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Sensitive detection and effective removal of copper ions (Cu2+) from water are still arduous tasks required to protect public health and environmental safety because of the serious impacts of Cu2+on humans and other organisms. Herein, we report the design and fabrication of self-supporting flexible amidated polyacrylonitrile/branched polyethyleneimine nanofiber membranes (abbreviated as aPAN/BPEI NMs) viafacile electrospinning and a subsequent hydrothermal method, which are used not only as strips for the visual detection of Cu2+but also as effective adsorbents for the removal of Cu2+from water. Because aPAN/BPEI NMs are self-supporting, they can be easily removed from the solution to reduce secondary pollution to the environment. Based on the high Cu2+binding capacity of BPEI, Cu2+ions are adsorbed on the aPAN/BPEI NMs, which leads to the appearance of new absorbance bands at 280 and 636 nm and a color change from yellow to blue. aPAN/BPEI NMs are utilized for the visual detection of Cu2+with a linear range of 50–700 μM and limits of detection of 11.5 and 4.8 μM (absorption peaks at 280 and 636 nm). More importantly, aPAN/BPEI NMs exhibit excellent selectivity and certain recovery with a simple treatment. Furthermore, by utilizing the adsorption characteristics of Cu2+in aqueous media, it can be effectively removed by aPAN/BPEI NMs with a remarkable adsorption capacity of 209.53 mg·g–1. Additionally, the removal of Cu2+by aPAN/BPEI NMs does not exhibit interference by other foreign ions. The adsorption process conforms well to the pseudo-second order (PSO) kinetic model and Jovanovich model, proving that adsorption occurs viachemical and monolayer adsorption mechanisms. Accordingly, this work will provide theoretical and technical support for the design and fabrication of novel heavy metal ion detection-removal integrated materials exhibiting high sensitivity and strong adsorption.

The construction of aerogel photocatalyst materials is a practical and effective strategy for hydrogen evolution and the reduction of heavy metal ions. Herein, ZnIn2S4nanosheets with S vacancies were in-situ grown on graphene aerogels (S-ZISA) by a facile one-pot oil bath method. The construction of S vacancies can improve light absorption by modulating the electron band structure, and becoming an effective active site for electron capture. Under visible light illumination, the optimum ratio of S-ZISA-2 achieved 98% reduction of photo-reduced Cr(VI) for 60min, and with a rate constant (0.054min-1) was 4.5 times higher than that of pure ZnIn2S4(0.012min-1). The cycling experiments show that S-ZISA-2 has good cyclability, and the coexisting anions and effects of pH value in solution on the photo-reduction of Cr(VI) were studied. In addition, the S-ZISA-2 exhibits a high rate of hydrogen evolution (2011.7 μmol g-1). The excellent photocatalytic activity is mainly attributed to the graphene aerogel backbone, which not only provides more active sites but also a unique three-dimensional network that provides abundant electron transport channels, accelerating the carrier transport rate and prolonging the visible light lifetime. In addition, the ZnIn2S4nanosheets can form Schottky heterojunction with graphene, which effectively enhances the migration of photo-induced carriers, hinders carrier recombination, and enhances the photocatalytic activity. This study provides new strategy in the synthesis of aerogel photocatalysts.