摘要
以不溶性腐殖酸(Insolubilized Humic Acid,IHA)为吸附剂,去除废水中的U(VI)。通过静态吸附试验,考察了p H值、时间、U(VI)初始质量浓度和温度等对吸附的影响,分析了吸附过程的动力学、热力学及等温吸附规律,并用红外光谱(FT-IR)和扫描电镜(SEM)分析了吸附机理。结果表明:35℃下1.4 g/L的IHA在p H值为5时对10mg/L U(VI)的去除率可达99.37%;IHA对U(VI)的吸附是自发的、放热的反应,符合Freundlich等温吸附方程,决定系数达0.99以上;吸附动力学过程符合准二级吸附速率方程,决定系数为1;IHA吸附U(VI)后表面形态发生了变化,与U(VI)相互作用的基团主要是羧基和酚羟基,综合看来,IHA吸附U(VI)的机理表现为离子交换。
The present paper is to introduce a report on the research findings of the adsorption experiments based on thermodynamics and kinetics of insolubilized humic acid adsorption to uranium（VI） ions by using the insolubilized humic acid（IHA） as the adsorbent to remove the U（VI） from the uranium-containing sewage. As is known,IHA enjoys an excellent adsorptive capability,which can be prepared by heating the highly soluble humic acid at the temperature of 330 ℃ and then treated with Ca Cl2.Before doing the experiment,evaluation should be done on the conditions of the effect of p H,contact time,initial concentration,temperature and dosage of adsorbent on the U（VI） removal process and removing rate,while the adsorption has to be analyzed by kinetics,thermodynamics and adsorption isotherm law.In addition,we have also made a discussion on the mechanisms of the U（VI） removal by scanning the electronic microscopy（SEM） and the Fourier Transform Infrared Spectroscopy（FTIR）. The experimental results of the maximum removal rate can be made to increase by 99. 37% at an initial concentration of 10 mg / L,the p H value of 5. 0 and in an adsorbent dose of 1. 4 g / L at 35 ℃ till the equilibrium state is expected to arrive in approximately 90 min. At the same time,we have also made a discussion on the adsorption kinetics of U（VI） onto IHA by using the pseudo-first-order,the pseudo-second-order and intra-particle diffusion models,which are expected to provide the best correlation of the experimental data at the relation coefficient of 1,while the experimental data should be well fit with Freundlich isotherm,with the relation coefficient being 0. 999 5. Thus, the adsorption process shows the intra-particle diffusion mechanism at high concentrations. Moreover,the equilibrium adsorption data of U（VI）onto IHA can be analyzed by using the Langmuir,Freundlich and Temkin isotherm models,and the thermodynamic parameters such as Gibbs free energy change,enthalpy change and entropy change can well be calculated. The results of our research prove that the adsorption of U（VI） onto IHA is feasible,spontaneous and exothermic in nature. The FT-IR of humic acid before and after the modification indicate that the hydrophobic group can be increased and enhanced by the insolubility. The SEM before and after the adsorption indicates that the adsorption of U（VI） on IHA can change the surface form of IHA,and the FT-IR of before and after the adsorption reveals that the main functional groups in reaction with U（VI） should be phenolic hydroxyl and carboxylic,whereas the mechanism of the removal of U（VI） ions by IHA should be based on the ion exchange reaction.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2015年第1期193-198,共6页
Journal of Safety and Environment
基金
国家自然科学基金项目(51174117)
关键词
环境工程学
U(VI)
不溶性腐殖酸
吸附动力学
吸附热力学
environmental engineering
U（VI）
insolubilized humic acid
adsorption kinetics
adsorption thermodynamics
