Mimicry between traditional method and solar method

Écrit par Rohan NOWAK et Waldan GIRARD le . Publié dans How to distill using solar energy ?

We went to Morocco from 18 to 20 November 2015 to meet artisans and women from the Medina who distilled floral waters. We realized that this tradition persists in certain families and that some artisans sell their products in the souk. We gathered quite a lot of information relative to the secrets concerning the process and the ratio of flowers/water used/distillate obtained.

The principle is simple and close to the one we encountered in a physics and chemistry lesson, called hydro distillation:

Œ       Water is brought to a boil

       The vapors pass through the flowers from which we wish to extract the essential oils

Ž       The oils are then carried by the water vapor in which they are entirely soluble in gas form

       These vapors are liquefied in a cooling system containing cold water 

       We recuperate a distillate in which it is sometimes possible to clearly distinguish an organic phase floating if the oils are really not very miscible in water in the liquid state, as we could see with rosemary.



Table 1: Choice of materials based on advice from Moroccan artisans

Advice from “Moroccan specialists”

Choice of material

Limit the loss of vapor

Airtight container: pressure cooker with a seal in good condition

A sufficient power source for good vapor output

Source providing the most power: “Solar dish” concentrating the sun rays under the pressure cooker

Maintain the plants as dry as possible

Paint the exterior black so the whole pressure cooker heats up and not just the underneath.

5L of water for 1 kg of flowers

In an 8L pressure cooker, only 2.5 L of water and 500g of flowers to leave a space between the water and the flowers

All the vapor must go through the plants

Basket of the same diameter as the inside of the pressure cooker to limit the amount of vapor that doesn’t pass through the plants

Maintain the distillate cold with a damp piece of cloth: their cooling system liquefies the vapors but only cools the distillate a little bit

Preference for a bigger cooling system such as in Fig. 1 so as the waters recuperated are cooler to limit the loss by evaporation, in the absence of a real Florentine vase which would be too expensive

Preference for a glass bottle

Glass bottle to recuperate the distillate. Test made with a plastic bottle: the non-polar oils adhere to the non-polar polyethylene