Degradation of reactive orange 4 azo dye using catalytic ozonation process
Advanced Oxidation Processes (AOPs) have received increasing attention in past few years due to its higher efficiencies in mineralizing organic pollutants of industrial wastewater. Among various AOPs, catalytic ozonation is widely employed in wastewater treatment. Many metal ions, metal oxides or metals/metal oxides on supports have been used as catalysts in catalytic ozonation. Selection of catalysts in catalytic ozonation is critical in improving efficiency of the process. Mesoporous materials due to its high surface area, uniform pore size, thicker pore walls and relatively high thermal stability have been explored as support for catalyst in various catalytic processes.
In the present study, catalytic ozonation experiments were carried out to mineralize reactive orange 4 (RO4) azo dye using mesoporous material supported catalyst such as Cu/SBA-15. Degradation of organic groups of azo dyes was expressed in terms of colour removal efficiency and TOC removal efficiency. Effects of various parameters like copper loadings on SBA-15, initial solution pH, ozone dose and radical scavenger was investigated in order to maximize degradation efficiency. Complete decolourization of RO4 solution was achieved in first 30 min of catalytic ozonation. In the presence of 2% Cu/SBA-15, TOC removal efficiency of 86.1 % was observed at optimized process conditions. Degradation mechanism was studied by adding radical scavenger like t-butanol into catalytic ozonation reaction. The ozonation reaction followed pseudo-fist-order kinetics with respective to azo dye. The reusability studies confirmed that Cu/SBA-15 is a promising catalyst in the ozonation of wastewater containing azo dyes.