Remediation of cobalt(II) by Myriophyllum spicatum and its secondary utilization in supercapacitor

Cobalt is a common contaminated metal exists in industrial wastewater and is also widely used in the field of energy storage as electrode materials. Cobalt(II) is the most familiar water-soluble form of cobalt element and its emission to environment causes serious problems. Traditional physical and chemical methods are unable to fully eradicate cobalt(II) in wastewater, especially at low concentrations. Therefore, phytoremediation is proposed and myriophyllum spicatum is chosen as the subject for absorbing cobalt(II) presented in the simulated wastewater. The results show that the myriophyllum spicatum can prominently but finitely absorb cobalt(II) from simulant wastewater; in order to reuse recycled cobalt(II), the composite material is obtained after carbonization and is applied to supercapacitors as electrode material. Under the condition of a current density of 0.5 A/g in 6 M KOH, the specific capacitance is 275 F/g, where good charge storage capacity and rate performance are obvious compared with other non-activated biomass-derived carbon materials.