Hydrogen bonding donor/acceptor active sites exposed on imide-functionalized carbon dots aid in enhancing arsenic adsorption performance

During the arsenic (As) adsorption process, amino-functionalization has been widely considered as one of the effective adsorbents optimization methods, while this study reveals that imide functional groups also play a non-negligible role. Herein, magnetic carbon dots (CDs) equipped with imide (FeCD-NH) or amino functional groups (FeCD-NH2) were synthesized to deduce the relationship between different configurations of amino-like functional groups and As. The results showed that FeCD-NH exhibited extraordinary As(V) adsorption behavior (with 97.80 % As(V) removal within 5 min), outperformed that equipped with amino functional groups (FeCD-NH2). An array of advanced characterization techniques and density functional theory (DFT) calculation collectively revealed a dual-configuration hydrogen bond synergistic mechanism of FeCD-NH toward As(V). Different from monomorphic hydrogen bond of amino functional group, imide functional group forms abundant adsorption sites through dual-configuration hydrogen bonds to realize the ultrafast adsorption of As(V). In addition, FeCD-NH can remove As(V) from other more complex water matrices to levels below the World Health Organization (WHO) drinking water standards and the Chinese surface water standards. Therefore, this work provides a promising strategy for As decontamination by fine-tune the surface chemistry of adsorbents.