Hydroxyapatite Coated with Co-Based Metal Organic Framework Nanoparticles as Heterojunctions for Catalytic Degradation of Organics

Hydroxyapatite (HA), as a kind of biocompatible inorganic material, is rich in hydroxyl groups on the surface and can easily undergo ion exchange reactions with metal ions. In this study, using HA nanowires (HAnW) as eco-friendly carriers and promoters, a HAnW-based heterojunction (HAnW@CoMOF), in which HA was coated by the cobalt-based metal–organic framework (Co-MOF), was synthesized by a simple in situ growth method and ion exchange method. Then, using HAnW@CoMOF to activate peroxymonosulfate, some typical organic pollutants including antibiotics and dyes, such as tetracycline (TC), malachite green, crystal violet, methylene blue, and rhodamine B, were excellently degraded. The removal rate of TC was 86% within 0.5 min and 97% within 15 min. It could also be reused for 10 times with the removal rate of TC being 95%. The catalytic mechanism was investigated with detecting reactive substances, including 1O2, •O2– •OH, and SO4–•. We considered the formation of Co–OH+ in the heterojunction of HAnW@CoMOF, as there are a lot of −OH in HAnW, which fixed Co2+ of Co-MOF. In summary, it provided an eco-friendly HA-based catalyst for effective and quick degradation of organic pollutants.