改性羧甲基纤维素对铀吸附机理的试验研究

对羧甲基纤维素(CMC)进行改性,并将其用于吸附废水中的铀.研究结果表明:在温度为70℃~80℃、单体质量浓度为30%~35%、羧甲基纤维素:丙烯酸(质量比)为10:2.5、反应时间为3.5~4h条件下,CMC改性效果最好;在改性CMC质量浓度为0.10g/L,温度为25℃, pH值为5.0,反应时间60min的条件下,对废水中铀去除率达到了97.1%;改性CMC对溶液中U(VI)的吸附过程符合Freundlich方程,其吸附动力学数据符合准一级方程(R2=0.9618),表明改性CMC的吸附主要是表面吸附;热力学研究表明,改性CMC对铀的吸附吉布斯自由能(ΔG0)0,吸附过程是自发的吸热反应、以物理吸附为主的过程.

Equilibrium, kinetic and thermodynamic study of the adsorption of uranium (VI) onto modified CMC

The acrylic acid(AA)-modified carboxymethyl cellulose(CMC) resin was prepared and was explored to adsorb uranium(VI) ions from aqueous solution in a batch system. The experimental results showed that on the condition of reaction temperature 70~80℃, CMC 30%~35% (w/w), CMC to AA (w/w) of 10:2.5 and reaction time 3.5~4h, the modification effect was the best. High removal efficient of U(VI) was obtained 97.1% at temperature of 25℃, pH value of 5.0, dosage of modified CMC resin 0.1 g/L and contact time of 60 min. It was found that the adsorption process was best described by Freundlich model and pseudo-first-order kinetic model (R2=0.9618), indicating that the adsorption was mainly on the surface of the resin. Thermodynamics parameters of negative value of ΔG0 and positive value of ΔH0 revealed the spontaneity and endothermic nature of the adsorption. The adsorption was primarily due to physical adsorption.