Acid-Neutralizing of Marine Cylinder Lubricants:  Effects of Nonionic Surfactants

Abstract

The neutralization reaction between a concentrated sulfuric acid droplet and a series of model marine cylinder lubricants (MCLs) formulated with an overbased sulfonate and a series of different nonionic surfactants was studied using a capillary video-microscope technique at room temperature and a phase transfer neutralization rate test at several temperatures up to 55 °C. The model MCLs were characterized using dynamic light scattering and transmission electron microscopy. On the basis of the observations, a mechanism is proposed for the neutralization reaction which involves the initial formation of a mixed reverse micelle system between the overbased sulfonate and the nonionic surfactant followed by the neutralization reaction at the aqueous acid/oil interface to form calcium sulfate crystals. The rate of the neutralization reaction is enhanced by the presence of the nonionic surfactants in the model MCLs and is consistent with the formation of the mixed micelle systems which makes the basic core (CaCO 3 /Ca(OH) 2 ) of the overbased sulfonate more accessible to the aqueous acid due to the increased size and flexibility of the overbased sulfonate reverse micelle.

Temperature and acid droplet size effects in acid neutralization of marine cylinder lubricants

“…with the same base concentration, the values of k + may not produce a big difference for a given temperature as long as the mass and size of base particles of various compositions are similar. This may explain Roman [2] and Wu et al [5] results that the higher the temperature, the lower the difference of neutralization ability between lubricants of various compositions.…”

“…This seems to contradict with Hosonuma and Tamura's results that the smaller the size of acid emulsions, the higher the reactivity [1]. In the temperature range of 25-55°C, Wu et al [5] investigated the neutralization between sulfuric acid and model MCLs by using a static phase-transfer technique. It was found that the higher the temperature, the smaller the difference among different nonionic surfactants in increasing the ability of acid neutralization, agreeing with Roman's results that lower difference of neutralization ability of various MCLs was found at higher reaction temperatures [2].…”

“…Equation (5) should become as Equation (3) or Equation (4) when h = 1 or h = 0, thus c 1 = c 2 = c 3 . The r t -t curves at 25, 100, and 130°C shown in figure 3 may validate equation (5) for a constant residence time s before a bulk-fluid/drop reaction enters into its ending phase.…”

Mixed Flow Reactor Experiments and Modeling of Sulfuric Acid Neutralization in Lube Oil for Large Two-Stroke Diesel Engines

“…However, the reaction is an acid-base reaction occurring irreversibly. Due to the small size of the CaCO 3 particles in lube oil (8-18 nanometers in diameter 22 ), and the fact that the reaction rate increases with decreasing CaCO 3 particle size in acid, 43 it is presumed that the surface reaction between CaCO 3 and H 2 SO 4 happens instantaneously, and the surface reaction is therefore not the ratelimiting step in the neutralization mechanism. 21 Finally, the reaction can also be controlled by the rate with which H 2 SO 4 droplets and CaCO 3 reverse micelles are mixed in the reactor.…”

Response of Calcium Carbonate Nanoparticles in Hydrophobic Solvent to Pressure, Temperature, and Water

“…17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 itself cannot be followed by this MD technique, and there is no acid in the present model, but these simulations can still give insights into the structural aspects of the reaction mechanism pathway and its sensitivity to surfactant type.…”