Application of nanomaterials in leather processing

1. Nanomaterials Used As Nanocomposite for
Antimicrobial Effect on Leather Processing
Presented By
Anower Jahan Tamanna
Roll No: 2119501

2. Objectives
At the end of this discussion, we would be able to
 Distinguish composite and Nano composite
 Understand nanoparticle
 Synthesize and apply nanoparticle in leather processing
 Common microorganism/microbes growth in different stages
of leather processing
 Describe the antimicrobial action mechanism of transition
metal nanoparticles (Ag, Au, Cu, Zn, Ti, Mg, Al ) 2
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3. Contents
• Introduction
• Microbes & Antimicrobial
• Structure of Bacteria & Fungi
• Composite and nanocomposite
• Nanomaterials
• Nanoparticles
• Synthesis and characterization of metal nanoparticles
• Application of nanomaterials in Leather Processing
• Action mechanism of nanoparticles
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4. Introduction
• Hides/skins are the outer covering of animal which are classified based on size,
weight and also on domestic and wild rear up.
• The hides/skins have high moisture and are a rich source of fats and proteins
that may serve as feed substrates for microorganisms.
• Bacterial and Fungal growth in hides/skins and leathers causes significant
damages like completely damage of raw stocks, cured, unhaired and wet-blue
stock of hides/skins or stains, surface roughness and loss of physical-mechanical
resistance.
• In one study, 414 micro-organisms from 80 cattle hide and 80 sheep skin
samples were isolated.
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5. Introduction
• During the processing of leather in tanneries in first stages the hide is attacked by
bacteria like Bacillus subtilis, Escherichia coli, Micrococcus spp., Proteus vulgaris
and Pseudomonas aeruginosa. When the hides are tanned, fungi such as Penicillium
spp., Aspergillus spp., Trichoderma spp., Rhizopus spp. and Mucor spp can grow on
the hides.
• Antimicrobial agents may have specific action on a specific type of microorganism, as
bactericides against bacteria attack, and fungicides that confer resistance to fungi, or
may have broad spectrum of action, providing resistance to microorganism without
distinction.
• So, antimicrobial action of nanoparticles from nanocomposite on different stages of
leather processing will be the tremendous solution of the problem.
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6. Antimicrobial
• An antimicrobial is an agent that kills microorganisms or stops their
growth. Antimicrobial medicines can be grouped according to the microorganisms
they act primarily against. For example, antibiotics are used against bacteria,
and antifungals are used against fungi.
Fig. 1.0 Antibacterial and antiviral defense icon stop vector image (Courtesy: http://antimicrobial image)
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7. Structure of Microbes
Fig. 3.0 Fungi structure (Courtesy: http://bacteria image)
Fig. 2.0 A typical bacterial cell (Courtesy: http://bacteria image) 7
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8. Composite and Nanocomposite
• Dispersion of discontinuous phase (reinforcement) within a continuous phase (matrix)
in a controlled manner to achieve superior properties than the individual components.
• Nanocomposite is any composite material one or more of whose components is some
form of nanoparticle.
Fig. 4.0 Nano, meso and micro structure.
Courtesy: The Functional Materials Synthesis & Integration, Materials Science Division, Lawrence Livermore National Laboratory
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9. Nanomaterial
The International Organization for Standardization (ISO) has defined nanomaterial (NM) as a
material with any external dimension in the nanoscale or having internal structure (clusters,
crystallites, or molecules) or surface structure in the nanoscale (1–100 nm range).
 Classification of Nanomaterial
a. Inorganic (metal, metal oxide, and ceramic-based ),
b. Organic based ( lipids, carbohydrates, or polymeric substances) nanomaterials and
c. Composite-based nanomaterials (combination of two or more nanoparticles)
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10. Nanoparticle
• Nanoparticles have those chemical and physical properties which makes them
very different from that of the corresponding bulk materials due to their small size
and large surface to volume ratio.
