Removal of extremely low concentration cobalt by intercalation composite material of carbon nitride/titanium dioxide

Due to the high toxicity and the great harm of radioactive cobalt to the human body and the environment, the removal of heavy metal cobalt ions from radioactive wastewater had attracted more and more scientific researchers. In this paper, the intercalation composite material of carbon nitride itanium dioxide (g-C₃N₄/TiO₂) composite material which combined the advantages of the two materials was prepared and its actual effect of removing Co (Ⅱ) from wastewater was evaluated. Batch experimental method was employed for the investigation of the impact of solution pH during adsorption, adsorption kinetics, adsorption thermodynamics and adsorption isotherms. In this experiment, the saturation adsorption capacity of the composite material to Co (Ⅱ) was 91.55 mg/g, while the bulk g-C₃N₄ was only 13.2 mg/g. The adsorption kinetics showed that the adsorption process followed a pseudo-second-order kinetic model. The adsorption thermodynamic showed that the adsorption of Co (Ⅱ) was a spontaneous endothermic process. The Langmuir isotherm adsorption model was more consistent with the adsorption isotherm than the Freundlich model. The experimental results proved that g-C₃N₄/TiO₂ composite material had a good adsorption and removal effect on extremely low concentration of Co (II) and was a promising adsorbent for removal radioactive Co (II) from nuclear industrial wastewater.