Magnetic graphene oxide for rapid capture and efficient separation of cobalt from radioactive wastewater

Removal of cobalt (Co) in radioactive wastewater from the primary circuit of nuclear plant has a significant meaning in the nuclear safety and environmental protection. Magnetic graphene oxide (MGO) was utilized for efficient removal of Co from radioactive wastewater in this work. The adsorption of Co2+ was governed by interaction between Co2+ and carboxyl groups/dissociated carboxyl groups on MGO. Hydrophilic MGO possessed excellent dispersibility in water thus MGO could in contact with Co2+ sufficiently, resulting in the ultrafast adsorption kinetic for Co2+ and adsorption achieved equilibrium within 30 s. Abundant carboxyl groups and dissociated carboxyl groups on MGO provided sufficient adsorption sites for Co2+, causing the high adsorption amount of 297.2 mg g-1. The ultrafast adsorption kinetic and high adsorption amount endow MGO with great capture ability for radioactive Co from water. Furtherly, the interaction between MGO and Co2+ generated floccule with magnetism, thus MGO after adsorption could be easily separated by a magnet and magnetic separation was completed within 5 min, which was beneficial for the rapid and convenient decontamination. Moreover, MGO exhibited outstanding adsorption ability for Co2+ with the coexistence of organic acids that commonly used for cleaning equipment of primary circuit. Meanwhile, MGO showed great irradiation resistance and broad-spectrum adsorption ability for radionuclides, which was important for the treatment of radioactive wastewater. This study suggested a potential adsorbent for efficient adsorption and convenient magnetic separation of radioactive Co in radioactive wastewater from the primary circuit of nuclear plant.