Application of cork as adsorbent for water and wastewater treatment using ciprofloxacin as pharmaceutical model

The present study investigated the biosorption efficiency of cork against the antibiotic ciprofloxacin, contained within a synthetic mixture made of atrazine, bisphenol A and methylene blue. The biosorbent was characterized for its functional groups via Fourier Transform Infrared spectroscopy, for its point of zero charge by a pH meter, and for its morphology via brightfield microscopy. The effect of temperature (25, 35, and 45 °C), pH (3.0, 7.0, and 9.0), adsorbent mass (0.25, 0.5, and 0.75 g), initial ciprofloxacin concentration (5, 25, and 50 mg L⁻¹), and the presence of ions (MgCl₂, KCl, Na₂SO₄, and CaCl₂) was evaluated for ciprofloxacin adsorption onto cork. Even though it followed the pseudo-second-order and Elovich kinetic models, the isotherm data fitted the Freundlich model better, suggesting a heterogeneous adsorptive process. An adsorption capacity of 2.88 mg g⁻¹ was reached at a temperature of 25 °C and a pH 7.0, using 0.25 g raw cork with a ciprofloxacin initial concentration of 25 mg L⁻¹. Raw cork regeneration was studied after five cycles of adsorption/desorption, with a 2 ± 0.1% loss of adsorptive efficiency from the first to the fifth cycle. The potential of the adsorbent for the wastewater treatment was then evaluated, presenting a reduction of contaminants by 94.65 ± 4.8% after 24 h of treatment. This manuscript showed that cork presents a double environmental interest, as it may improve waste management and is a promising adsorbent material for water and wastewater treatment, contributing to public health and environmental protection.