离子强度对孤东4~#原油油滴表面ζ电位的影响

研究了简单电解质离子强度对孤东4#原油油滴表面ζ电位的影响.结果表明,油滴表面ζ电位绝对值并没有随离子强度的增加呈现持续下降的趋势,而是在一定离子强度下出现了极大值或极小值.油滴表面同电荷离子的吸附作用、扩散层中离子交换作用、较高电位下的松弛阻滞效应以及油滴在外电场作用下的极化作用等都可造成上述现象的发生,但同电荷离子的吸附作用是影响油滴异常电动行为的重要因素.在较高离子强度条件下,电解质对双电层的压缩作用增强,油滴表面ζ电位绝对值随离子强度的增加持续下降.说明对原油乳状液体系,经典双电层理论只适用于离子强度较高、双电层厚度较小的体系.这一结论将对双电层理论的进一步发展起到一定的促进作用.

Effect of ion strength on the ζ potential on the surface of the droplets of the crude oil from Gudong Oilfield

The influence of the ion strength of simple electrolyte on ζ potential of crude oil droplets from Gudong Oilfield is studied by means of laboratory experiments.The results show that in the crude oil emulsions,the absolute value of ζ potential on the surface of oil droplets continuously decrease with the increase of the ion strength at higher electrolyte concentration because of the stronger compression of electrolyte to double electrode layer.But it does not continuously decrease with the increase of the ion strength at low electrolyte concentration,and it appears a maximum or a minimum at certain ion strength.The adsorption among the ions with the same electricity,the exchange of the ions in diffuse layer,the relaxed retarding effect of double electrode layer at higher potential,the polarity effect of the oil droplets under the action of external electric field,etc.all cause the above phenomenon,and the adsorption among the ions with the same electricity is main cause.This shows that classic double electrode layer theory only suits to the crude oil emulsion system with higher ion strength and thinner double electrode layer,which will play an important role in the development of the double electrode layer theory.