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Isolation of cellulose microfibrils - An enzymatic approach

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Isolation methods and applications of cellulose microfibrils are expanding rapidly due to environmental benefits and specific strength properties, especially in bio-composite science. In this research, we have success-fully developed and explored a novel bio-pretreatment for wood fibre that can substantially improve the microfibril yield, in comparison to current techniques used to isolate cellulose microfibrils. Microfibrils currently are isolated in the laboratory through a combination of high shear refining and cryocrushing. A high energy requirement of these procedures is hampering momentum in the direction of microfibril isolation on a sufficiently large scale to suit potential applications. Any attempt to loosen up the microfibrils by either complete or partial destruction of the hydrogen bonds before the mechanical process would be a step forward in the quest for economical isolation of cellulose microfibrils. Bleached kraft pulp was treated with OS1, a fungus isolated from Dutch Elm trees infected with Dutch elm disease, under different treatment conditions. The percentage yield of cellulose microfibrils, based on their diameter, showed a significant shift towards a lower diameter range after the high shear refining, compared to the yield of cellulose microfibrils from untreated fibres. The overall yield of cellulose microfibrils from the treated fibres did not show any sizeable decrease.
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Janardhnan and Sain (2006). “Cellulose Microfibril Isolation,” BioResources 1(2), 176-188. 176
ISOLATION OF CELLULOSE MICROFIBRILS – AN ENZYMATIC
APPROACH
Sreekumar Janardhnan* and Mohini M. Sain
Isolation methods and applications of cellulose microfibrils are expanding
rapidly due to environmental benefits and specific strength properties,
especially in bio-composite science. In this research, we have success-
fully developed and explored a novel bio-pretreatment for wood fibre that
can substantially improve the microfibril yield, in comparison to current
techniques used to isolate cellulose microfibrils. Microfibrils currently are
isolated in the laboratory through a combination of high shear refining
and cryocrushing. A high energy requirement of these procedures is
hampering momentum in the direction of microfibril isolation on a
sufficiently large scale to suit potential applications. Any attempt to
loosen up the microfibrils by either complete or partial destruction of the
hydrogen bonds before the mechanical process would be a step forward
in the quest for economical isolation of cellulose microfibrils. Bleached
kraft pulp was treated with OS1, a fungus isolated from Dutch Elm trees
infected with Dutch elm disease, under different treatment conditions.
The percentage yield of cellulose microfibrils, based on their diameter,
showed a significant shift towards a lower diameter range after the high
shear refining, compared to the yield of cellulose microfibrils from
untreated fibres. The overall yield of cellulose microfibrils from the
treated fibres did not show any sizeable decrease.
Keywords: Cellulose, Cellulose microfibrils, Fungal / Enzyme pretreatment, Cellulose microfibrils
isolation, Hydrogen bonds
Contact information: Department of Chemical Engineering and Applied Chemistry, 200 College Street
University of Toronto, Toronto, ON – M5S 3E5, Canada. *Corresponding author:
s.janardhnan@utoronto.ca
INTRODUCTION
Cellulose, the most abundant biopolymer on earth, is poly(β-1,4, D
anhydroglucopyranose), which through a regular network of inter and intramolecular
hydrogen bonds is organized into perfect sterioregular configurations called microfibrils.
Each chain is stabilized by intrachain hydrogen bonds formed between the pyranose ring
oxygen in one residue and the hydrogen of the OH group on C3 in the next residue
(O5...H-O3’) and between the hydroxyls on C2 and C6 in the next residue (O2-H...O6’)
(Liang and Marchessault 1959).
During biosynthesis, cellulose microfibrils are synthesized by the plasma
membrane using an enzyme called cellulose synthase and are deposited onto the cell wall.
In higher plants, despite its chemical simplicity, the physical and morphological structure
of native cellulose is complex and heterogeneous, and in cell walls cellulose molecules
are intimately associated with other polysaccharide moieties, resulting in even more
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complex morphologies. Breakdown of these close physical and chemical associations
between cellulose and other polysaccharides in a plant cell wall is vital for any
economical utilization of these polymers. Researchers have achieved significant progress
in converting lignocellulosic materials to materials of engineering importance such as
reinforcing fibres, bioplastics and even biofuels.
