Adsorption of ibuprofen from aqueous solution onto a raw and steam-activated biochar derived from recycled textiles insulation panels at end-of-life: Kinetic, isotherm and fixed-bed experiments

Abstract

This study explores the potential use of recycled textile biochar (RT-BC) and steam-activated biochar (RT-SABC), derived from insulation panels at end-of-life, as sorbents for removing ibuprofen from aqueous solutions. After steam activation, the surface area and micropore volume increased. Subsequently, kinetic and isotherm experiments were investigated at 20 °C, 200 rpm and 50 mg/L ibuprofen solution. Equilibrium was reached after 24 h for RT-BC and 120 h for RT-SABC. The kinetics of RT-BC and RT-SABC followed the pseudo-first-order and Elovich models, respectively. RT-SABC isotherm showed the highest adsorption capacity (53.9 mg g−1), well-fitted into the Sips model. Ibuprofen uptake by RT-SABC was nearly irreversible. Afterward, RT-SABC dynamic performance was evaluated in a fixed-bed column for three bed heights. The breakthrough point (41.7–476.7 h), the volume of effluent treated (0.6–6.4 L at breakthrough) and adsorption capacity (22.09–39.81 mg g−1) increased with bed height (10–30 cm). Thomas and Clark's models simulated the experimental points, confirming second-order kinetics and Sips isotherm. Different functional groups were involved in the adsorption mechanism. Preliminary experiments in tap water on RT-SABC showed a removal (>83 %) due to ionic strength and reduced pH. Therefore, RT-SABC could be an efficient adsorbent for ibuprofen removal from aqueous systems.