Sulfation of Castor Oil with Development of Emulsifiers

Al- satil Journal 61
Sulfation of Castor Oil with Development
of Emulsifiers
Dr. Abdul Baset M. Elgellal
Imad H. Al –Wahaib
Abstract:
The work is related to the field of preparation of emulsifiers for the
use in asphalt emulsions, and formulating of solution type cooling – lubricating
fluids. Thus, castor oil was reacted with gaseous sulfur trioxide at 25◦c using
carbon tetrachloride as a solvent. Emulsification properties of the sulfurized
castor oil were studied in relation to the content of combined SO3. The highest
emulsification tendency was attained at approximate 8 percentages by weight of
SO3 content corresponding to the sulfation of one hydroxide group in castor oil.
Introduction:
Sulfonation of Aromatic hydrocarbons, petroleum oil and vegetable oil has
great importance In industry, in which useful surfactants material could be
produced. Such surfactants could be used as detergent, emulsifying agent,
softening agents, de emulsifying agents etc. The sulfonation of aromatic
hydrocarbons is used to induce the sulfonyl group (SO3H) while the sulfation of
aliphatic organic molecules such as alcohols and olefins produce sulfuric acid
esters. The sulfated castor oil (Turkey red oil) is one of the most effective
surfactants. The sulfated castor oil is used in fabric manufacture as a softening
agent. This sulfated oil is classically prepared, in early 1970s, by gradual
addition of sulfuric acid to castor oil under harsh condition of high temperature
and long reaction time in addition to producing side products. 1-2
Recently, the sulphated castor oil is prepared by using diluted gaseous sulfur
trioxide 1 (diluted with 4% V in N2) under mild condition (i.g., at 45-50°C for
20-25 min). The resulted sulphated castor oil should be:
• Highly soluble in water, this makes it good surfactant and/or good
emulsifying agent.
Misurata University – Faculty of Science – Misurata – Libya.

Sulfation of Castor Oil with Development of Emulsifiers.
• Stable under acidic conditions.
The experimental data showed that the optimum reaction temperature was
45-50 o c. 1 lowering the temperature below this range leads to increasing the
viscosity of the reaction mixture resulting poor interaction between the gas and
liquid phases. However, raising the reaetion thempeature higher than 50 o c could
allow some oxidation reactions to take place producing sulphur dioxide.
It has been proved that the sulfation reaction of the castor oil at < 50 o c
occurs by a reaction between gaseous SO3 and the hydroxyl groups of esters of
ricinolic acid. 1
There have been a number of studies focusing on the sulfation of fatty acids
using SO3. 3-5
According to these studies, the esters of the higher sulfonyl fatty acids.
Based on that the sulfation of the castor oil takes place at relatively high
temperature c > 60 o c producing free sulfonates without the formation of sulfated
glycerides. 6 The sulfated castor oil has wide industrial uses. It is used in leather
industry as the aqueous filling material for leather contains about 3-4 % by
weight of the saponifiied sulfated castor oil. 7
The sulfated castor oil along with the coconut oil are used as a hydrating
material. 8 It is also used in processing leather in which 20% by volume of
ethanol is added to an aqueous solution of the sulfated castor oil to form an
emulsifier for so aching chrome – treated leather in order to enhance its
flexibility. In the presence of 6% by weight sulfated castor oil, the hydrating
and flexibility properties of the mixture have been improved. 9 The sulfated
castor oil has been used to purify the asphaltic sand from the asphalt. 10 In
addition, it has been involved with the lithium lipids for improving their thermal
properties. 11 Further more, the sulfated castor oil has been utilized with other
materials to form cooling – lubricating emulsifiers that are employed in cutting
and polishing the glass. 12
Other types of lubricating emulsifiers have been synthesized from the
sulfated castor oil and other substances concentration ranging between 30 to
50%. 13
2. Experimental:
2.1. Materials.
Pure castor oil (B.P) was used ricinolic acid (C12------OH,9C ) was prepared
by saponification pure castor oil using 20 % sodium hydroxide solution at 90-
95◦C with stirring for 2 hr. the resulting mixture was acidified by dilute
sulphuric acid. The resulted ricinolic acid was watched with hot water and
dried.
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Al- satil Journal 63
2. 2. Sulfation.
Two methods have been used for sulfation: in the first method. Oleum
containing 30% SO3 by weight was used. The oleum was added slowly over 30
minutes with stirring at certain temperature. In the second method, the
SO3diluted with nitrogen (approximate 4% by volume) was used .The excess
SO3 of was liberated by heating the oleum and passing current of nitrogen. The
sulfating agent (SO3 diluted with nitrogen) was passed through the gas
distributor placed in bottom of reactor that contains oil. This was within ±2°c.
by heating the reactor. by using sulfation in this way, the unreacted residual gas
was expelled at the end of reaction of reaction by heating to 70 ◦C.
The reaction depth was determined by measuring the content of reacted SO3
gas and also by measuring the acidity of the resulted sulfated oil. Hexane and
CCl4 were used as solvents.
2. 3. Method of test and extraction.
2. 3.1. Acidity of sulfated oil.
The acidity of sulfated oil was determined by titration with standard
solution of KOH. The sulfated castor oil (1g) was dissolved in mixture
(100cm 3 ) of toluene and iso propyl alcohol in ration of 2:1 V/V at high
temperature.
Acidity (mg KOH/g)
V × N × 56
=
W
V= volume of KOH (ml)
N= normality of KOH solution
W= weight of the sample (gm)
2.4. Emulsification properties.
The emulsification properties of sulfated castor oil and its derivatives were
studied by forming of asphaltic emulsions. The asphaltic emulsions were
prepared by mixing equal volumes of water, light asphalt and toluene in the
presence of emulsifying agent. The stability of the resulted emulsions was
monitored over 24 h. the amount of separated water gave indication to the
stability of the emulsion. thin asphalt, and toluene and in presence of certain
ration of emulsifier ,the stability of emulsion with time has been followed
. Over night separated water ration was standard for stability of emulsion.

