Insight into the enhanced adsorption behavior and mechanism of ibuprofen from water on polyaniline/acid-impregnated reed biochar composite

As a typical nonsteroidal anti-inflammatory drug, a significant amount of ibuprofen (IBP) can not be adsorbed by the human body and thus enters the environment, posing potential risks. Biochar (BC) adsorption is low-cost and easy to implement and is a potential technology for the removal of IBPs from water. To the best of our knowledge, the adsorption mechanism of IBP on BC is unclear, and certain physiochemical properties, such as low porosity, limit the adsorption capacity of IBP. In this study, a novel synthesis strategy involving the loading of nitrogen-rich polyaniline (PANI) particles is proposed to improve porosity and increase surface functional groups. A PANI/acid-impregnated reed BC (PANI/H-BC) composite was prepared through in-situ polymerization using reed BC synthesized via rapid pyrolysis. Adsorption experiments revealed that PANI/H-BC has a maximum adsorption capacity of 35.58 mg/g, which is 4.3 times and 3.7 times greater than those of PANI and BC, respectively. Besides, PANI/H-BC reached adsorption equilibrium within 30 min, reflecting a reduction of 50% compared to BC. It retains a significant adsorption capacity after ten cycles and is reusable. Moreover, the physical and chemical properties of PANI/H-BC were characterized, and the enhanced adsorption performance was demonstrated to be the result of multiple mechanisms, including π‒π conjugation, hydrogen bonding and electrostatic interactions. These findings offer theoretical support for the adsorption and removal of IBPs as well as optimization of BC adsorbents. Production cost assessment and comparison, including industrial factors, were conducted. The low cost and renewability underscore its significant potential in practical applications. (Figure presented.)