Sodium borohydride-triggered efficient adsorption and desorption behavior of methylene blue on the surface of Co0.85Se nanosheets

Adsorption is an effective method of removing contaminants from water, however, desorption often becomes more difficult after adsorption process, due to the strong binding force between the adsorbent and pollutants, so that the desorbent cannot be reused. In this paper, Co 0.85 Se nanosheets prepared through a hydrothermal reaction have been used to remove cationic dye methylene blue from aqueous solution in the presence of sodium borohydride. The results show that adsorption/desorption properties of the Co 0.85 Se nanosheets to MB can be greatly changed in the presence/absence of sodium borohydride (NaBH 4 ), and the equilibration time of the adsorption/desorption depends on the amount of NaBH 4 . When NaBH 4 or Co 0.85 Se nanosheets existed together, the residual quantity of MB in solution was less than one-twentieth of that in the system alone using either NaBH 4 or Co 0.85 Se nanosheets; while a large number of MB (ca.90%) was released once again into the solution after NaBH 4 was decomposed because of catalysis of Co 0.85 Se. The zeta potential and pH tests have been elucidated the mechanism for the adsorption of MB onto Co 0.85 Se nanosheets. The efficient adsorption and recovery of dyes indicate that the prepared Co 0.85 Se nanosheets have potential application in wastewater treatment under the assistance of NaBH 4 .