In-Situ Immobilization And Remediation Of Arsenic Contaminated Groundwater In Datong Basin Using Starch Stabilized Fe₃O₄ Nanoparticles

Arsenic is an environmental contaminant of worldwide concern due its high toxicity and presence in groundwater aquifers. Adsorption of arsenic onto iron-oxides is an important phenomenon that locally controls the transport of arsenic in groundwater systems. In this thesis, arsenic immobilization was evaluated using an Starch-stabilized Fe3O4 nanoparticles. The specific research results are as follows:1. Starch-stabilized Fe3O4 nanoparticles were synthesized by co-precipitation method. The average particle size of starch-bridged Fe3O4 nanoparticles range from 10 nm to 30 nm. The starch-bridged Fe3O4 nanoparticles were dispersed evenly in water, and not aggregated and precipitated.2. Batch experiments were conducted to investigate the kinetic parameters involved in As(V) immobilization. Parameters such as pH, reaction time, and initial As(V) concentration were varied to determine optimal conditions. Batch studies revealed that Starch-stabilized Fe3O4 nanoparticles can effectively remove As(V) from aqueous solution. The results showed that: at room temperature for 28 ?, the initial concentration was 375 ?g/L, the starch-bridged magnetite nanoparticles concentration was 77.7 mg/L, p H=8.0, after 60 h adsorption equilibrium was completed, the rate of removal arsenic was about 99%. Adsorption capacity of the Fe3O4 nanoparticles decreased with the increase of p H value, and the maximum adsorption capacity of 202.56 mg/L was obtained at pH 8.0. Humic acids reduces the adsorption of As(V) on starch-stabilized Fe3O4 nanoparticles.3. The study also used the stabilized Fe3O4 nanoparticles to treat the nature groundwater. Compared with DI water, the removal efficiency of starch-stabilized Fe3O4 nanoparticles on natural groundwater was decreased. The results showed that: at room temperature for 28?, the initial concentration was 344 ?g/L, the starch-bridged Fe3O4 nanoparticles concentration was 77.7 mg/L, pH =8.0, after 60 h adsorption equilibrium was completed, the rate of removal arsenic was about 95%. Adsorption capacity of the Fe3O4 nanoparticles decreased with the increase of temperature.4. The field test carried out in Daying Village, the northern of Shanxi Province. The results showed that: the Fe3O4 nanoparticles have strong migration ability in aquifer. The concentration of arsenic of observation wells was significantly reduced. The results also demonstrated that the injection of the stabilized Fe3O4 nanoparticles to groundwater in situ had effectively effect on arsenic removal.