Abstract Summary (Max 250 words)
Key targets of United Nations Sustainable Development Goal 2, namely the increase of agricultural productivity whilst ensuring sustainable food production to end hunger and malnutrition, aim to address the growing gap between food demand and supply. Plant based biopesticides are therefore receiving increasing attention to minimise crop losses whilst observing sustainable agricultural practices. Neem oil, obtained from the seeds of the neem tree, is an attractive candidate as it contains azadirachtin- a bioactive which is effective on hundreds of species of insects, and is also biodegradable with very low toxicity to mammals. This study has been performed taking the process intensification route to obtain fine emulsions of neem oil with the objective of determining breakup kinetics relevant to process design and scale-up. Neem oil (10%w:w)-in-deionised water emulsions in the presence of surfactants have been prepared using VMI Turbotest® Rayneri batch rotor–stator equipped with slotted and toothed mixer head. Covering a power input range of around 19-52 W, the process was monitored through drop size measurements. Results were compared to those with the Hielscher UP200S ultrasonic processor. Comparable Drops Size Distributions (DSD) from different parts of the emulsion demonstrated that the VMI alone can ensure spatial homogeneity; with the ultrasonic processor an impeller was also needed. The evolution of DSDs were similar with the kinetics being significantly slower when using the VMI. Equilibrium d32 values below 200 nm could be obtained. Detailed comparisons, also including equipment combinations/configurations will be elaborated in relation to process design and scale-up.
