ZnO/biochar nanocomposites via solvent free ball milling for enhanced adsorption and photocatalytic degradation of methylene blue.

There are challenges in developing multifunctional materials that can not only effectively adsorb but also completely eliminate organic contaminants in water. In this work, novel ZnO/biochar nanocomposites were synthesized using a facile ball-milling method. A series of characterization results showed that the ZnO nanoparticles dispersed uniformly on carbon surface within the biochar matrix. Ball milling increased the mesopores and macropores of the nanocomposites by breaking biochar and squeezing ZnO. The addition of appropriate amount of ZnO into biochar enhanced both the adsorption capacity and photocatalytic ability of the nanocomposites for methylene blue (MB) removal. When the initial concentration of MB was 160 mg/g, the nanocomposites exhibited high MB removal efficiency (up to 95.19%) under visible light through the combination of adsorption and photocatalysis. This work provides a feasible synthesis of metal oxide/biochar nanocomposites with excellent adsorption and photocatalysis properties for the treatment of organic dye wastewater. [Display omitted] • ZnO/biochar nanocomposites were fabricated through simple ball milling. • Varied sized ZnO nanoparticles dispersed uniformly in the biochar matrix. • Ball milling increased the mesopores and macropores of nanocomposites. • Adsorption and photocatalytic activity were enhanced with proper ZnO addition. • BZ-X exhibited efficient MB removal by combining adsorption and photocatalysis. [ABSTRACT FROM AUTHOR]