• Nano =
• 1 nm = 1/1 000 00000 m = 0.0000000010 m
Fig. 5.0 Dispersion of nanoparticles into the polymer matrix (Courtesy: Nanocomposite materials, Dr. V. Krishnakumar and Mousumi Sen)
9
10
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11. Classification of Nanoparticles (NPs)
• NPs are broadly divided into various categories depending on their
morphology, size and chemical properties. Based on physical and chemical
characteristics, some of the well-known classes of NPs are given as below:
a. Carbon-based NPs
b. Metal NPs
c. Ceramics NPs
d. Semiconductor NPs
e. Polymeric NPs
f. Lipid-based NPs 11
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12. Metal Nanoparticles (MNPs)
• Metal NPs are purely made of the metals precursors. Due to well-known
resonance characteristics, these NPs possess unique optoelectrical and magnetic
properties. NPs of the alkali, transition metals and noble metals i.e. Mg, Ti, Fe,
Cu, Ag, Au, Zn have a broad absorption band in the visible zone (400-700nm)
of the electromagnetic spectrum. The surface, size and shape controlled synthesis
of metal NPs is important in present day cutting-edge materials. Due to their
advanced optical, conducting, magnetic properties, metal NPs find applications in
many research areas.
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13. Synthesis of nanoparticles
Fig. 6.0 Top-down and bottom-up synthesis of nanoparticles. (Courtesy: Chan Oeurn Chey, doped ZnO nanostructures, their characterization and sensing applications)
Break-down Building-up
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14. Characterization Techniques
Name/technique/Instrument Characteristics/Output/Result
BET (Brunauer–Emmett–Teller) To determine the surface area of NPs materials.
DCS (Differential Centrifugal Sedimentation) It is used, in case of agglomeration and hydrophilicity, for high-resolution image & measurement.
DLS (Dynamic Light Scattering) Give better idea about the particle size at extremely low level.
EDX (Energy Dispersive X-ray Spectroscopy) Give elemental composition with a rough idea of % wt & structural properties of NPs.
FE-SEM (Field Emission Scanning Electron microscopy) To investigate molecular surface structures and their electronic properties.
NTA (Nanoparticle Tracking Analysis) Visualize and analyze the NPs in liquids media that relates the Brownian motion rate to particle size.
POM (Polarized Optical microscope) Morphology (texture, pores, pores size etc), metal organic frameworks
SEM (scanning electron microscope ) Morphology, dispersion of NPs at matrix, metal organic frameworks
TEM (Transmission Electron Microscope ) Morphology(high resulation), essential information about two or more layer materials, , the elemental composition with a
rough idea of % wt
UV– vis (Ultra Violet Visible Spectroscopy) The optical properties of NPs materials.
XRD (X-Ray Diffraction Spectroscopy)
XRF (X-Ray Flurescence)
Study structural (crystallinity, composition, phase) properties of NPs
Purity of nanoparticle
FTIR (Fourier-transform infrared spectroscopy) To know chemical bonds or functional groups
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15. Application of nanomaterials as nanocomposite
Engineering
Leather Engineering
Leather Manufacturing
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16. Nanomaterials Used for Antimicrobial Effect on Leather Processing
• Silver nanoparticles
• Gold nanoparticles
• Zinc oxide nanoparticle
• Copper oxide nanoparticles
• Titanium dioxide nanoparticles
• Magnesium oxide nanoparticles
• Aluminium nanoparticles
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17. Continued
• For transition metals, consider as the following common electronic configuration
• When the d-level is not completely filled, it is possible to promote and electron from a lower energy d-orbital to a
higher energy d-orbital by absorption of a photon of electromagnetic radiation having an appropriate energy.
• Due to the transition of electrons from lower state to higher state that is one orbital to another orbital , transition
metal provide coloring, optical, conducting, magnetic properties. And these absorptional property of electron and
electron shifting property are used in the UV- vis, SEM, TEM, FE-SEM etc techniques for characterization.
2
1
10
1
)
1
( 

 ns
d
n
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18. Silver nanoparticles
• Silver nanoparticles are nanoparticles of silver of between 1 nm and 100 nm in
size. While frequently described as being 'silver' some are composed of a large
percentage of silver oxide due to their large ratio of surface to bulk silver atoms.
• Shapes of silver nanoparticle
• Commonly used silver nanoparticles are spherical, but diamond, octagonal, and thin sheets are also common.
