Facile fabrication of robust, versatile, and recyclable biochar-graphene oxide composite monoliths for efficient removal of different contaminants in water

Water pollution produced by various contaminants is presently a major worldwide issue, posing a significant challenge to the development of novel materials for water treatment. Herein, robust and recyclable biochar-graphene oxide (BC-GO) composite monoliths were prepared utilizing lignin precursor as a carbon source in a one-pot hydrothermal process free of hazardous chemicals. Characterization results indicated the BC-GO com-posite monolith had abundant microchannels, nanopores, and a large specific surface area, thereby exhibiting a high adsorption capacity of 796.8 mg g(-1) to doxycycline in water, which was superior to conventional adsor-bents. Furthermore, by annealing the BC-GO composite monolith, it could be transformed to hydrophobic (CA = 140 degrees). The annealed BC-GO composite monolith retained a pronounced porous structure with a larger surface area and showed exceptional absorption capabilities of 55-130 g g(-1) toward various oils and solvents, which were higher/comparable to previously reported graphene-based materials. In addition, both BC-GO composite monoliths were highly stable and could be reused for a number of cycles of pollutants removal. The simplicity, environmental friendliness, and effectiveness of our approach to building BC-GO composite monoliths may pave the way for their future applications in the field of water purification.

Automated summary

This study developed BC-GO composite monoliths with abundant microchannels and nanopores, showing high adsorption capacity and exceptional oil absorption capabilities. They also exhibited good stability and reusability for pollutants removal, potentially paving the way for future applications in water purification.