N-doped lignin-based activated carbon aerogel derived from bamboo black pulp liquor for efficient removal of malachite green in wastewater

In this study, a lignin-based aerogel (LA) was prepared through acid precipitation of BPBL, followed by sol–gel method and freeze-drying. Additionally, a one-step activation-carbonization method was used to acquire nitrogen-doped lignin-based activated carbon aerogel (NLACA). The adsorption and catalytic degradation performance for malachite green (MG) were examined. The specific surface area of NLACA after N-doping was 2644.5 m 2 /g. The adsorption capacity for MG was increased to 3433 mg/g with the presence of nitrogenous functional groups on surface of NLACA compared without N-doping. Meanwhile, non-radical singlet oxygen is the primary active substance and degradation efficiency arrives at 91.8% after the catalytic degradation within 20 min and it has good stability and reuse. Three possible degradation pathways during degradation were analyzed by LC–MS technique. The adsorption isotherm and kinetic data demonstrated conformity with both the Langmuir model and the pseudo-second-order kinetic model. The primary mechanisms of the adsorption for MG dyes on NLACA include hydrogen bonding, π-π interactions, attraction of electrostatic and pore filling. Hence, NLACA derived from BPBL acts as a cost-effective and high-performance adsorbent and catalyst for removal of MG in dye wastewater. This concept introduces an innovative approach of “treatment of waste with waste” for developing a low-consumption, high-efficiency dye wastewater treatment and provides significant reference to treatment dye wastewater. Graphical Abstract