Production of Glues from Animal Bones

Abstract

The environmental and health risks associated with improper handling of waste bones will be greatly reduced if bone wastes generated from the abattoirs are converted to useful products. Waste cattle bones have been successfully used in the production of glue. The quality of the produced glue was ascertained by testing for quality indicators such as moisture content, pH, density, ash content and viscosity. The values of these quality indicators were greatly improved on investigation of the effects of water quantity and ratio of glue volume to polyvinyl volume used. The values of these quality indicators for the final glue produced with the new raw materials mix compared favorably with values of standard glue with maximum deviation of 0.20 for the ash content.

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VOL. 9, NO. 9, SEPTEMBER 2014 ISSN 1819-6608
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PRODUCTION OF GLUES FROM ANIMAL BONES
Akpa Jackson Gunorubon and Uku Misel
Department of Chemical/Petrochemical Engineering, Rivers State University of Science and Technology, Port-Harcourt,
Rivers State, Nigeria
E-Mail: jacksonakpa@yahoo.com
ABSTRACT
The environmental and health risks associated with improper handling of waste bones will be greatly reduced if
bone wastes generated from the abattoirs are converted to useful products. Waste cattle bones have been successfully used
in the production of glue. The quality of the produced glue was ascertained by testing for quality indicators such as
moisture content, pH, density, ash content and viscosity. The values of these quality indicators were greatly improved on
investigation of the effects of water quantity and ratio of glue volume to polyvinyl volume used. The values of these
quality indicators for the final glue produced with the new raw materials mix compared favorably with values of standard
glue with maximum deviation of 0.20 for the ash content.
Keywords: bone glue, cattle bones, polyvinyl acetate (PVA).
INTRODUCTION
Rapid industrialization has caused an enormous
increase in the amount of wastes generated particularly
solid waste in Nigeria and the world in general. Solid
wastes include all discarded solid materials from
municipal, industrial and agricultural activities (Glynn,
1996). The wastes generated from agricultural activities
especially from abattoirs in the processing of edible
portions of slaughtered animals for consumption was
estimated by Aniebo, et al. (2011) as shown in Table-1.
Table-1. Data for estimating abattoir effluent.
S/N Waste category Cow Goat
1 Blood/head (kg) 12.6 0.72
2 Intestinal
content/head (kg) 8.0 1.25
3 Waste tissue (kg) 6.4 0.80
4 Bone/head (kg) 11.8 2.06
The solid wastes consists mainly of bones,
undigested ingest and occasionally aborted foetuses while
the liquids comprise of blood, water, dissolved solids and
gut contents.
Table-1 showed that bones constitute the highest
quantity of solid waste and total waste generated from
abattoir operations. The bone dump of the Trans-Amadi
abattoir in Port-Harcourt, Rivers State shown in Figure-1
depicts a typical bone dump of an abattoir.
Figure-1. Bones disposed at the Trans-Amadi abattoir in
Port-Harcourt.
Inefficient management of these bones creates a
variety of problems that endanger public health and the
environment in general. These wastes are disposed in ways
that have been reported to cause the pollution of surface
and underground waters and air quality (Odoemelan and
Ajunwa, 2008); affect the health of residents living within
the vicinity of the abattoirs, destroy affected water bodies
thus affect fish yield, (Aina and Adedipe, 1991); discharge
of blood and animal faeces into streams has been reported
by Nwachukwu et al., (2011) to cause oxygen-depletion
while humans may also be affected through outbreak of
water borne diseases and other respiratory and chest
diseases (Mohammed and Musa, 2012). Bone wastes are
also ideal breeding grounds for disease causing organisms
(pathogens). These waste materials are disposed of
without regard to sound environmental management
practices, (Osibanjo and Adie, 2007); the waste bones are

