In-vitro toxicity assessment of a textile dye Eriochrome Black T and its nano-photocatalytic degradation through an innovative approach using Mf-NGr-CNTs-SnO 2 heterostructures

The present study aimed to assess the in-vitro toxicity of a popular azodye, Eriochrome Black T (EBT) which may be an environmental hazard causing water pollution if released by textile industries as waste effluents to nearby water ponds. We explored the toxic potential of EBT at 200, 400 and 800 μg/ml concentrations, which were selected based on quantification of EBT present in the pond water near carpet industries. We investigated the permeability of EBT across the organ barriers and found it to be 6.48 ± 0.44% at the highest concentration. EBT also showed up to 26.46 ± 0.533% hemolytic potential on human RBCs. MTT assay revealed toxicity of up to 64.9 ± 10.12%. A dose-dependent increase in intracellular ROS levels and Caspase 3/7 activity was observed and confocal microscopy also demonstrated a similar trend of cellular apoptosis indicating ROS mediated induction of apoptosis as a mechanism of EBT induced cytotoxicity. After establishing the toxicity of EBT, an innovative nano-photocatalytic approach for dye remediation was applied by using as synthesized Mf-NGr-CNTs-SnO 2 heterostructures. This catalyst showed dye degradation potential of up to 82% in 2 h in the presence of sun light. The degraded dye products were tested to have up to 30% reduced cellular toxicity as compared to the parent compound. This work successfully establishes the toxicity of EBT along with devising an innovative approach towards dye degradation where the catalyst is adhered on melamine foam and not being mixed in the effluents directly, thereby, reducing the possibility of catalyst being leached out into the river water.