Use of Cu(II)-incorporated zeolite Y for decolourization of dyes in water: a case study with aqueous methylene blue and Congo red

Abstract

Removal of colour from wastewater discharged by textile and dying industries is a major environmental issue. Catalytic wet air oxidation (CWAO) has emerged as one of the most acceptable, easy and environmental friendly techniques for the treatment of organic pollutants present in wastewater. The present work explores the decolourization of methylene blue and Congo red from aqueous solution by CWAO process using Cu(II)-incorporated zeolite Y as catalyst. The catalyst was prepared by refluxing zeolite Y with aqueous 1 M Cu(NO3)2·3H2O for 6 h. The prepared catalyst was characterized by XRD, FTIR, atomic absorption spectroscopy, SEM, EDAX, BET surface area and pore volume measurement. The oxidation was carried out in a stirred reactor with pH, temperature, amount of catalyst, dye concentration and interaction time as the process variables. Both the oxidation processes follow second-order kinetics. Almost 70% conversion of methylene blue and 90% conversion of Congo red could be achieved under optimum conditions. The results indicate that Cu(II)-incorporated zeolite Y is a promising catalyst for the removal of both cationic and anionic dyes.