Novel and High-Performance Magnetic Carbon Composite Prepared from Waste Hydrochar for Dye Removal

In recent years, more and more attention has been paid to the hydrothermal liquefaction (HTL) of waste biomass for the production of bio-oil and hydrochar (a solid residue from HTL process). However, hydrochar possesses limited porosity and surface area, hindering its environmental application. In the present work, to promote the development of a sustainable application of waste biomass, waste hydrochar was activated and modified to a novel magnetic carbon composite, which exhibited high performance for dye removal from aqueous solutions. The composite possessed a saturation magnetization of 38.5 emu g–1 at room temperature and could be facilely attracted from an aqueous solution by an external magnet. The as-prepared composite exhibited a superior malachite green (MG) adsorption capacity (476 mg g–1), which was much higher than the known magnetic adsorbents. Our results suggested that the waste hydrochar could be efficiently transformed to a high-performance sustainable material for dye removal.