Adsorption of arsenic (V) by biologically reductive lanthanum-loaded bentonite: Transportation and injection removal experiments

Iron reducing bacterium Acidiphilium cryputum JF-5 was used to biologically load lanthanum on bentonite (BLB) to remove arsenic(V) from solution. By biological reductive release of iron from bentonite and lanthanum loading, new lanthanum-loaded bentonite was prepared and the adsorption efficiency of arsenic(V) was improved from 7.87 mg/g to 22.69 mg/g in bath experiment. The mobilization of the dispersed biologically loaded lanthanum bentonite particles can be described by the Convection-Dispersion Equation. The breakthrough ability of biologically lanthanum-loaded bentonite (BLB) increased by 5.5 times when increasing flow velocities from 90 mL/h to 360 mL/h. When injected BLB into arsenic(V)-containing pre water of quartz column, the concentration of arsenic(V) could quickly decrease the initial concentration of arsenic(V) from 2000 μg/L to lower than limit for drinking water and keep relative stable. Meanwhile, the hydraulic conductivity of treatment system is also improved compared to prinstine bentonite due to iron-deficient in BLB. The results suggest that biologically load lanthanum bentonite may be an effective modified mineral for remediating arsenic(V)-containing soil.