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The current scientific work contains detailed information on the synthesis and some properties of the products obtained from the reaction between oleic acid and diethylene triamine. The composition and structure of the reaction products were identified by NMR spectroscopy. Some physical and chemical indicators of the synthesized compounds were determined, surface-active parameters were calculated, petrocollecting and petrodispersing properties were studied. In the end, the final recommendations were given, taking into account the applied properties of the salts.
surfactants, oleic acid, diethylenetriamine, petrodispersing, petrocollecting
Introduction
Thus, the oil layer creates an additional environment between air and water, preventing the dissolution of oxygen in the air, and the sun's rays entering the lower aquifers of the oceans and seas. The vital activity of flora and fauna within water basins, which cannot be enriched with oxygen and deprived of sunlight, is weakening. One of the most important branches of chemistry is the rapid accumulation of thin layers of oil in order to preserve the balance of nature. To do this, various surfactants are synthesized and investigated. About 10% of the demand for surfactants (more than 12 million tons) falls on nitrogen compounds. Although such substances have been known for about 50 years, they have been used more in the last 20 years due to their high efficacy surfactants. When surfactant collects oil from the water surface, the negative impact on the environment is relatively reduced [1-3].
There are different tools and techniques which specialists can employ to contain or remove oil from the environment when an oil spill occurs such as booms and skimmers [4]. However, those mechanical clean-up activities can never remove thin layer of oil remaining on the surface. Surfactants can be the very effective solution to this problem. Surfactants lower the surface and interfacial tension between two media because of their specific characteristics [5-8].
Purpose of the study: The present work is dedicated to obtainment and study of new surfactants based on oleic acid and diethylene triamine. It is aimed to analyse if obtained surfactants are applicable for clean-up activities for oil spills.
Material and methods: Relevant salts in two different proportions were synthesized as a result of a reaction based on oleic acid and diethylene triamine. The first salt was obtained from the reagents in equimolar proportions at 60-65 degrees Celsius for 9-10 hours. The other substance was the product of a 2: 1 reaction of oleic acid and diethylene triamine at a temperature of 55-60 0C. The reaction schemes are as follows:
The structure and composition of obtained salt were confirmed with NMR-spectroscopy in Figure 1,2 for 1H NMR of Salt 1 and Salt 3 and Figure 3,4 for 13C NMR of Salt 1 and Salt 2 respectively.
The melting point of the Salt1 and Salt2 are 62 and 58
respectively. Both products have good solubility in ethanol and acetone. Salt 1 is brownish, viscous liquid, while Salt 2 is lighter and more viscous substance than Salt 1. Amin number is 86 mgHCl/g for Salt1 and 45 mgHCl/g for Salt 2. Throughout various experiments surface activity parameters and specific electrical conductivity values/thermodynamic properties of the synthesized surfactants were determined and the graphs were plotted and described in Figure 5. Using the data obtained from Fig.5, surface activity parameters of the synthesized surfactants were determined using the method given in [3]
Results and discussions
Critical Micelle Concentrations (CMC) of the obtained salts were determined as 0.00194*10-4 and 0.00112*10-4mol/l respectively. Besides that, 
, surface pressure (
), C20 (the concentration for decrement of g by 20 mN/m), adsorption efficiency (𝑝𝐶20 = −𝑙𝑜𝑔𝐶20), as well as CMC/C20 (interfacial activity) parameters of obtained surfactants were determined.
Maximum surface excess concentration () and minimum area of one surfactant molecule at water-air border () were calculated using the given equations
where n is the number of dissociated ions which is 2 and 3 respectively for Salt 1 and Salt 2, R is universal gas constant (8.314 J/mol*K) and T is absolute temperature;
The surface activity parameters were tabulated in Table 1.
Table 1
Surface activity parameters of the synthesized surfactants
|
Surfactant |
CMC*104 (mol/L) |
(mN,m) |
(mN,m) |
C20*104 (mol/L) |
𝑝𝐶20 |
CMC/C20 |
(mol/cm2) |
(nm2) |
|
Salt 1 |
0.00194 |
28.17
|
43.87
|
0.000162 |
7.79
|
12
|
2.031 |
81.77
|
|
Salt 2 |
0.00112 |
25.93 |
45.09
|
0.000075 |
14.97
|
8.18 |
1.29 |
129.21
|
As it seems from the Table 1, salt 2 which is the gemini surfactant has a lower CMC value which is more desirable for surfactants. Besides that, the minimum area for one molecule of salt 2 surfactant is less than salt 1, which is also preferable.
