PREPARATION AND EVALUATION OF WOOL KERATIN BASED CHITOSAN NANOFIBERS FOR AIR AND WATER FILTRATION

International Journal of Innovative Research in Advanced Engineering (IJIRAE) ISSN: 2349-2163
Issue 02, Volume 6 (February 2019) www.ijirae.com
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PREPARATION AND EVALUATION OF WOOL
KERATIN BASED CHITOSAN NANOFIBERS FOR AIR
AND WATER FILTRATION
Chetan Mahajan
Wool Research Association, PO. Sandoz Baug, Kolshet Road,
Thane (W) 400607, Maharashtra, India
crmahajan4985@gmail.com
Shishir Tyagi
Wool Research Association, PO. Sandoz Baug, Kolshet Road
Thane (W) 400607, Maharashtra, India
zamiiict@gmail.com
Manuscript History
Number: IJIRAE/RS/Vol.06/Issue02/FBAE10083
Received: 03, February 2019
Final Correction: 10, February 2019
Final Accepted: 15, February 2019
Published: February 2019
Citation: Mahajan & Tyagi (2019). PREPARATION AND EVALUATION OF WOOL KERATIN BASED CHITOSAN
NANOFIBERS FOR AIR AND WATER FILTRATION. IJIRAE::International Journal of Innovative Research in
Advanced Engineering, Volume VI, 37-44.doi://10.26562/IJIRAE.2019.FBAE10083
Editor: Dr.A.Arul L.S, Chief Editor, IJIRAE, AM Publications, India
Copyright: ©2019 This is an open access article distributed under the terms of the Creative Commons
Attribution License, Which Permits unrestricted use, distribution, and reproduction in any medium, provided
the original author and source are credited
Abstract— In this article, we have extracted keratin from deccani wool waste and prepared the wool keratin
based Chitosan nanofibers by electrospinning technique. The prepared nanofibers mat were prepared with
different weight percent ratio like 1wt.%, 3wt.% and 5wt.% with respect to polymer i.e Chitosan. The
physicochemical and filtration properties of wool keratin based Chitosan nanofibers were studied. Wool keratin
based Chitosan nanofibers were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray
diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (FESEM). The
filtration efficiency of keratin Chitosan nanofibers were investigated through DOP test and heavy metal removal
capacity of evaluated through Atomic absorption spectroscopy. FTIR results were showed that Keratin gets
compatible with Chitosan. XRD patterns revealed keratin was in crystalline nature and increase the crystalline
nature of Chitosan nanofibers. FESEM images showed that uniform nanofibers generation with average fiber
diameter 80nm. Nanofibers filtration efficiency against a particulate matter in air was obtained more than 99.53%
and excellent property of removal of heavy metal.
Keywords — Wool keratin; Chitosan; nanofibers; Air filtration; Water filtration;
I. INTRODUCTION
Keratin is the major structural protein of wool fiber; also this is the key structural material making up the outer
layer of human skin. Wool fiber in its native state belongs to a group of proteins called alpha-keratins, which is the
crystalline portion of the protein having a particular X-ray diffraction pattern associated with the alpha -helical
structure for proteins. Keratins are defined as natural, cellular systems of fibrous proteins cross-linked by
cysteine sulphur. Keratin based biomaterials are extensively used in biomedical applications because of the
several key properties of keratins that contribute to the overall physical, chemical and biological behaviour of
these biomaterials. The extracted keratin proteins have an intrinsic ability to self-assemble and polymerize into
porous, fibrous scaffolds.

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This phenomenon of self-assembly is evident in the highly conserved superstructure of the wool fiber and when
processed correctly, is responsible for the reproducible architecture, dimensionality and porosity of keratin-based
materials. The keratin is biomaterials and extracted from wool and human hair. [1-3]. The synthetic and natural
origin polymers has been used to create electrospun fibers for different applications [4]. Recently, research on the
electrospun nanofibers of biocompatible polymeric materials has very much enlarged due to versatile application.
