Patented electrostatic spray nozzle developed at Embrapa Meio Ambiente

A new type of electrostatic pneumatic spray nozzle device, which employs induction electrification, increases deposition and improves the efficiency of deposition of pesticide droplets on the respective targets, developed by Aldemir Chaim and Luiz Guilherme Wadt from Embrapa Meio Ambiente, was patented by the National Institute of Industrial Property (INPI), in August 2022. 

The usual technique for applying agricultural pesticides is characterized by the use of hydraulic nozzles, whose operating principles were developed in the 19th century and have not been updated to this day. The droplets formed by the hydraulic nozzles are able to maintain some speed after formation, but they quickly decelerate and can be altered by winds or accelerated evaporation, meaning that the particles do not reach the target. Research has shown that the effective deposition of agrochemicals on crops rarely exceeds 50% of the applied volume, even with the most modern sprayers.

In traditional induction electrification systems, the electrified droplets are always attracted back to the induction electrode, causing it to become wet, to the point of dripping, which generates waste, in addition to short circuit problems in the system, which then stops working. According to researcher Aldemir Chaim, this new nozzle uses high-speed air to spray the syrup, blowing the drops away from the back-attraction effect of the induction electrode, which has an electrical polarization opposite to the electrified particles.

However, the biggest difference of this equipment is that it has a thin stainless steel wire inside the grout displacement duct, which facilitates the arrival of electrical charges that leave the ground, moving through the liquid, without resistance, to the region the droplet formation zone. One of the ends of this stainless steel wire is positioned one or two millimeters from the point of emergence of the liquid in the droplet formation zone, which provides the formation of a gigantic electric field, thus guaranteeing a very high intensity of electrification of the drops.

The use of electrostatically charged drops has proven to be a promising technique for increasing the deposition of pesticides in plants. When a cloud of electrically charged particles approaches a plant, the phenomenon of induction occurs, so that the surface of the plant becomes electrified with electrical charges of the opposite sign to that of the incoming drops. As a consequence, the plant strongly attracts electrified liquid particles, thus promoting an improvement in deposition, including on the abaxial surface of the leaves. 

Analyst Luiz Guilherme Wadt highlights another important aspect, characterized by the mutual repulsion between the drops. Since they have charges of the same polarity, the electrified drops do not collide with each other, forming a more spread out jet and therefore there will be an improvement in the distribution of pesticides on plants, considering a more homogeneous spatial distribution of the sprayed drops. Another extremely relevant aspect is that electrostatic attraction is inversely related to the size of the drops, resulting in greater use of small drops.

Because the electrified droplets are strongly attracted to the nearest grounded object (in this case the plant), the loss of pesticides to the soil is also much lower than that which occurs with the use of conventional spraying.

According to Chaim, some research shows that the use of electrostatics can easily reduce, by more than 50%, the active ingredients recommended in phytosanitary treatments without reducing biological effectiveness and, in addition, reduces the side effects of agrochemicals on the organisms that live in the soil, considering that losses to the soil can be 20 times lower than those that occur in conventional spraying.