Carbon Nano-Sphere Derived From Crop Residues by Acidic Lithium Bromide Treatment and as an Excellent Adsorbent to Both Heavy Ions and Methyl Orange

Abstract

Carbon spheres, as a widely used carbon material, has attracted extensive attentions. The hydrothermal carbonization (HTC) method was a promising candidate for production of carbon-sphere. But the raw lignocellulose was natural resistant and hardly transformed into the carbon-spheres during HTC. Herein, acidic lithium bromide (LiBr) was supplied in the HTC process to break the resistance of lignocellulose and promoted the nano-carbon spheres forming in mild conditions: 140°C for 150 min. The carbon spheres from raw corn stover showed decent morphology properties and abundant functional groups, which was better than that from pine and poplar wood. It led to the high removal efficiency of the biochar-corn stover to both heavy ions and methyl orange in the waste water. Meanwhile, the filtrate under the optimal reaction was already reused. After five runs, the recycling showed slight effect on the morphology properties and the adsorption capability of biochar. These results verified the practical production of biochar spheres from lignocellulose in mild conditions, which provided more potential for the synthesis of novel biomass-based materials for wide applications.