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usually disposed by burning which further pollutes the air
and endanger human lives.
This work investigates the production of glue
from these waste bones thus provides an efficient
method/means of waste abattoir bones disposal that does
not pollute the environment and also creates wealth.
Glue is an adhesive substance used for sticking
objects or materials together or any substance applied to
the surfaces of materials that binds them together and
resists separation (Roberts and Etherington, 1982).
Adhesives may be found naturally or produced
synthetically. Adhesives of “animal” origin have been
found (Thorndahl, 2009) to be non-toxic, biodegradable
and environmentally friendly. However, difficulty of
storage in the wet state, it darkens with age and shrinks as
it dry thus can potentially damage what it is applied on are
some disadvantages of its use (Ebnesajjad, 2010). Hence
this work also seeks the improvement in the quality of
glue from this source by utilizing polyvinyl acetate and
formaldehyde to improve the gel strength, odor and shelf
life that make animal glue not applicable for most
applications.
MATERIAL AND METHODS
In the city of Port Harcourt, there are four
abattoirs (Trans-Amadi, Ogbunabali, Rumuokoro and
Ngboshimini). The activities of the Trans-Amadi abattoir
was monitored and used as a basis for this work. The
quantity of bones generated from this abattoir was
estimated with the assistance of the workers as an average
of 14, 850lbs daily over a one month period.
PRODUCTION OF BONE GLUE
The glue production was performed in the unit
operations laboratory of the Department of
Chemical/Petrochemical Engineering, Rivers State
University of Science and Technology, Port-Harcourt. The
steps involved in a typical glue production from cattle
bones were followed for the laboratory production of the
bone glues as follows:
SAMPLE COLLECTION
Samples of cattle bones were collected from the
Trans-Amadi abattoir in Port-Harcourt, Rivers State,
Nigeria. These samples were properly packed in a
polyethylene sack and taken to the laboratory.
SAMPLE TREATMENT
The bone samples were processed as follows:
Size reduction
The bones were reduced to smaller sizes as
shown in Figure-2 with the aid of a hammer.
Figure-2. Reduction of bone sample.
Washing and treatment with lime water
The bones were washed thoroughly with warm
water to remove fat and dirt. Hydrated lime solution was
produced (74g/mol of Ca(OH)2 dissolved in 1000cm3 of
water), 200g of the bone samples were soaked in the
hydrated lime solution for three days to eliminate odor and
all traces of hair and flesh attached to the bones as shown
in Figure-3.
Figure-3. Treatment of sample with lime water.
The bones were removed and washed with
distilled water to rinse off the hydrated lime.
Preheating with dilute acid
The samples were treated with dilute
hydrochloric acid (HCL) to control the pH, thus ensure
optimum breakdown of the collagen to glue as shown in
Figure-4.

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Figure-4. Treatment of bones sample with Hydrochloric
Acid (HCL).
Shredding/crushing
The bone samples were dried for two days and
crushed in a Jaw crusher to particle size of about 0.015mm
(300mesh) as shown in Figure-5.
Figure-5. Crushed bone samples.
Heating/evaporating
75ml of water was added to 100g of fine bone
sample. The bone solution was transferred into a beaker
and heated at 70oC for three hours to loosen the collagen
contained in the bone.
Figure-6. Heating of crushed bone solution.
Gelling/cooling
The resulting bone glue was allowed to stand for
40 minutes. On cooling, a jelly-like material was formed
as shown in Figure-7.
Figure-7. Jelly-like glue formed on cooling.
QUALITY CONTROL/IMPROVEMENT
Polyvinyl acetate (PVA) was added to the glue in
the ratio 1:4 (volume) to make the glue formed more jelly.
The mixture was stirred vigorously to achieve
homogeneity. The ratio can be varied to control the
desired degree of flexibility to improve elasticity. 10ml of
formaldehyde was added to prevent mold, bacterial growth
and improve shelf life.
Drying and pulverization
The glue was dried in a dryer to remove
unwanted moisture. This gives hard and brittle sheets of
the glue which can be stored. The brittle sheets can be
broken into pieces or flakes and ground into fine particles
according to the desired particle size or user’s
specification.
ANALYSIS OF PRODUCED GLUE
The quality of glue produced was ascertained by
determining the following quality indicators of the
produced glue: moisture content, pH, density, ash content
and viscosity. All results were the average of duplicate
analysis
Moisture content
5ml of the glue sample was weighed in a crucible
and heated in the oven at a temperature of 60oC until no
form of moisture was visible. Heating was continued till
no water was visible in any part of the apparatus except in
the trap and the volume of water in the trap remained
constant for five minutes. The sample was cooled to room
temperature and weighed. The moisture content was
calculated using the formula:
Moisture content (%) = Weight of moisture in glue x100%
Weight of glue before drying
Determination of pH
This was determined using a digital pH meter
(model HI 8424 with pH buffer 7). The pH meter was

