Environmental sustainable ZrO2 -phosphorous Biochar nano composite derived from sugarcane bagasse and their adsorption behavior of antidepressant drugs

Phosphorous biochar was synthesized from sugarcane bagasse (SB) by applying a 2:1 weight ratio of H₃PO₄ to OP and pyrolyzing it at 600 °C under nitrogen. Sugarcane bagasse was selected for its affordability and environmental benefits as a carbon support. Following this, a zirconium-loaded PC nanocomposite (ZrP400) was developed by impregnating zirconium hydroxide in concentrations 5-30% onto the mesoporous phosphorous biochar, which was then thermally treated at 400ºC. Analytical techniques showed that the ZrP400 adsorbents had a high surface area (1697-2434 m²/g) and considerable porosity. The effectiveness of these adsorbents in removing the hazardous tricyclic antidepressant amitriptyline (AMT) from water was tested. At a pH of 6.52, the neutral adsorbent provided various chemical functional groups that facilitated the binding of amitriptyline. With 20 mg of adsorbent at 35ºC, the capacity for amitriptyline adsorption reached up to 585 mg/g. Adsorption equilibrium was reached within 120 min over a concentration range of 10 to 300 mg/L. Kinetic and equilibrium data showed that the adsorption was well described by the pseudo-second-order and Freundlich isotherm models, indicating that chemisorption was the primary mechanism, with physisorption also contributing significantly to amitriptyline removal. The spent adsorbent could be effectively regenerated using ethanol. Additionally, the process's sustainability was assessed using GAPI and AGREE metrics, which confirmed its environmental friendliness, practicality, and sustainability.