Deep eutectic solvent-assisted synthesis of porous Ni2CO3(OH)2/SiO2 nanosheets for ultra-efficient removal of anionic dyes from water

Wastewater treatment is a severe environment issue, especially the discharge of excessive synthetic dyestuffs in the aquatic environment. In this study, a facile binary deep eutectic solvothermal process plus silica surface modification was successfully applied for preparation of porous nanosheet Ni2CO3(OH)2/SiO2 composites. The composites show powerful anionic dyes removal ability due to the high specific surface areas, hydrogen bond connection, coordination effect and strong electrostatic interactions with anionic dyes. A maximum adsorption capacity of 2637 mg g−1 at neutral pH (ca.7) and 303 K was achieved for Ni2CO3(OH)2/SiO2 composite to adsorb Congo red, a representative anionic dye. Moreover, the composite has an excellent specificity for anionic dyes and could maintain above 95% removal efficiency after 5 cycles. Therefore, the as-prepared nanocomposites could be qualified as candidates for industrial environmental remedy. Furthermore, the proposed material preparation strategy could be extended to fabricate various advanced energy and environmental materials.