Novel bifunctional in-based metal–organic gel/bacterial cellulose composite gels for effective tetracycline antibiotics removal: Synergistic behavior and mechanism insight of adsorption-photocatalysis

The widespread pollution by tetracycline antibiotics has been proved to be a serious problem to human health and biological systems. Synergistic adsorption-photocatalysis method has demonstrated satisfactory miraculous results for the removal of recalcitrant pollutants. Here we constructed a novel bifunctional In-MOG with hierarchical pore structures, large specific areas and abundant active sites via room-temperature synthesis, achieving 92.93% and 95.58% removal of chlortetracycline (CTC) and tetracycline (TTC) in 60 min, respectively. The excellent removal performance was attributed to the synergistic adsorption-photocatalysis process that resembled a repetitive assembly line work of “enriching and destroying” pollutants. Briefly, CTC/TTC molecules in the aqueous environment were rapidly adsorbed by In-MOG through pore filling, electrostatic interaction, hydrogen bonding interaction, complexation and π-π stacking interaction to accomplish enrichment of pollutants; meanwhile, the generated h+ and •O2− were involved as the main active species in the rapid in-situ photodegradation of pollutants to complete their destruction. Furthermore, In-MOG exhibited excellent anti-interference ability and reusability. Afterwards, in order to address the drawback of easy agglomeration and difficult recycle of powdered In-MOG, In-MOG/BC with the advantages of good removal performance and fine stability was constructed by immobilizing In-MOG into bacterial cellulose (BC) flexible substrate. Further exploration of In-MOG/BC in a self-built reactor for CTC/TTC removal from dynamic systems was carried out to assess the prospect for large-scale applications. Overall, the facile rational design for In-MOG/BC with synergistic adsorption-photocatalysis and the continuous flow reactor provides worthwhile insights in the water purification field.