碱性条件下Cr(Ⅵ)和腐殖酸对赤铁矿胶体在多孔介质中迁移过程的机理研究  

Mechanisms of Cr(Ⅵ)and Humic Acid Effect on Migration of Hematite Colloids in Porous Media Under Alkaline Conditions

作　　者：高羽 卢合峰 秦雪芬 吕媛 杨潇 商建英 阎秀兰[1] GAO Yu;LU Hefeng;QIN Xuefen;LÜYuan;YANG Xiao;SHANG Jianying;YAN Xiulan(Key Laboratory of Land Surface Patterns and Simulation,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China;Xingdong New District Branch,Xingtai Bureau of Ecological Environment,Xingtai 054001,China;College of Land Science and Technology,China Agricultural University,Beijing 100193,China)

机构地区：[1]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 [2]中国科学院大学,北京100049 [3]邢台市生态环境局邢东新区分局,河北邢台054001 [4]中国农业大学土地科学与技术学院,北京100193

出　　处：《环境科学研究》2024年第4期901-907,共7页Research of Environmental Sciences

基　　金：国家自然科学基金项目(No.U21A2023,42207456);天津市科技计划项目(No.22YFYSHZ00310)。

摘　　要：赤铁矿胶体是一种广泛存在于土壤中的活性组分,可与重金属Cr(Ⅵ)发生吸附、沉淀、络合等多种化学作用,从而影响Cr(Ⅵ)在土壤中的迁移富集.探究赤铁矿胶体-Cr(Ⅵ)-腐殖酸(HA)三元体系在多孔介质中的共迁移过程,对于深入理解Cr(Ⅵ)污染过程和防控原理具有重要意义.该研究通过吸附、聚集和柱迁移实验,探究了碱性条件下Cr(Ⅵ)和HA对赤铁矿胶体的聚集动力学和迁移能力的影响.结果表明:与不加Cr(Ⅵ)相比,加入0.25~10 mg/L Cr(Ⅵ)会提高赤铁矿胶体的ζ电势,降低胶体与石英砂之间的最大排斥势垒,阻滞赤铁矿胶体在砂柱中迁移,穿透峰值从61%降至50%左右.引入HA会增加赤铁矿胶体表面负电荷,增强Cr(Ⅵ)与赤铁矿胶体之间的静电斥力,且与Cr(Ⅵ)竞争吸附赤铁矿胶体表面的结合位点,抑制Cr(Ⅵ)在赤铁矿胶体上的吸附,导致胶体与石英砂之间的最大排斥势垒升高.Cr(Ⅵ)和HA的吸附先后顺序对赤铁矿胶体稳定性和迁移性有显著影响.赤铁矿胶体在HA-Cr(Ⅵ)体系中的ζ电势和水合粒径(分别为−30 mV和200~300 nm)比Cr(Ⅵ)-HA体系(分别为−28 mV和400~500 nm)要小,且在HA-Cr(Ⅵ)体系中穿透峰值更高.研究显示,在碱性条件下,尽管HA会抑制Cr(Ⅵ)在赤铁矿胶体表面上的吸附,但会增加赤铁矿胶体在环境中的稳定性和迁移性,使得吸附在赤铁矿胶体表面的Cr(Ⅵ)随胶体发生共迁移的可能性增加,具有潜在的环境风险.Hematite colloids are widespread and one of most active components in soil matrix.It was found that various chemical interactions could take place between hematite colloids and Cr(Ⅵ)via adsorption,precipitation,and complexation,thus affecting the migration and enrichment of Cr(Ⅵ)in soil.It is of great significance to investigate the co-migration process of hematite colloid-Cr(Ⅵ)-humic acid(HA)ternary system in porous media for the in-depth understanding of Cr(Ⅵ)contamination process and the principle of prevention and control.This study explored the effects of Cr(Ⅵ)and HA on the aggregation kinetics and migration patterns of hematite colloids under alkaline conditions through adsorption,aggregation and column migration experiments.The results showed that the addition of 0.25-10 mg/L Cr(Ⅵ)increased theζ-potential of hematite colloid and reduced the maximum repulsive potential barrier between the colloids and quartz sand as compared with the absence of Cr(Ⅵ).The migration of hematite colloids in the sand column slowed down significantly,and the peak penetration decreased from 61%to about 50%.The addition of HA increased the negative charge on the surface of hematite colloid and the electrostatic repulsion between Cr(Ⅵ)and hematite colloid.HA competed with Cr(Ⅵ)for the binding sites on the surface of hematite colloid,therefore inhibiting the adsorption of Cr(Ⅵ)on hematite colloid.Meanwhile,HA increased the maximum repulsive potential barrier between colloid and quartz sand.The adsorption sequence of Cr(Ⅵ)and HA had a significant effect on hematite colloid stability and migration.Theζ-potential and hydrated particle size of hematite colloids were smaller in the HA-Cr(Ⅵ)system(−30 mV and 200-300 nm)than in the Cr(Ⅵ)-HA system(−28 mV and 400-500 nm),and the peak penetration was higher in the HA-Cr(Ⅵ)system.Our results indicated that under alkaline condition,although HA inhibited the adsorption of Cr(Ⅵ)on the surface of hematite colloids,it increased the stability and mobility of hema

关 键 词：赤铁矿胶体 腐殖酸 Cr(Ⅵ) 稳定性 迁移 

分 类 号：X53[环境科学与工程—环境工程]