Drenagem de espumas gas-liquido na presença de campo eletrico CC
AUTOR(ES)
Maria Elisabete Darbello Zaniquelli
DATA DE PUBLICAÇÃO
1987
RESUMO
Air-liquid foam drainage is affected by electric de fields in the range of 10 - 70 V.cm. Fams were prepared by stirring aqueous surfactant solutions. Sodium lauryl sulfate (SDS), cetyltrimethyl- ammonium bromide (CTAB), [ [p-1,1,3,3 tetramethyl-butyl ] phenyl poly(etilenglycol) ether (TRITON X-100) were the surfactants used. Detergent foams containing:1-octanol,1-butanol, ovoalbumin and sodium chloride were also studied. Foam drainage was monitored by voluletric and conductometric measurements. Two different experimental setups were used: in the first, the electric field is parallel to the gravitational field while in the second both fields are perpendicular. Foam drainage pattern modifications were observed in the presence of dc fields, when both setups were utilized. Electrical field effect upon individual detergent films was also examined : it was found that dc fields decrease film rupture time. The effects observed were discussed in terms of eletroosotic liquid mass transfer in foams. The classical Smoluchowski equation for eIectroosmosis in capillaries was modified to account for the pressure variation that arises in foam films due to surface tension gradients at the films and the consequent changes in Plateau s border curvatures. The apparent average electroosmotic coefficient was determined: (3,4±0.5)x10m.C. for a foam prepared with 5,3x10M SDS solution the electrokinetic potential at the gas-liquid calculated and the value of -162 mV was obtained.
ASSUNTO(S)
campos eletricos solventes solução (quimica)