Sulfation of Castor Oil with Development of Emulsifiers.
3. Results and discussion:
3.1. Sulfation of castor oil using SO3 and studying the properties of the
resulting emulsion.
3.1.1. The relation ship between the depth of sulfation and acidity of the
sulfated castor oil.
The sulfation was carried out at 45 using different ratios of sulphur trioxide
and the castor oil after which the acidity of the products was determined.
The theoretical values of the acidity of the sulfated oil were calculated bored
or a comparison between the theoretical and experimental data.
The content of SO3 in the product when one hydroxide group was sulfated
= 8.
6%
80 × 100
=
932
Mwt.
ofSO3×
100
= Is:
Mwt.
0 fCastoroil
This means that the molecular weight of the product is 1012 and the
acidity of product is 55mg KOH ⁄ gm.
The experimental and theoretical correlation (Figure 1), Show the sulfation
of castor oil without observing any side products. More over, the experimental
results are in accordance with the theoretical calculation with error percentage
of 3.5%.
Figure 1: The relationship between sulphation's depths and the acidity of the
product (sulphation was carried out at 45 °C)
3.1.2 .Optimization of the sulfation of the castor oil.
A range of chlorinated hydrocarbons and other low-poiling hydrocarbon
were used as solvent in the sulfation process. These solvents are in reactive
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Al- satil Journal 65
towards sulfur trioxide. In addition, such solvents are easy to remove by
evaporation where the sulfation is complete. The ration of solvent to caster oil
was (2:1w/w). The temperature of the sulfation reaction was reduced to 25◦C
due to the use of such Low-boiling solvents.
The rate of the sulfation reaction in carbon tetrachloride was found to be
much faster than the reaction rate when the sulfation was carried out on neat
castor oil or in hexane. The rate of the sulfation, in carbon tetrachloride,
increased by 2.4 times (Table 1).
Table 1: The effect of solvents on the rate of the sulfation of
Solvent
NO Solvent
Hexane
Carbon tetrachloride
castor oil using SO3
Temperature of Reaction rate (increase of
the sulfation (°C) acidity/h) (mgKOH/gr/h)
50
19
25
5
25
46
3.1.3. Study of the Emulsification properties of sulfated Castor oil.
The sulfated castor oil with different levels of sulfation was emulsified with
petroleum asphalt in which the content of the emulsifying agent (sulfated caster
oil) was 2% by weight. The stability of the resulting emulsions was evaluated
according to the content of SO3 in the sulfated castor oil (Figure 2). The pure
caster oil showed on emulsification properties, however, the sulfation of one
hydroxide group in the oil (8-10 , by wt of SO3) ,improved dramatically the
emulsification properties. Sulfation of a second hydroxyl group decreased the
emulsification ability of the product.
Figure 2: Changing the emulsification properties of the sulphated oil by
changing the acidity.