The elementarization of natural fibres into their elementary cellulosic constituents
such as nano- and microfibrils is gaining wider attention due to their (1) high strength and
stiffness (Tashiro 1991), (2) high reinforcing potential, and (3) their biodegradability and
renewability. Depending on the degree of elementarization, the defects and dimensions of
the partly crystalline fibres of wood decrease, thereby improving their strength properties.
The literature differentiates between Microfibrillated Cellulose (MFC) obtained through a
mechanical homogenization (Herrick et al., 1983) and Microcrystalline Cellulose (MCC)
that is generated by chemical treatment of various plant fibres. MFC has an aspect ratio
around 50 to 100 and is extensively investigated for its reinforcing potential, while MCC
with an aspect ration of about 3 is widely used as rheology control agents and as binders
in the pharmaceutical industry.
Preparation and application of nanocomposites using cellulose nano- and
microfibrils are expanding rapidly in biocomposite science. Numerous other high-end
potential applications for cellulose microfibrils are currently being explored. Poor
economics due to a high energy requirement in the isolation of cellulose microfibrils is a
key challenge that could hamper the current momentum in the direction of
commercialization. Microfibrils have been generated in the laboratory through a
combination of high energy refining in a PFI mill, and subsequent cryocrushing under the
presence of liquid nitrogen (Chakraborty and Sain 2005).
Isolation of Cellulose Microfibrils
Microfibrils are joined laterally by means of hydrogen bonding (Brown et al.
1976). In the cited study, as the microfibrils were generated, they were found to coalesce
laterally through interfibrillar hydrogen bonding to form bundles. As stated by the
authors, “the bundles associate with neighboring bundles to produce a composite ribbon
of cellulose microfibrils”.
The glucose and cellobiose structures show the presence of several hydroxyl
radicals in the cellulose chain, and all these hydroxyl groups participate in hydrogen
bonding. The interfibrillar hydrogen bonding energy has to be overcome in order to
separate the microfibrils into individual entities. More than one type of H-bond is present
in cellulose - intermolecular and intramolecular, so only a range of values can be used to
quantify the hydrogen bond strength. This energy (U) for cellulose ranges between 19
and 21 MJ/kg mol (Nissan et al., 1985).
Young’s modulus (E) of a hydrogen bond-dominated solid such as paper has been
quantified (Nissan et al. 1985) as follows:
E = <kR>n1/3 (1)
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where R is the total H-bond length, <kR> is the average value of the force constant for
stretching R by a unit distance, and n is the effective number of H-bonds per unit volume
involved in taking up strain under uniaxial stress conditions.
Microfibrils are more flexible and agglomerate less in the presence of water.
Fengel (1974) indicated that intensive disintegration in a homogenizer could split even
the elementary fibrils and microfibrils down to molecular diameters.
Any attempt to loosen up the microfibrils by either complete or partial destruction
of the hydrogen bonds before the mechanical process would be a step forward in the
quest for energy-efficient generation of cellulose microfibrils. The focus of this research
is to investigate and establish an enzymatic chemistry that would partially or completely
nullify the hydrogen bonds between the microfibrils, making their isolation energy-
efficient.
Enzyme Technology in Fibre Processing
The application of enzymes in fibre processing has been mainly directed towards
the degradation or modification of hemicelluloses and lignin, while retaining the
cellulosic portion. The enzymatic approach in the fibre processing sector has been based
the idea of selected hydrolysis of certain components or limited hydrolysis of several
components in the fibre. Some of the important areas of applications are (1) Fibrillation,
inter-fibre bonding and strength enhancement (Bolaski et al. 1959; Yerkes 1968; Nomura
1985), (2) Drainage (Fuentes, 1988), (3) Modification of pulp properties (Uchimoto
1988; Paice 1984; Senior 1988; Jurasek 1988), (4) Enzymatic pulping (Nazareth 1987;
Sharma and 1987, Morvan, C., 1990), and (5) Enzymatic pretreatments for bleaching
(Tolan 1992; Viikari 1990).