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19. Chemical Synthesis of Ag NPs
• Chemicals /reagents:
• Silver nitrate solution (AgNO3), 0.001M e.g. (Source of silver ion).
• Sodium borohydride solution (NaBH4), 0.002M or Trisodium citrate, Na3C6H5O7
e.g. (Act as a reducing agent)
• Saturated Sodium chloride solution (NaCl) e.g. (Act as a buffer solution as to
maintain constant pH).
• Potassium bromide (KBr), 250 mg/mL e.g. (Act as a stabilizing agent is to control
particle size)
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20. Chemical Synthesis of Ag NPs
Procedure:
1. Measure 30cm3 of NaBH4 solution by a measuring cylinder into a 100 cm3 beaker, after
that place the beaker into an ice bath and continue cooling up to 5-10 minutes.
2. Take another clean cylinder to measure 10 cm3 AgNO3 solution and immediately transfer
the solution into a burette.
3. Place the temperature control stirring plate under the burette and place the complete ice
bath set on the hot plate stirrer and stir the NaBH4 solution by adding a magnetic stirrer
at 200 C with 450-500 rpm.
4. Then add AgNO3 solution from burette to beaker drop wise (1.0 drop/sec) and continue
stirring and wait till the end of the finishing of AgNO3 solution at burette. 20
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21. Chemical Synthesis (Top-down)of Ag NPs
Procedure:
5. Then remove the beaker from the ice bath and also remove the magnetic stir from the beaker.
6. The solution turned into yellow. Take 40 cm3 fresh water into another beaker and place side by side and
observe by passing a laser light beam through these two beaker and the result in main Ag nanoparticle
beaker transmit the green light.
• Test
1. Then half of the solution take into another beaker and add Saturated Sodium chloride solution And observe the
change of color from light yellow to light pink which indicates Ag NPs presence.
2. Or observe in UV-vis and it was shown weave length at 490nm indicates it “Ag”
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22. Why Silver Nanoparticle Based nanocomposites exhibits Antimicrobial action?
The antimicrobial activity of silver (Ag) is due to its Ag+ ions, as the ions provided the
following characteristics:
Ag+ inhibits the electron transport chain of microbes
Ag+ damages DNA and RNA by binding with them
Ag+ also inhibits cell division by inhibiting DNA replication
Ag+ ions form ROS(Reactive Oxygen Species), ROS produce oxidative stress which are toxic to both bacterial
cells and eukaryotic host cells
 The high affinity of silver (Ag+) ion for the sulphur in the thiol protein of bacteria & this affinity leads to the
breakage of disulphide bonds in thiols. 'the protein tertiary structure is eventually disrupted, resulting in cell death.
Due to positive charge on silver (Ag+) ion produces an electrostatic interaction with bacteria cell and an osmotic
pressure is produced and eventually silver nano particle enter the cell by breakage the cell wall.
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23. Antibacterial Action Mechanism of Silver Nanoparticles
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Ag NPs
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24. Application on Leather Processing
Preservation of Hides/Skins
 Preservation of cured or uncured hide/skin for a certain period of time by Ag-NPs based nanomaterial is possible by a
great extent. small diameter Ag nanoparticles with (ZnO/Ag or CuO/Ag) have a superior antimicrobial effect .
Unhairing:
 PVA(polyvinyl alcohol)-Ag NPs immobilized β-keratinase nanocomposite act as up-to-date antibacterial and dehairing
agent.
Tanning :
 The hydrophilic character of vegetable tanned leather is potentially a medium for bacterial growth. Vegetable tanned
leather coated with silica (leather@ ) and vegetable tanned leather coated with silica/ silver (leather@ /Ag)
nanocomposite are thermally stable materials and act as an antimicrobial agents to inhibit Staphylococcus aureus (S.
aureus).
 Chitosan based antibacterial nanocomposite materials impregnated with basic chromium sulphate ( ) show
certain degree of antibacterial activity.
