Study of the catalytic activity of multilayer graphene (MLG), molybdenum oxide (MoO2), and manganese ferrite (MnFe2O4) on the melanoidin removal by ozonation process

Melanoidin is a compound produced by food industries and distilleries, which has negative impacts on the water environment due to the high content of dissolved organic carbon and dark color. Consequently, this work aims to study the catalytic properties of multilayer graphene (MLG), molybdenum oxide (MoO2), and manganese ferrite (MnFe2O4) in the ozonation process to remove melanoidin from water solution. The results show that the reaction rate constant (k) of the melanoidin decolorization process using catalytic ozonation is 1.7 times higher than the non-catalytic ozonation process. The same results were observed for all catalytic materials with no significant difference among them. On the other hand, MLG was the most efficient catalyst in removing total organic carbon. The removal efficiency was 32% for the non-catalytic ozonation process and 63% for the catalytic ozonation using MLG. This increase in efficiency is attributed to a better production of hydroxyl radicals in the presence of MLG, which was confirmed using isopropanol as a radical scavenger. The efficiencies using MoO2 and MnFe2O4 were 46% and 51%, respectively. The results show that catalytic ozonation by MLG is a promising treatment for melanoidin removal.