Although enzymes have been widely used to modify cellulosic fibres for various
applications, there hasn’t been any research effort to understand and utilize the enzyme –
fibre interaction at microfibrilar level. An understanding of the chemistry at this level and
its exploitation to isolate high strength micro- and nanofibrils from plant cell walls in an
economical manner would be a huge step towards isolation of cellulose microfibrils and
their commercial scale utilization in various applications.
EXPERIMENTAL
Materials
Wood Fibre: Bleached kraft pulp – northern black spruce was used as the
starting material for the isolation of microfibrils. Typical composition is described in
Table 1.
Table.1. Composition of Bleached Kraft Pulp
Composition %
Cellulose 86
Hemicellulose 14
Fungus: The fungus OS1, isolated in our laboratory from Elm tree infected with
Dutch elm disease was used as the source of enzyme for the fibre treatment.
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Methods
Bio-treatment: Twenty-four grams of oven-dry bleached kraft fibre was soaked
overnight, disintegrated in 2 liters of water, and autoclaved for 20 minutes. A 24 gram
sample size of fibre was chosen, as it was the optimum fibre charge to the high shear
refiner that was used for further mechanical defibrillation for cellulose microfibrils
isolation. OS1 fungal culture was added to this fibre suspension in a sterile flask with
appropriate amount of sucrose and yeast extract to support the fungal growth. The fungus
was left to act on the fibres at room temperature for different time duration with slow
agitation. The fibres were autoclaved after their respective treatment time, washed and
made into sheets of 10% fibre consistency ready for the mechanical refining and
cryocrushing.
High shear refining: The fibres at 10% consistency were then sheared in a
refiner for 125000 revolutions.
Cryocrushing: The refined fibres were then subjected to cryocrushing in which
the fibres were frozen, using liquid nitrogen, and high shear was applied, using a mortar
in a pestle. This step is critical in librating the microfibrils from the cell wall. The
cryocrushed fibres were then dispersed in to water suspension using a disintegrator and
filtered through a 60-mesh filter. The filtrate, a dilute water suspension of microfibrils,
was used for further investigation.
Characterization of Ophiostoma Ulmi treated fibres
Weight loss: The weight loss of the bio-treated fibres was determined by simple
difference between the weight of fibres before and after treatment.
Fibre composition: The cellulose and hemicellulose contents of the fibre after
the bio-treatment were determined using the procedure adapted from Zobel and McElwee
1966).
Cellulose Microfibril Characterization
Scanning electron microscopy (SEM) and transmission electron microscopy
(TEM) were used to understand the surface morphology and diameter distribution of the
treated fibres and cellulose microfibrils isolated.
RESULTS AND DISCUSSION
The results presented here focus on the effect of OS1 fungal pretreatment of
bleached kraft softwood fibres on yield and diameter distribution of cellulose microfibrils
obtained through subsequent defibrillation techniques such as high shear refining and
cryocrushing. The action of fungal treatment on the morphology and the capacity of the
bio-treatment to facilitate the internal defibrillation are extensively detailed here through
Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).
The impact of bio-treatment and its extent on the physical and chemical characteristics of
the fibres were studied by determining weight loss and cellulose content of the fibres.
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Effect of OS1 Fungal Pretreatment of Fibres on Cellulose Microfibril Yield
and Fibre Diameter Distribution
One of the major challenges impeding the isolation of cellulose microfibrils on a
sizable scale for any intended application is the predominating hydrogen bonding
between the cellulose microfibrils and also between microfibrils and hemicellulose.
Cellulose microfibrils are generated and isolated through a combination of high energy
refining, and subsequent cryocrushing under the presence of liquid nitrogen. A key
reason for high shear refining of the fibres is to cause internal defibrillation, a process
where only a minor portion of the total energy supplied to the refiner is utilized for
internal defibrillation.
The interfibrillar hydrogen bonding energy has to be overcome in order to
separate the microfibres into individual entities. This association energy for cellulose
ranges between 19 and 21 MJ/kg.mol, with 20 MJ/kg.mol being used as an average value
in most cases. If this value is taken to be the intermolecular H-bond energy binding the
fibres together, then this much energy should be supplied to separate the microfibres into
separate entities.