Petrodispersing and petrocollecting properties of the surfactants was determined according to the known procedure described in [2]. 40 ml of water are placed in a Petri dish. 1 ml of crude oil (in this work, Pirallahi) is spread over the water (thickness of the film is ~ 0.17 mm). Then, 0.02 g of the surfactant (or its 5% wt. solution) is added to the film from the side wards. The surface area of the initial oil film and current areas of the formed oil slicks are measured at certain time intervals. The coefficient Kd - denoting the degree of the surface cleaning is calculated (in %).
Table 2
Petrodispersing and petrocollecting properties of the synthesized surfactants
|
Ratio |
State of surfactant |
Sea water |
Tap water |
Distilled water |
|||
|
Kd |
Duration-
|
Kd |
Duration-
|
Kd |
Duration-
|
||
|
1:1 |
5 wt. % aqueous solution |
86.7% |
0-20 |
10 |
0-3 |
12.3 |
0-3 |
|
80.2% |
20-72 |
15.1 |
3-5 |
74% |
3-16 |
||
|
70% |
72-216 |
87% |
5-20 |
84% |
16-260 |
||
|
68% |
216-312 |
2.67 |
20-72 |
spilling |
|||
|
spilling |
1.92 |
72-264 |
|||||
|
spilling |
|||||||
Continuation of Table 2
|
|
5 wt. % ethanolic solution |
88% |
0-20 |
90% |
0-23 |
12.3 |
0-3 |
|
80% |
20-72 |
6.4 |
23-51 |
18.02 |
3-5 |
||
|
2.04 |
72-240 |
1.96 |
51-243 |
6 |
5-21 |
||
|
drying |
spilling |
84% |
21-145 |
||||
|
spilling |
|||||||
|
Solid |
95% |
0-1 |
11 |
0-1 |
8.5 |
0-19 |
|
|
86% |
1-17 |
13.75 |
1-3 |
spilling |
|||
|
15.4 |
17-141 |
92% |
3-43 |
||||
|
6.41 |
141-237 |
spilling |
|||||
|
spilling |
|||||||
|
2:1 |
5 wt. % aqueous solution |
94% |
0-19 |
16.7
|
0-72 |
12.8 |
0-1 |
|
88% |
19-163 |
9 |
72-168 |
5.57 |
1-73 |
||
|
1.5 |
163-513 |
spilling |
5 |
73-265 |
|||
|
spilling |
spilling |
||||||
|
5 wt. % ethanolic solution |
9.89 |
0-72 |
12.03 |
0-1 |
12.26 |
0-1 |
|
|
84 |
72-88 |
89% |
1-73 |
88% |
1-217 |
||
|
89 |
88-232 |
86% |
73-169 |
dag |
|
||
|
2.03 |
232-328 |
||||||
|
Solid |
87% |
0-168 |
12.03 |
0-1 |
12.26 |
0-1 |
|
|
spilling |
9.625 |
1-3 |
10.13 |
1-3 |
|||
|
11 |
3-19 |
9.625 |
3-19 |
||||
|
12.83 |
19-312 |
spilling |
|||||
|
spilling |
|||||||
It can be seen from the Table 3, salt 1 shows the maximum petrocollecting property in the distilled water treated with 5 wt% ethanolic solution which is 18.02, while its maximum petrodispersing factor is seen in sea water treated with solid. Observing salt 2, it can be noted that maximum petrocollecting property is seen in tap water treated with 5 wt% aqueous solution, which is 16.7%. Maximum petrodipersing factor for the mentioned salt is inspected in sea water treated with 5 wt% aqueous solution, which is 94%.
Conclusion
Analyzing the results of surface activity measurements, petrocollecting and petrodispersing properties, it can be concluded that both salts have good surface activity and are recommended for the process of cleaning thin oil layers from the water surface.
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