NiO-decorated BN fiber composites with high surface charges for tetracycline adsorption and rapid desorption capacities.

It is known that BN fibers with functional groups on their surfaces and excellent recyclability are used in the adsorption and removal of antibiotics. However, the antibiotics are difficult to desorb after adsorption, which makes it challenging to continuously use BN fibers on a large scale. In this study, NiO-modified BN fiber composites were prepared through an alkali activation and impregnation process. Among them, uniform loading of NiO on the BN fiber surface was achieved at the NiO content of 7.58% (BN-NiO-0.2), which was due to the generation of hydroxyl groups and B-O-Ni bonds on the fiber surface. Although BN-NiO-0.2 has a low specific surface area of 127.46 m2/g, it exhibited a high adsorption capacity for tetracycline (504.12 mg/g) due to the maximum negative charge (-26.501 mV) on the BN fibers surface. Ni2+ serves as a junction between TC molecules and BN adsorbents to facilitate charge transfer on the surface of BN, thereby forming stable complexes with TC and enhancing its adsorption from theoretical calculations. Notably, the adsorption rate of BN-NiO-0.2 remained above 98% after five cycles, and the release rate of Ni ions (0.0301 mg/L) was extremely low. Furthermore, after five cycles of tetracycline adsorption, the adsorbed tetracycline in BN-NiO-0.2 can rapidly reach 99% desorption by adjusting the pH to reverse the surface charges, enabling quick separation between the adsorbent and tetracycline. This shows excellent environmental friendliness and potential for application. [Display omitted] • Uniformly NiO-decorated BN fiber was obtained by alkali activation and impregnation. • The decoration of BN fiber with a proper NiO maximizes the surface charges. • BN-NiO-0.2 with a low specific surface area achieves highest TC adsorption capacity. • Reversal of surface charge promotes rapid desorption of adsorbed TC. [ABSTRACT FROM AUTHOR]