Low‐temperature synthesis of maize straw biochar‐ZnO nanocomposites for efficient adsorption and photocatalytic degradation of methylene blue

Abstract

AbstractAs a new type of environmental functional material, biochar composites have become the focus of considerable interest in wastewater treatment research owing to their excellent adsorption and photocatalytic properties. However, the fabrication of cost‐effective biochar composites with high photocatalytic efficiencies at low synthesis temperatures remains challenging. In this study, biochar was prepared using an environmentally friendly hydrothermal method at a low temperature with maize straw as the waste material, instead high costs pyrolysis process. Hexagonal zinc oxide nanoparticles were grown in and on the biochar framework using the chemical deposition method. The adsorption and photocatalytic degradation performance of aqueous methylene blue (MB) solutions were investigated. We demonstrated that the photocatalytic degradation performance of the biochar‐ZnO composites was considerably higher than that of the most other reports. The degradation of the MB solutions (60 mg/L) reached 98.0 % in 240 min under low‐power ultraviolet light (50 W) irradiation. We propose that the synergetic effect of the high adsorption of the porous biochar and the photocatalytic activity of ZnO led to a high degradation efficiency. This study provides theoretical and practical guidance for the preparation of photocatalytic composites obtained from waste biomass materials by a cost‐efficient, fast, and environmentally friendly method, and the efficient degradation of dye pollutants in water.