DMF-treated strategy of carbon nanospheres for high-efficient and selective removal of organic dyes

Designing adsorbents possessing high-efficient and selective adsorption performance is valuable for water pollution control, yet challengeable. Herein, a new N , N -dimethylformamide (DMF)-hydrothermal strategy was introduced to treat amorphous carbon nanospheres (CNPs) to make it possess a pH-sensitive and high selective adsorption behavior for organic dye. Excitingly, the surface electrical behavior of DMF-CNPs and CNPs are entirely different at pH 5.0, and thus in striking contrast to CNPs, DMF-CNPs exhibits a rapid removal of 70 mg L −1 cationic rhodamine B (at least 99% within 10 min), and also a pH-sensitive adsorption with a maximum adsorbability of 63.85 mg g −1 at pH 9.0 and a minimum value of 32.99 mg g −1 at pH 3.0. The DMF-CNPs's adsorption mechanism could be well explained the pseudo-second-order kinetic model and better fitted the Langmuir isotherm model with a high adsorption capacity of 56.56 mg g −1 at pH 6.5. The significantly improved adsorption performance of DMF-CNPs could be mainly ascribed to its doubled specific surface area, more positive charged active sites of oxygen-containing functional groups available for synergistic adsorption.