Topics in Current Chemistry (2020) 378:29
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4.3.2 Use of ZnO Catalyst
Zinc oxide has been reported to be an active catalyst for the SPC (UV + US) degradation of phenol [86]. The synergistic effect was demonstrated, with about 89% degradation achieved, which was higher than that achieved by sonochemical and photocatalytic degradation separately. Comparison of the two catalysts used in the work,
ZnO and TiO 2 , confirmed better efficacy for the ZnO catalyst (Fig. 16) in all treatment approaches, which the authors attributed to its higher ability to absorb energy
in the spectrum. Acidic pH was reported to be preferred for SPC degradation of
phenol due to the increased formation of hydroxyl radicals [86]. In two other studies, heterogeneous ZnO-based SPC oxidation was reported to degrade 98% of the
Fig. 15 Data for the effect of catalyst loading on the degradation of diazinon in presence of Fe-doped
TiO 2 using photocatalytic (a), sonocatalytic (b) and SPC (c) treatment approaches. Data reproduced from
Tabasideh et al. [71]
Fig. 16 Effect of type of catalyst and the treatment approach on the degradation of phenol. Data reproduced from Anju et al. [86]
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