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.

Automated summary

In this study, Bi2MoO6 and bamboo-derived biochar composite was synthesized by ball milling method, and its adsorption and photodegradation abilities were evaluated. The results showed that the composite had high adsorption capacity and photodegradation efficiency, and could completely remove methylene blue within a wide pH range.