CC BY
38CHEMISTRY
SYNTHESIS AND STUDY OF NEW SURFACTANTS BASED ON ETHYLENE DIAMINE AND
OLEIC ACID
Asadov Ziyafaddin Hamid,
Doctor of chemical sciences, professor, corresponding member of Azerbaijan National Academy of Science; head of laboratory of surfactants of Institute of Petrochemical
Processes (IPCP) Nabiyeva Hajar Tahir Post-graduate researcher of laboratory of surfactants of IPCP
Baku,Azerbaijan
Abstract
This article contains information about the synthesis and properties of the surfactants obtained from the reaction between oleic acid and ethylene diamine. The conditions and schemes of the reactions have been included. The composition and structure of the synthesized salts have been confirmed by NMR-, IR- and UV-spectroscopy. Physical properties such as surface activity and electrical conductivity have been measured. Petrodispersing properties of the obtained surfactants have been revealed. Solubility of products in different solvents has been determined. At the end, final recommendations have been given considering the applied properties of the products. Keywords: oleic acid; ethylene diamine; surfactant; petrodispersing
Introduction diamine was carried out at 55-60°C during 9-10 hours
Surfactant or surface-active compound is charac- at equimolar ratio. The other product was obtained at terized as a compound having, at least, one hydrophilic 2:1 ratio of oleic acid and ethylene diamine. The reac-
and one hydrophobic group in the molecule [1]. Surfactants lower the surface and interfacial tension between two media because of their specific characteristics. There are different application fields of surfactants [2]. One of their most significant application areas is petroleum industry [3]. Accidents during production and transportation of crude oil are unavoidable. Floating oil spills on sea water surface can damage the flora and fauna of underwater ecosystem and destroy the food chain in nature. After removing of thick petroleum slicks over the sea water by mechanical way, it is impossible to clean the area from thin layer of oil spills which can be dealt with using surfactants. Scientists have obtained valuable results from using fatty acid and amines as reactants [4-7]. The present work is dedicated to obtainment and study of new surfactants based on oleic acid and ethylene diamine.
Experimental part
Oleic acid was a product of Moscow's ''Compo-nentReactant'' Joint Stock Company (Russia) with > 98% purity. Etylene diamine was a product of Alfa Ae-sar O (Great Britain) with > 99% purity.
Two salts have been synthesized using these reactants. At first, reaction between oleic acid and etylene
tion continued 9-10 hours at 50-55 °C. The final product at equimolar ratio was brownish and viscous oily compound while for the second product was dark-red.
IR spectra were recorded by an ALPHA FTIR spectrometer (Bruker,USA) using KBr tablets. NMR-spectra were recorded using Bruker TOP SPIN and solving the salts in D2O. Surface tension (y) values were determined by using a KSV Sigma 702 tensiometer (Finland). Specific electroconductivity (k) values were measured by "Anion-4120" electroconductometer (Russia).
Petrodispersing capacity of the surfactants was determined according to the known procedure described in [8]. 40 ml of water are placed in a Petri dish. 1 ml of crude oil (in this work, of "Azeri Light" trade mark) 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 sidewards. 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 %).
Results and discussions
The schemes of the both reactions are illustrated below:
The structure and composition of the synthesized salts were confirmed by NMR-, IR- and UV- spectroscopy.
Fig. 1. NMR spectra of the synthesized salts a) Salt 1; b) Salt 2
In NMR-spectra, Fig.la and b, it was defined that signals at 0.636 and 0.656 ppm in the first spectrum, 0.648 ppm in the second one represent CH3-groups. Resonance signal of CH2-group of the hydrocarbon chain is observed at 0.803 ppm in the first spectrum, while it is seen at 0.798 ppm for the second one. A peak of CH2-groups of ethylene diamine fragment is recorded at 1.195 ppm for the first salt, 1.199, 1.359 and 1.431 ppm in the second salt. The signals of NH2-group protons, N+H3 group protons and double bond protons
can be defined at 2.637, 2.954 and 3.631 ppm respectively in the first spectrum, while the resonance signals of these groups can be seen at 2.506, 3.214 and 3.600 ppm in the second spectrum.
In UV-spectrum Fig.2a, for the 1st salt at 202.5 nm, the band of ammonium group absorption (n^ a*) is seen, while the same group absorption bond (n^ a*) for salt 2 is observed at 202 nm for Fig.2b.
