A comparison of single and catalytic ozonation for decolorization of malachite green

Considering harmful environmental and health effects of malachite green (MG), its removal from dye
wastewater is necessary. Accordingly, the aim of this interventional–experimental study is to compare
single and alumina-catalytic ozonation processes (COPs) for decolorization of MG in a lab-scale rector
for the first time. The full decolorization of 50 mg L–1 MG was carried out in single ozonation process
(SOP) after 30 min but after 15 min in the case of COP. For 3,000 mg L–1 MG, the decolorization efficiency
increased from 95.38% to 99.53% after 30 min in optimal conditions by converting the process from
SOP to COP. However, the chemical oxygen demand removal increased from 60% to 82.35%, but the
total organic carbon (TOC) removal rose from 62.39% to 69.76%. The reaction rate coefficients of COP
at the initial MG concentrations of 50 and 3,000 mg L–1 are about 3.6 and 14 times, respectively, more
than the reaction rate coefficients of SOP