One of the main reasons to choose OS1 as the first fungal candidate for fibre
treatment is our prior knowledge (Modification of interface in natural fibre reinforced
composites, MASc Thesis, Deepak Gulati, 2006) of their effect on hemp fibres – its
capacity to degrade and probably hydrolyze the cellulose. In this work, bleached kraft
pulp was pretreated with OS1 fungus to study its effect on (a) overall yield of
microfibrils, (b) number averaged fibre diameter distribution.
Yield of Cellulose Microfibrils
The yield of cellulose microfibrils is determined as the percent by weight of
microfibrils that pass through a 60-mesh screen after refining and cryocrushing. The yield
comparison is detailed in the Fig. 1. The overall yield of cellulose microfibrils from OS1
treated fibre is seen to decrease by an average of 5%. The decrease in yield of
microfibrils seems to be noticeable only after a minimum of 4 days of treatment, which
indicates that the fungus needs a minimum of 4 days to establish an active community
and produce enzymes in an effective quantity.
The yield of microfibrils is seen to stabilize after 5 days of treatment, and there is
no noticeable decrease with any further extent of treatment. This observation contradicts
results of the earlier study of the effect of OS1 fungus on hemp fibres, which showed a
significant activity of the fungus towards cellulose accompanied by a significant loss in
the fibre strength after 4 days of treatment (Modification of interface in natural fibre
reinforced composites, MASc Thesis, Deepak Gulati, Department of Chemical
Engineering and Applied Chemistry, University of Toronto, 2006).
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Fig.1. Yield of cellulose microfibrils with different Ophiostoma Ulmi treatment conditions
The low cellulolytic activity of OS1 fungus was further confirmed by a study of
the weight loss and cellulose content of the treated fibres. The loss in fibre weight, as
depicted in Fig. 2, showed a gradual drop up to a maximum 7.5 % of original fibre weight
for 4 days treatment and tended to be insignificant thereafter. A similar trend is seen with
respect to the cellulose content of the treated fibres. This is evident in Fig. 3, where the
cellulose content is seen to decrease with the extent of treatment, and the loss of cellulose
is proportionate with the weight loss of the treated fibres.
Fig. 2. Weight loss of fibres with different OS1 fungus treatment conditions
50
60
70
80
0358
Ophiostoma Ulmi Treatment (days)
% Yield
0
0.06
0.12
0.18
0.24
012348
Ophiostoma Ulmi Treatment (days)
Wt. loss gm / 2 gm fibre
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Fig. 3. Cellulose content of fibres with different OS1 treatment conditions
The weight loss and a proportionate decrease in cellulose content of the treated
fibres imply that the action of fungal enzymes on the fibres is mostly limited to cellulose
and not the hemicellulose. Now, the reason for this low level of activity against cellulose
can be explained only once the specific enzymes are isolated and identified. This is the
next phase of this project.
Microfibril Diameter Distribution
Having understood the level of OS1 activity against cellulose, it is vital to
understand the effect of OS1 fungal treatment on the internal defibrillation tendency of
the treated fibres during subsequent mechanical defibrillation techniques such as high
shear refining or high-pressure homogenization. This is the first step towards testing the
hypothesis that enzymes can help in internal defibrillation through either weakening the
hydrogen bonds that exist between microfibrils or loosening up the fibrils through
controlled hydrolytic activity.
Fibres treated with OS1 fungus were refined and the number-average diameter
distributions of these refined fibres for a 4 days treatment are detailed in Fig. 4. A very
significant shift in the diameter distribution of the fibres occurred towards the lower
diameter range, with the maximum yield of fibres below 100 nm range for the 4 days
treated fibres, while that for the untreated fibre were between 100 – 250 nm range. The
fibre diameter distribution did not change in an appreciable manner with increase in
treatment time longer than 4 days treatment (results not shown here). This shift in fibre
diameter distribution curve towards the lower diameter range for a treated fibre after the
refining is of importance in this work as this observed phenomenon can happen only if
the treatment had an effect of facilitating the internal defibrillation in the fibre during
refining. The mechanism is not apparent yet, but a good supposition is that the enzymes
might have worked to reduce the hydrogen bonding between the fibrils, thus improving
70
80
90
012348
Ophiostoma Ulmi Treatment (days)
% cellulose conten
t
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the internal defibrillation during refining. This concept is more visible in the TEM images
of an unrefined treated fibre as shown in Fig. 5 and the refined fibres treated with the
fungus as detailed in Fig. 6.
