Particle Characterization for the Agrochemical Industry

Agrochemicals play a significant role in food production, both for the elimination of pests and weeds and for the optimization of fertilizers.

Malvern Instruments' contribution to optimizing the performance of Agrochemicals is not just limited to their production. In many cases, the effective delivery of pesticides and herbicides is heavily dependent on the particle size distribution and rheological properties of sprays and dusts.

Typical areas where particle size and rheology has an impact on agrochemicals are:

Pesticide sprays

Droplet size of pesticide sprays is of paramount importance. Droplets that are too large only wet the top of the leaves and run off quickly. Large droplets are extremely wasteful (one 500µm droplet is equivalent to 125,000 10µm droplets.

Droplets that are too small will drift into neighboring fields, creating a health hazard. Their small size also means they will evaporate rapidly. Also, the interaction between the particles can cause instability and affect rheological properties, which impacts their flow properties.

Droplets that are perfectly sized; coat the leaves evenly (including the undersides), don't evaporate too quickly and do not drift.

Fertilizers and pesticides in powder form

Agricultural storage conditions are notoriously variable - damp is always a problem. Sacks full of fine powder can set like concrete and quickly become unusable on exposure to damp. Granulating or pelletizing the bulk chemicals inhibits capillary action so that the bulk of the product remains relatively unaffected by damp storage conditions. The uniformity of the chemical formulation of granules will depend on the component ingredients having been sufficiently finely milled prior to granulation or pelletization. However, material, which is milled too finely, will produce pellets or granules that are difficult to dissolve compared with pellets made from coarser powders, which fall apart more quickly when immersed in water. When put into suspension,Malvern rheometers can help determine the physical stability and optimal use of additives to enhance suspension stability.

Stability of suspensions for agrochemical use

Different regions of the world have well-characterized variations in the pH and salt contents of their water supplies and these can have a significant effect on the stability of suspensions produced for use in these regions. Consequently many agrochemical companies will design formulations of their compounds for use in these regions and will use zeta potential measurements, together with rheological measurements to predict the stability of their formulations.