Decolorization of Remazol Brilliant Violet 5R and Brilliant Green dyes by Hypnum cupressiforme using response surface methodology-central composite design methodology: toxicity assessment studies by Daphnia magna

This study is the first report that aims to optimize the removal of Remazol Brilliant Violet 5R (RBV 5R) and Brilliant Green (BG) from synthetic solutions using Hypnum cupressiforme samples from Abant Mountains of Bolu (Turkey) as biosorbent and to conduct toxicity evaluation studies of treated wastewater using Daphnia magna. Optimization was performed using central composite design under response surface methodology with the operational factors of dye concentration, H. cupressiforme dose, and process time. The optimal conditions for dye concentration, H. cupres-siforme dose, and process time obtained by the numerical analysis were 19.02 mg/L, 0.18 g/50 mL and 110.59 min for RBV 5R, while these values were 18.57 mg/L, 0.18 g/50 mL and 99.45 min for BG, respectively. At the optimum values, maximum RBV 5R and BG removal were achieved as 99.39% and 99.22%, respectively. The D. magna mortality rates showed that treatment with adsorption were sufficient to remove the complete toxicity of dyes especially for RBV 5R.