A self-assembly all-polysaccharide hydrogel for the aquatic heavy metal ions management and utilization

Abstract

Hydrogels with a unique three-dimensional porous structure are regarded as good adsorbents to treat heavy metal ions-contaminated water. However, the post-treatment of the hydrogels after the wastewater treatment is still a big problem. We herein proposed to use the TEMPO-oxidized cellulose nanofibers (TOCN)/cationic guar gum (CGG) self-assembly hydrogel to adsorb Cu2+ from its contaminated water. The Cu2+-adsorbed hydrogel was demonstrated to be a good stress-sensing material responsive to the loading weight. In addition, the Cu2+-adsorbed hydrogel was transformed into a Cu-doped carbon aerogel after the freeze-drying and carbonization treatments and the resultant carbon aerogel exhibited good and stable electrochemical property. It had an aerial specific capacitance of 3.14 F·cm−2 when the current density was 3 mA·cm−2. Importantly, the existence of copper largely enhanced the electrochemical property of the carbon aerogel since it led to the improvement in conductivity and pseudocapacitance. This work might spur the application of hydrogel in heavy metal ions-contaminated water treatment and provide new ways to convert pollutants into products.