柚皮基活性炭的微波制备及其对U(VI)的吸附

为探究U(VI)溶液初始浓度、溶液pH、活性炭投加量、吸附时间对U(VI)去除效果的影响,以农业废弃物柚子皮为原料、氯化锌为活化剂、微波为热源,制备了柚皮基活性炭,将制得的最优活性炭进行U(VI)吸附实验,并分析了其吸附动力学方程,探讨了其吸附U(VI)的机理。实验结果表明:在活化浓度为30%、活化剂浸渍时间为24 h、微波功率为700 W、辐照时间为90 s的条件下,柚皮基活性炭对碘的吸附值最高,达到769.9 mg/g;在U(VI)溶液初始质量浓度为5 mg/L、溶液pH为7、活性炭投加量为0.6 g/L、吸附时间为24 h时可以达到吸附平衡,U(VI)的饱和吸附容量为8.25 mg/g,吸附率为99.01%;其吸附U(VI)的行为符合准二级动力学模型,吸附U(VI)前后自身结构发生较大变化,柚皮基活性炭对U(VI)的吸附是一种以化学吸附为主、活性炭表面的羰基、CC、羟基和羧酸等官能团与U(VI)水解后的离子作用并存的吸附方式。

The Preparation of Activated Carbon from Pomelo Peel by Microwave Radiation and its Adsorption of Uranium

In order to explore the effect of initial concentration of U(VI) solution, pH of solution, dosage of activated carbon, adsorption time on the removal effect of U(VI), the activated carbon which taking pomelo skin from agricultural waste as raw material was prepared by using Zinc chloride as activator before microwave pretreatment, the optimal activated carbon was used for U(VI) adsorption experiment, and its adsorption kinetic equation was analyzed, and the adsorption mechanism of U(VI) on naringin activated carbon was studied by SEM, EDS and FTIR. The experimental results show that the adsorption value of iodine on naringin activated carbon reach the highest when the activator concentration was 30%, immersion time was 24 h, and the power of microwave was 700 W which irradiated 90 seconds. The adsorption value will reach 769.9 mg/g. The adsorption equilibrium can be reached when the initial concentration of U(VI) solution is 5 mg/L, the pH of the solution is 7, the dosage of activated carbon is 0.6 g/L, and the adsorption time is 24 h. At this point, the adsorption capacity of U(VI) was 8.25 mg/g, and the adsorption rate was 99.01%. The adsorption behavior of U(VI) is more in line with the quasi-second-order kinetic model. The structure of adsorption U(VI) changed greatly after adsorption. The adsorption of U(VI) is a kind of chemical adsorption which the carbonyl, CN, CC, hydroxyl groups and carboxylic acid functional groups on the surface of activated carbon have effect on hydrolysate of U(VI).