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inserted into a beaker containing the glue sample and the
reading taken.
Determination of density
The densities of the glue were determined by
taking the weight of a known volume of the glue in a
density bottle (pycnometer) using an analytical balance.
Determination of ash content
100ml of the glue sample was weighed in a
beaker. The beaker with its content was heated to 500oC
until the glue became very dry and the visible appearance
of black spots on the glue sample. The dried glue was
cooled to room temperature and weighed. The ash content
of the glue was calculated using the expression:
% Ash content = Mass of dry glue sample x 100
Mass of original glue sample
Determination of viscosity
The Viscosity profile of the glue was obtained
using a viscometer (LvDv I+, Brookfield, USA) with the
spindle set at 60rpm following the technique proposed by
AOAC, (2000).
RESULTS
The results of the laboratory test of some quality
indicators performed on the produced glue are shown in
Table-2. The values of these quality indicators for standard
animal glue as giving by Pizzi and Mittal, (2008) are also
shown in Table-2 for comparison.
Table-2. Laboratory results of quality indicators for produced glue.
Parameter Produced glue Standard glue Deviation
pH 5.86 6.06 0.0330
Density (g/cm3) 1.015 1.270 0.2008
Viscosity (cp) 46.26 80.00 0.4218
Moisture content (%) 17.88 15.00 0.1913
Ash content (%) 3.029 2.000 0.5149
Table-2 shows that the quality indicator ash
content had the maximum deviation while pH had the
minimum deviation between the values of the quality
indicators for standard glue compared with values
obtained for the produced glue. The produced glue was
more acidic, less dense, had lower viscosity (less resistant
to flow), contained more water and had more ash.
PRODUCT OPTIMIZATION
The effect of water and PVA on the quality
indicators of glue produced was investigated.
EFFECT OF WATER
The quantity of water used in the production of
the glue was varied between 35 to 125 ml. The results of
the quality test on the produced glue are as shown in
Table-3.
Table-3. Effect of water on quality indicators of produced glue.
Water content
(ml) Viscosity
(cp) pH Density
(g/cm3) Moisture content
(%) Ash content
(%)
38 180.20 5.33 1.0449 11.93 4.43
50 106.15 5.64 1.0226 17.71 3.09
75 46.25 5.86 1.0152 17.87 3.03
100 34.10 5.99 1.0103 22.90 1.14
125 24.10 6.22 1.0035 30.20 0.25
pH: pH is the degree of acidity or alkalinity of a
substance. Increase in water quantity in the produced glue
neutralizes the acidity of the glue. Therefore, the more
water in the glue the less acidic the glue. This trend is
shown in Table-3 where increase in water increases the pH
of the glue.
Density: Density is the mass per unit volume of a
substance; increase in water quantity in produced glue
increases the volume of the glue thus reduces its density.
This trend is shown in Table-3 where increase in water
content decreases the density of the glue.
Viscosity: Viscosity is the resistance to flow. The
more water added to the glue, the lighter and less sticky it
becomes, it flows faster (its resistance to flow reduces).
Hence, the viscosity reduces. This trend is shown in Table-
3 where increase in water quantity in the glue decreases
the viscosity of the glue.

