Template-free synthesis of three dimensional porous boron nitride nanosheets for efficient water cleaning

Preparation of efficient and reusable adsorption materials for water treatment and purification is still remarkably challenging. In this paper, three dimensional porous boron nitride nanosheets (3D porous BNNSs) with high chemical stability and excellent adsorption capacity for organic dyes have been successfully synthesized through a template-free route. The 3D porous BNNSs consist of uniform nanosheets with average diameter of about 200 nm and thickness of about 3 nm. The adsorption conditions have been optimized by varying the experimental parameters such as initial dye concentration, solution pH, contact time, etc. As expected, the 3D porous BNNSs exhibit superior adsorption activity toward methylene blue (MB) in aqueous solution: more than 95.3% of the dye can be removed within 5 min compared with the adsorption efficiency of 10% for conventional activated carbon and 67.5% for the 3D porous BNNSs reported previously at pH 8.0 and 30 °C. The unique 3D structure and high density adsorption sites are believed to play a key role in the efficient removal performance. Moreover, about 94.5% of the starting adsorption capacity is maintained after ten adsorption-regeneration cycles. With the high adsorption efficiency and reusability performance, the 3D porous BNNSs are suitable for water cleaning and meet the requirement of mass production.