The role of counter ions in nano-hematite synthesis: Implications for surface area and selenium adsorption capacity

Nano metal oxides are of interest for aqueous selenium (Se) remediation, and as such, nano-hematite (n alpha-Fe2O3) was examined for use as a Se adsorbent. The effect of surface area on adsorption was also studied. n alpha-Fe2O3 particles were synthesized from Fe(NO3)(3) and FeCl3 via forced hydrolysis. The resulting particles have similar sizes, morphologies, aggregate size, pore size, and PZC. The n alpha-Fe2O3 from FeCl3 (n alpha-Fe2O3-C) differs from the n alpha-Fe2O3 from Fe(NO3)(3) (n alpha-Fe2O3-N) with a similar to 25 +/- 2 m(2)/g greater surface area. Selenite Se(IV) adsorption capacity on n alpha-Fe2O3 has a q(max) similar to 17 mg/g for the freeze-dried and resuspended n alpha-Fe2O3. The Delta q(max) for n alpha-Fe2O3 from Fe(NO3)(3) and FeCl3 that remained in suspension was 4.6 mg/g. For selenate Se(VI), the freeze-dried and re-suspended particles realize a Delta q(max) = 1.5 mg/g for n alpha-Fe2O3 from Fe(NO3)(3) and FeCl3. The n alpha-Fe2O3 from Fe(NO3)(3) and FeCl3 that remained in suspension demonstrated Se(VI) Delta q(max)=5.4 mg/g.