Carbon nanomaterials have proven their wide applicability in molecular separation and water purification techniques. Here, an unzipped carbon nanotubes (CNT) embedded graphene oxide (GO) membrane (uCNTm) is reported. The multiwalled CNTs were longitudinally cut into multilayer graphene oxide nanoribbons by a modified Hummer method. To investigate the varying effects of different bandwidths of unzipped CNTs on their properties, four uCNTms were prepared by a vacuum-assisted filtration process. Unzipped-CNTs with different bandwidths were made by unzipping multiwalled CNTs with outer diameters of 0–10, 10–20, 20–30, and 30–50 nm and named uCNTm-1, uCNTm-2, uCNTm-3, and uCNTm-4, respectively. The uCNTms exhibited good stability in different pH solutions, and the water permeability of the composite membranes showed an increasing trend with the increase of the inserted uCNTm’s bandwidth up to 107 L·m–2·h–1·bar–1, which was more than 10 times greater than that of pure GO membranes. The composite membranes showed decent dye screening performance with the rejection rate of methylene blue and rhodamine B both greater than 99%.

This study aims to investigate the effect of the stepwise marine fuel oil regulations on the concentrations of vanadium (V) and nickel (Ni) in ambient air based on a 4-y (2017–2020) online measurement in Shanghai, a coastal city in China. The annual concentration of V was reduced by 58% due to the switch from Domestic Emission Control Area (DECA) 1.0 to DECA 2.0 and further by 74% after the implementation of the International Maritime Organization (IMO) 2020 regulation, while the reduction rate for Ni was only 27% and then 18% respectively. Consistently, a reduction of 84% in V content and a negligible change in Ni content were measured in 180cst ship oil samples from 2010 to 2020. The similar increasing trend of Ni/V ratios (from <0.4 to >2.0) in both ambient measurement and heavy fuel oil samples suggests that the DECA and IMO 2020 regulations effectively reduced the ambient V. However, nickel content is still enriched in the in-use desulfurized residual oils and ship-emitted particles in coastal China. Meanwhile, the previous ratio between V and Ni cannot be used as a tracer for identifying ship-emitted particles due to its large variation in oils. Further updating of the source profile of ship traffic emissions in coastal cities is necessary in the future.

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In the present work, atactic polypropylene (aPP)/isotactic polypropylene (iPP) with different aPP content was prepared through an injection-molding process to improve the toughness of iPP and make large scale use of aPP. The hierarchic structure of the injection-molded parts was characterized through differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), small-angle Xray scattering (SAXS), and scanning electron microscopy (SEM). It was found that the network of iPP crystals was still integral with shish-kebab structures in the skin layer and the relatively high crystallinity of iPP in injection-molded parts with low aPP content utilizing suitable process conditions. Therefore, the toughness of iPP was enhanced from 31.8 to 42.6 MJ/m 3 due to the addition of a 20 wt % aPP component, meanwhile the tensile strength only decreased from 45.9 to 40.5 MPa. Furthermore, when aPP content reached 50 wt %, the toughness of the aPP/iPP blends increased to 52.0 MJ/m 3 with the tensile strength staying at the level of 20 MPa, indicating that the A50 sample also has good toughness with reasonable strength. The results demonstrated that the aPP/iPP blends with high mechanical properties owing to the optimized inner structure can be obtained through the suitable processing method. Our results set up a new method to make large scale use of aPP. Moreover, with an increase in aPP content, the mechanical properties of the injection-molded part can be divided into three evolution stages with distinct differences. At high and low aPP content, the mechanical properties were not sensitive to aPP content. However, when aPP content fell between 20 and 50 wt %, the mechanical properties of the injection-molded part, especially the elongation at the break, changed dramatically acting like percolation phenomenon in electro-conductive polymer composites, which may be the result of phase inversion of aPP/iPP blends. The percolation in mechanical properties is meaningful to prepare the blend of crystallizable/noncrystallizable blends with different properties.

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