Electrospining is a technique based on electrostatic charges that utilizes a high voltage charge helps to create jet of
polymer and travels towards collecting plate due to charge difference. The resulting fibers have diameters in the
rages from nano- to micro-scale and form a non-woven fibrous mat. The non-woven fibrous mat enhanced
physical properties due to small pore size, high porosity, three-dimensional features, and high surface area-to-
volume ratio. Recently, the electrospining process has also been extended to include regenerated keratin
extracted from hair and wool fibers. Due to the intrinsically poor mechanical characteristics of pure keratin,
however, many researchers have resorted to the addition of synthetic or natural polymers in order to increase the
processability of keratin for fiber formation [5-13]. This present focuses on the preparation of keratin embedded
Chitosan nanofibers for air and water filtration.
II. MATERIALS AND METHODS
A. Materials: Waste wool supplied by Raymond ltd, Petroleum Ether, Urea, 2-Mercaptoethanol, sodium dodecyl
sulfate (SDS), Formic acid 85 %, Acetic acid was procured from SD Fine Chemicals Limited (Mumbai, Maharashtra),
Cellulose Dialysis Tubing (molecular weight cut off 12000-14000Da) and chitosan purchased from Himedia
laboratories (Mumbai, Maharashtra).
B. Keratin extraction: Extraction of Keratin from waste as per method reported previously (Yamauchi et al.,
1996). The wool fibres were flooded in petroleum ether for 4 hours to de-waxing and removal of impurities like
dust etc. The keratin was extracted with a mixture of 0.2 M SDS, 8 M urea and 2 mercapto ethanol at 70°C for 5
hours. Wool fibers were dissolved in the mixture solution and form the dark red colour. The keratin solution was
then filtered to remove the un-dissolved wool fibre and thoroughly dialyzed against distilled water using cellulose
dialysis tubing to remove the chemicals. The pure form of aqueous keratin solution was obtained, poured the
solution into a petri dish and placed it in oven for 2 days and to get hydrolysed keratin powder.
C. Preparation of Keratin Chitosan nanofibers: Chitosan solution and keratin/Chitosan composites were
prepared in 2% acetic acid. The keratin/Chitosan composites were prepared with different weight % ratio with
respect to chitosan (C1) like 1wt.%(C2), 3wt.% (C3)and 5wt.% (C4). The keratin/Chitosan composites were
electrospun at a 15-cm working distance between collecting plate and tip of syringe. The applied voltages were
between 25-30 kV and about 2 mL of the polymer solution was placed in the syringe. The tip was positively
charged by the generator, when a steady voltage was reached between the tip and collector, the delivery pump
switched on and fed the fixed flow 0.5 ml/hr of the solution through the capillary, and the electrospinning process
started. The process was stopped after about 4hr. During the electrospinning process the temperature was ranged
from 20 to 25°C, and the relative humidity was in the range of 30–45%.
III. CHARACTERIZATION
A.UV Visible spectroscopy: UV Visible spectroscopy of powdered keratin was obtained by making the solution in
water and analyzing UV Visible spectra with help of Specord 201 Analytik Jena Germany.
B.Fourier Transform Infra Red (FTIR) Analysis: Fourier transform infra red (FTIR) spectra of lyophilized
reduced keratin was obtained by using the ATR technique (Attenuated Total Reflection). An infrared spectrum of
keratin was recorded from 5000 to 500 cm-1 using Alpha Bruker spectrophotometer Germany
C. Differential Scanning Calorimeter (DSC) Analysis: Differential scanning calorimeter (DSC) analysis of keratin
after conditioning the samples at 24C, 65% R.H was performed from 30C to 500C, at 10C/min using
instruments DSC 3 Mettelar Toledo, Switzerland,. The instrument was calibrated by an indium standard and the
calorimeter cell was flushed with 40 ml/min liquid nitrogen.
