A floatable and anisotropic composite aerogel for enhanced synergistic adsorption-catalysis of antibiotics in marine aquaculture wastewater

The widespread use of antibiotics in marine aquaculture poses a significant threat to the ecological equilibrium and human health. Collaborative adsorption-photocatalysis based on metal organic framework (MOF) catalysts has emerged as an advanced and highly effective strategy for removing antibiotics from aquatic environments. However, the intrinsic limitations of MOF including their low photocatalytic efficiency and susceptibility to structural collapse hinder their widespread practical application. Inspired by the symbiotic relationship between sea anemones and hermit crabs, we prepared a floating, anisotropic MIL-53 (Fe/Co)-graphene oxide/sodium alginate/nanocellulose composite aerogel (FCG/SC) catalyst via graphene oxide (GO) interface regulation and directional freeze-drying technology for efficient degradation of antibiotics in water. Strategic doping of Co elements within Fe-MOF metal nodes constructed defect structures and improved the catalytic performance. The introduction of GO in the hydrothermal reaction not only facilitates the nucleation of Fe/Co metal cations but also regulates the catalyst particle size and suppresses electron-hole recombination, ultimately enhancing photocatalytic efficiency. Furthermore, the directional channel structure of the aerogel shortens the light path, maximizing light absorption on the catalyst surface. The results indicated that the synergistic adsorption-photocatalytic (SAP) degradation of tetracycline hydrochloride (TC-HCl) exhibited superior efficiency compared to the pre-adsorption photocatalysis (PAP) processes. A significant SAP efficiency of 99.32 % was achieved when the MIL-53 (Fe/Co)-graphene oxide loading rate reached 30 wt%. Moreover, FCG/SC exhibited exceptional SAP degradation efficiency of 70.12 % even challenged with aquaculture wastewater containing NH₄Cl, KNO₃, NaNO₂, KH₂PO₄, and glucose. Crucially, the FCG/SC demonstrated exceptional stability and reusability. Five consecutive cycles revealed no substantial damage to the surface structure or catalyst leaching, and the degradation efficiency still can be remained at 96.16 %. This highly efficient and reusable composite aerogel offers a novel approach for the removal of TC-HCl from marine aquaculture wastewater.