Degradation of Crystal Violet by catalytic ozonation using Fe/activated carbon catalyst

• Fe/activated carbon promoted the degradation of Crystal Violet during ozonation.
• The effect of operating parameters on the decolorization was investigated.
• The initial degradation pathway of Crystal Violet was proposed.
• The changes of COD and the acute toxicity during the treatment were monitored.

An Fe/activated carbon catalyst was prepared and used in catalytic ozonation of Crystal Violet. The catalyst was characterized by SEM and XRD, and the results showed that the iron loaded on activated carbon existed in α-FeOOH phase. An improved effect was achieved in the decolorization of Crystal Violet via catalytic ozonation in the presence of Fe/activated carbon compared with ozonation alone. Almost complete decolorization (>96%) of 400 mg/L Crystal Violet was achieved after 30 min reaction under the conditions of 4.44 mg/min ozone dosage, 300 mL/min gas flow rate, 2.5 g/L catalyst dosage and pH 7, while 57% COD removal efficiency was obtained when the reaction time was prolonged to 90 min. The acute toxicity to Daphnia magna decreased during 90 min of catalytic ozonation. The main intermediates were separated and identified by gas chromatography–mass spectrometry (GC–MS) technique and an initial degradation pathway of Crystal Violet was proposed.