A direct synthesis of adsorbable hydrochar by hydrothermal conversion of lignin

Hydrothermal conversion of lignosulfonate with or without formaldehyde as polymerization agent was conducted at 320 degrees C. Compared with the hydrochar produced without formaldehyde addition (WF-hydrochar), the yield and surface area of the hydrochar produced with formaldehyde addition (F-hydrochar) increased 33.8 and 46.4%, respectively. The F-hydrochar showed much higher adsorption ability of Cu2+ than that of WF-hydrochar, while its adsorption ability of methyl orange was a little lower than that of WF-hydrochar. These discoveries explored a high yield of hydrochar production and a potential new application of hydrochar.