Hydroxyapatite nanowires-based Janus micro-rods for selective separation of organics

Abstract

The selective separation of organics is very important in environment management and experiment, and the development of functional materials for selective adsorption is still a challenge. In this study, using hydroxyapatite nanowires (HAnW) as an eco-friendly artificial inorganic carrier and manganese dioxide (MnO2) nanoparticles (MnO2NPs) as active ingredients, a rime-like HAnW-based Janus micro-rods (MnO2NPs@HAnW), which HAnW was coated by MnO2NPs, was synthesized by ion exchange and hydrothermal reactions. The obtained Janus micro-rods MnO2NPs@HAnW were applied to adsorb organic pollutants, including different antibiotics and dyes, such as tetracycline (TC), ciprofloxacin (CIP), amoxicillin (AMX), rhodamine B (RhB), methyl blue (MeB), basic fuchsin (BF), methylene blue (MB), crystal violet (CV), and malachite green (MG). It was found that MnO2NPs@HAnW could very efficiently and selectively adsorb organics. Taking TC and BF for studying adsorption kinetics and thermodynamics, it indicated that their adsorption process followed pseudo-second-order kinetics and Freundlich thermodynamic model. More importantly, the mixture of organics containing RhB could be efficiently separated by MnO2NPs@HAnW with the simple separation device, and it had good reusability. In summary, the eco-friendly MnO2NPs@HAnW is an excellent candidate for the sustainable treatment of dyes wastewater and efficient separation of the mixture of organics. And we developed a new strategy of heterogeneous combination for preparation of inorganic functional materials.