“Nanocomposites and nanomaterials”

Cryptomelane modified with transition metal ions 
in the reaction of ozone decomposition
Rakitskaya T.L., Truba A.S., Sokolova Z.V., Slobodianyk I.O.
Faculty of Chemistry and Pharmacy, Odessa I.I. Mechnikov National University,2, St. Dvoryanskaya, 65082, Odessa, Ukraine. 
E-mail: email.of. corresponding truba@onu.edu.ua

a

, mg/m3

, min

, mg/m3

, min

b

Single studies have shown that transition metal ions can enhance or inhibit the catalytic properties of cryptomelane in the ozone decomposition reaction. The effects of cryptomelane production and the nature of doped metals on their catalytic activity are unclear. Original samples of cryptomelane OMS-2(Refl) and OMS-2(MS), respectively, were synthesized by the reflux method using the KMnO4 reduction reaction with Mn(II) chloride and the KNO3 and MnSO4 melting together. Based on them, cryptomelane samples doped with transition metals were obtained by impregnation – M/OMS-2(Refl) and M/OMS-2(MS). All the samples thus obtained were characterized by XRD, SEM, and FT-IR spectroscopy methods. It is shown that all samples are homogeneous – they contain only the cryptomelane phase. Doped metal ions do not form oxide phases. The figure shows examples of testing samples of M/OMS-2(Refl) (a) and M/OMS-2(MS) (b) in the decomposition reaction of ozone at its initial concentration of 100 mg/m3 compared to the original samples of cryptomelane. Under selected conditions, metal ions inhibit the catalytic properties of cryptomelane.

Figure. The time dependences of  for ozone decomposition by samples: 
a) OMS-2(Refl) and M/ОMS-2(Refl);   b) OMS-2(MS) and M/ОMS-2(MS)
(= 100 mg/m3; ms = 0,5 g)