4
)
( SO
OH
Cr
2
SiO 2
SiO
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25. Continued
 Ag doping with transition metal nanocomposite give better sensitivity to destroy bacterial cell damage, hence highly
antimicrobial.
 e.g. CuO/Ag was more effective against both E. coli and S. aureus as compared to ZnO/Ag.
 The results prove the novelty that CuO/Ag nanocomposite has better antibacterial activity against both Gram-positive and
Gram-negative bacteria species compared to ZnO/Ag.
Retanning:
• To fabricate functional leather, gallic acid modified silver nanoparticles (GA@AgNPs) were used as retanning agent. Due
to its hydrophilic gallic acid surface, the GA@AgNPs possessed excellent stability against bacteria.
Finishing:
 Antimicrobial performance of nano silver coatings on leather finishing materials protects fungi growth in a great extent.
 Tanned leather and polyurethane leatherette (artificial leather), typically employed in the automotive and footwear industries,
which were modified by photo-deposition of antibacterial silver nanoparticles (AgNPs).
 Development of antimicrobial leather modified with Ag– nanoparticles for footwear industry plays a great role.
 Antibacterial of Cu–Ag/PU - nanomaterial based sputtered polyurethane coating for antimicrobial leather manufacture.
 Antimicrobial electrochemically obtained nanosilver solutions for leather and furskin treatment, odor free finishing coat is
possible.
2
TiO
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26. Continued
Chitosan based antibacterial composite materials Polyethyleneglycol-chistosan-AgNPs based
(PEG/CS@Ag) coated leather act as antibacterial tanning agent for leather industry.
Chromium cross-linking based immobilization of GA(galic acid)@AgNPs on leather surface
act against broad-spectrum of microbes and give high durability of leather.
Ag-NPs are also very good protector against a large range of fungi.
Antimicrobial Nano-Ag- Coating for Lining Leather is also possible.
2
TiO
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27. Preservation of Hides by Antibacterial CuO/Ag and ZnO/Ag Nanocomposites Against
Escherichia coli (E. coli) & Staphylococcus aureus (S. aureus)
• Different concentrations of 5mg/ml, 2mg/ml, 1mg/ml, 0.5mg/ml, 0.25mg/ml, 0.1mg/ml, and 0mg/m of CuO/Ag and ZnO/Ag
nanocomposites against Escherichia coli (E. coli) & Staphylococcus aureus (S. aureus)
were applied and their inhibition zones was observed.
MIC (Minimum Inhibition
Concentration)
MIC (Minimum
Inhibition
Concentration)
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28. Continued
Death
Cell
Bacteria
NPs
of 
c
Con
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29. Continued
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30. Antimicrobial PVA@Ag-NPs- β-keratinase unhairing agent and its activity
The SEM image also confirmed the agglomeration of Ag NP post-binding with β-keratinase enzyme.
Ag NPs
β-keratinase
(Immobilized )
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31. Antimicrobial PVA@Ag-NPs- β-keratinase unhairing agent and its activity
TEM image
shown the
dimension of
AgNPs (Penta &
hexa gonal)
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PVA@Ag-NPs-
β-keratinase is in an
agglomerated state in
side leather
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32. XRD graph of Ag NPs bound β-keratinase for structural determination
FCC =Face Centered Cubic
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Intensitty (near
about 300 a.u)
600A.U
(b)
300(+)
A.U
(a)
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33. PVA@Ag-NPs- β-keratinase unhairing agent or nanocomposite, (Action of unhairing)
• This nanocomposite (PVA@Ag-NPs- β-keratinase) plays a great role in case of dehairing.
PVA@Ag NPs application Only β-keratinase application
Nanocomposite
(PVA@AgNPs- β-keratinase)
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34. Gallic acid modified silver nanoparticles (GA@AgNPs) were used as retanning agent.
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GA@AgNP bounded
with Cr ion inside
the tanned leather
Cr ion inside the
tanned leather
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35. Fig. 5. SEM images of parallel section of (A) pristine leather without GA@AgNPs retanning and (B) leather with
GA@AgNPs retanning
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36. Fixation of the nanocomposite (GA@AgNPs) retanning agents inside the leather
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39. Finishing
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40. Zinc oxide nanoparticle
• Zinc oxide nanoparticles are nanoparticles of zinc oxide (ZnO) that have diameters less than
100 nanometers. They have a large surface area relative to their size and high catalytic activity.