Fig. 4. Effect of OS1 fungal treatments on number averaged diameter distribution of fibres after
refining for a 4 days treatment
(a) (b)
Fig. 5. OS1 fungal treatment of fibres, (a) fungus growing on the fibre, (b) treated fibre before
high shear refining
The fibrillation of the treated fibres, as seen in Fig.6 (b), is more pronounced after
refining, compared to the untreated fibres. The actual separation of elementary fibres
takes place to a good extent with treated fibres, while high shear refining seems to have a
reduced fibril separation effect on untreated fibres. This observation can explain the
difference in fibre diameter distribution associated with treated and untreated fibres.
0
10
20
30
0-10 10-
25.0
25-50 50-75 75-100 100-
150
150-
250
Fibre diameter nm
% Yield
OS Treated
Untreated
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(a) (b)
Fig. 6. Effect of OS1 fibre treatments on internal defibrillation - (a) TEM of untreated fibre after
high shear refining, (b) TEM of treated fibre after high shear refining
Cryocrushing is the final step that helps in the isolation of cellulose microfibrils
into individual entities from the fibrillated fibres. An interesting point to note here is that
a significant difference in fibre diameter distribution observed between treated and
untreated fibres after refining, as was detailed in Fig. 4, no longer seems to demonstrate
their significance in Fig. 7, which depicts the fibre diameter distribution of treated and
untreated fibres after cryocrushing. The reason for such a distribution may be explained
by a strong and positive effect of cryocrushing on microfibril isolation from fibres, such
that the better defibrillation attained by treated fibres after refining is subdued.
Fig.7. Effect of OS1 treatments of fibres on the yield and distribution of cellulose microfibrils after
refining and cryocrushing
0
10
20
30
40
50
60
0-10 10.0-25 25-50 50-75 75-100 100-
150
150-
250
Fibre diameter nm
% yiel
d
OS Treated
Untreated
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The fibre diameter distribution trend is similar for both treated and untreated
fibres, with microfibrils from treated fibres showing a slight shift towards lower diameter
range, and with the major fraction of fibres in the 0 – 50 nm range. The cellulose
microfibrils isolated from treated fibres after cryocrushing showed very clear and distinct
separation, as compared to cellulose microfibrils isolated from untreated fibre, as seen in
Fig. 8 and Fig. 9.
This narrow shift in the fibre diameter distribution, as shown in Fig. 8, stems from
the fact that isolation of cellulose microfibrils into distinct entities is not as good with
untreated fibres as with treated fibres. This effect is evident from a closer look at TEM
pictures, as shown in Fig. 8 and Fig. 9.
Fig. 8. TEM of cellulose microfibrils isolated from OS1 treated fibres through refining and
cryocrushing
10000x 2 microns
10000x 2 microns
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Fig. 9. TEM of cellulose microfibrils isolated from untreated fibres through refining and
cryocrushing
The observations detailed above steer our thinking in two directions.
(a). The effect of fungal treatment has been shown to have a significant impact on the
defibrillation characteristics of the fibres during defibrillation techniques such as the PFI
refining we have used here. However, the impact seems to lose its significance once
these refined fibres are cryocrushed. Therefore one may ask whether this enzymatic fibre
treatment really benefits the isolation of cellulose microfibrils in a two-step process that
includes PFI refining and cryocrushing.
(b). Having demonstrated the encouraging effect of OS1 treatment on the
defibrillation of fibres during subsequent refining, it is worthwhile adopting a one-step
process such as homogenization in a microfluidizer to authenticate the effect of fibre
treatment and see if fewer passes through the microfluidizer are enough to isolate
cellulose microfibrils, as compared to the number of passes required for untreated fibres.
