Activation-self-activation craft for one-step synthesis of GO-inbuilt mesopore-dominated N-doped hierarchical porous carbon in capacitive deionization capture of Ni(II)

Capacitive deionization (CDI) is considered a polar-promising technology to remove heavy-metal ions from wastewater. Herein, a green activation-self-activation strategy was exploited to build graphene (GO)-inbuilt mesopore-dominated N-doped hierarchical porous carbons (ENHPCs) using sodium lignosulfonate (SLS) as carbon sources/self-activators. Different from SLS self-activation and K2C2O4-SLS activation-self-activation, ENHPCLKG gained via GO-mediated K2C2O4-SLS activation-self-activation showed suitable mesoporedominated micro-mesoporous structures with high surface area of 1795.5 m2/g, large mesoporous volume of 0.87 m3/g, 3.65 % N-doping and excellent conductivity. Its unique hierarchical porous structure and abundant active sites facilitated the ion rapid insertion and extraction. When utilized to capture low-concentration nickel (Ni2+) ions, ENHPCLKG delivered splendid salt removal capacity of 17.86 mg/g, rapid average salt removal rate of 0.99 mg/g/min and standout cycle stability. Meanwhile, ENHPCLKG was further extended to remove NaCl, MgCl2, CaCl2 and Ni-containing wastewater, showing superior CDI property. Moreover, the recycled ENHPCLKG (10th) taken to eliminate indomethacin (IDM) depicted a splendid adsorption capacity. This work proved the significant applicant potential of the novel and green ENHPCLKG for disposing of Ni2+ ions via CDI technology.