/ <
2.0
300 4(H)
Wuvclcnght < nm)
(a)
2 : I nislH'li koinplck*
300 400 i
Wavclenght (nm)
(b)
Fig. 2. UV spectra of the synthesized salts a) Salt 1; b) Salt 2
By examining IR spectra, (Fig.3) it can be deduced that valence vibrations of N-H bond in NH2 group are observed at 3293.97 cm-1 in the first salt and
3293.64 cm-1 in the second salt. 3063.00 and 3007.54 cm-1 absorption signals in the first spectrum and 3007.88 cm-1 in the second spectrum represent the valence vibrations of C-H bond of the double bond. Valence vibrations of C-H bond in CH3 and CH2-groups can be defined at 2953.50, 2921.39 and 2851.95 cm-1 in the first one and 2953.8, 2921.51 and 2852.13 cm-1 in the second one. Absorption signals at 2690.03, 2597.42, 2533.15 and 2446.45 cm-1 are attributed to the valence vibrations of N+-H bond in ammonium group for the first product, while the same bond valence vibrations can be observed at 2695.43, 2597.04, 2533.93 and 2176.27 cm-1 for the second one. Valence vibrations of C=C bond and deformational vibrations of N+-H bond exist at 1641.4 and 1547.21 cm-1 respectively in
Salt 1 spectrum, while these bonds are at 1643.95 and 1542.22 cm-1 in Salt 2. Deformational vibrations of CH bond in CH3 and CH2-groups can be found at 1463.6 and 1398.64 cm-1 for the first one, while these can be seen at 1462.46 and 1400.23 cm-1 in the second spectrum. 1313.95 and 1186.54 cm-1 signals are related to valence vibrations of C-N bond in the first product, while they are seen at 1304.68 and 1184.16 cm-1 in the second one.
Deformational vibrations of C-H bonds of the double bond can be seen at 967.24 and 919.95 cm-1, 967.20 and 918.86 cm-1 respectively in the first and second spectra. 819.41 cm-1 shows the deformational vibrations of N-H bond for the first salt, while there is no absorption signal representing these vibrations in the second salt spectrum. (CH2)x "pendulum" vibrations can be found at 721.00 and 721.41 cm-1 respectively in the first and second products' spectra.
Fig. 3. IR spectra spectra of the synthesized salts a) Salt 1; b) Salt 2
The melting point for the first product is 57°C , for the second product - 52°C.
In the table below, the solubility of the salts in distilled water, ethanol, isooctane, n-heptane, cyclohexane, acetone and methanol has been described.
Table 1
№ Solvents Solubility, g/ml Mass of salt/volume of solvent
1:1 2:1
1 Water 0.017 0.0084
2 Ethanol 0.053 0.086
3 n-Heptane 0.010 0.261
4 Cyclohexane 0.045 0.110
5 Isooctane 0.177 0.258
6 Acetone 0.206 0.039
7 Methanol 0.074 0.085
Solubility of the salts based on oleic acid and ethylene diamine Surface tension - y of salts has been measured and dependence of y from concenration has been illustrated below.
80
70 £ 60 ^ 50
I 40
30 ^ 20 10 0
1
>>ê» H i I'-1--
Salt 1 Salt 2
0 0,0005 0,001 0,0015 0,002 0,0025 0,003 0,0035
c, mol/l
Fig. 4. Surface tension at water-air interface versus concentration of the obtained salts at 21 °C.
dy
Using the data obtained from Fig. 4, surface activity parameters of the synthesized surfactants were determined. Critical Micelle Concentrations (CMC) of the obtained salts were determined as 2.19*10-4 and 1.6*10-4 mol/l respectively. Besides that, yCMC, surface pressure (nCMC), C20 (the concentration for decrement of y 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 (rmax) and minimum area of one surfactant molecule at water-air border (Amin) were calculated using the given equations
r
1 max
1
lim
n * R *T c^cmc dine 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;
1016
A . =_
Amin NA*Tmax Surface activity parameters for two salts are shown in Table 2.
Table 2
Surface activity parameters of the synthesized surfactants
Surfactant CMC*104 (mol/L) Ycmc (mN,m) nCMC (mN,m) C20*104 (mol/L) pC 20 CMC/C20 r *1010 1max 10 (mol/cm2) A . *1f)2 ^min 10 (nm2)
Salt 1 2.19 25.84 46.54 1.09 4.9 20.04 2.1 47.6
Salt 2 1.60 28.37 44.01 1.96 4.70 8.18 1.65 60.6
Relationship between specific electrical conductivity and concentration of the obtained salts at 25 °C was measured and isotherms of electrical conductivity were illustrated in Fig.5.
salt 1 salt 2
0 0,0005 0,001 0,0015 0,002 0,0025 0,003 0,0035
c, mol/l
Fig. 5. Electrical conductivity versus concentration of the synthesized salts at 25 C
The slopes of straight line before (S1) and after (S2) CMC values were found out and thermodynamic properties as Gibbs free energy of micellization (AGmic) and Gibbs free energy of adsorption (AGad) were calculated using equations given below:
A Gmic = (2 -a)*R*T* In (CMC) AGad = AGmic - 0.6023 * nCMC * ACMC
where ACMC represents surface area of one surfactant molecule at water-air border at CMC in terms of A2.
