功能化多孔氮化碳材料对铀的吸附性能研究

Adsorption properties of functionalized porous carbon nitride materials for uranium

从海水和废水中分离和富集铀对能源的可持续发展和保护环境具有重要意义。通过一步碱化和热缩聚三聚氰胺制备了一种富含氰基和羟基的多孔氮化碳吸附剂(d-g-CN),研究其对铀的吸附性能。吸附实验结果表明,在pH=6.0和298 K的条件下,d-g-CN对铀的吸附在3 h达到吸附平衡,饱和吸附容量为2476.23 mg∙g^(-1)。吸附过程符合拟二级动力学模型和Freundlich等温模型。此外,d-g-CN具有优异的选择性和循环性,在溶液中存在多种竞争离子时,d-g-CN对铀的吸附分配系数达到1.48×10^(4)ml∙g^(-1),并且6次循环后吸附效率仍保持在89.5%。由于d-g-CN较大的比表面积提供了更多的吸附位点,同时氰基和羟基等功能基团与铀存在配位作用,因此d-g-CN表现出优异的吸附性能,在低浓度铀的提取方面具有一定的应用潜力。

The separation and enrichment of uranium from seawater and wastewater is of great significance to the sustainable development of energy and environmental protection.A porous carbon nitride adsorbent(d-g-CN)rich in cyano groups and hydroxyl groups was prepared through one-step alkalization and heat-condensation polymerization of melamine,and its adsorption performance for uranium was studied.The results of adsorption experiments showed that under the conditions of pH=6.0 and 298 K,the adsorption of uranium by d-g-CN reached equilibrium in about 3 h,and the saturated adsorption capacity was 2476.23 mg∙g^(-1).The adsorption process conformed to the pseudo second order kinetic model and Freundlich isotherm model.In addition,d-g-CN had excellent selectivity and cyclicity.When there were many competitive ions in the solution,the adsorption distribution coefficient of d-g-CN for uranium reached 1.48×10^(4)ml∙g^(-1).The adsorption efficiency remained about 89.5%after six cycles.Because the large specific surface area of d-g-CN provided more adsorption sites,and functional groups of cyano and hydroxyl had coordination effect with uranium,d-g-CN showed excellent adsorption performance,and had certain application potential in the extraction of low concentration uranium.