Green synthesis of the functional bio-macromolecular composite film based on cellulose material for the photocatalytic degradation of tetracycline: performance and mechanism

Functional bio-macromolecules such as cellulose nanofibers are excellent photocatalytic carriers. They were prepared by a green chemistry approach using office waste paper as raw material to produce 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized cellulose nanofibers (TOCNF), and dendrimer (macromolecule)-modified clay was immobilized to add functionality and strength to film, and nano-ZnO was loaded on the film to activate photocatalytic activity. This composite film was used for the catalytic degradation of tetracycline (TC). When the mixing ratio of clay and TOCNF was clay /TOCNF (g/g) =15 %, the mechanical properties were best. Photosensitized nano-ZnO was immobilized to activate the film's photocatalytic activity, with dendrimers acting as reservoirs for TC pollutants and carriers of electron transfer, which can greatly improve TC degradation. The results show that the composite film has a good degradation effect on low concentrations of TC in a neutral environment. Under the condition of pH 7, the degradation rate of TC at 10 ppm can reach 70.5 % within 180 min. The photocatalytic degradation of TC followed the pseudo-first-order kinetic model and a 3E analysis model was deployed to comprehensively evaluate the process. The TOCNF composite film offers a new way to choose the photocatalytic support and overcomes the disadvantages of powder materials that agglomerate and are difficult to recover.