A synergistic approach to synthesize nitrogen-doped nanobiochars with high adsorptive performance

Abstract

Developing versatile and energy-efficient processes to synthesize functional nanomaterials is of significant in response to economic concerns, enviroment, and technological challenges. This study presents a synergistic route for the facile, green, and low-cost synthesis of nitrogen-doped nanobiochars (NNBs) from an agriculture waste without any chemical supplements, promoting environmental sustainability. Specifically, rice husk is treated at 800 oC for 5 minutes in an enclosed reactor, followed by quenching in water and ultrasonic vibration in a water/ethanol mixed solvent. Surface morphology, specific surface area, crystalline structure, phase component, and chemical composition of the NNBs are characterized by electron microscopy, Brunauer-Emmett-Teller, X-ray diffraction, Raman, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy measurements, respectively. The results indicate that the NNBs possess porous structures with a high specific surface area of 303.4 m2/g and a large pore volume of 1.23 cm3 g-1. Moreover, the porous nature and functional groups, including C=NH (55.0%) and N-H (34.35%), in NNBs are harnessed for removing Ciprofloxacin, a common antibiotic pollutant in water, via hydrogen bonding and other interactions. As expected, NNBs demonstrate a high removal efficiency of 72.73% and and adsorption capacity of 7.27 mg/g at a pH of 5 and contact time of 150 min. These findings therefore opens new possibilities for scalable production of value-added materials from agriculture wastes for water treatment, enhancing public health and environmental protection.