ZIF-8-decorated wood sponge derived from biomimetic mineralization of polydopamine

Zeolitic imidazolate framework-8 (ZIF-8) is extensively researched and used because of its exclusive structural and excellent physicochemical properties; however, significant challenges of alleviating the adverse effects of its particle form in many aspects are still faced by the scientific community. In this study, in situ growth of ZIF-8 within the pore channels and surfaces of green cellulose-based wood sponge was attempted through polydopamine-mediated incubation. The wood sponge was prepared by eliminating lignin and hemicellulose from natural balsa wood. Then, the sponge was impregnated with dopamine aqueous solution to yield polydopamine-covered wood sponge (PWS). ZIF-8 crystals were ultimately in situ grown in the substrate after sequential impregnation with zinc nitrate hexahydrate and 2-methylimidazole aqueous solutions at room temperature. Additionally, the effects of the deposition concentration of the dopamine aqueous solution and ZIF-8 incubation time were investigated. The obtained ZIF-8@PWS was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis and thermogravimetric analysis. Finally, the toluene adsorption performance of porous ZIF-8@PWS in aqueous solution was also briefly evaluated, and it was demonstrated that the maximum adsorption capacity was 106.4 mg/g and the removal rate was as high as 94.2%. This work validates the envisioned universal protocol of preparing ZIF-8-decorated porous substrates through the integrated mediating role of polydopamine.