Introducing lignocellulose valorization into multifunctional water purification: Metal-ion sensing, antibiotic dissociation, and capacitive deionization

Abstract

State-of-the art biomass valorization represents a classic yet fast-growing area in striding the threshold of sustainable energy-environmental research. How to explore a waste-free route is of great concern to maneuver lignocellulose potentials with multifunctional water purification. As a proof-of-concept, we proposed a tandem manufacture with the aid of acidic hydrothermal fractionation for the multi-scale wheat straw valorization into green-emitting carbon quantum dots (GCQDs), as well as, the Co, N co-doped biochar (Co-N-C). By means of xylan-based oligomers and m-phenylenediamine (m-PDA), the GCQDs emit stable green luminescence in a broad excitation span, which can be adopted to selectively sense metal-ions (e.g., Ag+ and Fe3+) within an ultra-wide concentration. Through a facile confinement of Co-MOFs, the hierarchically porous Co-N-C with lamellar edge structure and redox active sites are achieved to exert high-performance catalytic antibiotic dissociation (an optimal rate of degrading ∼97 % tetracycline, TC) and capacitive deionization (CDI, salt adsorption capacities of 23.5 mg g−1 NaCl and 44.07 mg g−1 CdCl2) with excellent cycling stability. Taking advantages of theoretical models, radicals trapping and direct charge-transfer, a synergistic benefit from reactive oxygen species and interface electron shuttling is exerted to efficient antibiotic decomposition. The salt-ionic diffusion and capture mechanisms of Co-N-C are plotted via layered conductive framework, ion intercalation/electro-sorption, and faradaic redox conversion. We believe that the present work paves a new avenue to waste-free lignocellulose conversion that involves matching the sustainable water purification with maximum biorefining revenue and feasibility.