Conversion of invasive plant species (Bidens pilosa L.) into bioadsorbents for simultaneous removal of ciprofloxacin antibiotic and crystal violet dye

Here, we present the production of carbonaceous bioadsorbent derived from Bidens pilosa L. invasive plant biomass. The bioadsorbent, pyrolyzed at 400 °C, was selected to assess the adsorption performance against ciprofloxacin antibiotic and crystal violet dye from water. This bioadsorbent exhibited a porous structure with a surface area of 4.0 m² g⁻¹ and a point of zero charge of 7.7. To optimize simultaneous removal conditions, a Box-Behnken design and response surface methodology were employed. The model predicted the optimum condition at a dosage of 1.23 g L⁻¹, a ciprofloxacin concentration of 12.82 mg L⁻¹, a crystal violet concentration of 20.5 mg/L, and pH of 3. Notably, the tested values closely matched the predicted values. Additionally, kinetic and isotherm models were applied, indicating excellent adherence to pseudo-first and second-order kinetics, as well as Langmuir and Freundlich isotherms, respectively. Due to high adsorption capacities, i.e., 31.89 mg/g for ciprofloxacin and 58.42 mg g⁻¹ for crystal violet of the bioadsorbent, it is proposed that the conversion of Bidens pilosa L. invasive plant biomass into bioadsorbents is both feasible and sustainable for the simultaneous removal of antibiotics and dyes from water.