Enhanced reactivity of nanoscale zero-valent iron prepared by a rotating packed bed with blade packings

• RPB with blade packings can prepare nanoscale zero-valent iron (nZVI).
• The prepared nZVI had a mean grain size of 11.5 nm.
• The prepared nZVI exhibited superior reactivity to degrade RR2.

Nanoscale zero-valent iron (nZVI) was prepared by continuously pumping aqueous FeCl2·4H2O (0.1 mol/L) and NaBH4 (0.2 mol/L) into a rotating packed bed (RPB) with blade packings. A rotational speed of 1400 rpm, liquid flow rates of 0.6 L/min, and a temperature of 21 °C were used. nZVI that was prepared in this way had a mean grain size of 11.5 nm and a BET surface area of 17.1 m2/g. The reactivity of the thus prepared nZVI was measured using the degradation of Reactive Red 2 (RR2) in the presence of dissolved oxygen. At pH 4 and 30 °C with an nZVI dosage of 0.30 g/L, the prepared nZVI degraded approximately 92% of the RR2 in 5 min; this efficiency of degradation greatly exceeded that obtained using nZVI that was purchased from Centron Biochemistry Technology (CBT).

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