Sulfation of Castor Oil with Development of Emulsifiers.
3-2. Study of Emulsification Properties of the sulfated Ricinolic Acid
and its salts.
3-2-1. The sulfated ricinolic acid and its salts as emulsifiers.
Ricinolic acid showed no ability to product emulsion with petroleum asphalt.
This was observed when ricinolic acid was combined with water and petroleum
asphalt (diluted with toluene) in ration of (1: 1: 1 w/ w) with concentration
between 0.5 and 2.0%. An immediate separation of the layers was occurred.
However, when the ricinolic acid was sulfated, using diluted SO3 (diluted with
N2) in which different levels of sulfation were obtained, the resulting products
showed emulsification properties. The most stable emulsion resulted from the
use of sulfated ricinolic acid containing 2.3% of SO3. The emulsification
property decreased as the SO3 content increased (Figure 3).
Figure 3: Stability of asphalitic emulsions of the sulphated ricinolic acid
(concentration of emulsifying agent is 2.0% by weight).
This due to the fact that the sulfated ricinolic acid became a detergent rather
than emulsifying agent as the content of SO3 increased. The initial stability
sulfated of ricinoleic acid emulsion changed as the depth of sulfation
increases from 2.3 to 10 % (Figure 4).
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Al- satil Journal 67
Figure 4: The relationship between the initial stability of asphaltic emulsions
and the depths of the sulphation of ricinolic acid (concentration of ricinolic acid
is 2.0% by weight).
The sodium salt of ricinoleic acid showed no emulsification properties.
However, partial emulsification properties were seen when the sodium salt of
sulfated ricinolic acid was used (Figure 5). The emulsification properties of the
latter case decreased as the content of SO3 increased which means that the
sodium salt of the sulfated ricinolic acid became a detergent rather than
emulsifying agent.
Figure 5: The stability of asphaltic emulsion that contain sodium salt of
sulphated ricinolic acid (concentration of emulsifying agent 2.0% by weight).

Sulfation of Castor Oil with Development of Emulsifiers.
3-2-2. The Formation of Emulsifying Agent By the Partial
Neutralization of Sulfated Ricinolic Acid
The possibility of preparing some emulsions by partial neutralization of high
molecular weight carboxylic acids has been mentioned in the literature, This
technique leads to the formation of emulsions consisting of free carboxylic acid
and their salts (e.g sodium salts) in the same time. Based on that, an attempt was
made to form an asphaltic emulsion containing an emulsifying agent prepared
by the partial neutralization of sulfated ricinolic acid. The emulsifying agent
was prepared by the sulfation of ricinolic acid up to 2.3 % (by weight) of SO3
content. Partial neutralization of the resulting sulfated acid was carried out using
a concentrated solution of sodium hydroxide to afford 25% neutralization. This
allowed a good level of solubility in water. An asphaltic emulsion was prepared
from water, toluene and liquid petroleum asphalt in ration of 1 : 1 : 1 (by
weight) in the presence of 2.0 % (by weight) of the emulsifying agent. This
emulsion showed high level of stability. For comparison, the partial
neutralization of ricinolic acid resulted to no emulsification properties.
Conclusion:
1- The sulfation of castor oil with gaseous sulfur trioxide was studied by using
carbon tetrachloride as solvent, therefore, the rate of the reaction was very
fast and the sulfation process was carried out low temperature.
2- the properties of emulsified sulfated castor oil changes according to the
depth of sulfation with the enhancement of the concentration of sulfur
trioxide in emulsifier up to (8%w). this percentage lead to sulfation of one
hydroxyl group in caster oil and the ability of the emulsifier increases,
whereas if it is more than this percentage the ability of the emulsifier
decrease and lead to formation of bisulfonic acids.
3- Stable tar emulsion was formed by using prepared emulsifier through
molecular neutralization of sulfated ricinolic acid. This emulsifier contains
free sulfuric acids and their salts.
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Al- satil Journal 69
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