镧改性钢渣对水中氟离子的吸附性能

Adsorption performance of lanthanum-modified steel slag towards fluoride ion in water

为有效去除铁路隧道开挖过程中涌出的地下水中的氟离子,避免对当地环境和居民身体健康造成危害,利用镧改性钢渣得到一种除氟材料,通过扫描电镜、比表面积测定、能量散射光谱、X射线衍射及傅里叶红外光谱等方法对材料进行表征。此外,结合吸附热力学和吸附动力学模型拟合,探究了改性钢渣对水中氟离子的吸附机理。结果表明:改性钢渣的比表面积由未改性的0.549 9 m^(2)·g^(-1)增大到23.367 5 m^(2)·g^(-1),小粒径的钢渣比例增大且表面粗糙程度增强。能谱分析表明通过改性,可成功的将镧负载于钢渣表面。吸附拟合模型表明,钢渣对氟离子的吸附遵循Langmuir模型,说明钢渣对氟离子的吸附更接近于单层吸附,且主要为化学吸附。热力学参数表明,吸附吉布斯自由能(ΔG^(0))>0,焓变(ΔH^(0))和熵变(ΔS^(0))<0,表明该反应是放热过程,改性钢渣的除氟过程符合伪二级动力学过程。改性钢渣有望成为一种具有应用前景的除氟材料。

To effectively remove fluoride ions in the groundwater gushed from Sichuan-tibet railway tunnel excavation process,and avoid the harm to the local environment and physical health of residents,a new type of fluoride removal material was prepared by using lanthanum modified steel slag.Scanning electron microscope and the measurement of specific surface area analysis,X-ray energy spectrum were used to characterize the material.The adsorption mechanism of fluoride ions in water by modified steel slag was investigated by adsorption thermodynamics and kinetics model fitting.The results showed that the specific surface area of modified steel slag increased from 0.5499m^(2)·g^(−1) of unmodified steel slag to 23.3675 m^(2)·g^(−1),the proportion of steel slag with small particle size and the surface roughness increased.Energy spectrum analysis showed that lanthanum could be successfully loaded on the surface of steel slag by modification.The adsorption fitting model showed that the adsorption of fluoride ions by steel slag followed the Langmuir model,indicating that the adsorption process was closer to monolayer one,and was dominated by chemical adsorption.Thermodynamic parameters showed that the adsorption Gibbs free energy(∆G^(0))was greater than 0,enthalpy change(∆H^(0))and entropy change(∆S^(0))were lower than 0,indicating that the reaction was an exothermic and entropy reduction process,and the fluorine removal process by modified steel slag fitted well with the pseudo second-order kinetics process.Modified steel slag is expected to be a kind of fluoride removal material with a good application prospect.