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To enhance the adsorption capacity and improve agglomeration properties of kaolin during the adsorption process of Hg2+ from aqueous solution, kaolin was bi-functionally modified using L-cysteine and polypyrrole. The as-synthetized adsorbent of L-Ppy-Fe3O4/kaolin was characterized before and after modification. The removal conditions were optimized by response surface methodology, and the optimized results show that the optimal adsorption capacity of Hg2+ reaches 482.71 mg/g at pH of 7.9, temperature of 315 K, initial concentration of 40 mg/L and dosage of 0.05 g/L. And the effects of adsorption conditions on Hg2+ removal follow the order of solution pH > temperature > initial concentration > dosage. The adsorption process of Hg2+ in aqueous solution can be well described by pseudo-second-order kinetic model and Langmuir isothermal model. Moreover, the thermodynamic fitting indicates that the adsorption of Hg2+ is an endothermic and spontaneous process. The adsorption mechanism of Hg2+ onto L-Ppy-Fe3O4/kaolin is mainly the complexation between divalent Hg2+ and sulfhydryl/amino groups to form stable metal complexes, and electrostatic attraction is also a part of the reaction mechanism. In addition, L-Ppy-Fe3O4/kaolin is proved to have satisfactory dispersion ability and chemical stability and can be easily separated and recovered after adsorption in aqueous solution. Therefore, L-Ppy-Fe3O4/kaolin is a promising adsorbent for the efficient removal of mercury ions. [ABSTRACT FROM AUTHOR]

Membrane fouling problem is now limiting the rapid development of membrane technology. A newly synthesized cationic polyionic liquid (PIL) [P(PEGMA‐co‐BVIm‐Br)] was blended with poly(vinylidene fluoride) (PVDF) to prepare antifouling PVDF membranes. The PVDF/P(PEGMA‐co‐BVIm‐Br) exhibited an increased surface hydrophilicity, the water contact angle was reduced from 77.8° (pristine PVDF) to 57.9°. More porous membrane structure was obtained by adding PIL into the blending polymers, as high as 478.0 L/m2·h of pure water flux was detected for the blend PVDF membrane in comparison with pristine PVDF (17.2 L/m2·h). Blending of the cationic PIL with PVDF gave a more positive surface charge than pristine PVDF membrane. Blend membranes showed very high rejection rate (99.1%) and flux recovery rate (FRR, 83.0%) to the positive bovine serum albumin (BSA), due to the electrostatic repulsion between the membrane surface and proteins. After three repeated filtration cycles of positive BSA, the blend PVDF membranes demonstrated excellent antifouling performance, the permeation flux of the membranes was recovered very well after a simple deionized water washing, and as high as 70% of FRR was obtained, the water flux was maintained at above 350 L/m2·h. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48878. [ABSTRACT FROM AUTHOR]

By the treatment of N-3-bromo-3-alkenylthioamides with sodium hydroxide in DMF-H2O in the presence of tetra-butylammonium bromide, series of 6-alkylidene-5,6-dihydro-4 H-1,3-thiazine derivatives were prepared in moderate to good yields. The cyclization is supposed to proceed via both the intramolecular vinylic nucleophilic substitution and the elimination-addition mechanisms (formation of acetylenic intermediates) in a competitive manner. [ABSTRACT FROM AUTHOR]

In this study, a triple-component copolymer of P(Stx-co-MAAy)-g-fPEGz containing hydrophobic (styrene, St), hydrophilic (methacrylic acid, MAA), and oleophobic (perfluoroalkyl polyethylene glycol, fPEG) segments was synthesized and used as an additive polymer to prepare modified PVDF membrane for enhanced anti-fouling performance. Two compositions of St:MAA at 4:1 and 1:1 for the additive and two blending ratios of the additive:PVDF at 1:9 and 3:7 for the modified membranes were specifically examined. The results showed that the presence of the copolymer additive greatly affected the morphology and performance of the modified PVDF membranes. Especially, in a lower ratio of St to MAA (e.g., St:MAA at 1:1 versus 4:1), the additive polymer and therefore the modified PVDF membrane exhibited both better hydrophilic as well as oleophobic surface property. The prepared membrane can achieve a water contact angle at as low as 48.80° and display an underwater oil contact angle at as high as 160°. Adsorption experiments showed that BSA adsorption (in the concentration range of 0.8 to 2 g/L) on the modified PVDF membrane can be reduced by as much as 93%. From the filtration of BSA solution, HA solution, and oil/water emulsion, it was confirmed that the obtained membrane showed excellent resistance to these organic foulants that are often considered challenging in membrane water treatment. The performance displayed slow flux decay during filtration and high flux recovery after simple water cleaning. The developed membrane can therefore have a good potential to be used in such applications as water and wastewater treatment where protein and other organic pollutants (including oils) may cause severe fouling problems to conventional polymeric membranes. [ABSTRACT FROM AUTHOR]