Removal of suspended solids from water by waste biomass-based cationized cellulose nanofibers: a comparative analysis of flocculation performance from different biomass sources†

In response to the growing focus on bio-waste valorization, this study extracted cellulose fibers from rice straw, coffee grounds, corncob, and rape straw. The extracted fibers were subsequently cationically modified into cellulose nanofibers (QCNFs) for effective flocculation in high-turbidity wastewater treatment. Scanning electron microscopy (SEM) revealed that the QCNFs derived from the four biomass sources displayed a three-dimensional network structure, with each displaying distinct fiber morphologies. The QCNFs derived from coffee grounds exhibited a flaky structure, the QCNFs derived from corncob displayed short, rod-like fibers, and the QCNFs derived from rice straw and rape straw showed chain-like structures, with rice straw fibers appearing particularly attenuated. The results indicate significant variation in the flocculation efficiency of QCNFs derived from different bio-sources. QCNFs prepared from rice straw exhibited the highest flocculation efficiency, achieving a removal rate of 90.6%. SEM analysis of the physical structure and morphology of the four types of QCNFs revealed that nanofibers with slender chain-like structures are particularly well-suited for developing biomass-based flocculants.