In addition to isolating and identifying the extracellular enzymes involved in the
treatment, the next phase of this work will include the isolation of cellulose microfibrils
from Ophiostoma-treated fibre, using single-step / multipass high-pressure homogeniz-
10000x
2 microns
10000x
2 microns
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ation. Fewer passes for treated fibres through a homogenizer for comparable microfibril
yield will undeniably suggest a lower energy scenario in cellulose microfibril isolation.
CONCLUSIONS
1. The fungus OS1 treatment was shown to have a significant impact on the defibrillation
characteristics of the fibres – a major step in the isolation of cellulose microfibrils.
2. Cellulose microfibrils isolated by refining and cryocrushing of treated fibres yielded
very distinct microfibrils and a narrower microfibril diameter distribution, compared
to that obtained for untreated fibres.
3. The fungus OS1 treatment of bleached kraft fibres seems to have only a mild activity
against cellulose, which is of interest to this work, as this minimizes the loss of
cellulose.
ACKNOWLEDGMENTS
The authors are grateful for the support of Natural Science and Engineering Research
Council of Canada – BIOCAP.
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Article submitted August 16, 2006; Revision accepted September 20, 2006; Published
September 21, 2006
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Plant food wastes generated through the food chain have attracted increasing attention over the last few years not only due to critical environmental and economic issues but also as an available source of valuable components such as dietary fibers. However, the exploitation of plant waste remains limited due to the lack of appropriate processing technologies to recover and tailor fiber functionalities. Among the different technologies developed for waste valorization, mechanical techniques were suggested to be a promising and sustainable strat�egy to extract fibers with improved functionalities. In this context, the present review describes different mechanical technologies (conventional and innova�tive) with potential applications to produce micro/nanofibers from various plant residues, highlighting the operating principle as well as the main advantages and pitfalls. The impact on the structural, technological, and functional properties of fibrous materials is comprehensively discussed. The extent of fiber modification not only highly depended on the technology and operation conditions used but also on fiber composition and the application of post-treatments such as dehydration. Other variables, including economic and environmental issues such as equipment cost, energy demand, and eco-friendly features, are also reviewed. The outputs of this review can be used by both the industrial sector and academia to select a suitable combination of fiber and processing technology for designing novel foods with improved functionalities that fulfill market trends and consumer needs.
... Cryocrushing is an attractive approach to produce nanofibers by freezing fibrous materials using liquid nitrogen followed by high shear forces ( Figure 9) (Chakraborty et al., 2005). When high impact forces are applied, the ice crystals inside the fibers exert pressure on the cell walls, leading to cell rupture and release of the nanocellulose fiber (Janardhnan & Sain, 2006;. This method could be applied to various cellulosic materials in combination with chemical and mechanical methods to reduce the PS to less than 100 nm . ...
... This method could be applied to various cellulosic materials in combination with chemical and mechanical methods to reduce the PS to less than 100 nm . The advantage of the cryocrushing process is the generation of completely distinct nanofibers compared to nontreated samples (Janardhnan & Sain, 2006). However, this method is not well suited for large-scale production due to high energy consumption (Hietala & Oksman, 2014;Kargarzadeh et al., 2017). ...
Article
Plant food wastes generated through the food chain have attracted increasing attention over the last few years not only due to critical environmental and economic issues but also as an available source of valuable components such as dietary fibers. However, the exploitation of plant waste remains limited due to the lack of appropriate processing technologies to recover and tailor fiber functionalities. Among the different technologies developed for waste valorization, mechanical techniques were suggested to be a promising and sustainable strategy to extract fibers with improved functionalities. In this context, the present review describes different mechanical technologies (conventional and innovative) with potential applications to produce micro/nanofibers from various plant residues, highlighting the operating principle as well as the main advantages and pitfalls. The impact on the structural, technological, and functional properties of fibrous materials is comprehensively discussed. The extent of fiber modification not only highly depended on the technology and operation conditions used but also on fiber composition and the application of post treatments such as dehydration. Other variables, including economic and environmental issues such as equipment cost, energy demand, and eco-friendly features, are also reviewed. The outputs of this review can be used by both the industrial sector and academia to select a suitable combination of fiber and processing technology for designing novel foods with improved functionalities that fulfill market trends and consumer needs.
