Effect of Salinity, pH, and Temperature on Stability of Gas Condensate in Water Emulsions Using Different Surfactants

Document Type: Research Article


Department of Chemical and Petroleum Engineering, School of Chemical and Petroleum Engineering, Enhanced Oil and Gas Recovery Institute, Enhanced Gas Condensate Recovery Research Group, Shiraz University, Shiraz, I.R. IRAN


Light hydrocarbons in water emulsions are formed in many gas refinery wastewaters, and its stability depends on some parameters such as temperature, pH and salinity. In this study, different surfactants have been used to prepare gas condensates in water emulsion along with four surfactant kinds namely, Span 80, Tween 80, CTAB, SDS and Span 80 and Tween 80 mixture. For this purpose, the effects of temperature (25 and 60° C), pH (3, 5, 7 and 11) and salinity (2, 10 and 26 wt. % NaCl in water) on the stability of the emulsion have been studied. In order to evaluate the stability of these emulsions, the droplet size distribution was measured by an optical microscope. The results confirm that the increasing of salinity, as well as temperature of non-ionic surfactants (Such as Span 80 and Tween 80), lead to more stability of the emulsion. The increasing temperature didn’t have a dominant effect on the stability of those emulsions which contain the ionic surfactants i.e., CTAB and SDS. Those emulsions formed by the combination of Span 80 and Tween 80 are more stable than the other ones. Results of the investigation the effect of pH on the emulsion stability clear that the emulsions are less stable at high pH than other ones.


Main Subjects

[1] Dalgleish D.G., Food Emulsions: Their Structures and Structure-Forming Properties, Food Hydrocoll. 20(4): 415–422 (2006).

[2] Berrin T., Orhan S., Coalescence and Size Distribution Characteristics of Oil Droplets Attached on Flocs After Coagulation, Water, Air, and Soil Poll., 169(1): 293–302 (2006).

[3] Hanapi M., Ariffin S., Wan Abdul Rahman W.A., Othman N., Chieng Y.Y., Jong S.C., Zulkania A., “Study on Demulsifier formulation for Teating Malaysian Crude Oil Emulsion”, MSc. Thesis, University Technology Malaysia. (2006).

[4] Mahmood L.H., “Demulsifiers for Simulated Basrah Crude Oil”, MSc. Thesis in Chemical Engineering, University of Technology Republic of Iraq, (2009).

[5] AL-Jassim S.A., “De-Emulsification of Different Iraqi Crude Oil Emulsion”, MSc. Thesis, University Baghdad, Iraq, (1998).

[6] Ezzati A., Gorouhi E., Mohammadi T., Separation of Water in Oil Emulsions Using Microfiltration, Desal., 185(1): 371-382 (2005).

[7] Esmaeili H., Esmaeilzadeh F., Mowla D., Effect of Surfactant on Stability and Size Distribution of Gas Condensate Droplets in Water, J. Chem. Eng. Data, 59(5): 1461-1467 (2014).

[8] Jurado E., Bravo V., Camacho F., Vicaria M.J., Fern´andez-Arteaga A., Estimation of the Distribution of Droplet Size, Interfacial Area and Volume in Emulsions, Colloids and Surfaces A: Physicochem. Eng. Aspects, 295(1): 91–98 (2007).

[9] Coca J., Gutierrez G., Benito J., “Treatment of Oily Wastewater”, Water Purification and Management, Springer, Dordrecht (2011).

[10] Yi X.S., Yu S.L., Shi W.X., Sun N., Jin L.M., Wang S., Zhang B., Ma C., Sun L.P., The Influence of Important Factors on Utrafiltration of Oil/Water Emulsion Using PVDF Membrane Modified by Nano-Sized TiO2/Al2O3, Desalin., 281: 179-184 (2011).

[12] Dickinson E., Hydrocolloids as Emulsifiers and Emulsions Stabilizers, Food Hydrocoll., 23(6): 1473–1482 (2009).

[13] Bengoechea C., Romero A., Aguilar J.M., Cordobés F., Guerrero A., Temperature and pH as Factors Influencing Droplet Size Distribution and Linear viscoelasticity of O/W Emulsions Stabilized by Soy and Gluten Proteins, Food Hydrocoll., 24(8): 783-791 (2010).

[14] Dickinson E., “An Introduction to Food Colloids”. Oxford Univ. Press, Oxford UK (1992).

[15] Gupta S., Sanyal S. K., Datta S., Moulik S. P., Preparation of Prospective Plant Oil Derived Micro-Emulsion Vehicles for Drug Delivery, Indian J. Biochem. Biophys., 43(4): 254-257 (2006).

[16] Mahdi E.S., Sakeena M.H., Abdulkarim M.F., Abdullah G.Z., Sattar M.A., Noor A.M., Effect of Surfactant and Surfactant Blends on Pseudoternary Phase Diagram Behavior of Newly Synthesized Palm Kernel Oil Esters, Drug Des. Devel. Ther., 5: 311-323 (2011).

[17] Wang Z., “Pseudo-Ternary Phase Diagrams of a Drug Delivery System”, A Thesis for the Degree of Master of Applied Science, University of Waterloo, (2009).