The exact physical and chemical properties of zinc oxide nanoparticles depend on the different
ways they are synthesized.
Size and Shapes
ZnO nanoparticles have different shapes (rod-like, star-like and isometric (3D shape)) and a
broad size distribution range of 30–150 nm. The ZnO particles were present mainly as clusters. In addition, spherical
particles with a size between 200 nm and 1 μm were present.
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41. Synthesis of ZnO nanoparticles
 Preparation of peel extracts
1. Orange fruits were washed and dried before being peeled as thinly as possible.
2. The peel was then placed in a food drier for 12 hrs until completely dry and then ground into a moderately fine
powder.
3. Afterwards, 1 g of the powder was placed in different glass containers with 50 mL of de-ionized water in each
container and was stirred for 3 hrs.
4. Once macerated, each mixture was placed in a water bath at for 60 minutes.
5. Finally, the mixtures were filtered.
 Preparation ZnO NPs
1. Take 2 g of zinc nitrate and then
2. Mixed with 42.5 mL of deionized water each of the extracts (orange fruit peel).
3. These mixtures were then stirred for 60 minutes and then placed in a water bath at for 60 minutes.
4. Subsequently, the mixtures were dried at and
5. then heat-treated at for 1 hour.
C
600
C
4000
C
600
C
1500
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42. Synthesis of ZnO nanoparticles (Green synthesis)
C
4000
Calcination (High
temperature heated
for purification &
removal of volatile
organic compounds)
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43. Zinc oxide nanoparticle
• Why Zinc oxide-containing nanoparticles (ZnO NPs) act as antimicrobial agent
(a) ZnO NPs destroy both lipids and the proteins of the membrane, which can cause
cell death
(b) ZnO NPs also form Zn2+ ions and ROS, including hydrogen peroxide
( ),which damage the bacterial cell
2
2O
H
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44. Action Mechanism
The anticipated mechanism of antimicrobial action of ZnO nanoparticles is:
(1) ROS generation,
(2) zinc ion release on the surface,
(3) membrane dysfunction, and
(4) entry into the cell.
It was assumed that nanoparticles should cross the bacterial cell membrane to damage
the crucial enzymes of bacteria, which further induce cell death. For instance, green
synthesized nanoparticles show enhanced antimicrobial activity compared to
chemically synthesized or commercial nanoparticles. 44
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45. Application on leather Processing
(ZnO) and copper oxide (CuO) are cheaper, widely available, less toxic to mammalian cells,
stable, and more environmentally friendly.
ZnO nanoparticles were shown to have a wide range of antimicrobial activity against various
microorganisms.
 ZnO-NPs sputtering coating is used as UV-protective clothing such as leather and textile
apparel.
 Protease immobilized ZnO nano-biocatalyst (Enzyme-ZnO nanomaterial)on to
nanoparticles (termed as Nano-biocatalyst) is used as dehairing agents.
Coupling of ZnO nanoparticle with Ag can act as hides/skins preservation and act as
bacteriostatic agents (E. coli, S. aureus).
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46. Continued
Polyacrylate/ZnO composite coatings on a leather matrix plays an important role
as an antibacterial and UV-shielding.
ZnO@GA (galic acid) NPs plays an important role as an antibacterial agents for
preservation of hides/skins for a short period of time.
Sonochemical Coating on Textiles and leather with Hybrid ZnO/Chitosan
nanoparticles for antimicrobial purpose is widely popular.
