Impact of Cr(Ⅲ) complexation with organic acid on its adsorption in silts and fine sands  

作　　者：Zi-xuan Zhang Lin Wu Xiang-ke Kong Hui Li Le Song Ping Wang Yan-yan Wang 

机构地区：[1]School of Water Resources and Environment,China University of Geosciences(Beijing),Beijing 100083,China [2]Key Laboratory of Groundwater Remediation of Hebei Province and China Geological Survey,Chinese Academy of Geological Sciences,Shijiazhuang 050061,China [3]Fujian Provincial Key Laboratory of Water Cycling and Eco-Geological Processes,Xiamen 361021,Fujian,China [4]Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Xiamen 361021,Fujian,China [5]College of Water Resources,North China University of Water Resources and Electric Power,Zhengzhou 450046,China [6]Shenzhen Geokey Group Co.Ltd.,Shenzhen 518000,Guangzhou,China.

出　　处：《Journal of Groundwater Science and Engineering》2024年第4期347-359,共13页地下水科学与工程（英文版）

基　　金：financially supported jointly by Natural Science Foundation of Fujian Province of China(NO.2023J01227);Natural Science Foundation of Hebei Province(NO.D2020504003);Key Laboratory of Groundwater Remediation of Hebei Province and China Geological Survey(NO.SK202303).

摘　　要：Trivalent chromium(Cr(Ⅲ))can form stable soluble complexes with organic components,altering its adsorption properties in the water-soil environment.This increases the risk of Cr(Ⅲ)migrating to deeper soils and transforming into toxic Cr(VI)due to the presence of manganese oxides in sediments.In this study,Citric Acid(CA)was selected as a representative organic ligand to prepare and characterize Cr(III)-CA complexes.The characteristics,mechanisms and environmental factors influencing the adsorption of Cr(Ⅲ)-CA on porous media(silts and fine sands)were investigated in the study.The results show that Cr(Ⅲ)coordinates with CA at a 1:1 molar ratio,forming stable and soluble Cr(Ⅲ)-CA complexes.Compared to Cr(III)ions,the equilibrium adsorption capacity of Cr(Ⅲ)-CA is an order of magnitude lower in silts and fine sands.The adsorption of Cr(Ⅲ)-CA in silts and fine sands is dominated by chemical adsorption of monolayers,following the pseudo-second-order kinetic equation and the Langmuir isotherm adsorption model.Varying contents of clay minerals and iron-aluminum oxides prove to be the main causes of differences in adsorption capacity of Cr(Ⅲ)-CA in silts and fine sands.Changes in solution pH affect the adsorption rate and capacity of Cr(Ⅲ)-CA by altering its ionic form.The adsorption process is irreversible and only minimally influenced by ionic strength,suggesting that inner-sphere complexation serves as the dominant Cr(Ⅲ)-CA adsorption mechanism.

关 键 词：Cr(Ⅲ) Cr(Ⅲ)-citric acid Porous media ADSORPTION Inner-sphere complexation 

分 类 号：P641[天文地球—地质矿产勘探] P314[天文地球—地质学] X523[环境科学与工程—环境工程]