D. X-Ray diffraction analysis: Crystalline nature and structure was judged by Bruker, D8 ADVANCE (Bruker
Corporation, Tokyo, Japan) X-ray powder diffractometer (XRD) using monochromatic CuKα radiation (λ = 1.5406
Å) at 40 kV and 40 mA. Scan rate was 50/min between the angles 5-80.
E. Scanning electron microscopy: Surface morphology was observed using field emission scanning electron
microscope (FE-SEM), HITACHI S-4800, operated at 5 to 15 Kv. Suspension was drop casted onto carbon tape and
dried at room temperature. Prior to analysis sample was coated with gold to avoid degradation or burning due to
high power.
F. Air permeability: This test method covers the measurement of the air permeability--the rate of air flow
passing perpendicularly through a known area under a prescribed air pressure differential between the two
surfaces of a material of textile fabrics and is applicable to most fabrics including woven fabrics, Non woven fabric,
air bag fabrics, blankets, napped fabrics, knitted fabrics, layered fabrics, and pile fabrics. Nanofibrous mat comes
under None woven fabric, therefore it’s important to evaluate air permeability of nanofibrous mat.

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Determination air permeability of keratin based nanofibrous mat under designated pressure analyzed standard
ASTM D 0737 by applying pressure 125pa and test area 38cm2 using Air permeability tester MO211A SDL ATLAS
Hong kong.
G.Heavy metal absorption: Heavy-metal adsorption from aqueous solutions by keratin based bio films and
nanofibrous membranes was performed in dynamic conditions. Practically, accurately weight bio-film nanofibers
mat and, was placed in the solution containing heavy metals for required period of time. All the adsorption
experiments were carried out at a temperature of 25°C. The concentration of the metal ions after the adsorption
was determined with an atomic absorption spectroscopy 906AA GBC Scientific Australia.
where The removal efficiency was evaluated using the following equation adsorption capacity of the biofilms and
nanofibers membrane at C0 and Ct (mg/L) are the initial heavy-metal ion concentration and final heavy-metal ion
concentration respectively, Heavy metal stock solutions of 1000 ppm were prepared using their chloride and
nitrate salts, from which solutions of lower concentrations were obtained by dilution. Batch adsorption tests were
conducted in conical flasks with the desired adsorbent to adsorbate ratio. The suspensions were agitated by
shaking in a water bath shaker at 100 revolutions per minute (rpm). The conditioning temperature was adjusted
and maintained at the desired level. Deionized water was used in all experiments and all chemicals used were of
analytical grade.
H. Filtration efficiency (DOP) Test: Filtration efficiency with pressure drop evaluated by PALAS2010 instrument
were 0.3-4 particle size dust/aero-gel passed through nanofibers coated membrane and evaluate % retention
of solid particles and pressure drop. DOP/PAO testing is a very quick process that tests the integrity of the HEPA
(High Efficiency Particulate Air) filter using DOP or PAO solutions in their operational conditions. These solutions
generate a gas type smoke and then generate gas particles that will be greater than 0.3 microns. The test will
certify the HEPA filter is fully functioning and there is no leakage or damage.
IV. RESULT AND DISCUSSION
A. UV Visible spectroscopy:
Fig. 1.UV visible spectra of extracted keratin
UV-Vis absorption measurement of extracted keratin solution (fig 1) shows λmax at 273 nm with the absorbance 2.0779.
Keratin was absorbs mainly in the far UV, but has an absorption tail out as far 380nm. The main chromospheres
absorbing in the UV region are aromatic amino acids, tryptophan, tyrosine and phenylalanine, which are present in the
keratin chain. [11]
B. FTIR analysis:
FTIR analysis of keratin showed fig 2. the peptide bonds (–CONH–) were seen in the vibrational spectra. The
vibrations in the peptide bonds can be attributed to Amide A group which is characteristic bond in keratin i.e
amide I, II, III. The amide A band, which falls at 3327.12 cm-1 represents stretching vibration of N–H bonds .The
amide I band due to C––O stretching vibration occurs in the range of 1700–1600 cm-1. 1544.47 cm-1 represent
amide II was related to N–H bending and C–H stretching vibration. The amide III band observed in between 1220–
1300 cm-1 was highlighted at 1245.18 cm-1 as a sharp peak. The carbohydrate moieties band was observed at
1083.10 cm-1. [10-12]

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Fig. 2.FTIR Spectra of Keratin
C. DSC analysis of keratin
The DSC thermo gram of keratin is shown in Fig 3. The denaturation temperature observed around 56°C is due to
water evaporation. The endothermic peak observed above 148°C is reported for α helix denaturation in keratin.
