Characterization of the Chemical and Physical Properties of Bar Soap Made with Different Concentrations of Bentonite as a Filler

• Main Authors: Lilis Sukeksi, Iriany, Maria Grace, Vera Diana
• Format: Article
• Language: English
• Published: Universitas Indonesia 2021-04-01
• Series: International Journal of Technology
• Subjects: bar soap; bentonite; characterization; sem-edx; stoichiometry
• Online Access: https://ijtech.eng.ui.ac.id/article/view/4130
• ISSN: 2086-9614; 2087-2100

The use of bentonite in cosmetics is considered beneficial for absorbing dirt and moisturizing and detoxifying the skin. In this study, different amounts of bentonite (10, 12.5, 15, 17.5, and 20 g) were used as a filler in 5 separate formulations of natural bar soap having coconut oil as the primary ingredient. Each type of bentonite soap was analyzed in accordance with the Indonesian National Standards (SNI). The free alkali content for each of the five preparations of bentonite soap was zero, the moisture content ranged from 0.88 to 1.15 %, the pH ranged from 8.7 to 8.8, the total free fatty acid content ranged from 0.28 to 0.72, and the foam or bubble stability was above 70%, while the soap’s hardness ranged from 1.49 N/m2 to 1.54 N/m2. All five soap types fulfilled SNI standards, but the soaps containing 15 g and 17.5 g of bentonite had a far better appearance. The chemical compositions of the bar soap composed of 15 g bentonite (BS 15) and the bar soap composed of 17.5 g bentonite (BS 17.5) were calculated using material balance and compared by Energy Dispersive X-ray (EDX) analysis. The EDX analysis revealed that both BS 15 and BS 17.5 contained the Si and Al metals originating from the bentonite. No heavy metals considered harmful to skin health (e.g., Hg, Pb, As, or Cd) were detected. Scanning electron microscopy (SEM) of the topography and texture of BS 15 and BS 17.5 revealed a more even distribution of Si and Al throughout BS 17.5 than in BS 15. BS 17.5 was therefore deemed the best formula as it meets SNI standards and has a better appearance and a more even mineral distribution.