Enhanced Selective Degradation of Pharmaceutical and Personal Care Products by β-Cyclodextrin-Decorated ZIF-67 Nanocomposites in Reclaimed Water

Abstract

A peroxymonosulfate oxidation system was developed via modification of β-cyclodextrin (β-CD) on the surface of Fe²⁺-doped ZIF-67 (CD/Fe@ZIF-67) as an activator. The 99.7% carbamazepine, 91.3% bisphenol A (BPA), and 95.4% diclofenac (DCF) degradation efficiency were achieved within 10 min, 60, and 1 min, respectively. The hydrophobicity of these three pollutants is positively correlated with their adsorption kinetic constants by CD/Fe@ZIF-67 due to the introduction of β-CD. Scavenger experiments and electron spin resonance spectra confirmed that carbamazepine was preferentially oxidized by SO₄^•- [λ(SO₄^•-)(70.5%) > λ(^•OH)(28.2%) > λ(O₂^•-)(1.3%)], where SO₄^•- and O₂^•- played dominant roles in the degradation of BPA [λ(SO₄^•-)(71.7%) > λ(O₂^•-)(22.8%) > λ(^•OH)(5.5%)], and O₂^•- was responsible for DCF removal [λ(O₂^•-) = 93.2%]. Additionally, the particulate catalyst was immobilized in the shell side of a ceramic membrane in a membrane reactor for catalyst recovery. This reactor achieved nearly 100% removal efficiency under optimal conditions: 0.036 wt % catalyst loading, 0.5 mM peroxymonosulfate concentration, 1 L inflow, 10 mg/L initial carbamazepine concentration, and 0.012 L/min hydraulic retention time. In summary, this study elucidates the active role of β-CD in a polymetallic/peroxymonosulfate system and provides valuable insights into the development of effective oxidation methods for pharmaceutical and personal care products in wastewater.