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 tocompletely 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 peroxideoxidation of reactive yellow 145 (RY-145) and basic red 46 (BR-46). The catalysts were characterized by chemical analysis, X-ray diffraction, Raman spectroscopy, N$_2$ adsorption isotherms, scanning electron microscopy and transmission electron microscopy. The results showed that the synthesized catalysts possess nanotubular structure with good mesoporosity, andthe spinel structure CuCo$_2$O$_4$ was identified as the active phase deposited on Ha. The catalysts degraded these azo-dyes in diluted solutions (22 mg l$^{−1}$ of RY-145 and 35 mg l$^{−1}$ of BR-46) under mild reaction conditions (25$^{\circ}$C, atmospheric pressure, pH 4 and minimum amounts of both catalyst and H2O2). Significant levels of dye conversion (93.1 $±$ 2.2% forRY-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 CO$_2$ and H$_2$O.

[学科分类] 材料工程

[关键词] Halloysite;Cu–Co oxide;catalytic wet peroxide oxidation;azo-dye;textile dye.