 The most intense antibacterial activity was reported for the ZnO nanoparticles
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47. Others nanocomposite (transition, alkali earth &, basic metal) used in Leather Processing
No Nanocomposite
(nanoparticle)
Size
nm
Action Mechanism Morphology Application in Leather
Processing
1. Copper-containing
nanoparticles
(Cu NPs)
20–95 1. Copper ( ) interacts with amine and carboxyl groups, which are
present on microbes such as B. subtilis
2. Higher concentrations of ions can produce ROS.
Cube,
hemisphere
agglomerate
Preservation of rawstock, Finishing
2. Titanium
dioxide-containing
nanoparticles( NPs)
20,
50-70
1. In the photo catalysis process, NPs generate ROS, including
hydrogen peroxide ( ) and hydroxyl radicals (·OH), upon exposure to
near-UV and UVA radiation
Spherical Lining leather, Finishing
3. Gold nanoparticles 7-
12.4,
20-50
1. Antimicrobial action of gold nanoparticles is not associated with the
production of any ROS-related process. To investigate the antibacterial
potential of the Au nanoparticles, researchers attempted to attach
nanoparticles to the bacterial membrane followed by modifying the
membrane potential, which lowered the ATP level. This attachment also
inhibited tRNA binding with the ribosome
Rod-shaped,
Spherical,
triangular,
hexagonal
Au nanoparticles is highly useful in
Metallic Finishing on Leather for
effective antibacterial agents
because of
their non-toxic nature.
Dyeing of leather
4. Magnesium oxide
nanoparticles
50–70 1. NPs also cause lipid peroxidation of the microbial cell envelope by
generating ROS
2. NPs can cause lipid peroxidation and a drop in cytoplasmic pH,
which raises membrane potential.
Spherical,
hexagonal
---------
5. Aluminium nanoparticles 50–70 1. Disorganization of the membrane
2. Increases membrane permeability
3. Accumulation of NPs in the
bacterial membrane and
cytoplasm regions of the cells
Spherical Finishing.

2
Cu

2
Cu
2
TiO
2
TiO
2
2O
H
2
MgX
2
MgF
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48. Effectiveness of NPs Parameters Against Microbes Cell
Parameters
Affecting
Microbes
Cell
NPs
Surface
Characteristics
NPs
Concentration
NPs
Charge
NPs
Size
NPs
Shape
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Fig. Parameters of NPs Upsetting Microorganism Growth
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49. References
Book
Tanning chemistry the science of leather by Anthony D Covington, edition 2017.
• An Introduction To The Principles of Leather Manufacture by S. S. Dutta, 4th edition, 2008.
• The Role of Leather Microbes in Human Health By Richard O. Oruko, John O. Odiyo and Joshua N. Edokpayi, 1st Edition, 2019.
• Nanocomposite Materials by Mousumi Sen, Edition 2019.
• An introduction to nanoparticles and nanotechnology by Maria Benelmekki, Edition 2015.
Journal
 Nanoparticles as Antimicrobial Agents: Their Toxicity and Mechanisms of Action, A. Herman1and A. P. Herman, Journal of Nanoscience and Nanotechnology Vol.
14, 946–957, 2014 .
 Characterization and antimicrobial performance of nano silver coatings on leather materials, N. Lkhagvajav1, M. Koizhaiganova1, Yasa, E. Çelik, and O. Sari1,
Brazilian Journal of Microbiology, Vol 1, 41-48, 2015.
 Green synthesis of silver nanoparticles using soluble soybean polysaccharide and their application in antibacterial coatings, Zhengxin Ma, Jie Liu, Yanchun Liu,
Xuejing Zheng and Keyong Tang, International Journal of Biological Macromolecules, 2020
 Chitosan based antibacterial composite materials for leather industry: a review, L. Yuan, Q. Yao, Y. Liang, et. al., Journal of Leather Science and Engineering, 3-12,
2021.
 Nanoparticles: Properties, applications and toxicities, Ibrahim Khan, Khalid Saeed, Idrees Khan, Arabian Journal of Chemistry, 12, 908–931, 2019.
 Fabrication of silver nanoparticle sponge leather with durable antibacterial property, Gongyan Liu, Haiqi Gao, Kaijun Li, Jun Xiang, Tian xiang Lan, Zongcai Zhang,
Journal of Colloid and Interface Science, 514 ,338–348, 2018.
 Alternative Antimicrobial Approach: Nano-Antimicrobial Materials, NuritBeyth, Yael Houri-Haddad, Avi Domb, Wahid Khan, Ronen Hazan, -Evidence-Based
Complementary and AlternativeMedicine, 1-16, 2015.
 wikipedia.com
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THANK YOU ALL
TAMANNA