Effect of Surfactant Type and Order of Addition on Droplet Size and Dynamic Interfacial Properties

Abstract

A model system containing a nonionic surfactant (nonylphenol + 9.5EO) and an anionic surfactant (Sodium C14-16 alpha-olefin Sulfonate) was used to study the effect of surfactants on droplet size and dynamic interfacial tension. BLANDOL™ (white mineral oil) was selected as the oil phase and the dynamic interfacial tension of the two surfactants at various concentrations, temperatures and in the presence of electrolyte was measured. The effect of using the surfactants separately and together was also measured. In addition, the effect of adding the surfactant to the oil phase and the water phase to the oil phase was determined. The implications of the results are discussed with respect to emulsion stability, demulsification, spray drying, spray drift control, wetting and spreading.

Effect of Drift Retardant Adjuvants on Spray Droplet Size of Water and Paraffinic Oil Applied at Ultralow Volume

“…Data for a given liquid-flow rate and drift-retardant adjuvant consisted of five concentrations of adjuvant in water and three concentrations in oil evaluated over five air pressures, averaged over three replications. Regression analysis was used to fit volume median diameter (D v 5 ) 3 and percent volume sprayed in droplets < 105 (im (LT105) 3 as a response surface for air pressure and concentration of adjuvant. The full response surface was y = f(x b x 2 2 , x 2 , x 2 2 , XiX 2 ),where y = D v5 or LT105, Xj = concentration of drift retardant (C) 3 and x 2 = air pressure (AP) 3 .…”

“…Regression analysis was used to fit volume median diameter (D v 5 ) 3 and percent volume sprayed in droplets < 105 (im (LT105) 3 as a response surface for air pressure and concentration of adjuvant. The full response surface was y = f(x b x 2 2 , x 2 , x 2 2 , XiX 2 ),where y = D v5 or LT105, Xj = concentration of drift retardant (C) 3 and x 2 = air pressure (AP) 3 . This model was reduced by eliminating any non-significant terms for liquid flow rate/drift retardant combinations.…”

“…Bouse et al (5) reported that other formulation factors are important in determining droplet size, when droplet size decreased with increasing concentrations of the adjuvant X-77, but surface tension, viscosity, and specific gravity varied only slightly. Droplet size is not only affected by the ingredients in the spray solution, but also by the order in which the various components are mixed (3). Although the physical proper ties of solutions change, a given atomizer will respond to the change and produce droplet size in relation to this change (1).…”

“…Reduction in spray volumes, even at equivalent rates of herbicide, result in savings by allowing more acreage to be covered with each load and minimizes the amount of water that must be transported to the fields. Ultralow volume (ULV) 3 applications are com monly associated with small driftable size droplets or lack of plant coverage when low volumes are applied with large droplets. Studies indicate that herbicides mixed in paraffinic oil can be applied at low volumes with larger droplets than in water and maintain good coverage of the plant due to the spreadability of the oil on the plant surface (10,15).…”