Chromate immobilization in groundwater and soil using Iron-Manganese binary metal oxide nanoparticles

Abstract

Fe-Mn (iron – manganese binary oxide) nanoparticle were synthesized and test for the Cr(VI) immobilization in soil and groundwater. Water soluble starch and carboxymethyl cellulose (CMC) were applied to stabilize the nanoparticles. All three particles exhibited a fast adsorption kinetic while only bare and starch stabilized Fe-Mn showed a high removal efficiency. The Langmuir adsorption capacity of bare, starch and CMC stabilized nanoparticle were 59 mg/g, 54mg/g, and 2 mg/g, respectively. The high removal efficiency was observed at pH rang of 3-6. Competing ions and humic acid test indicated the starch coating could shield the core Fe-Mn from effect by sulfate and phosphate, the removal efficiency of starch Fe-Mn remain greater than 95% in the presence of 5 mg/L humic acid. Column tests show that after 4 pore volume about 20% of starch stabilized Fe-Mn was retained in soil, which indicated the deliverable of starch stabilized particles. Treatment with starch stabilized Fe-Mn could reduce up to 85% of soluble Cr(VI) leaching in soil compare to DI water.