Abstract:
Soap referred to as stain removal material as a result of a saponification reaction between lye solution
and fat/oil. In some soap industries clay minerals are used as a filler material which facilitate the
structure and riser attribute of soap. Instead of that these clay minerals have the ability to remove
stain and exfoliate the dead skin and act as a moisturizer. There are many clay types that can be found
locally which are related to kaolin. However, those clay types do not showcase some qualities such as
anti-bacterial effect, anti-fungal effect, moisturizing effect, foaming effect related to skin care.
Therefore, those natural clay types have not been used previously for cosmetic purposes. Under this
investigation, a non-ionic natural bio surfactant called saponin which was extracted from the dry fruit
of Sapindus emerginata (soapnut) was used to improve above mentioned lacking qualities. Saponin
makes skin soft and acts as moisturizing agent, gentle foaming agent, natural exfoliant, and very good
anti- fungal and anti-bacterial agent. Four clays were used for this investigation. Except
montmorillonite clay, other three were obtained from different areas of Sri Lanka i.e; kaolin clay
from Meetiyagoda, kirimati from Kandy, Makulu clay from Wadduwa. From each clay type, three
samples were prepared by varying the clay amount as 2g (6.7 wt%), 4g (13.3 wt%) and 6g (20 wt%)
by maintaining the temperature of the solution as 30 °C in order to find out the best clay species for
soap production. Each of the sample were tested for the TFM value, total alkalinity content, moisture
content, foam height and pH value. These values were compared with the international standards of
soaps. Almost all the parameters of prepared soap samples were within the standard ranges. As per
the results, Meetiyagoda clay and Makulu clay were the best clays for soap production and the best
composition is 20 wt% which contain 6g of clay.
Keywords: Kaolin; Sapindus emerginata; saponin, montmorillonite; Saponification
