Characterization of the aggregation of non-ionic dispersants and their adsorption on carbon black particles Yu Shen May 16, 2006
Dispersants Used in Industry Industry Use to stabilize carbon rich particles from aggregation to prevent oil blockage Steric Mechanism Polar core is fixed on particles surfaces on-polar chain is well dissolved in oil CRP 2
Dispersants used as additives Without dispersant Form deposits Cause corrosion With dispersant o deposits Prevent corrosion Intake valve of a Mercedes Benz M102E engine after 60 test hours www.basf.com/automotive-oil 3
Dispersant: BAB tri-block copolymer CH 3 H 3 C H CH 3 n H p H 3 C n H Polyisobutylene succinic anhydride (PIBSA) Polyamines Polyisobutylene succinic anhydride (PIBSA) DETA (diethylene triamine) TEPA (tetraethylene pentamine) PEHA (pentaethylene hexamine) Η 2 Ν CH 2 CH 2 H CH 2 CH 2 H 2 Η 2 Ν (CH 2 CH 2 H) 3 CH 2 CH 2 H 2 Η 2 Ν (CH 2 CH 2 H) 4 CH 2 CH 2 H 2 4
utline Synthesis of dispersants Characterization of dispersants Measurement of associative strength of dispersants Adsorption of dispersants on carbon black particles Conclusions 5
Synthesis of Dispersants 2 H CH 3 CH 3 33 + H 2 Xylene H p H 2 170 H CH 3 CH 3 H H 33 33 p H 3 C H 3 C p 1 3 4 Dispersant PIB-DETA PIB-TEPA PIB-PEHA 6
Characterization of Dispersants (FT-IR) 3A ν (PIB) CH 3 1390 cm 1 υ C= (Succinimide) 1717cm -1 ( d ) PIB-PEHA Absorbance ( c ) PIB-TEPA ( b ) PIB-DETA υ C= (SA) 1785cm -1 ( a ) PIBSA 0 1000 1500 2000 wavenumber (cm -1 ) 7
Characterization of Dispersants (GPC) H CH 3 CH 3 n H H 3 C H 3 C n H PIB-DETA CH 3 PIBSA H CH 3 n 0 5 10 15 20 25 30 35 40 Volume (ml) 8
Succinimide Content of Dispersant CH 3 Calibration by FT-IR: + polyisobutylene (model compound) 1.2 Abs(1717 cm -1 )/Abs(1390 cm -1 ) 0.9 0.6 0.3 y = 28.38x + 0.0126 0.01 0.02 0.03 0.04 [Methyl succinimide], mol/ mol PIB 9
Characterization of Dispersant Building Block Absorption Ratio Abs(1785 cm 1 )/Abs(1390 cm 1 ) SA / IB PIBSA 0.79 1:(33) Dispersant Absorption Ratio Abs(1717 cm 1 )/Abs(1390 cm 1 ) succinimide / IB PIB-DETA 0.87 1:(33.3+3.8) PIB-TEPA 0.89 1:(32.3+4.1) PIB-PEHA 0.89 1:(32.5+3.1) 10
Measurement of the Associative Strength of Dispersants Associative Strength Ability of dispersants to self-associate in solution into reverse micelles Characterized by the CMC CMC: critical micelle concentration Measurements of the Associative Strength of Dispersants Light scattering Fluorescence techniques 11
Measurement of the Associative Strength of Dispersants by Light Scattering Intensity (a.u.) 40 30 20 10 Light scattering intensity increase with increasing dispersant concentration in the sequence of dispersants with longer polyamine links PIB-PEHA PIB-TEPA PIB-DETA PIBSA 0 0.1 1 10 100 [Dispersant], g/l 12
Measurement of the Associative Strength of Dispersants by Fluorescence The advantages of chromophore Ruthenium bisbipyridine 5- aminophenanthroline hexafluorophosphate (Ru-bpy): confirm existence of dispersant aggregates probe the polar core of dispersant micelles not soluble in apolar solvents ideal to study the CMC of dispersants in hexane 2+ Ru H 2 13
Absorption/Emission Spectra of Ru-bpy in methanol Absorption (a.u.) 0.4 0.3 0.2 0.1 2+ Ru Absorption 454 nm H 2 Emission 610 nm 30 20 10 Emission (a.u.) 0.0 340 440 540 640 740 Wavelength (nm) 0 14
Absorption/Emission Spectra of Ru-bpy in hexane with dispersant 1.0 H 2 15 Absorption (a.u.) 0.5 2+ Ru 10 5 Emission (a.u.) 0.0 0 340 440 540 640 740 Wavelength (nm) 15
Fluorescence Measurement with Ru-bpy 16 Intensity (a.u.) 12 8 4 Ru-bpy with PIB-PEHA PIB-PEHA 0 470 520 570 620 670 Wavelength (nm) 16 Ru-bpy in PIB-PEHA normalized by pure PIB-PEHA 0.3g/L in the emission spectrum
Fluorescence Measurement with Ru-bpy 16 Intensity (a.u.) 12 8 4 Ru-bpy 0 470 520 570 620 670 Wavelength (nm) 17 Ru-bpy in PIB-PEHA normalized by pure PIB-PEHA 0.3g/L in the emission spectrum