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Moisture content: Increase in water increases
the water content in the glue. This trend is shown in Table-
3.
Ash content: Ash content is the amount of
residue obtained when a sample is burnt under controlled
condition so that all ignitable mass is removed. The denser
the glue, the more the ash obtained (Milligan and Higgins,
2009). Increase in water content of the glue increases the
volume of the glue and reduces its density. Therefore
increase in water content of the glue makes the glue less
dense, hence reduces its ash content. This trend is also
shown in Table-3.
EFFECT OF POLYVINYL ACETATE (PVA)
The effect of polyvinyl acetate (PVA) on the
quality of the glue produced was investigated. The ratio of
glue volume produced to PVA volume was varied from
1:0.125 to 1:1. The results of the quality indicators of the
produced glue are shown in Table-4.
Table-4. Effect of polyvinyl Acetate on quality indicators of produced glue.
Ratio of glue to
PVA Viscosity
(cp) pH Density
(g/cm3) Moisture content
(%) Ash content
(%)
1:1 251.2 5.33 1.3806 15.30 4.7002
1:0.50 104.7 5.52 1.2401 19.00 3.8964
1: 0.40 83.81 5.58 1.2290 19.80 3.2059
1: 0.33 51.75 5.63 1.1452 21.80 3.1420
1: 0.167 3.44 6.20 1.1431 22.70 2.1925
1:0.125 1.72 7.00 1.0176 28.99 2.0024
Poly vinyl acetate is acidic; hence an increase in
its quantity in the produced glue makes the glue acidic
(decrease in pH value) while a decrease makes the glue
less acidic (increase in pH value). Glues with high acidity
have been reported (Milligan and Higgins, 2009) to absorb
less water; this is seen in Table-4, as the quantity of PVA
is increased, the glue became more acidic; it absorbed less
water leading to a decrease in glue volume and
subsequently an increase in its density. As the density of
the glue increases, it becomes thicker, produces more ash
(Milligan and Higgins, 2009); flows slower, thus its
resistance to flow increases (the viscosity of the glue
increases). These trends are shown in Table-4.
The water quantity and glue to polyvinyl volume
ratio had minimal effect on the density and pH but had
tremendous effect on the viscosity and moisture content of
the produced glue. The effect of water content and
polyvinyl ratio can be used to determine the optimum
values of these raw materials to use in the glue production
based on the values of the quality indicators of the
produced glue compared with values of the standard glue.
A couple of new trial raw material mix (proportions)
(water content: 50 - 75ml; PVA: 1:0.40) were used again
for the glue production from which a new optimum raw
materials mix was obtained; (ratio of glue to PVA of 1:
0.40 and the quantity of water 70 ml) was proposed and
used for the production of the last sample of glue.
This glue was subjected to quality test and the
results obtained for the quality indicators are shown in
Table-5.
Table-5. Comparison between new optimum glue and standard glue.
Parameter Optimum produced glue Standard glue Deviation
pH 5.82 6.06 0.0396
Density (g/cm3) 1.23 1.27 0.0315
Viscosity (cp) 83.25 80.00 -0.0406
Moisture content (%) 16.57 15.00 -0.1047
Ash content (%) 2.40 2.00 -0.2000
The values of the quality indicators of the new
produced glue compared favorably with those of the
standard glue with deviations as shown in Table-5. The
quality indicator; ash content had the maximum deviation
of 0.2000. There were also great improvements in the
quality indicators of the glue produced with the ‘new mix’
in Table-5 compared with the values of the quality
indicators of the initial glue produced in Table-2.
CONCLUSIONS
The hazardous effects of inadequate disposal of
waste bones are very glaring and cannot be ignored. There
is therefore the need for a proper approach to manage
waste bones from all sources especially the abattoirs,
particularly through Waste to wealth - schemes where
wastes are converted to useful products. Cattle bone
wastes were successfully used to produced glue, an

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adhesive. The quality of the produced glue was improved
by investigating the effects of two raw material used:
quantity of water and polyvinyl acetate used. The final
glue produced was tested and the quality indicators
compared favorably with those of standard glue.
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