THESIS - ROC CH ... - FINAL - resubmission.pdf - University of Guelph

5.3 METHODS
5.3.1 CELLULOSE EXTRACTION
The procedure for isolation of nanofibers was adapted from Wang and Sain (2007a,b).
The modified process consists of multiple steps with both chemical and mechanical treatments
as seen in Figure 5.1. Two fractions of fibers were obtained from the extraction process with
differing sizes; soy nano fibers (SNF) and soy micro-fibers (SMF). SNF was released from the
stock SF after chemical treatment. The remaining SF after this treatment was further processed
mechanically to produce SMF.
To prepare for chemical treatment, SF was grounded using a mill grinder fitted with a 1
mm sieve (Thomas Wiley Model 3, Swedesboro, NJ, US). The grounded SF was then
rehydrated in distilled water for 3 hours at room temperature of ~ 23°C. The swollen SF’s were
then treated with a sodium hydroxide solution of 17.5% w/wSF at 90°C for 2 hours. A 3:10 ratio
of water to SF was used for solubilizing NaOH. The SF’s were neutralized by filtering against
running water for 20 - 24 hours. A 2 stage filter in series was designed for this purpose (Figure
5.1d). Filters with a mesh size of 20 to 200 µm were used for both stages. The pH of the slurry
was checked to be near 7±0.5 using a pH meter (Accumet XL60, Fisher Scientific, Ottawa, ON,
Canada). Fibers were treated with 1M HCl at 90°C for 2 hours. SF was filtered again for 24 hrs.
At this stage, SNF were released and concentrated in the second stage filter while bulk SF was
retained in the first stage filter. The SNF obtained was further concentrated via centrifugation for
20 min. The remaining SF from the first stage was then treated with 2% NaOH w/wSF using the
3:10 ratio of water to initial SF content for 2 hours at 90°C. The chemically treated SF was
filtered for the last time against water for 24 hours.
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