A novel nanocatalyst of the multi-walled carbon nanotubes decorated with niobium pentoxide for the Eriochrome black T dye degradation.

Nowadays, considerable fractions of emerging chemical contaminants are released into the environment by industries, hospitals, agriculture, and domestic sewage. Among these pollutants, Eriochrome black T (EbT) is a dye widely used in the textile, paper printing, leather, paint, cosmetics, and carpet manufacturing industries. The development of new materials for application in the environmental field aiming to remove EbT and other dyes from wastewater is essential in the characterization of a multi-walled carbon nanotubes with niobium(V) oxide (CNTs@Nb2O5) for the EbT removal by heterogeneous photocatalysis. CNT@Nb2O5 demonstrated crystalline peaks of multi-wall carbon nanotubes and orthorhombic Nb2O5 with a surface charge of + 16.7 ± 2.03 mV. The ideal condition for the EbT photodegradation was the [CNT@Nb2O5] of 0.35 g L-1, [EbT] of 40 mg L-1, pH ≈ 1.70, and T of 298.15 ± 2 K with 89.89% of the photodegradation after 180 min under visible irradiation. Regarding photocatalytic activity, it presented a reusability after 5 cycles at acidic pH (1.7) with 89.89% (k = 0.0292 min-1) of photodegradation in the first cycle and 75.64% (k = 0.0139 min-1) in the last one. In total, a dye removal capacity of 88.89% (photodegradation) was observed. These results make CNT@Nb2O5 a promising nanomaterial for removing dyes from effluents.