Comparative study of the production of cellulose nanofibers from agro-industrial waste streams of Salicornia ramosissima by acid and enzymatic treatment

The study of the suitability of two isolation processes to produce cellulose nanofibers (CNFs) from Salicornia ramosissima waste, with potential applicability as a reinforcing agent of polymeric composites was carried out. To separate the cellulose fibrils from the cell wall and obtain CNFs an alkaline treatment was applied followed by a bleaching treat-ment and, the insoluble residue was next hydrolyzed by either an acid treatment (AT) or an enzyme treatment (ET). SEM and TEM images indicated fiber exposure caused by both treatments. The diameter, length, aspect ratio, and polydispersity index, were measured for both CNFs. CNF (ET) showed high zeta potential values suggesting that ET produces more electrically stable and thinner nanofibers. The FTIR spectra revealed that both treatments effectively removed the amorphous components allowing the CNFs isolation, and XRD patterns evidenced the increase in the degree of crystallinity of both CNFs. Nonetheless, CNF(AT) presented a lower mechanical resistance due to its smaller particle size, compared to the CNF(ET). In summary, the (ET) could successfully isolate CNFs from the Salicornia waste, encouraging the use of this treatment, once when compared to (AT), it does not generate toxic residues, presents mild thermal conditions, and produces CNFs with higher-value applications.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of Institution of Chemical Engineers. This is an open access article under the CC BY-NC-ND license (http://creati-vecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The suitability of isolation processes for producing cellulose nanofibers (CNFs) from Salicornia ramosissima waste was investigated. Both alkaline treatment and bleaching treatment were used to separate cellulose fibrils and obtain CNFs, which were further hydrolyzed by acid treatment or enzyme treatment. The results showed that both treatments effectively removed amorphous components, increased crystallinity, and exposed fibers. However, CNF(ET) exhibited higher zeta potential values and mechanical resistance compared to CNF(AT). Overall, the enzyme treatment showed potential for isolating CNFs with higher-value applications due to its environmentally friendly nature and production of thinner nanofibers.