Abstract:
Spent pickling liquor containing almost FeCl2 is a considered hazardous waste because of its very high level of acidity and high metal concentration, and the conventional neutralization method regenerates an excessive quantity of sludge that poses a serious problem concerning to the landfill disposal and risk of ground water contamination. Therefore, recovery of spent pickling liquor is necessary. Several approaches have been investigated for spent pickling liquor recovery, but they are generally costly and lead to produce various iron salts or oxides which have a limited value. In the present study, we explore the potential of using spent pickling liquor and FeCl2 solution as iron precursor for the synthesis of magnetic nanoparticles. Here, Fe3O4 nanoparticles were prepared easily by oxidation-precipitation from spent hydrochloride acid pickling liquors in aqueous saturated solution of calcium hydroxide at room temperature, in the air, and under suitable speed of rotation. The FT-IR, XRD and TEM results shown that monodisperse Fe3O4 nanoparticles in the size range of 10-40 nm were obtained, with a high level of crystalline. The BET surface area of particles from spent pickling liquor was about 46 m2g-1, and from FeCl2 salt was about 24 m2g-1. The synthesized Fe3O4 nanoparticles exhibited the super paramagnetic behavior with relatively high saturation magnetization, from spent pickling liquor about Ms=73 emu g-1 and from FeCl2 salt was higher, about 83 emu g-1. The tested adsorbed capacity of As (V) of particles from spent pickling liquor was about 90 mg As/g Fe3O4, and from FeCl2 salt was about 42 mg As/g Fe3O4. This proves that some impurities in the pickling solution such as Mn, C … help to develop the surface and adsorption capacity.
Key words: spent pickling liquor, FeCl2 salt, magnetic nanoparticles, oxidation-precipitation,
and calcium hydroxide.