Optimization of Hemp Bast Microfiber Production Using Response Surface Modelling

Jessica Tsakani Mhlongo, Yannick Nuapia, Boitumelo Tlhaole, Oranso Themba Mahlangu , Anita Etale*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

4 Citations (Scopus)
70 Downloads (Pure)


Non-wood biomass is particularly attractive as a cellulose source because of the lower lignin content. However, optimal cellulose extraction conditions are required as lignin content varies between plant sources. Further, the use of organic acids in place of harsh mineral acids is of interest in “greening” the cellulose production process. This study sought to establish optimum parameters for the extraction of cellulose microfibers (CMFs) from hemp (Cannabis sativa) biomass, using maleic and formic acids. Hemp fibers were pre-treated in NaOH (4 wt%) and aqueous chlorite in acetate buffer before ultrasonic treatment to break down bundles. The CMFs produced were compared with those generated from sulfuric acid hydrolysis. Response surface methodology (RSM) was used to determine combinations of three processing conditions, including acid concentration (45–64%), hydrolysis time (30–90 min), and temperature (45–65 °C). A central composite design (RSM-CCD) model with 21 experimental runs was optimized using MODDE 13.1 software. The model suitably described the data (R2 = 0.99; R2adj = 0.96). Microfibers with an average width of 6.91 µm, crystallinity range 40–75%, and good thermal stability were produced. Crystallinity was influenced by all three factors. The optimal crystallinity predicted by the model was 83.21%, which could be achieved using formic acid 62 wt% formic acid, 36 min hydrolysis time, and 47 °C hydrolysis temperature. These conditions resulted in a crystallinity degree of 82%. These data suggest formic acid can be used as an alternative to sulfuric acid for synthesis of cellulose microfibers from biodegradable hemp waste fibers.
Original languageEnglish
Article number1150
Number of pages20
Issue number6
Publication statusPublished - 8 Jun 2022

Bibliographical note

Funding Information:
This research was funded by the National Research Foundation South Africa (Grant No. 123493) and the Royal Society Foundation, United Kingdom (Grant No. FLR/R1/190087).

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.


  • Cellulose
  • Response surface methods
  • cellulose microfibres


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