石墨相氮化碳/壳聚糖复合材料对水中U(Ⅵ)的吸附性能与机理

Adsorption performance and mechanism of g-C_(3)N_(4)/CS composite for U(Ⅵ)from aqueous solution

针对核能发展与应用过程中产生的含铀废水所导致的环境铀污染难题,通过共混交联法将石墨相氮化碳(g-C_(3)N_(4))负载在壳聚糖(CS)上,制备了复合材料-石墨相氮化碳/壳聚糖(g-C_(3)N_(4)/CS),用来吸附水溶液中的U(Ⅵ)。对g-C_(3)N_(4)/CS的表面性质和作用机制进行了分析。结果表明:g-C_(3)N_(4)/CS投加量为0.2 g/L,g-C_(3)N_(4)质量分数为20%,吸附时间为120 min,温度为308 K,pH=6条件下,g-C_(3)N_(4)/CS对U(Ⅵ)的最大吸附量达到324.45 mg/g。Langmuir等温模型和准二级动力学模型符合该吸附过程,是一个自发吸热过程。g-C_(3)N_(4)/CS对U(Ⅵ)的吸附机理主要为—NH,—OH,C—O,C=O,C—N等官能团与U(Ⅵ)发生的配位络合。g-C_(3)N_(4)/CS在循环再生实验中显示出良好的重复利用性。

Aimed at the problem of environmental uranium pollution caused by uranium-containing wastewater generated in the process of nuclear energy development and application,by loading g-C_(3)N_(4) on chitosan(CS)through the cross-linking method,g-C_(3)N_(4)/CS composite was synthesized and used to remove U(Ⅵ)from aqueous solutions.The surface properties and the interaction mechanism of g-C_(3)N_(4)/CS were analyzed.The results show that when the adsorbent dosage of g-C_(3)N_(4)/CS is 0.2 g/L,mass fraction of g-C_(3)N_(4) is 20%,adsorption time is 120 min,adsorption temperature is 308 K,and pH is 6,the maximum adsorption capacity of g-C_(3)N_(4)/CS on U(Ⅵ)reaches 324.45 mg/g.The adsorption of U(Ⅵ)by g-C_(3)N_(4)/CS involves a spontaneous endothermic process that follows the Langmuir isotherm model and quasi-second-order kinetic model.The adsorption mechanism of U(Ⅵ)by g-C_(3)N_(4)/CS is primarily attributed to the coordinated complexation of functional groups such as—NH,—OH,C—O,C=O,and C—N.The results of the recycling experiments show that g-C_(3)N_(4)/CS has good reusability.