[Intensified Electrosorption of Pb by 2,6-diaminoanthraquinone/Graphene Composite Electrode].

The key to efficient removal of heavy metal ions from water by electrosorption is to develop electrode materials with excellent performance. In this study, 2,6-diaminoanthraquinone (DA)-modified reduced graphene oxide (rGO) was used to prepare a DA@rGO composite electrode using the solvothermal method. The electrochemical properties, electrosorption of Pb, adsorption kinetics, and cycle regeneration performance of the composite electrode were investigated. Cyclic voltammetry showed that the composite electrode had excellent electrochemical properties, and the specific capacitance reached 304.4 F·g at a current density of 1 A·g. The DA modification significantly increased the pseudocapacitance of the composite electrode. The electrosorption Pb test showed that optimal electrosorption was achieved with -1.2 V of the applied voltage, and the removal rate of the Pb reached 94.8% after 60 min. The electrosorption process is in accord with the first-order kinetic equation. The saturated adsorption capacity of Pb obtained by the Langmuir model was 356.66 mg·g, which is significantly higher than that of rGO electrode, at 319.40 mg·g. The increase in Pb adsorption amount of the composite electrode can be attributed to the increase in capacitance caused by DA modification. Treatment with 0.5 mol·L nitric acid can desorb the Pb within 5 min to achieve regeneration of the composite electrode. After 10 adsorption-desorption cycles, the adsorption removal rate of Pb by the composite electrode was kept at 88%, indicating robust stability.