The second endothermic peak for the hoof keratin is observed around 224°C.
Fig. 3 DSC analysis of Keratin
D. X Ray diffraction of Keratin:
An x-ray diffraction spectrum of extracted keratin was shown in fig 4. In XRD spectra peak arise at 2ϴ, 21.2 are
index for the b-sheet crystalline structure of keratin. XRD spectra clearly indicate the extracted keratin was in
highly crystalline state. [11]
Fig. 4. X -ray diffraction of Keratin

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Evaluation of Keratin/Chitosan composite nanofibers:
F. FTIR analysis:
The FT-IR spectra of prepared Chitosan showed significant absorption bands to identify the characteristic
functional groups which were recorded in the middle infrared (4000 cm-1 to 500 cm-1 ). The infrared spectra for
chitosan biopolymers are shown in Fig. 5. The stretching vibrations of -OH bond of the prepared chitosan was
found at 3478.68cm-1 and that for C–H were observed at 2924.13 cm-1. The absorption peaks at 1656.88 cm -1 ,
1571.05 cm -1 , 1422.53 cm -1 , 1378.16 cm -1 were associated with the presence of the C=O stretching of the
amide I band, bending vibrations of the N–H (N-acetylated residues, amide II band), C-H bending, OH −1 bending
respectively. The peak at 1157.31 cm was assigned for anti- symmetric stretching of bridge, 1075.33cm -1 and
1025.18 cm-1 were anticipated to the skeletal vibration involving C–O stretching. Spectra of pure polyamide 6 and
protein from wool showed overlapping bands at about 3478cm-1 (Amide I) and 1571 cm-1 (Amide II) . Only in the
region between 1000 cm-1 and 800 cm-1 absorptions in Chitosan spectrum were present
4000 3500 3000 2500 2000 1500 1000 500
%T
Wavenumber(cm
-1
)
C1
C2
C3
C4
Fig. 5. FTIR spectra of keratin/chitosan composite nanofibers
F. XRD analysis:
X-ray diffraction spectra of keratin and keratin/Chitosan composite nanofibers was shown in fig.6. In XRD spectra
peak has been rises at 2ϴ, 21.2 are index for the b-sheet crystalline structure of keratin. XRD spectra clearly
indicated the extracted keratin was in highly crystalline state. In case of keratin/ Chitosan nanofibers intensity of
peak at 2ϴ, 21.2 increased due to addition of keratin.
Fig. 1. XRD analysis of Keratin /Chitosan composite nanofibers
G. DSC analysis:
Fig 7 illustrated the DSC curves of keratin/Chitosan composite nanofibers, the endothermic peak at approximately
78.59 °C can be attributed to the evaporation of bound water, representing the energy required to vaporize bound
water present in the films, followed by another endothermic peak observed at about 238°C related to the
crystalline melting (Tm) of the keratin/Chitosan composite nanofibers.

_________________________________________________________________________________________________
Chitosan has interferes with the keratin self-assembling, causing the protein chains to organize in a thermally
more stable than neat chitosan. Degradation temperature for keratin/Chitosan composite nanofibers was found to
be 339.10°C .
100 200 300 400 500
Temp
C1
Heatflowendodown(mW)
C2
Degradationtemparature
238.10
0
C
78.59
0
C
C3
339.10
0
C
Tm C4
Fig. 7. DSC analysis of keratin/Chitosan composite nanofibers
H. Heavy metal adsorption (%) Efficiency in water:
Metal like Cd, Ni Pb and Fe were removed with the help of keratin/chitosan nanofibers with different weight ratio.
