A Study of Treatment of Reactive Red 45 Dye by Advanced Oxidation Processes and Toxicity Evaluation Using Bioassays

Abstract

Advanced oxidation processes (AOPs) hold great promise to degrade and detoxify industrial-based effluents. The Reactive Red 45 dye aqueous solutions were treated with AOP using UV and gamma radiation alone and then in the presence of H2O2. The dye initial concentration, UV exposure time, and gamma-ray absorbed dose were optimized for maximum degradation. The degradation of dye was 88.85% and 77.7% using UV/H2O2 (1 mL/L) at a UV exposure time of 180 min for 50 mg/L and 100 mg/L, respectively. The degradation was noted as 100% and 93.82% as the solutions were subjected to a gamma/H2O2 (1 mL/L) absorbed dose of 2 kGy. The chemical oxygen demand was reduced to 77% and 85% by treating the dye samples with UV/H2O2 and gamma/H2O2, respectively. The removal efficiency (G-value), dose constant (k), D0.50, D0.90, and D0.99 for gamma-irradiated samples were also calculated. The reduction in toxicity for treated samples was monitored by using the Allium cepa, Hemolytic, and brine shrimp (Artemia salina) tests while the Ames test was performed for mutagenic assessment. The A. cepa test showed 39.13%, 36.36%, and 47.82% increases in root length (RL), root count (RC), and mitotic index (MI), respectively, in UV/H2O2-treated samples while 48.78%, 48.14%, and 57.14% increases were shown with gamma-ray in conjunction with H2O2. The hemolytic test showed 21.25% and 23.21% hemolysis after UV/H2O2 and gamma/H2O2 treatments, respectively. The brine shrimp (Artemia salina) test showed 84.09% and 90.90% decreases in the nauplii death after UV/H2O2 and gamma/H2O2 treatments, respectively. The mutagenicity of UV/H2O2-treated solutions was reduced up to 84.41% and 77.87%, while it was 87.83% and 80.88% using gamma/H2O2 using TA98 and TA100 bacterial strains, respectively. The advanced oxidation processes based on UV and gamma radiation in conjunction with H2O2 can be applied for the degradation and detoxification of textile waste effluents efficiently.