Interface selectivity-based biochar: Directional evolution of properties, application & carbon neutralization evaluation

Hydrophobic organic contaminants (HOCs) threaten human health and ecosystems. The most economical and low-carbon remediation method employs surfactants to mobilize HOCs, followed by separation using carbon-based materials. A carbon-structure superimposition strategy (CSSS) was developed to prepare interface selectivity-based colloidal biochar (CBC-AO). In a solution with a pollutant concentration of 2.5 mg/L phenanthrene, a 99 % removal efficiency was achieved, and a 100 % recovery rate was obtained for common anionic surfactants. Notably, CSSS offers a unique approach to using lignocellulose-based biomass (LB)-derived biochar as an alternative to activated carbon (AC). The uniqueness of CSSS lies in revealing the carbon structure transfer mechanism, where cellulase pretreatment converts LB into aromatic carbon substrates, followed by air oxidation and colloidal treatment to transform unfavorable carbon structures into those beneficial for selective adsorption. This modification grants biochar selectivity and stability, addressing the challenge of balancing different carbon structures and functions. CBC-AO achieved a 90 % reuse rate after six cycles. Compared with traditional biochar, its acute biological toxicity was reduced by 77 %, and its environmental friendliness was further increased. In terms of carbon emissions and cost, CBC-AO outperforms AC, reducing emissions by 0.62 tons of CO 2 per year, whereas AC increases emissions. CSSS overcomes traditional biomass selection limitations, broadening biomass options and providing efficient, economical, and carbon-negative alternatives to conventional carbon-based materials. Furthermore, integrating CSSS with biofuel production results in biochar performance comparable to commercial AC, potentially advancing both industries.