Journal of Chemical and Pharmaceutical Research, 2016, 8(1): Research Article

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1 Available online Journal o Chemical and Pharmaceutical Research, 216, 8(1:23-27 Research Article ISSN : CODEN(USA : JCPRC5 Stability o oil in water emulsions stabilized by polymer and suractant Bin u Department o Chemical Engineering, Binzhou University, Binzhou, Shandong, China ABSTRACT Polymer/suractant looding produced liquid is diicult to treat compared with water looding due to large quantities o residual chemicals which lead to serious emulsiication. Dewatering rate o O/W emulsions by bottle test, particle size distribution measurement and multiple light scattering measurements were employed to study the stability o the O/W emulsions stabilized by both polymer and suractant. O/W emulsions stabilized by polymer and suractant get more stable when polymer/suractant concentration increased. Polymer contributes more to the stability o O/W emulsions compared with suractant. Polymer concentration is the key actor to stabilize O/W emulsion because polymer can orm rigid cross-link network at oil-water interace to enhance the stability o the emulsions while polymer can enhance the viscosity o water and thus decrease the collision probability o oil droplets. Key words: Stability, polymer, suractant, O/W emulsion, dewatering rate INTRODUCTION Emulsion systems have been widely used in many industrial ields. During the process o oil extraction, produced liquid is generated as a kind o emulsions, such as W/O emulsions with low water content or O/W emulsions with high water content. The produced liquid is a mixture o oil, water, clay particles and some other chemicals such as polymer and suractant in chemical looding produced waste water [1-2]. Polymer/suractant looding produced liquid is diicult to treat compared with that rom water looding due to large quantities o residual chemicals which lead to serious emulsiication. The destability o O/W emulsions can be accelerated by several chemical and physical methods such as the use o locculants [3] or demulsiiers [4] or acids or bases [5] or low external electric ield [6]. It is o great necessity to study the stability o the O/W emulsions irstly beore selecting treatment methods o destability o O/W emulsions [7-8]. In most ield applications o polymer & suractant looding (SP looding in china, the concentration o polymer is about 1~15 mg/l while the concentration o suractant is about 3~5 mg/l. In this study, dewatering rate o O/W emulsions, particle size distribution measurement and multiple light scattering measurements were employed to study the stability o the O/W emulsions stabilized by both polymer and suractant to explain the inluence o both polymer and suractant on the stability o the O/W emulsions and illustrate the stability mechanism o the O/W emulsions stabilized by both polymer and suractant. EPERIMENTAL SECTION 2.1 Materials The crude oil rom ieng oilield has a water content o less than.5%, and density and viscosity o 872 kg.m 3 and 12.4 mpa s (at 5, respectively. The total salinity o ieng simulation ormation water is 5446 mg/l; the ion 23

2 composition is: K +, Na mg/l; Ca mg/l; Mg mg/l; Cl mg/l; SO mg/l; HCO mg/l. The polymer (partly hydrolyzed polyacrylamide, HPAM with an average molecular weight (MW o and a degree o hydrolysis o 28% and suractant with a major component o petroleum sulphonate are all industry products Preparation o synthetic O/W crude oil emulsions The synthetic O/W emulsions stabilized by polymer and suractant were prepared by mixing the crude oil and the simulated water with a certain amounts o polymer and suractant (2:8, V/V using a FM-2 homogenizer (Fluko Corp. at 45 with a rotating speed o 6 rpm or 1 mins Stability o synthetic O/W emulsion Dewatering rate was employed to evaluate the stability o the synthetic O/W crude oil emulsion which can be calculated by the ollowing ormula: = Vt V 1% (1 Where V is the original water volume o an emulsion sample beore bottle test, V t is the separated water volume ater setting a certain time at 45. The bigger the dewatering rate is, the higher the stability o the synthetic O/W emulsion. 2.4 Particle size distribution measurement Particle size distribution was analyzed by Rise-26 laser particle size analyzer (Jinan Rise Science & Technology Co., Ltd. according to the ull range Mie scattering theory at room temperature. The measurement range is rom.2 µm to 12 µm. 2.5 Multiple light scattering measurements The stability o waste water was monitored by measuring the transmittance and back scattering o a pulsed near inrared light (λ=88 nm by Turbiscan Lab Expert manuactured by Formulaction (France. The transmittance detector received the light which passed through the dispersion at an angle o 18º with respect to the source, while the back scattering detector received the light scattered backward by the dispersion at an angle o 45º. Polymer and suractant stabilized O/W emulsions were placed into cylindrical glass tubes and submitted to Turbiscan Lab Expert stability analysis. The stability o emulsions can be evaluated by TSI parameter (Turbiscan Stability Index by Turbiscan EasySot [9]. RESULTS AND DISCUSSION The dewatering rate o the O/W emulsions stabilized by 1 mg/l polymer, 3 mg/l suractant and polymer & suractant at 45 is shown in Fig. 1. It can be seen rom Fig. 1 that the O/W emulsion stabilized by 3 mg/l suractant is less stable than that stabilized by 1 mg/l polymer. The O/W emulsion stabilized by polymer & suractant is more stable than that stabilized by polymer or suractant mg/l suractant + 1 mg/l polymer 1 mg/l polymer 3 mg/l suractant Dewatering rate (% Time (h Figure 1. The dewatering rate o the O/W emulsions stabilized by polymer and suractant The emulsion decomposition [1] rate can be expressed as a power-law unction o the instantaneous emulsion raction available or decomposition according to: 24

