Aligned porous carbon material derived from cellulose nanocrystal for high-efficiency oil/water separation

Abstract

The demand for sustainable materials suitable for oil separation from water-in-oil emulsions or oil-water mixtures as well as for oily water treatment is increasing. In this study, a biomass-derived carbon aerogel with radially aligned channels (P-CCNCA) was obtained from cellulose nanocrystal (CNC) via directional freeze-drying, carbonization, and subsequent polydimethylsiloxane (PDMS) modification. The unique channel orientation enables rapid thermal conduction and electron transport, which synergistically enhance both oil absorption and separation performance. P-CCNCA exhibits high hydrophobicity (water contact angle of 135°), high porosity (about 84 %), stable oil absorption capacity (10.5 g/g), and excellent oil/water separation efficiency of 98.2–99.5 % with permeation fluxes up to 14,023 L/m2 h. More importantly, the photothermal and Joule heating of P-CCNCA markedly reduce oil viscosity, shortening absorption time by 41.7 % under solar irradiation and increasing emulsion separation rate by 83.3 % at 12 V. The P-CCNCA can maintain about 99 % separation efficiency and mechanical integrity after multiple cycles. This work provides a sustainable strategy for constructing intelligent, thermally responsive adsorbents and demonstrates their potential in high-viscosity oil spill recovery and industrial oily wastewater treatment.