Nanofer - Model 25DS - Aqueous Dispersion of Fe(0) Nanoparticles
A novel aqueous dispersion of Fe(0) nanoparticles coated by inorganic sulphur-based structures. The product is extremly efficient in reduction of TCE while it keeps stable in water environment resulting in much better shelf life and longevity in comparision to standard products. The reactivity of NANOFER 25DS to chlorinated hydrocarbons is probably attributed to the higher hydrophobicity and conductivity of sulfide structures compared to iron oxides present on the surface of nanoparticles. The same structures inhibit corrosion of nanoparticles in water, improve resistance against fouling and passivation and result thus in higher longevity of nanoparticles.
Reactivity of new sulfidated nanoparticles (NANOFER 25DS) were compared to bare nZVI (non modiffied NANOFER 25) in batch experiments where high concentration of TCE (~100mg/L) was present. Results show higher degradation rate of TCE by NANOFER 25DS (100% TCE removed) comparing to NANOFER 25 (35% TCE removed). Degradation of TCE resulted in production of chlorides (49,3mg/L of Cl- produced by sulfidated particles; 15,05mg/L by bare nZVI), which corresponds to the degradation rate.
Also the shelf life of sulfidated nZVI and bare nZVI has been studied: bottles with both products were stored at same conditions at ambient temperature of 25°C (77°F), the content of metallic iron was analyzed at certain intervals by the hydrogen evolution method and detailed composition of both products was studied by Mossbauer spectroscopy after 60 days since products were manufactured. Sulfidated product shows much higher stability comparing to bare nZVI: NANOFER 25DS contains 72% of metallic iron after 60 days, bare nZVI just 7%.
Sulfide coating of nZVI enhances also migration properties, first results indicates that NANOFER 25DS has same or even better migration properties comparing to organic modified nZVI.