Synergy between adsorption and bio-degradation of real wastewater polycyclic aromatic hydrocarbons (PAHs) by laccase immobilized on pineapples waste activated carbon : Recyclability, performance, and DFT analysis

The contamination of micropollutants in wastewater has become a global issue due to their persistent impact on ecosystems and human health. The enzymatic degradation of polycyclic aromatic hydrocarbons (PAHs) offers a promising, sustainable approach, although it is limited by reduced stability and recycling challenges. In this study, we demonstrated the use of pineapple peel waste as a novel support for the immobilization of laccase (Trametes versicolor) via an adsorption technique (laccase@PPAC). The activated carbon synthesized using potassium hydroxide (PPAC), and laccase@PPAC were characterized through various methods. The laccase@PPAC exhibited excellent performance, achieving maximum adsorption capacities of 270.38 mg/g for benzo[a]pyrene (BaP) and 335.27 mg/g for anthracene (Ant). When combined with enzymatic degradation, total removal reached 98.72 % for BaP and 99.87 % for Ant, corresponding to total degradation-enhanced capacities of 301.21 mg/g and 317.41 mg/g, respectively. Additionally, laccase@PPAC maintained high removal efficiency over 20 reuse cycles. The system showed superior thermostability and pH tolerance compared to free-state laccase. Adsorption kinetics followed the pseudo-first-order model, while equilibrium data were best described by the Langmuir isotherm. This work highlights the potential of pineapple waste-derived activated carbon as a sustainable and effective support for enzyme immobilization in the bioremediation of PAHs-contaminated wastewater.