N-doped highly microporous carbon derived from the self-assembled lignin/chitosan composites beads for selective CO2 capture and efficient p-nitrophenol adsorption

Green and low-cost biomass-based porous carbon adsorbents have a good prospect for the removal of some environmental pollutants. Here, sodium lignosulphonate, chitosan, and activator were firstly combined into wet gel microbeads through in situ self-assembly method, and then derived the novel porous carbon adsorption materials (LC-Cs) by freeze-drying and one-step activation carbonization. The results showed that LC-Cs had large specific surface areas (892.4-1307.8 m2/g), high microporosity (87.4-89.2%), and rich nitrogen content (3.01-4.92%), and these structural parameters showed good linear dependence with the dosage ratio of lignin to chitosan. Next, LC-Cs carbon showed efficient CO2 capture (173.9-215.2 mg/g) and high CO2/N2 selectivity (up to IAST:145.9, Henry's law: 23.5), specially, the relationships between the CO2 capture and the structural parameters were investigated in detail, and also performed DFT calculation. In addition, LC-C22 had the maximum adsorption capacity of p-nitrophenol (PNP) as 592.8 mg/g, and the adsorption isotherms and kinetic study indicated that they belonged to the multilayer adsorption on the heterogeneous surfaces, and the chemical adsorption played the dominated roles, and then further studied the adsorption mechanism by characterization techniques. This work provided a green and facile strategy for preparing structurally controllable N-doped porous carbon materials, as well as offered good potential adsorbents for PNP removal and CO2 capture.

Automated summary

Sodium lignosulphonate, chitosan, and activator were combined into wet gel microbeads, which were then freeze-dried and one-step activated carbonized to obtain novel porous carbon adsorption materials (LC-Cs). The LC-Cs showed large specific surface areas, high microporosity, and rich nitrogen content. They exhibited efficient CO2 capture and high CO2/N2 selectivity, as well as high adsorption capacity for p-nitrophenol (PNP).