Controlled production of eco-friendly emulsions using direct and premix membrane emulsification

Eco-friendly O/W emulsions were produced by membrane emulsification using nickel membrane consisting of hexagonal arrays of cylindrical pores of 10 or 20 μm diameter and 200 μm spacing. The dispersed phase was a mixture of N,N-dimethyldecanamide (AMD-10TM) and d-limonene containing 0–35 wt% AMD-10TM in the dispersed phase and the continuous aqueous phase was 3 wt% polyoxyethylene glycerol fatty acid ester (Levenol® C-201). In direct membrane emulsification, the droplet-to-pore size ratio was 1.5–4.6 and the most uniform droplets were obtained with pure d-limonene at a stirrer speed of 620 rpm, corresponding to the peak shear stress on the membrane surface of 7 Pa. In premix membrane emulsification, the median droplet diameter decreased with increasing the transmembrane flux and was smaller than the pore size at the flux above 2000 L m−2 h−1. The droplet size was 6 μm after two passes through the membrane with a pore diameter of either 10 or 20 μm. The viscosity of emulsions with 30 wt% was not influenced by the shear rate but an emulsion with a dispersed phase content of 40 wt% showed shear thinning behaviour and viscoelastic properties. The produced emulsions can be used as environmentally friendly matrices for incorporation of agrochemical actives.