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Surfactants are chemicals that decrease the surface tension of liquids dramatically. Surfactants are common adjuvants to herbicides in formulations for improved performance. Surfactants increase the wettability of water so herbicides stick better to plant leaves, and are more effective against weeds.

How Do Surfactants Work in Herbicide Formulations?

Basic Principles of Surfactant Action

Surfactants act by weakening the surface tension of water so that droplets of spray are more likely to permeate and coat plant leaves. The loss of surface tension makes the spray more wettable and dispersed, thus reducing the distance and length of time the herbicide contacts the plant.

The Role of Surfactants in Droplet Size and Spray Retention

Surfactants also minimize rebound and evaporation so that the droplets get distributed more evenly on the plant surface. This is good for spray uniformity and also longer lasting on the leaves. Surfactants can also make the spray performance better by modifying the droplet shape and size to allow them to pass through the capillary systems of the leaves.

Impact on Herbicide Efficacy and Plant Absorption

Surfactants improve the performance of herbicides by increasing the amount of contact of the herbicide on the surface of the plant, allowing it to permeate and absorb better. They're solvents that make herbicides bleed through the waxy skin of the plant and be more biologically active and effective. But the action of surfactants is also determined by their chemical composition and amount. Too much can result in a thin film that can diminish the residual herbicide.

Surfactants contribute to the herbicide formulations by reducing surface tension, increasing wettability and coverage, decreasing the size of droplets and spray time, and increasing the herbicide's permeability and absorption, all of which will greatly enhance herbicide performance.

What Are Non-Ionic Surfactants?

Definition and Characteristics of Non-Ionic Surfactants

Non-ionic surfactants are chargeless (they do not ionize in water, nor do they change the pH of the solution). Their hydrophilic part consists mostly of polyethylene glycol chains, and their hydrophobic portion contains saturated or unsaturated fatty acids, fatty alcohols or fatty oils. Non-ionic surfactants, being charge-free, are irritant and toxic less, so can be used in the biomedical and food markets. They are also stable in hard water and not easily influenced by calcium and magnesium ions.

Common Examples

Common non-ionic surfactants include polyethylene glycol esters (such as polyethylene glycol fatty acid esters), alkylphenol ethoxylates (such as nonylphenol ethoxylates), and fatty alcohol ethoxylates. These compounds are widely used in areas such as cleaners, emulsifiers, and solubilizers.