High-performance porous biochar from the pyrolysis of natural and renewable seaweed (Gelidiella acerosa) and its application for the adsorption of methylene blue.

•High performance biochar was prepared from seaweed.•Favorable pore characteristics of 926.39 m2/g and 0.57 cm3/g were obtained.•Adsorption behaviors were detected for methylene blue removal.•Maximum MB uptake of 512.67 mg/g was achieved at 30 °C.