Removal of uranium from wastewater through Ni–Al-layered double hydroxide@carbon nanotubes functionalized by polyethyleneimine

Nuclear energy is widely used as an efficient energy. However, the production of a large amount of uranium-containing wastewater is considerably harmful to the environment. Adsorption is a commonly used method for removing uranium ions from water. In this study, carbon nanotubes (CNTs) were first modified with polyethyleneimine (PEI), and then Ni–Al-layered double hydroxide (LDH) was anchored to CNT-PEI (CNT-P) by using the co-precipitation method to obtain CNT-P/LDH (NO3−). The experimental results indicated that the adsorption process was consistent with Langmuir kinetic adsorption and Sips adsorption isotherm models at the pH of 6. The fit result of the Sips adsorption isotherm model indicated that the adsorption capacity of CNT-P/LDH was 646.6 mg g−1. XPS analyses showed that the adsorption of uranium on CNT-P/LDH mainly involved three aspects. Tests were conducted for different salinities, and the results showed a uranium removal rate of >95% at a salinity of 3.5%.