Kuide Qin

Modeling the spray atomization of emulsion embedded agricultural solutions.

A typical agricultural chemical spray process involves atomizing a liquid stream of diluted pesticide solution through hydraulic spray nozzles that inherently produce a wide spectrum of spray droplet sizes. Finer droplets have higher potential for off-target movement or drift, which is of concern due to its potential impact on neighboring crops and livestock, sensitive ecological resources, and human health. Research by the Spray Drift Task Force and others has demonstrated that, although spray nozzle selection and application parameters are the key factors to produce the desired droplet size spectrum, the physical properties of the spray solution have significant effects on the droplet size distribution for various kinds of nozzles. One of these properties of many spray fluids is the inclusion of an oil phase in the form of an emulsion. The effect of oil-in-water emulsions on the spray droplet size distribution has been demonstrated by previous work. However, the mechanisms of this effect are largely unknown. In this study, a method to model this effect was proposed. A characteristic dimensionless number for connecting the bulk spray properties and the microscopic emulsion droplet properties was defined as the ratio between the emulsion recovery time and the spray atomization time. This study will help in the design of agricultural spray nozzles and the optimization of anti-drift spray additives.

Assessment of Oil Dispersion Pesticide Formulations Using Rheology and Near Infrared Centrifugation Techniques

Oil dispersion (OD), as a formulation type in the pesticide industry, has become more important over the past few years. This increased importance is due to (1) new water sensitive active ingredients, (2) the compatibility of active ingredient mixtures, (3) the need to build-in adjuvancy properties, and (4) customer preference of liquid formulations. Unlike well known technologies such as aqueous suspension concentrates (SCs), for which scientists have extensive experience in formulation practices resulting in readily available technologies for developing a stable formulation, OD is a relatively new technology. Technical knowledge for developing a stable OD formulation is still an area that needs significant investigation. The present work seeks to determine useful criteria for characterizing and predicting long term stability of OD formulations using readily accessible technologies such as rheological measurements and centrifugation. The characterization results are reported for systems that are commercially available from two agricultural companies.