Bicarbonate charging of hydrophobic/water interfaces
Abstract
Most surfaces in contact with water are negatively charged. The reason for that has long been debated in the physics community as arising either from hdyroxide ion adsorption or water reorganization towards a hydrophobic interface. We have recently proposed another explanation coming from the carbonation of water. Bicarbonates, which in distilled water are the most present ions at intermediate pHs (from 5 to 10), are chatropic ions that stick to interfaces. We made use of a combination of interfacial tension measurements of oil droplets in water, and nanoprecipitation assays of polymers in a large range of pH, to show such affinity of HCO3- for hexadecane oil and PMMA. This prefered adsorption of bicarbonate allows also explaining why freeze/thaw cycles contribute to emulsifying oil/water mixtures.
ANR PREPROPOSAL ANR-15-CE09-0021 ANR LimOuzInE ANR-10-BLAN-0942.- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..MARL70368G