aquaporin-based proteoliposomes were incorporated with an appropriated protein-to-lipid ratio and liposome concentration. The addition arrangement of aquaporins during the interfacial polymerisation procedure significantly influence the obtained membrane's structure. Lastly, this article introduces valuable and systematic research on interfacial polymerisation fabricated aquaporin-based biomimetic membranes with outstanding separation performance.

Correction: Performance evaluation of interfacial polymerisation-fabricated aquaporin-based biomimetic membranes in forward osmosis.

[This corrects the article DOI: 10.1039/C9RA00787C.].

Preparation and characterization of monodisperse molecularly imprinted polymer microspheres by precipitation polymerization for kaempferol.

A new kind of molecularly imprinted polymer (MIP) microspheres for the selective extraction of kaempferol was prepared by precipitation polymerization using 4-vinylpridine (4-VP) and ethylene glycol dimethacrylate (EDMA) as functional monomer and cross-linker respectively. The synthesis conditions, such as ratios of 4-VP/EDMA and polymerization time were discussed in detail. Results showed that the 2% was the optimal concentration of co-monomers to obtain monodisperse MIP microspheres, the best ratio of 4-VP/EDMA was 1:2, and 24 h was considered as the proper polymerization time. Compared with the MIP agglomeration or coagulum particles, monodisperse MIP microspheres showed the better adsorption capacity: the saturated adsorption capacity of monodisperse MIP microspheres was 7.47 mg g-1, the adsorption equilibrium could be obtained in 30 min. Finally, the adsorption performances of the optimal MIP microspheres were evaluated by kinetic adsorption, adsorption isotherm, and selective adsorption experiments, which indicated that the adsorption mechanism were chemical single layer adsorption and the separation factor was up to 3.91 by comparing with the structure similar compound (quercetin). The MIP microspheres exhibit prospects in the kaempferol efficient and selective separation.

Flocculation of Microcystis aeruginosa using modified larch tannin.

To flocculate the cyanobacterium Microcystis aeruginosa from water, larch tannin, a natural polymer, was modified by Mannich reaction to obtain a flocculant, named A-TN, which was then quaternized to yield another flocculant, named Q-TN. A-TN and Q-TN were characterized by Fourier transform infrared spectra (FTIR) and zeta potential analysis. The effects of the flocculation parameters, e.g., dosage, pH, cell density, culture time, and extracellular organic materials, were studied. The results showed that Q-TN was effective under a wider range of pH values than A-TN and could work under a pH of 9.0, whereas A-TN could work only under a pH of 7.0. For algal samples with densities from 1 × 10(8) to 5 × 10(9) cells/L, the optimum dosages of Q-TN to achieve more than 90% removal efficiency ranged from 0.5 to 20 mg/L, and the optimum dosages had a good linear relationship with cell density. Furthermore, the required dosage of Q-TN clearly increased along with the algae culture time, most of which was consumed by the extracellular organic materials (EOM) excreted from the cells. The spectra of the three-dimensional excitation-emission matrix showed that 100% of simple aromatic proteins and 78.8% of protein-like substances in the EOM could be removed by Q-TN. However, Q-TN was less effective in humic/fulvic-like substance flocculation. Q-TN functioned to settle the algae cells and a large amount of their metabolites effectively.