Development of self-assembled nanocrystalline cellulose as a promising practical adsorbent for methylene blue removal

•Unlike NCC Powder, Self-assembled NCC can be separated from wastewater.•The separation problem of NCC from dye wastewater is solved.•Curing temperature and time during self-assembly affect the dye uptake of MB.•Highest dye uptake of MB is 123.2 mg/g. This study is focused on nanocrystalline cellulose (NCC) flakes for methylene blue (MB) removal via adsorption. NCC flakes exhibit a high adsorption capacity (188.7 mg/g fixed at 0.7 g/L adsorbent dosage, 25 °C and pH 6) compared to other nanomaterials, such as carbon nanotube and other cellulosic materials, such as coffee husks. Unlike NCC powder, it was observed that NCC flakes can be easily separated from wastewater containing MB. Further adsorption studies were conducted on NCC flakes, and it was found that 0.7 g/L was the optimum adsorbent dosage, which fitted well with the Langmuir Isotherm. The mean free energy value from Dubinin-Radushkevich isotherm was less than 8 kJ/mol. ΔGo values at different temperatures were within the -20 kJ/mol to 0 kJ/mol range. In conclusion, NCC flakes is a promising and practical ‘green’ nanomaterial that can be further developed for industrial applications.