Deep eutectic solvent assisted preparation of ZnO deposited carbonized wood for efficient CO2 storage and oil absorption

Abstract

Wood-derived carbon materials with high porosity are promising for gas capture and wastewater treatment. In this work, ZnO coated carbon foams were fabricated by in situ growth of ZnO crystals on the biomass scaffold. A specially designed deep eutectic solvent (DES) composed of ZnCl2 and lactic acid was utilized for wood delignification. In particular, the DES has a dual role as a lignin removal agent and ZnO precursor. After carbonization, spherical ZnO particles were uniformly and tightly deposited on the carbonized balsa wood matrix. The interconnected channels of pristine wood are well inherited by the carbon foam. The ZnO@carbon foam (DW-800) prepared with a carbonization temperature of 800 °C displayed a specific surface area of 446 m2/g, and a water contact angle of 133°. The CO2 adsorption and oil absorption tests were performed to evaluate the applied performance of the composites. Results demonstrated that DW-800 showed a superior CO2 adsorption capacity of 3.03 mmol/g (25 °C, 1 bar). Moreover, the flame-retardant DW-800 possessed a desirable oil/water separation ability for both heavy oil and light oil. This work presents a facile, low-cost and top-down approach to the fabrication of wood-derived carbon materials.