Search

The construction of highly efficient membranes toward oil/water separation is crucial in severe oily sewage treatment while graphene materials are considered stable blocks for oil/water separating membranes. Herein, first, with the presence of graphene oxide, in-situ polymerization of caprolactam was carried out and polyamide-6-reduced graphene oxide composites (PA6-rGO) were successfully synthesized. Then the PA6-rGO nanofiber membranes were prepared by electrospinning combining electrospraying process. Nanofiber skin with microshphere/bead fiber structure on the surface of ordinary electrospun fiber membrane was prepared in 2 steps. Hence the nanofiber membrane separation performance to emulsions under gravity driving was investigated. The results showed that the flux of surfactant-stabilized emulsions would reach up to 765.4 Lm−2·h−1 with the rejection up to 99.6%. It is expected to be practically applied in a low-pressure driven membrane separation system to achieve preliminary separation of severe oily sewage.

Mycobacterium tuberculosis (Mtb), the pathogenic agent of tuberculosis, remains a primary inducement of morbidity and mortality globally. Mtb have evolved mechanisms to recognize diverse signals, such as acidic pH within phagolysosomes and therefore to reprogram multiple physiological and metabolic processes to adapt to intracellular survival. Moreover, lysine malonylation has been suggested to participate in regulation of enzymes in carbon metabolism. However, lysine malonylation in Mtb and its association with acidic pH associated metabolism adaptation remain unknown. Here, we systematically characterized the comparative malonylome of Mtb H37Rv grown in normal (7H9-Tyloxapol (Ty)-7.4) and acidic (7H9-Ty-4.5) medium mimicking lysosome pH. In total, 2467 lysine malonylation sites within 1026 proteins were identified, which related to diverse biological processes, particularly accumulated in metabolic process. 1090 lysine malonylation sites from 562 proteins were quantified, among which 391 lysine malonylation sites in 273 protein were down-regulated while 40 lysine malonylation sites from 36 proteins were up-regulated in acidic medium, indicating that malonylation may participate in acidic pH associated metabolism. Accordingly, the enzyme activity of GlcB was reduced under acidic stress corresponding to decreased malonylation of GlcB compared with that of normal condition and this was further demonstrated by site-specific mutations. We further found that Mtb-CobB, a sirtuin-like deacetylase and desuccinylase, involved in demalonylase activity. Together, the Mtb malonylome not only indicates the critical role of malonylation in metabolism regulation, but may provide new insights of malonylation on metabolism adaptation to acidic micro-environment in vivo.

Nanofiltration is widely used in separation of ions with different sizes and charges. However, thin-film composite nanofiltration membrane is hard to reach satisfied selectivity for monovalent ions from divalent ions. In this study, polyamide thin film nanocomposite (TFN) nanofiltration membranes were prepared via interfacial polymerization of piperazine and trimesoyl chloride on a PES substrate by incorporation of aminated titanium dioxide (APTES-TiO2). Surface morphology, roughness of the TFN membranes with varied concentration of aminated TiO2 were tested by SEM, AFM and Zeta analysis. The results showed membrane containing 0.3(w/v%) amino-modified titanium dioxide with ion-selective properties had greatly improved pure water flux while the Na2SO4 rejection keeps at a relative high level (>95%). For the separation of single salt solution, 0.3(w/v%) TFN has a higher rejection for sodium chloride (23.2%) and sodium sulfate (99.7%). For monovalent/divalent mixed salt solution has a separation factor of 477.89 in terms of chloride ion (Cl−) and sulfate (SO42−) in the mixed solution with a salt concentration ratio of 1:19, which was higher than that of the conventional commercial NF membranes, such as Desal-DL, NF 270. This method provides the possibility of recovering concentrated brine and industrial separation of monovalent and divalent ions.

In this study, Ag@ZnO-Oleic acid (OAc)/polyamide (PA) thin film nanocomposite (TFN) membranes were prepared by interfacial polymerization with dispersing hydrophobic Ag@ZnO-OAc core-shell nanoparticles in trimesoyl chloride (TMC) solutions. The Ag@ZnO-OAc nanoparticle structure and interactions between OAc and TMC were confirmed by TEM, XPS and FTIR. Surface morphology, roughness, chemical composition, hydrophilicity and charges of the synthesized membranes were characterized by SEM, FTIR, contact angle and zeta potential analyses. The results showed that incorporating the Ag@ZnO-OAc nanoparticles into the PA layer improved chemical and physical properties of the TFN membranes. Compared with the nanoparticle-free TFC membrane, the Ag@ZnO-OAc/PA TFN membrane showed a considerably higher salt rejection, and a lower flux decline rate when tested with filtration of BSA solution as a model foulant and a higher flux recovery with water flush. In addition, the Ag@ZnO-OAc/PA TFN membrane showed excellent antibacterial performance against E. coli and S. aureus.