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Covalent linkages are the key component of covalent organic frameworks (COFs). The development of stable and functional linkages is essential to expand the COFs family and broaden their application prospects. In this work, we report the synthesis of crystalline and chemical stable 4-carboxyl-quinoline linked COFs (QL-COFs) via Doebner reactions in both one-pot (OP) and post-synthetic modification (PSM) methods. Both methods can be universally applied to most of the reported imine COFs family via bottom-up construction or linkage conversion. Owing to the contractive pore size, more hydrophilic structure and better chemical stability than the conventional imine COFs endowed by 4-carboxyl-quinoline linkage, QL-COFs are supposed to possess a wider application range. We further demonstrate the nanofiltration membrane (NFM) based on QL-COF exhibited a desirable separation capacity with high rejection for small dye molecules (> 90%), high water permeance (850 L m−2 h−1 MPa−1) and tolerance of extreme conditions (1 M HCl/NaOH), which were benefitted from the enhanced properties of QL-COFs. Additionally, efficient ion sieving properties were also achieved by QL-COF membrane. We anticipate that this work opens up a way for the construction of robust and functional COFs materials for practical applications.

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Arsenic contamination has posed a health risk to millions of people around the world. In this study, a novel adsorbent, hydrous cerium oxide modified graphene (GNP-HCO), was synthesized for arsenic removal from aqueous solution. In the kinetics study, >88% of the equilibrium adsorption capacity of arsenate (As(V)) can be achieved within the initial 20 min. Such a rapid adsorption rate showed its promising potential towards actual application. The experimental data was better described by the Langmuir isotherm model, and the maximum adsorption capacities were 62.33 and 41.31 mg-As g À1 at pH 4.0 and 7.0, respectively, which are much higher than many modified carbon-based adsorbents previously reported. Phosphate appeared to be the most severe competitive interferent on arsenic adsorption. Furthermore, the adsorptive removal of arsenic from surface water matrix was also evaluated and the results demonstrated that only 15 mg L À1 adsorbent was required to reduce the arsenic concentration from 100 mg L À1 to <10 mg L À1 . X-ray photoelectron spectroscopy (XPS) analysis indicated that the major chemical state of cerium (Ce) element in the adsorbent was +IV and the hydroxyl group might be involved in the adsorption process. Fig. 5 Adsorption isotherms of arsenate on the adsorbent: (a) pH ¼ 4.0;This journal is

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