Cyanobacteria-based activated carbon (CBAC) was successfully prepared by pyrolysis-activation of Taihu cyanobacteria. When the impregnation ratio and activated temperature were 2 and 800 ℃

respectively

the optimal CBACs possessed an ultra-high specific surface (2178.90 m

2

·g

-1

) and plenty of micro- and meso-pores

as well as a high pore volume (1.01 cm

3

·g

-1

). Ascribed to ultra-high surface area

π-π interaction

electrostatic interaction

as well as hydrogen-bonding interactions

the CBACs displayed huge superiority in efficient dye removal. The saturated methylene blue adsorption capacity by CBACs could be as high as 1143.4 mg·g

-1

superior to that of other reported biomass-activated carbons. The adsorption was endothermic and modeled well by the pseudo-second-order kinetic

intra-particle diffusion

and Langmuir models. This work presented the effectiveness of Taihu cyanobacteria adsorbent ascribed to its super large specific surface area and high adsorption ability.