Porous cellulose gel-regulated flower-like ZnO-Cu nanoparticles for enhancing interfacial catalysis activity and recyclability in environmental catalysis

The recyclability of heterogeneous catalysts directly affects their utilization efficiency, use cost, sustainability, and environmental issues. Herein, the flower-like ZnO-Cu nanoparticles with high interfacial reactivity were in-situ synthesized in the porous cellulose gel to obtain the ZnO-Cu/cellulose composite gel (ZnO-Cu/CCG) catalyst, which possesses superior recycling and reusing stability thanks to the bulk nature of the gel. The ZnO-Cu/CCG catalysts with tunable sheet-like and flower-like ZnO were fabricated by the dissolution of cellulose into zinc chloride (ZnCl 2 ) solvent and regeneration using different coagulating baths (water, ethanol, or isopropanol). The CCG prepared from isopropanol coagulation exhibited the highest specific surface area (291.6 m 2 /g) and porosity (92.3%). The various network structures of CCG provided different nucleation sites and growing spaces for controllable preparation of ZnO with tunable morphology. The complete removal of methyl orange (MO), Congo red (CR), and methylene blue (MB) required only 80 sec, 3 min, and 5 min, using flower-like ZnO-Cu/CCG catalysts prepared by isopropanol coagulating bath, the pseudo-first-order rate constant (k) is 2.8170 min −1 , 1.1330 min −1 , and 0.8506 min −1 , respectively, much higher than that of the ZnO-Cu powders. Furthermore, the catalytic reusability of ZnO-Cu/CCG can be investigated over 50 successive cycles, in which the catalytic efficiency did not decrease appreciably.