研究报告
刘思言,杨潇,冯依涛,阎秀兰.改性褐铁矿对砷吸附的强化机制和效果研究[J].环境科学学报,2022,42(3):418-430
改性褐铁矿对砷吸附的强化机制和效果研究
- Enhanced arsenic adsorption by modified limonites： Mechanisms and performance
- 基金项目：国家自然科学基金（No.41571309）
- 作者
- 单位
- 刘思言
- 中国科学院地理科学与资源研究所，陆地表层格局与模拟院重点实验室，北京 100101;中国科学院大学，北京 100049
- 杨潇
- 中国科学院地理科学与资源研究所，陆地表层格局与模拟院重点实验室，北京 100101
- 冯依涛
- 中国科学院地理科学与资源研究所，陆地表层格局与模拟院重点实验室，北京 100101
- 阎秀兰
- 中国科学院地理科学与资源研究所，陆地表层格局与模拟院重点实验室，北京 100101
- 摘要：为了提高褐铁矿对砷的吸附能力，分别采用球磨和煅烧的方式对褐铁矿进行改性处理.使用氮气吸脱附法、X射线衍射光谱（XRD）、傅里叶红外光谱（FTIR）、X射线光电子能谱（XPS）等方法对改性材料进行表征，探究其去除水体中As（V）的吸附机理及对土壤砷的稳定化效果.结果表明，两种改性方法制备的材料对As（V）的吸附过程均符合准二级吸附动力学模型，吸附速率由颗粒内扩散控制，等温吸附线符合Langmuir吸附模型.球磨24 h的褐铁矿对As（V）的吸附量可达到5.76 mg·g-1；而400 ℃煅烧后的褐铁矿对As（V）的吸附量最大，为7.26 mg·g-1.球磨改性后材料表面羟基和羧基含量明显升高，其对砷的吸附机理主要包括含氧官能团的络合和氢键结合等；煅烧改性处理下，As（V）的吸附量与材料比表面积和总孔容的变化一致，且表面羧基显著提升，说明主要的吸附机制为孔隙填充和化学吸附.土壤稳定化实验表明，投加10%的球磨24 h和400 ℃煅烧后的褐铁矿对土壤砷稳定化效率分别为66.08%和68.07%.土壤中可交换态和碳酸盐结合态砷含量降低，残渣态砷含量显著增加.本研究为以天然矿物为原料的高效水净化与土壤修复材料的研制提供了科学依据，并丰富了相关修复原理.
- Abstract：To improve the adsorption capacity of limonite for arsenic， ball milling and calcination were used for limonite modification. The modified materials were characterized by nitrogen adsorption and desorption， X-ray diffraction spectroscopy， Fourier infrared spectroscopy， X-ray photoelectron spectroscopy and Boehm titration. The two modified limonites were applied for decontaminating arsenic from aqueous and soil， and corresponding mechanisms were explored. The results showed that the adsorption of As（V） by the ball milled limonite and calcined limonite were fitting well with the pseudo-second-order kinetic model. The adsorption rates were mainly controlled by intra-particle diffusion and both adsorption isotherms conformed to the Langmuir adsorption model. As（V） adsorption efficiency of limonite increases with increasing ball milling time， the adsorption capacity of As（V） after 24 h ball milling was 5.76 mg·g-1. The adsorption capacity of As（V） for limonite calcined at 400 ℃ was peaked with a value of 7.26 mg·g-1. The density of hydroxyl and carboxyl groups of ball milled limonite is significantly higher than the untreated one， and its adsorption mechanism is mainly controlled by the complexation and hydrogen bonding of oxygen-containing functional groups. For the calcined limonite， the As adsorption capacity is varied with the changes in the specific surface area and total pore volume of the material， and the surface carboxyl groups are significantly increased， indicating that pore filling and chemisorption are the main adsorption mechanisms. Soil stabilization experiments revealed that the As stabilization efficiency after adding 10% limonite of 24 h ball milling or calcined at 400 ℃ reached 66.08% and 68.07%， respectively. The exchangeable As and carbonates-bound As in soil were significantly reduced， however， the residual As was increased. This research provides a scientific basis for upgrading the natural limonite towards arsenic decontamination and has a promising prospect in field scale application.
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