Ball-milled Bi2MoO6/biochar composites for synergistic adsorption and photodegradation of methylene blue: Kinetics and mechanisms

The adsorption of reactants is highly correlated with photocatalysis. Improving the adsorption ability of photocatalyst may realize highly efficient removal performance. In this work, Bi2MoO6 and bamboo-derived biochar composite was developed by a facile ball milling method. The adsorption and photodegradation abilities of the composites were evaluated by removing methylene blue (MB), which is a most commonly used aromatic-cationic dye. The maximum adsorption capacity of MB on the optimized 20 % Bi2MoO6/biochar sample was 160.6 mg/g, and the synergistic adsorption-photocatalytic removal efficiency of MB reached 93.3 % within 30 min, which were superior to Bi2MoO6 (13.3 mg/g, 31.6 %) and biochar (127.7 mg/g, 69.8 %). Compared to Bi2MoO6, the Bi2MoO6/biochar composites showed decreased bandgap and enhanced charge separation efficiency. The strong interfacial interactions between Bi2MoO6 and biochar in composites facilitated the photo-induced electrons transfer. Furthermore, the photodegradation efficiency enhanced along with the adsorption efficiency while pH value increased, which further proves the synergy between adsorption and photodegradation. Noticeably, the 20 % Bi2MoO6/biochar can completely remove MB at pH between 3 and 11. This work proves Bi2MoO6 modified biochar prepared by ball milling is a promising material for synergistic adsorption and photodegradation removal of organic pollutants. [Display omitted] •The optimized 20 % BMO/BC had the maximum adsorption capacity of 160.6 mg/g.•The 20 % BMO/BC showed high MB removal efficiency under light (99.7 %, 60 min).•Removal kinetics were applied to analyze the processes under light or dark.•Synergistic adsorption and photodegradation removal mechanism was elucidated.•Biochar promoted photo-inducted charges transfer in composites.