Removal of diphenols using pine biochar. Kinetics, equilibrium, thermodynamics, and mechanism of uptake

•Biochar with a high surface area (1473 m2g−1) was produced with mesoporous features.•The biochar successfully removed emerging pollutants from synthetic wastewater.•DFT calculation successfully elucidated the diphenol adsorption mechanism on biochar.•The HOMO-LUMO energy gap explored the electron properties of the diphenol-biochar system.•The mechanism suggested π electrons at high-energy states with stable π–π conjugation.