Fluorescence Measurement with Ru-bpy 200 Dispersant CMC (g/l) Intensity of Ru-bpy (a.u.) 150 100 50 0 PIB-DETA >6 PIB-TEPA 0.9 PIB-PEHA 0.2 PIB-PEHA PIB-TEPA PIB-DETA 0.001 0.01 0.1 1 10 100 [Dispersant], g/l 18
Adsorption Measurements Determination of the specific area of carbon black Measurement of the amount of adsorbed dispersants on carbon black Analysis with di-langmuir Model 19
Determination of the Specific Area of Carbon Black (CB) Particles Constant volume of aqueous MB solutions with different amount of CB are prepared The concentration of MB in supernatant is measured The specific area of CB is determined from the absorbed amount of MB Cl - + Me 2 S M e 2 Methylene Blue (MB) Tomlinson, A. ; Danks, T.. ; Heyes, D. M.; Taylor, S. E.; Moreton, D. J. Carbon 2000, 38, 13-28 20
Determination of the Extinction Coefficient of Methylene Blue 2.0 1.6 Cl - + Me 2 S M e 2.D.(a.u) 1.2 0.8 ε = 58400 ± 60 dm 3 mol -1 cm -1 at 664nm 0.4 0.0 0.00 0.01 0.02 0.03 0.04 [Methylene Blue], mmol/l 21
Determination of the Specific Area of Carbon Black (CB) Particles 1.2 nads/m 0.8 0.4 A MB = 1.35 nm 2 A CB = n ads /m A A MB = 764 m 2 /g 0.0 0.0 1.0 2.0 3.0 4.0 Ceq (mm) C eq : concentration of MB at equilibrium in supernatant n ads /m: mmol of adsorbed MB per gram of carbon black 22
Determination of the Specific Area of Carbon Black (CB) Particles 1.2 0.8 nads/m 0.4 A MB = 1.35 nm 2 A CB = n ads /m A A MB = 764 m 2 /g 0.0 0.0 1.0 2.0 3.0 4.0 Ceq (mm) A CB measured by MB < A CB measured by 2 adsorption (1600 M 2 /g) limited accessible surface area reduced ability of MB molecules to follow the surface contours 23
Adsorption Measurements Determination of the specific area of carbon black Measurement of the amount of adsorbed dispersants on carbon black Analysis with di-langmuir Model 24
Measurement of Adsorbed Dispersants on CB Particles Br Br Dispersant + TBPE DisTBPE (complex) Br C H.D.(a.u.) 1.2 0.8 0.4 TBPE, 410nm Adding dispersant Complex, 608nm C CH 2 CH 3 TBPE (ph indicator) Br 0.0 370 470 570 670 Wavelength (nm) 25
Calibration of Dispersants Concentration 2.5.D. at 608 nm 2.0 1.5 1.0 0.5 Y = 1.59-0.34 PIB-PEHA y = 1.20x - 0.31 PIB-TEPA y = 0.45x - 0.16 PIB-DETA 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 [Dispersant], mmol/l 26
Adsorption Isotherm ( C0 Ceq ) V 2 Γ = ( µ mol / m ) ma Γ: adsorbed amount of dispersant per unit area C eq : concentration of dispersant in supernatant at equilbrium m: CB weight V: volume of solution C 0 : initial concentration of the dispersant A: specific area of CB Adsorbed Amount, Γ (umol/m 2 ) 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 PIB-PEHA PIB-TEPA PIB-DETA 0.00 0 20 40 60 80 C eq (mmol/m 3 ) 27
Adsorption Measurements Determination of the specific area of carbon black Measurement of the amount of adsorbed dispersants on carbon black Analysis with di-langmuir Model 28
Analyzing the Adsorption Isotherm with di-langmuir Model Γ = Γ 1 1+ K C 1 K C 1 eq eq Γ2 K + 1+ K 2 C 2 C eq eq Γ 1 1+ K C 1 K C 1 eq eq + Γ 2 K 2 C eq Γ1, Γ2 : maximum amount of dispersant adsorbed at saturation K1, K2 : equilibrium constants of the two sites Г 1 (mol.m -2 ) K 1 (m 3.mol -1 ) Г 2 K 2 (m) PIB-DETA 1.70 10-7 43 1.13 10-7 PIB-TEPA 6.31 10-8 193 6.91 10-7 PIB-PEHA 3.35 10-8 336 4.82 10-7 29
Conclusions A series of oil-soluble dispersants were synthesized. H CH 3 CH 3 H 33 * P H 3 C H 3 C H 33 The CMC of the dispersants was determined by using the fluorescence of Ru-bpy. The CMC decreases with increasing p values. The adsorption of the dispersants onto carbon black particles was investigated. Dispersants adsorbed on carbon black particles more strongly for larger p values. 30
Acknowledgements Dr. Jean Duhamel Dr. Mario Gauthier Colleagues from both labs Special thanks to Cristina Quinn Imperial il and SERC for funding 31