FAT HOPE : BENEFITS FROM HOUSEHOLD WASTES
Page
• Current Situation
2
• Proposed Changes
6
• Chemistry
7
• Procedures
10
• Equipment Used
22
• Potential Benefits
24
• Process Flow
25
Submitted by :
Aow Jie Wei (1101172C), Gan Shi Yun (1102884B), Mohd Aidil (1100519F)
Supervisor :
Siew Yong Pau (siewyong@tp.edu.sg , hp : 98796781, Lecturer, ASc)
1
1. Current Situation

In this era of healthy living, many households would
remove fats and skins from meats before cooking them.
The removed fats and skins (from chicken meat, etc.) are
often discarded. This is because they are viewed as of
no value or worst, bad for health (Figure 1).
Figure 1 : Fats/Skin
removed from chicken
2

Chicken skin is generally made up of fat and protein.
34 g of chicken skin can yield 15 g of fat. The solid fat,
found under the chicken skin will yield even more fats.
Esters of linoleic acid (C18H32O2) constitute about 20%
of the chicken fats.
3

Exhausted
alkaline
batteries
(Figure 2) are often immediately
discarded as they are presumed to
have no more values.
Figure 2 : Example of an
alkaline battery

Alkaline batteries contain potassium hydroxide (KOH).
If leaked, KOH is a caustic agent that can cause
respiratory, eye and skin irritation (Figure 3).
Figure 3 : Leaked battery
http://www.wikihow.com/Clean-Battery-Leaks/Spills
4
• Cost of living is increasing at a stupendous pace.
Singapore inflation reaches 5.2% in June
July 25, 2011 - SINGAPORE: Singapore's Consumer Price
Index (CPI) in June rose 5.2 per cent year-on-year.
This was in line with market expectations, and higher than
the 4.5 per cent rise in May.
The upward cost pressures were concentrated in the usual
sectors of transport, housing and food.
http://www.channelnewsasia.com
Household cost of living
has sky-rocketed.
• Cost of liquid soap ranges from $5/lt to $64/liter
2. Proposed Changes

Make use of discarded chicken skins/fats and potassium
hydroxide (KOH) electrolyte from exhausted batteries to
manufacture home-made soap.
+
→
Figure 4 : Soap from waste materials
6
3. Chemistry

Fats in chicken skin/fats are often in the ester forms.
This mean there are 2 types of molecules joined together:
◦ Glycerol (alcohol with hydroxyl group, OH, on each of
its 3 carbons)
H
H C
OH
H
C OH
H
C OH
H
◦ Fatty acids joined to the glycerol by dehydration
process.
O
R
C OH
(for linoleic acid fats, R = C17H31)
7

