Degradation of aqueous bisphenol A in the CoCN/Vis/PMS system: Catalyst design, reaction kinetic and mechanism analysis

Low levels of pharmaceutical and personal care products (PPCPs) in the environment have attracted widespread attention as a new class of organic pollutants. Degradation of these PPCPs by optimizing advanced oxidation processes (AOPs) is highly desirable, but remains a huge challenge. Here, the Co sites embedded in carbon nitride catalyst (CoCN) was synthesized by a simple one-step pyrolysis of Co-based Zeolitic Imidazolate Framework-67 (ZIF-67) and melamine, of which highly dispersed Co atom sites were uniformly doped in the CN ring of g-C3N4. In the optimized system of visible light irradiation involving CoCN and peroxymonosulfate (CoCN/Vis/PMS system) (lambda >= 420 nm, [PMS] = 0.2 g L-1, pH = 7.0), 100% of bisphenol A (BPA, 20 mg L--(1)) was removed after 2 min and the total organic carbon (TOC) removal rate of BPA reached 88.8% after 90 min reaction. Detailed characterization showed that a specially designed unique Co-N bond structure was crucial for the high degradation performance of BPA in the CoCN/Vis/PMS system. HO center dot, SO4 center dot(-), O-2 center dot(-), h(+) and O-1(2) contributed to the BPA degradation in the CoCN/Vis/PMS system. Besides, the effect of solution pH and several common anions in environmental water on BPA removal was evaluated. Several typical pollutants, sulfamethoxazole (SMX), ciprofloxacin (CIP), 4-chlorophenol (4-CP) and atrazine (ATZ), were effectively degraded by the same CoCN/Vis/ PMS system, which exhibited universal applicability of this AOP reaction. The cycling degradation experiment showed the stability and reusability of the CoCN/Vis/PMS system. This work offers immense hope to the environmental purification and provides numerous new opportunities for the effective removal of other pollutants beyond BPA, SMX, CIP, 4-CP and ATZ.

Automated summary

Low levels of PPCPs in the environment have attracted attention as a new class of organic pollutants, and their degradation by optimizing AOPs remains a challenge. The Co sites embedded in carbon nitride catalyst showed high efficiency in removing BPA and other pollutants under visible light irradiation, demonstrating universal applicability and reusability. This work offers potential for environmental purification and effective removal of various pollutants beyond BPA.