3 d / dt = k ( d n (2 Where is the instantaneous decomposed raction o the emulsion, is the maximum achievable raction o the emulsion decomposition, n is the order o reaction, and t is time, k d is the decomposition rate constant. The initial condition is deined by: =, t=td. 1 n 1 n ( = kd ( t td (3 The hal-lie o the emulsion based on the maximum decomposable emulsion raction can be determined by substituting =.5. (1 n (1 n (.5 ( t td 1/ 2 = (1 n kd (4 For our experiment data, n=.4, =1. The Straight-line plot o the present data o dewatering rate o the O/W emulsions versus time is shown in Fig. 2. The remaining undecomposed emulsion versus time is shown in Fig. 3, which was calculated with these values in Eq. ( mg/l suractant + 1 mg/l polymer 1 mg/l polymer.12 3 mg/l suractant.1 x (1-n -(x -x (1-n t-t d (h Figure 2. Straight-line plot o the present data o the raction o separated water rom O/W crude oil emulsions vs. time mg/l suractant + 1 mg/l polymer 1 mg/l polymer 3 mg/l suractant Time (h Figure 3. Fraction o remaining undecomposed emulsions The inluence o 1 mg/l polymer, 3 mg/l suractant and polymer & suractant on particle size distribution o O/W emulsions is shown in Fig. 4. The average oil droplets size o the O/W emulsion stabilized by 1 mg/l 25

4 polymer is smaller than that stabilized by 3 mg/l suractant while the oil droplets o the ormer is more uniormly distributed. Accordingly, the average oil droplets size o O/W emulsion stabilized by polymer & suractant is smaller than that stabilized by polymer or suractant. Frequency (% (a (b (c Particle size ( µm (a 1mg/L polymer + 3 mg/l suractant; (b 1mg/L polymer; (c 3 mg/l suractant Figure 4. Particle size distribution o O/W emulsions stabilized by polymer and suractant 6 5 1mg/L polymer + suractant polymer suractant 4 TSI Concentration / mg.l -1 Figure 5. Inluence o polymer & suractant concentration on stability o O/W emulsions To urther study the inluence degree o polymer and suractant on the stability o O/W emulsion stabilized by polymer and suractant, inluence o polymer and suractant concentration on TSI o the O/W emulsions stabilized by polymer and suractant is urther studied and the results is shown in Fig. 5. The higher the TSI value, the less stable o the emulsion. It can be seen rom Fig. 5 that TSI values o the emulsions stabilized by polymer decreased more sharply with the increasing concentration o polymer compared with that stabilized by suractant. The results show that polymer contributes more to the stability o synthetic O/W emulsions stabilized by polymer and suractant compared with suractant. All the results showed that polymer contributes more to enhance the stability o the O/W emulsions compared with suractant. Polymer concentration is the key actor to stabilize the O/W crude oil emulsion. The eect o suractant is mainly to decrease oil-water interacial tension while the main eect o polymer to stabilize the O/W emulsion is to increase oil-water interacial elasticity. But low interacial tension is not the key actor to stabilize emulsions [11] pointed. Polymer can orm rigid cross-link network at oil-water interace to enhance the stability o the emulsions while polymer can enhance the viscosity o water and thus decrease the collision probability o oil droplets. 26

5 CONCLUSION O/W emulsions stabilized by polymer and suractant get more stable when polymer/suractant concentration increased. Polymer contributes more to the stability o synthetic O/W emulsions stabilized by polymer and suractant compared with suractant. Polymer concentration is the key actor to stabilize O/W emulsion because polymer can orm rigid cross-link network at oil-water interace to enhance the stability o the emulsions while polymer can enhance the viscosity o water and thus decrease the collision probability o oil droplets. Acknowledgements This research was supported by the Natural Science Foundation o Shandong Province o China (No. ZR215PB7, ZR215BL12, the Doctoral Scientiic Research Foundation o Binzhou University (214Y15. REFERENCES [1] SB Deng; RB Bai; JP Chen, Sep. Puri. Technol., 22, 29, 27. [2] Z Khatib; P Verbeek, J. Petro. Technol., 23, 55, [3] YB Zeng; CZ Yang; JD Zhang, J. Hazard. Mater., 27, 147(3, [4] YH Kim; DT Wasan; PJ Breen, Colloids Sur. A, 1995, 95, 235. [5] CM Chen; CH Lu; CH Chang; YM Yang, Colloids Sur. A, 2, 17, 73. [6] I Tsuneki; I Keisuk; Y Shigeki; S Masanao, Colloids Sur. A, 24, 242, [7] J Qiu, Petrol. Sci. Technol., 212, 31(2, [8] T Sharma; GS Kumar; BH Chon; JS Sangwai, J. Ind. Eng. Chem., 215, 22, [9] O Mengual; G Meunier; I Cayre, Talanta, 1999, 5, [1] F Civan; LJ Alarcon; SE Campbell, J. Pet. Sci. Eng., 24, 43, [11] N Aderangi; DT Wasan, Chem. Eng. Commun., 1995, 132,