Fabrication of cellulose nanocrystal from Carex meyeriana Kunth and its application in the adsorption of methylene blue

•CNC was first extracted from Carex Meyeriana Kunth successfully.•Aqueous biphasic system was applied to facilitate the extraction from raw material.•H2O2 was added during the adsorption experiments to facilitate the dye removal.•The adsorption behavior of CNC for methylene blue was systematically investigated. Cellulose nanocrystal (CNC) was extracted from Carex meyeriana Kunth (CMK) by a combination of TEMPO oxidation and mechanical homogenization method, and used to remove methylene blue (MB) from aqueous solution. After alkali-oxygen treatment, the aqueous biphasic system (polyethylene glycol/inorganic salt) was applied to further remove lignin from CMK. The characteriazation of CNC, and the effects of H2O2 dosage, CNC dosage, adsorption time, and initial MB concentration on the MB removal capacity of CNC were investigated. The results showed that the removal percentage of MB by CNC was raised with the increase of H2O2 and CNC dosage. The adsorption kinetics of prepared CNC followed the pseudo-second-order model, and the adsorption isotherms fitted well to the Langmuir model with a calculated maximum adsoption capacity of 217.4mg/g, which was higher than those of CNC extracted by acid hydrolysis method, indicating CNC extracted from CMK had promising potentials in the field of MB adsorption.