论文部分内容阅读
Arsenic(As)contamination in groundwater has been reported all over the world.The groundwater As can be removed by many iron oxide adsorbents,which could produce large amounts of sludge and cause oxidative damage to humans.Alternatively,arsenic removal can be successfully achieved using granular TiO2 in our previous reports.The motivation for this study is to develop a practical drinking water treatment system and explore the arsenic adsorption mechanism in real-life groundwater in the column using multiple complementary techniques.The granular TiO2 column can treat 2,955 bed volumes of groundwater with initially 454 ?g/L As(Ⅲ)and 88 ? g/L As(Ⅴ)before the effluent As concentration exceeded 10 ? g/L,corresponding to an adsorption capacity of 1.53 mg As/g TiO2.The absorbent can be regenerated with NaOH,and then can be used to treat another 2,560 bed volumes of groundwater,corresponding to 1.36 mg As/g TiO2.The adsorption and transport behaviors of arsenic and major ions in groundwater were investigated.Ca,Si,and HCO3 in groundwater would interfere with the As adsorption.As K-edge EXAFS results suggested Si would not interfere As adsorption structures on TiO2,the reduction of As adsorption could be due to the competition of surface sites.While Ca could enhance As adsorption by the formation of Ca-As-Ti ternary surface complex.The charge distribution multi-site complexation(CD-MUSIC)and one-dimensional advective transport model were integrated to simulate the adsorption and transport behaviors of As and other major ions.With the addition of adsorption reactions of Ca,Si,and HCO3,groundwater As,Ca,Si,and HCO3 adsorption and transport behaviors in columns were modeled reasonably well.