... The quality, quantity, and morphology of NFCs and NCCs are wholly and solely dependent on the lignocellulosic biomass source. They can be efficaciously extracted from a range of lignocellulosic sources by using various treatments including mechanical [101][102][103][104], chemical [105][106][107] and biological [108,109]. The conversion of cellulose to NCC is obtained by the dissolution of cellulose fibrils within the lignocellulose biomass by means of mechanical treatments that involve the use of high shear forces to rend the cellulose fibrils along the longitudinal direction [1,32,110]. ...
Chapter
The most abundant biopolymer on earth is cellulose. As it is the principal structural polysaccharide of plants, cellulose forms major proportions of the agro- and food-industry wastes. Native cellulose extracted from its sources and its chemical macro-derivatives are used in the paper, textile, adsorbent, food, and several other industries. Micro- and nanoderivatives of cellulose are obtained by controlled hydrolysis of the semicrystalline biomaterial. Efficacy of such treatments is often enhanced by coupling with modern physical size reduction techniques like freeze-maceration, high-pressure homogenization, ball milling, and sonication. Such ultramicroscopic derivatives of cellulose attain unique properties to be applied in sophisticated applications like physiologically targeted drug and nutraceutical delivery, synthesis of metal nanoparticles, and designing of smart and biodegradable composite materials. The current status of research and development in cellulose extraction from different bio-wastes, derivatization approaches, and application for capitalized utilization of the bio-material has been critically discussed in this chapter.
... Green algae such as Ulva lactuca biomass had been treated by methanol and hypochlorite to remove pigments [181]. The most common methods for extraction NC are acid hydrolysis [182,183], TEMPO-mediated oxidation [184], mechanical fragmentation [185] and enzyme-supported hydrolysis [186]. Until now acid hydrolysis like (H 2 SO 4 ), (HCl), and (H 3 PO 4 ) is reflected the most operative and extremely effective in the function of cellulose depolymerization route for alteration of cellulose into its NC materials, acids disrupted cellulose polymeric chain into minor lengths and widths, under the regulated hydrolysis circumstances such as "time, temperature, acid concentration and agitation", the amorphous dominions of [187]. ...
... The highest yield in their work was 32.4%. The enzymes help in restrictive hydrolysis of several elements or selective hydrolysis of specified components in the cellulosic fibres (Janardhnan and Sain, 2006). The use of enzymes is a controlled hydrolysis, and results depend on the extent of treatment and pretreatment as well. ...
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anocrystalline (NCC) cellulose is a renewable natural resource obtained from cellulose-based materials. It is typically rod-shaped monocrystalline cellulose with tens to hundreds of nanometers in length and 1-100nm in diameter. Nigeria is blessed with an abundance of different sources of cellulose, more especially our agricultural waste. Although there are various ways of getting rid of these wastes, production of NCC is a very profitable alternative. This paper will discuss the different methods employed by researchers towards the production of NCC, likely limitations of these methods, properties of NCC and its applications in the modern world. This is, with the hope that our researchers take into consideration the exploration of this topic from the well-documented areas to the grey areas.
... The choice of cellulose extraction method depends on the cellulose plant source, desired fiber dimensions, required purity and yield, both of which depend on the further application of the obtained cellulose [53]. Methods such as: (i) alkaline treatment [54,55]; (ii) acid treatment [56]; (iii) bleaching [57]; (iv) ionic liquid extraction [58,59]; (v) microwave extraction [60]; (vi) ultrasonic extraction [61]; (vii) enzymatic treatment [62]; and (viii) combinations thereof [63,64], have been described for cellulose extraction and were comprehensively reviewed by Radotić & Mićić [53]. Although these methods have been extensively reported in the literature, they possess many limitations that restrict their development and application in the industry. ...
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