Supported N-doped carbon quantum dots as the highly effective peroxydisulfate catalysts for bisphenol F degradation

As an alternative additive for bisphenol A, bisphenol F (BPF) also has very strong endocrine-disrupting effects. In the present study, N-doped carbon quantum dots (NCQDs) supported on three supports (e.g., SiO2, ceria-zirconia solid solution/CeZrO2 and gamma-Al2O3) were prepared, and catalytic peroxydisulfate (PDS) activation for BPF degradation was investigated. Catalyst characterization results showed that NCQDs were highly dispersed on the surface of both Al2O3 and CeZrO2 due to strong electrostatic attractive interactions between NCQDs and supports, while remarked agglomeration of NCQDs was identified on SiO2 surface because of repulsive interactions between NCQDs and SiO2 support. For the catalytic PDS activation for BPF degradation, the catalysts displayed an increasing catalytic activity ordered as: NCQD/SiO2 < NCQD/CeZrO2 < NCQD/Al2O3. The higher catalytic activity of NCQD/Al2O3 was ascribed to its higher NCQDs dispersion and stronger adsorption of PDS on the catalyst. Accordingly, the reaction of adsorbed PDS and BPF was found to be the rate controlling steps, which could be well described using the binary Langmuir-Hinshelwood model. Moreover, a volcano type dependence of BPF degradation rate on the NCQDs loading amount over Al2O3 was identified. The degradation intermediates of BPF were identified using gas chromatography-mass spectrometer and the degradation pathway was proposed. The present findings highlight that NCQDs supported on Al2O3 can be used a highly active catalyst in PDS activation for the degradation of organic pollutants.