Metal salt of Cd, Ni Pb and Fe in known concentration containing solution was passed through Nanofibrous mat
and evaluated the amount of the heavy metal adsorbed on the surface of the Nanofibrous layer. Chitosan
nanofibers shows good amount of heavy metal adsorption but in case of keratin/Chitosan composite nanofibers
shows excellent adsorption ability than neat chitosan nanofibers shown in table 1. The spectacularly enhanced in
adsorption efficiency due to special characteristic nature of keratin and nanofibers. Keratin is functionally active
protein which has functional moieties helps to bind the metal ions to them, therefore keratin showed additive
effect for removal of heavy metals with Chitosan nanofibers.
Table 1. Heavy metal adsorption efficiency of Chitosan and Keratin/chitosan composite nanofibers
Membrane Heavy metal removal efficiency (%)
Cd Ni Pb Fe
Chitosan nanofibers coated non woven fabric (C1) 24.9 28.74 22.1 31.65
Keratin/chitosan composite nanofibers non woven fabric(C2) 88.9 86.4 89.46 97.11
Keratin/chitosan composite nanofibers coated non woven fabric (C3) 89.2 87.1 88.46 96.56
Keratin/chitosan composite nanofibers coated non woven fabric (C4) 90.1 91.47 89.58 98.97
I. Particulate matter filtration efficiency: Filtration efficiency with pressure drop was evaluated by DOP test
(Dispersed oil particulate). The 0.3-4 particle size dust/aero-gel passed through Chitosan and Keratin/chitosan
composite nanofibers coated membrane and evaluate % retention of solid particles and pressure drop. The
particulate matter (aerogel) passed through nanofibers at 95 L/m and evaluates the filtration efficiency. Obtained
result shows excellent filtration efficiency 97-98% due to the presence of nanofibers. Nanofibers are play an
important role in filtration, nanofibrous mat contains very small pores upto 100nm which helps to restrict
particulate matter which will more than 100nm. The densities of nano pores are numerous due to that air can
easily pass through membrane but particulate matter get restricted. Maximum density of nano pores helps to
maintain pressure drop.
Table 2. Evalution of filtration efficiency (%) Chitosan and Keratin/chitosan composite nanofibers
Membrane (%) Filtration
efficiency
Pressure drop(H)
mmwg
Air flow
Inlet Count (C1) Outlet count (C2)
(C1) 141476 3458 97.55 20
95L/m
(C2) 149548 2248 98.49 24
(C3) 114597 1146 98.99 24.6
(C4) 179892 892 99.53 25.1
J. Surface Morphology Chitosan and Keratin/ Chitosan Nanofibers:
The surface morphology of keratin/Chitosan nanofibers were evaluated by scanning electron microscopy shown
in fig. 8. Nanofibers are prepared with mixture of Keratin with Chitosan.

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Nanofibers are uniformly formed with the diameter 68nm-79 nm. The Nanofibers make non woven fibrous
structure which was uniform in nature. The surface morphology of nanofibers has been undoubtedly shown that
the nanofibers mat forms the mesh like structure which helps in filtration air as well as water.
Fig.8. SEM analysis of Chitosan and keratin/Chitosan composite nanofibers
V. CONCLUSION
Keratin extracted from deccani wool waste and blended with chitosan at different concentration. The
electrospinning process appeared stable and successful for keratin/chitosan composite solutions. All the
nanofibers were found to be smooth and bead-free with favourable compatibility between keratin and Chitosan.
The filtration efficiency keratin/chitosan nanofibers were shown 99.53% filtration efficiency and excellent heavy
metal adsorption from water for Cd, Ni,Pb and Fe metals . Overall, the present work demonstrated the possibility
to incorporate Keratin into Chitosan nanofibers that have the potential to be applied in the filtration for air as well
as water.
ACKNOWLEDGMENT
Authors thank to Ministry of Textile, Govt of India for financial support.
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