1. The nucleation theory K.-M. Valant*, B. Prunet-Foch*, M. Adler *, P. Lehuédé** *LPMDI**Saint-Gobain Recherche Motivation: gushing bottles Normal bottle t = 2.88 s Gushing bottle t = 3.8 s Bubbles foam 1) Intempestive foaming occurring during filling of carbonated beverages (water, beer, champagne…) 2) unwanted foaming may occur after bottle opening Sparkling wine hydroalcoholic solution pH ~ 3.2 CO 2 supersaturation = 6 atm foaming liquid Bottle neck ~ 6 cm 3 timescale = 10 sec The critical radius R c of gas bubble nucleation in supersaturated solution X eq CO 2 = H  P CO 2 (Henry’s law)  = P i / P f – 1  > 0 Supersaturation: PiPi PfPf Water in bottle  = 0, P L = 7 atm  = 0.061 N/m (after Lubetkin, 1995) R c = 52.3 µm CO 2 Supersaturated water  = 6, P L = 1 atm  = 0.071 N/m R c = 0.24 µm Sparkling wine  = 6, P L = 1 atm  = 0.045 N/m R c = 0.15 µm P sat = 0.023 atm  ~ 1 Homogeneous Nucleation Energy W H nuc 10 7 R (m) W H (10 -14 J ) RcRc Case H 2 O/CO 2 123 R > R c = bubble growth R < R c = bubble dissolution 0 1 2 3 0.5 1 1.5 -2 0 1 2 3 0 1 2 3 0.5 1 1.5  C   0 <  C < 1       C = 1  C > 1  C = 0  C < 0   C (  ) Homogeneous nucleation (  ) Hydrophobic surface (  ) hydrophilic surface (  )   Nucleation on a flat surface (  ) Nucleation energy W C nuc in a conical cavity:   C : form factor depending on  and  W C nuc = W H nuc  C W h nuc : Homogeneous nucleation energy  = contact angle  = conical cavity angle   R Heterogeneous Nucleation Energy (case of a conical cavity) pre-existing gas cavities Type III Semi-classical Type IV Non-classical R < R c R  R c (R c = critical radius) Type I Classical homogeneous Nucleation in the bulk  ~ 10 3 (beverages:  ~ 6) Type II Classical heterogeneous Heteronucleation at the interface liquid/glass The types of gas bubble nucleation The known types of nucleation (After Jones et Al., 1999) The chemically aided heteronucleation (This work) at the surface of a calcium carbonate crystal pre-existing gas cavities (?) CaCO 3 Crystal Acidified liquid Type V heteronucleation CaCO 3 + 2H + ⇄ Ca 2+ + CO 2 dis + H 2 O Dissolution of CaCO 3 with HCl What can generate bubbles on glass surface? in air-filled cavities (small, deep, hydrophobic) on hydrophobic coatings on the glass But these sites of nucleation are still too rare in bottles to explain the gushing phenomenon Physical heteronucleation (type III & IV) can occur on the glass surface: The beverages themselves can be at the origin of a gushing phenomenon (particles in the liquid) In this work, we are focusing on GLASS SURFACE ONLY 3 1 2 4 High speed camera 1kHz frame grabbing Capillary Temperature controlled bath Stroboscopic light CO 2 Supersaturated water Height Wine Beer Perrier 25°C Polynomial fit : V(h) =  h 2 +  h + V 0 V 0 being negligible in our case Example: at 25 °C Perrier:V(h) = 4.1 x 10 -5 h 2 + 2.4 x10 -3 h Wine: V(h) = 1.1 x 10 -5 h 2 + 1.2 x10 -3 h Beer: V(h) = 2.5 x 10 -6 h 2 + 1.9 x10 -3 h several nucleations per siteAggravating factor Volume of CO 2 in the bottleneck generated by type V nucleations as a function of the crystal density Case of the wine at 25°C Unusual crystallization on glass bottles CaCO 3 Insoluble in water Soluble in acidic liquids Na 2 CO 3 Soluble in water Ageing of glass 100µm Heteronucleation occurs on CaCO 3 crystals in wine (pH  3) Type V nucleation and the gushing phenomenon Density of sites: d V total = V b + V ms + V ts Fond Bord droit Bord conique H ts H R t b z bottom middle section top section H H ms R R z H 0 Bubbles rising… Experiment Foam Volume > Bottle Neck Volume close to critical volume for gushing (~ 6 cm 3 ) Chemical contribution to the nucleation increases decreases 2 bubbles growing in non supersaturated acidic liquid More nucleation sites with CaCO 3 in acidific supersaturated beverages Nucleation if R c < R hole 4mm 12mm 4mm 20.90.65µm 0.80.50.71 0.50.810.7 0.9250.6 R hole R bubble R min = R hole Dissolution  Local Supersaturation   Local Critical Radius R c  nucleation Chemically Aided Nucleation of Bubbles in Sparkling Baverages