Engineering of 3D architectures with yttrium on reduced-graphene oxide nanosheets for effective co-adsorption of tetracycline and phosphate

Abstract

Effective removal of composite pollutants containing antibiotic and phosphorus is still facing challenges for the wastewater treatment. In this study, yttrium-hydroxide component was loaded onto the surface of reduced GO nanosheets via low-temperature hydrothermal method, to synthesize the 3D YrGO architectures. The optimized YrGO-8 hydrogels showed the maximum adsorption capacity of 226.45 mg/g for tetracycline (TC), and 33.403 mg/g for phosphate, which was higher than many other reported adsorbents. The characterization results demonstrated that the rGO nanosheets were successfully crosslinked by Y(III) to form a porous 3D structure, which was beneficial to the mass transfer and active sites exposure. The adsorption behaviors of TC or phosphate was suppressed by the co-existing phosphate ions or TC, with slower adsorption rate and lower adsorption amount. Importantly, column adsorption analyzed by Thomas model illustrated the rate basis of YrGO-8beads to capture TC/phosphate in an adsorbate diffusion rate. Moreover, the 3D YrGO-8 remained stable and high reusability in multi-uptake-release rounds via pH regulation. The mechanism study suggested that the sequence of adsorption process of TC followed the order of hydrogen bond (HB) > π – π electron donor–acceptor (EDA), n − π EDA > Y(III) bridging interactions, while the uptake of phosphate formed Y-O-P inner-sphere complexes prior to HB. This study proposes a novel insight into the development of 3D architectures for effectively simultaneous treatment of composite TC and phosphate pollution.