Facial foam product from charcoal derived of macadamia processing waste

Abstract

This study was conducted with the objective of developing a facial cleansing foam derived from charcoal obtained from macadamia nutshells and investigating the relationship between charcoal particle size and loading concentration on the physicochemical and functional properties of the formulation. A two-factor (3 × 5) full factorial experimental design was employed, comprising three levels of particle size (0.05, 0.10, and 0.15 millimeters) and five levels of charcoal loading concentration (10, 20, 30, 40, and 50 percent by weight). The full factorial design was applied during the formulation development stage to evaluate pH, surface tension, and cleansing efficiency. The optimal formulation was subsequently selected for evaluation of skin irritation potential and user satisfaction in 40 volunteers. The experimental results suggested that both particle size and loading concentration influenced the properties of the formulation. The particle size 0.05 millimeters demonstrated superior cleansing efficiency, which was attributed to its higher specific surface area and enhanced adsorption capability. Among the tested formulations, the 20 percent by weight charcoal concentration was identified as the optimal level, yielding a mean pH of 5.3, which is appropriate for topical skin application. In addition, this formulation exhibited a surface tension within the range of 25–35 mN/m and the highest cleansing efficiency of approximately 94.8% compared with other experimental conditions. Evaluation in human subjects confirmed that the formulation was well tolerated, with only mild initial skin irritation that diminished over time. Overall user acceptance was high, with a mean satisfaction score of 8 out of 9, indicating favorable consumer response to the developed product.