A high-performance biochar produced from bamboo pyrolysis with in-situ nitrogen doping and activation for adsorption of phenol and methylene blue

Abstract Nitrogen doping is a promising method for the preparation of functional carbon materials. In this study, a nitrogen-doped porous coral biochar was prepared by using bamboo as raw material, urea as nitrogen source, and KHCO3 as green activator through in-situ pyrolysis. The structure of the obtained biochar was characterized by various techniques including nitrogen adsorption and desorption, Raman spectroscopy, X-ray photoelectron spectrometer, and etc. The adsorption properties of nitrogen-doped biochar were evaluated with phenol and methylene blue probes. The results showed that the nitrogen source ratio had a significant effect on the evolution of pore structure of biochar. Low urea addition ratio was beneficial to the development of pore structures. The optimum specific surface area of nitrogen-doped biochar could be up to 1693 m2·g-1. Nitrogen doping can effectively improve the adsorption capacity of biochar to phenol and methylene blue. Biochar prepared at 973.15 K with low urea addition ratio exhibited the highest adsorption capacity for phenol and methylene blue, and the equilibrium adsorption capacity was 169.0 mg·g-1 and 499.3 mg·g-1, respectively. By comparing the adsorption capacity of various adsorbents in related fields, it is proved that the nitrogen-doped biochar prepared in this study has a good adsorption effect.