Valorization of Urtica dioica roots as a highly-effective and eco-friendly biosorbent for adsorptive removal of hazardous textile dyes

[Display omitted] •Anionic CR and cationic SO dyes were removed from wastewater by Urtica dioica roots.•The qm values were found as 417 mg/g for CR and 625 mg/g for SO dyes at 25 °C.•Adsorption of CR and SO dyes is thermodynamically exothermic and spontaneous.•Adsorption process follows the pseudo-second-order kinetic.•The surface area and pore volume were found as 14.648 m2/g and 0.031 cm3/g. In this study, Urtica dioica roots were used in the biosorption of CR and SO dyes for the first time. FTIR-ATR, SEM, and BET were applied to characterize the biosorbent. The isotherm, kinetic, thermodynamic, and error analyses were investigated. Langmuir isotherm was found to be the most feasible for biosorption according to the highest r2. The qm for CR and SO dyes were calculated from the Langmuir model as 417 and 625 mg/g at 25 °C, respectively. It was found that the removal of CR and SO followed the PSO model. Besides, it was determined that the biosorption process from the IPD occurred in three stages. Negative values of ΔGo and ΔHo confirmed that the biosorption was spontaneous and exothermic. All results illustrated that biosorbent can be used as an eco-friendly, low-cost, and reusable biosorbent in the scope of zero waste in the removal of different textile dyes from wastewater.