Polygonatum kingianum Dregs Biochar Accelerated Fe(Ⅱ)/Fe(Ⅲ) Cycle in Pyrite for Efficient Activation of Peroxymonosulfate to Degrade Carbamazepine in Water

• • PH-BC3-600 achieved 88.19% removal of 2.5 mg·L−1 carbamazepine within 5 minutes, demonstrating rapid kinetics suitable for continuous-flow water treatment systems. • • The composite exhibited high resistance to Cl−, NO3−, and humic acid, ensuring stable performance in complex water matrices typical of real wastewater. • • Incorporation of Polygonatum kingianum biochar increased highly reductive sulfur species (S2−, S2−2, Sn2−), which accelerated Fe(III)/Fe(II) cycling, enhancing PMS activation efficiency. • • PH-BC3-600 showed lower iron leaching than traditional pyrite, reducing secondary pollution and extending catalyst lifespan for sustainable operation.