[18] Jiao J., Burgess D., Rheology and Stability of Water-in-Oil-in-Water Multiple Emulsions Containing Span 83 and Tween 80, American Association of Pharmaceutical Scientists Journal, 5(1): 62–73 (2003).

[19] Griffin W.C., Classification of surface-active agents by 'HLB'. J. Soc. Cosmet. Chem., 1: 311-326 (1949).

[20] Griffin W.C., Calculation of HLB Values of Non-Ionic Surfactants, J. Soc. Cosmet. Chem., 5: 249-256 (1954).

[21] Porras M., Solans C., Gonza´lez C., Gutie´rrez J.M., Properties of Water-in-Oil (W/O) Nano-Emulsions Prepared by a Low-Energy Emulsification Method, Colloids Surf. A Physicochem. Eng. Asp., 324(1): 181-188 (2008).

[22] Förster T., Rybinski W.V., Wadle A., Influence of Microemulsion Phases on the Preparation of Fine-Disperse Emulsions, Adv. Colloid Interface Sci., 58(2-3): 119-149 (1995).

[23] Davies R., Graham D.E., Vincent B. Water-Cyclohexane-“Span 80”-“Tween 80” Systems: Solution Properties and Water/Oil Emulsion Formation, J. Colloid Interface Sci., 116(1) 88-99 (1987).

[24] Schramm L.L., Petroleum Emulsions. Advances in Chemistry. American Chemical Society, Washington, DC, 231 (1992).

[25] Poteau S., Argillier J.F., Langevin D., Pincet F., Perez E., Influence of pH on Stability and Dynamic Properties of Asphaltenes and other Amphiphilic Molecules at the Oil–Water Interface, Energy Fuels, 19(4) :1337-1341 (2005).

[26] Fortuny M., Oliveira C.B.Z., Melo R.L.F.V., Nele M., Coutinho R.C.C., Santos A.F. Effect of Salinity, Temperature, Water Content, and pH on the Microwave Demulsification of Crude Oil Emulsions, Energy Fuels, 21(3): 1358-1364 (2007).

[27] Tambe D.E., Sharma M.K., Factors Controlling the Stability of Colloid-Stabilized Emulsions. I. An Experimental Investigation, J. Colloid Interface Sci., 157(1): 244-253 (1993).

[28] Sjoblom J., Yuan L.M., Hoiland H., Johansen J.E. Water-in-Crude Oil Emulsions from the Norwegian Continental Shelf Part III. A Comparative Destabilization of Model Systems, Colloid Surf., 46(2): 127-139 (1990).

[29] Binks B.P., Surfactant Monolayers at Oil-Water Interfaces, Chemistry and Industry. 14: 537-541 (1993).

[30] Aveyard R., Binks B.P., Fletcher P.D.I., Ye X., Lu J.R. The Resolution of Emulsions, Including Crude Oil Emulsions, in Relation to HLB Behaviour, Emulsions-A Fundamental and Practical Approach. 363: 97-110 (1992).

[31] Strassner J.E., Effect of pH on Interfacial Films and Stability of Crude Oil-Water Emulsions, J. Petrol. Technol., 20(3): 303-312 (1968).

[32] Esmaeili H., Esmaeilzadeh F., Mowla D., Destabilization and Separation of Gas Condensate from Wastewater using Different Surfactant Demulsifiers, Tenside Surfactants Detergents, 55(2): 153-161 (2018).

[33] Rukmini A., Raharjo S., Hastuti P., Supriyadi S., Formulation and Stability of Water-in-Virgin Coconut Oil Microemulsion using Ternary Food Grade Nonionic Surfactants, International Food Research Journal, 19(1): 259-264 (2012).

[34] Droppo I.G., Flanigan D.T., Leppard G.G., Jaskot C., Liss S.N. Floc Stabilization for multiple Microscopic Techniques. Appl. Environ. Microbiol., 62(9): 3508–3515 (1996).

[36] Koh A., Gillies G., Gore J., Saunders B.R., Flocculation and Coalescence of Oil-in-Water Poly (dimethylsiloxane) Emulsions, J. Colloid Interface Sci., 227(2): 390–397 (2000).

[37] Schuster S., Bernewitz R., Guthausen G., Zapp J., Greiner A.M., Kohler K., Schuchmann H.P., Analysis of W1/O/W2 Double Emulsions with CLSM: Statistical Image Processing for Droplet Size Distribution, Chem. Eng. Sci., 81: 84-90 (2012).

[38] Koorepazan Moftakhar M., Habibi L., Yaftian M.R., Selective and Efficient Ligandless Water-in-Oil Emulsion Liquid Membrane Transport of Thorium(IV) Ions, Iran. J. Chem. Chem. Eng. (IJCCE), 35(4): 125-134 (2016).

[39] Tcholakova S., Denkov N., Ivanov I.B., Marinov R., Evaluation of Short-Term and Long-Term Stability of Emulsions by Centrifugation and NMR, Bulg. J. Phys., 31(3-4): 96–11