In fats, the glycerol are joined to the fatty acids by
dehydration process.
H C
OH
H
C OH
H
C OH
H
O
H
H
H C
O
+ 3R C OH
→
O
C R
O
C R
H
C
O
H
C
O C R
H
O
+ 3H2O
Fats (triglycerides)
8
•
In saponification reaction with potassium hydroxide
(KOH), fats will cleave to glycerol and fatty acid salt of
potassium.
O
H
H C
O
C R
O
C R
H
C
O
H
C
O C R
H
O
H
H C
OH
+ KOH → H C OH
H
C OH
H
O
+
3R
C O- K+
Potassium salt of
fatty acid
(soft soap)
O
•
The “tail” of the fatty acid salt ( R C O- ) is hydrophobic
and is soluble in oily dirt. The “head” of the fatty acid
salt (K+) is hydrophilic and soluble in water. These
combination will emulsify and wash away oily dirt.
9
4.
Procedures to Obtain Oils from Waste
Skins/Fats
• Heat the animal fat/skin with water.
This will be enough to dissolve the fats.
Figure 5 : Heating the skin/fats
• Squeeze the oil out by using spatula,
etc. This will expedite the process.
10
Figure 6 : Squeezing out the oil
• Released oils, being lower in density,
will float to the top. Water and pieces
of skin/fats will settle at the bottom.
Figure 7 : Oil extracted from the skin/fats
• Pour the oils into a
separation
funnel
using a mesh filter.
Remnants
of
skins/fats will be
trapped by the mesh
filter.
11
Figure 8 : Filtering out skins/fats
• Allow the oils to settle in the separation funnel for 5
minutes. This will enable a clear separation of oils from
the water. Bleed out the water components by opening
the valve at the bottom of the separation funnel.
Figure 9 : Removing the water
from the bottom of the
separation funnel
Figure 10 : Oils remaining in the separation
funnel after the water component have been
almost all removed
12
• Using water, wash the oils sticking on
the funnel and the wall of the separation
funnel. This process will also clean the
oil of the residue chicken smell.
Figure 11 : Washing the wall of
the separation funnel
• After the oil is well washed, collect it
using a beaker. Weight the mass of
oil collected.
13
Figure 12 : Collected clean oils
Procedures to Obtain KOH from
Exhausted Batteries
• Use a simple saw to cut off the
base of the exhausted batteries.
Figure 13 : Cutting the
exhausted batteries
• Remove the electrolyte (with zinc
powder).
Figure 14 : Removing the KOH electrolyte
14
• Add some (≈ 100 ml) water to dissolve the potassium
hydroxide (KOH). Zinc powder does not dissolve.
Figure 16 : Undissolved zinc
powder collected at bottom
Figure 15 : Dissolving the KOH
electrolyte
15
• Collect the clear liquid either by filtration or just
skimming the clear top layer from the undissolved zinc
powder.
or
Figure 17 : Separating the KOH from zinc powder
through filtration (optional)
16
• The clear liquid (KOH) can be analyzed for its strength
(titration with acid) and then used in the saponification
reaction with the oils.
Figure 18 : Clear KOH solution
minus the zinc powder
17
Saponification Procedures
• Calculate the amount of potassium hydroxide (KOH) to
be used using literature saponification number :
Saponification number =
Saponification number KOH = 0.1944
= 0.1944
Mass of oil collected = 12.43 g
= 0.1944
Oil
Apricot Kernel
Arachis
Butterfat, Cow
Butterfat, Goat
Canola
Castor
Chicken Fat
Saponification
NaOH
0.135
0.136
0.162
0.167
0.124
0.129
0.139
Number
KOH
0.189
0.190
0.227
0.234
0.174
0.180
0.194
Source : http://www.countryfarmlifestyles.com/saponification-chart.html
Mass of KOH to be used = 2.42 g
Mass of water to be used = 6.05 g
= 0.286
pH = 13.5
18
• The soap is left to cure for a few days. The pH of the
soap is then measured. The pH should be no more than
pH 10.0. If pH exceed 10.0, the saponification number is
reduced and the saponification reaction repeated.
Saponification number =
Saponification number KOH = 0.0500
= 0.0500
Mass of oil collected = 0.8325 g
Mass of KOH to be used = 0.8325 g
Mass of water to be used = 2.08 g
pH = 9.80
19
• React the oil with the potassium
hydroxide (KOH) obtained from the used
battery. You will be able to catch the
scented smell as reaction produces
soap.
Heat will help speed up the
reaction.
Figure 19 : Oil / KOH Reaction
Figure 20 : Foam forming
indicating soap formation
20
• Glycerol (alcohol) produced will evaporate after pro-long
heating, leaving the soap to solidify behind. Addition of
water to the solid soap will produce foam, an indication
of soap formation.
Foam
formation
Figure 21 : Solid soap formed
Figure 22 : Foam formation on
addition of water
21
5.
Equipment Used
• Vacuum flask is used to liquefy the skins/fats to oils.
Vacuum flask is able to retain the heat of hot water
poured into it, reducing the energy cost of producing the
soap.
Figure 23 : Common vacuum
flask to hold heat in while fats
are dissolved
22
• Other secondary utensils used.
Funnel
pH paper
Spatula
Separation
funnel
Thermometer
Magnetic
stirrer
Strainer /
filter mesh
Heater /
Stirrer
Figure 24 : Secondary utensils used
23
6. Potential Benefits
● Reduce pollution due to leaching of electrolyte (KOH)
into the environment when exhausted batteries are
discarded.
● Reuse waste materials often deemed of little value
such as chicken skin/fats.
● Promoting healthy living by encouraging removal of
skins/fats from meat before they are consumed.
● Produce useful daily household-used items such as
soap from wastes. This helps to reduce household
spending ; appropriate at this time when cost of living
is sky-rocketing.
24
7.
Process Flow
Exhausted batteries are stripped
of KOH
Skins/fats are removed and kept,
not thrown away
Water is added to dissolve the
KOH and filtered to remove zinc
powder (optional)
Hot water are added with skins/fats
into vacuum flask to liquefy the
fats to oil
Strength of KOH is analyzed
Spatula used to physically extract
the oil
Oils separated using separation
funnel
Saponification reaction between oils and
KOH using saponification number 0.05
pH below 10?
No
25
Pass
Yes