Insights into heterogeneous catalytic activation of peroxymonosulfate by Pd/g-C3N4: The role of superoxide radical and singlet oxygen

Pd nanoparticles anchored on graphitic nitride carbon (Pd/g-C3N4) hybrid catalytic system was prepared by a simple KBH4 reduction method. Pd/g-C3N4 was very active in the degradation of bisphenol A (BPA) by efficiently activating peroxymonosulfate (PMS). Important influencing factors, such as catalyst dosage, PMS concentration, pH and reaction temperature for the BPA removal were investigated. Pd/g-C3N4-PMS demonstrated a wide effective pH range, namely 3.0-9.0. Radical quenching tests and electron spin response (ESR) analyses revealed that superoxide radical (O-2 center dot(-)) and singlet oxygen (O-1(2)) instead of sulfate radical (SO4 center dot(-)) and hydroxyl radicals (" OH) were the major oxidized species for the degradation of BPA.