Catalytic degradation of real-textile azo-dyes in aqueous solutions by using Cu-Co/halloysite

摘要

Catalytic degradation of textile dyes in diluted aqueous solutions with minimal consumption of energy is a great challenge for wastewater treatment and environmental protection. Efficient heterogeneous catalysts are needed to completely oxidize azo-dyes under soft conditions. In this work, catalysts of Cu-Co oxide (1: 2 molar ratio) supported on halloysite (Ha) nanotubes (CuCo(5%)/Ha and CuCo(10%)/Ha) were synthesized and used in the catalytic wet peroxide oxidation of reactive yellow 145 (RY-145) and basic red 46 (BR-46). The catalysts were characterized by chemical analysis, X-ray diffraction, Raman spectroscopy, N2 adsorption isotherms, scanning electron microscopy and transmission electron microscopy. The results showed that the synthesized catalysts possess nanotubular structure with good mesoporosity, and the spinel structure CuCo2O4 was identified as the active phase deposited on Ha. The catalysts degraded these azo-dyes in diluted solutions (22mg l -1 of RY-145 and 35mg l -1 of BR-46) under mild reaction conditions (25. C, atmospheric pressure, pH 4 and minimum amounts of both catalyst and H2O2). Significant levels of dye conversion (93.1 +/- 2.2% for RY-145 and 54.4 +/- 2.0% for BR-46) were achieved in a relatively short time. In addition, significant values of total organic carbon removal (59.5 +/- 1.8% for RY-145 and 33.9 +/- 1.4% for BR-46) were obtained, indicating the total oxidation of a significant fraction of these dyes to CO2 and H2O.