Biodecolorization of azo dye Acid Blue 92 (AB92) by Ceratophyllum de-mersum L.: process optimization using Taguchi method and toxicity as-sessment

This study evaluated the ability of the submerged aquatic plant Ceratophyllum demersum to remove the Acid Blue 92 (AB92) dye. The effect of some operational parameters such as the reaction time, initial dye concentration, initial plant biomass, and pH, on dye removal efficiency was studied. Based on Taguchi’s results, the optimized conditions for dye removal were time 7 days, dye concentration 20 mg l-1, initial plant biomass 4 g, and initial pH 5. Fourier-transform infrared spectroscopy (FTIR) results confirmed the interaction between dye molecules and plants. Based on the results of this study, C. demersum had a reusability to remove the dye, this fact confirming the mechanism of biodegradation in the dye removal process. Also, the effect of AB92 on the physiological responses of C. demersum was investigated. Minimum relative growth rate, tolerance index, chlorophyll a, chlorophyll b, total chlorophyll, and total carotenoids at a concentration of 20 mg l-1 of AB92 were observed. The concentration of cyanidin glycoside, lipid peroxidation, and antioxidant activity increased in both concentrations of 10 and 20 mg l-1. It can be concluded that both concentrations of AB92 induced antioxidant activity and the risk of oxidative stress for Ceratophyllum.