Adsorption performance and mechanism of U(VI) removal from wastewater by polyaniline-coated and carbon dot functionalized CoMn₂O₄

Uranium-containing wastewater posed a serious threat to human health and the ecological environment. Its effective treatment had strategic significance for the green development of nuclear energy and environmental protection. A novel polyaniline-coated carbon dot functionalized manganese cobalt metal oxide was synthesized by chemical polymerization method (CMC20%/PANI). The abundant oxygen and nitrogen groups on the surface of the adsorbent provided active sites for the efficient capture of U(VI). The performance of the material in removing uranium from the solution was evaluated using a static adsorption method. The results show the adsorption capacity of uranium reaches 285 mg/g at pH = 5 and 120 min. The adsorption process is in line with pseudo-second-order kinetic and the Sips model, suggesting that uranium adsorption by the adsorbent involves monolayer and multilayer chemisorption as well as a theoretical adsorption capacity of 659.7 mg/g fitted by Sips. Adsorption mechanism analysis shows that electrostatic attraction, pore diffusion and complex coordination of oxygen and nitrogen groups are the main removal mechanism with CMC20%/PANI on U(VI).