Table 3
Specific electrical conductivity values^ and thermodynamic ^ parameters of the synthesized surfactants
Surfactant a В AGmic, kJ/mol AGnd, kJ/mol
Salt 1 0.72 0.28 -26.72 -28.05
Salt 2 0.51 0.49 -32.25 -33.8563
The petrodispersing property of the salts was examined applying the salts in solid state, 5% wt. aqueous solution and 5% wt. ethanolic solution on the film of "Azeri Light" Crude Oil on the surface of waters with different salinity which are Caspian Sea water, tap water and distilled water.
Table 4
The results of study of petrodispersing property of the synthesized salts; "Azeri Light" Crude Oil
Sea water Tap water Distilled water
Ratio State of surfactant Kd Duration- Kd Duration- Kd Duration-
T, hours T, hours T, hours
5 wt. % aqueous solution 98.57% 48 95% 96 94.85% 110
1:1 5 wt. % ethanolic solution 98.57% 48 95.71% 96 97.14% 120
Solid 97.14% 120 95.52% 96 94.28% 96
2:1 5 wt. % aqueous solution 97.86% 24 95.65% 48 96.2% 120
5 wt. % ethanolic solution 98.57% 36 95% 48 96.1% 120
Solid 98.57% 24 96.68% 48 94.21% 120
By examining the thermodynamic parameters of the obtained salts, it can be concluded that AGad of Salt 1 and Salt 2 is more negative than AGmic, which focuses at preference of the adsorption of the surfactants over the micelle formation.
Looking at the results of the studies of petrodispersing properties given in the table, it can be concluded that both salts in the form of solution and solid state exhibit very good petrodispersing effect in sea water (Kd=98.57%). Based on the obtained results, the synthesized surfactants can be recommended as good petrodispersants for cleaning water surface from petroleum slicks.
References:
1. A.Bhardwaj, S. Hartland, Applications of Surfactants in Petroleum Industry. Journal of Dispersion Science and Technology, 1993, Volume 14, - Issue 1, p.87-116
2. L.L.Schramm, E.N.Stasiuk, D.G.Marongoni, Surfactants and their applications. Annual Reports Section C, August 2003, 99, p.3-48
3. R.Nagy, R.Kothenez, Surfactants and their investigation for Petroleum Industrial Applications. International Journal of Petroleum and Petrochemical Engineering, 2015, Vol1, Issue 3, p.11-21
4. Z.H.Asadov, S.H.Zargarova, I.A.Zarbaliyeva, et al. Synthesis and study of surface-active salts based
on propoxy derivatives of hexadecylamine and mono-carboxylic aliphatic acids. Norwegian Journal of development of the International Science 2019,No 27, p.3-7
5. Z.H. Asadov, A.H. Tantawy, A.H. Azizov, I.A. Zarbaliyeva, R.A. Rahimov. Synthesis of new complexes surfactants based on fatty acids and Study the effect of length of fatty acid chain on the petroleum and surface-active properties. Caspian Journal of Applied Sciences Research, 2013 2(3), p. 24-34
6. K. E. Greber. Synthesis and Surface Activity of Cationic Amino Acid-Based Surfactants in Aqueous Solution. Journal of Surfactants and Detergents, 2017, volume 20, pages1189-1196 (2017)
7. Z.H. Asadov, S.M. Huseynova, G.A.Ah-madova, R.A.Rahimov. et al. Synthesis, colloidal-chemical and petroleum collecting properties of new counterion coupled gemini surfactants based on hexa-decylbis(2- hydroxypropyl)amine and dicarboxylic ac-ids.Journal of Dispersion Science and Technology. 9 p. Published online 07 August 2019: DOI:10.1080/01932691.2019.1650755
8. H.H.Humbatov, R.A.Dashdiyev, Liquidation of accidental petroleum spills using surfactants Baku: Elm,1998.200 p.(in Russian)
