Hierarchically porous bacterial cellulose nanofibrous membranes for selective adsorption and real-time colorimetric monitoring of volatile carboxylic acids

Volatile carboxylic acids (VCAs) are intensively generated via bioengineering and widely used in food, textile, and cosmetic industries, but the efficient separation, collection, and regeneration of VCAs still face challenges. Here, we report a design and application of novel hierarchically porous structures built on bacterial cellulose nanofibrous membrane to effectively adsorb VCAs and to reveal the adsorptive status of the material at the same time. By in situ growing a triazine-based porous organic polymer on the nanofibers, the composite achieved integrated features of the co-existence of micro/meso/macropores, high specific surface area (255 m 2 /g), good flexibility, and selective affinity to VCAs, resulting in record-high adsorption capacities toward formic acid (815.36 mg/g) and acetic acid (754.21 mg/g). Moreover, the introduction of colorimetric probes onto the composite allows a visual indication of the adsorption-desorption process, i.e., the working status of the material, in real time. The successful fabrication of a bifunctional, hierarchical porous cellulose-based nanofibrous membrane could inspire the development of green adsorbents with improved efficacy and flexibility for gas capture and filtration. Graphical abstract