Lignosulfonate functionalized g-C 3 N 4 /carbonized wood sponge for highly efficient heavy metal ion scavenging

Wood-based adsorbents have important engineering significance in removing toxic heavy metals from wastewater due to their natural abundance, sustainability and biodegradability together with superior sorption performance. Herein, a novel adsorbent, lignosulfonate functionalized g-C 3 N 4 /carbonized wood sponge (denoted as LS-C 3 N 4 /CWS), has been successfully fabricated through pyrolysis of urea impregnated wood sponge under an argon atmosphere, followed by subsequent modification with lignosulfonate (LS). As expected, the resulting LS-C 3 N 4 /CWS shows excellent decontamination capability toward Pb 2+ , Cd 2+ and Cu 2+ with high uptake capacities of 659.6, 329.1 and 173.5 mg g −1 , respectively, outperforming most of the previously reported wood-based adsorbents and other nanomaterials. Moreover, the spent LS-C 3 N 4 /CWS can be readily recovered and maintains high removal efficiency after ten adsorption–regeneration cycles, revealing its excellent recyclability. Significantly, LS-C 3 N 4 /CWS can be directly utilized as an ultrafiltration membrane to continuously treat large volumes of simulated wastewater (9550 mL g −1 for Pb 2+ , 1500 mL g −1 for Cd 2+ and 8700 mL g −1 for Cu 2+ ) to below the permitted level in drinking water. The superior decontamination performance coupled with facile separation, cost-effectiveness and no secondary pollution underscores the huge potential of LS-C 3 N 4 /CWS in effectively removing heavy metals from polluted waters.