Application of Box Behnken design in optimization of bentonite self-foaming clay soap (SFCS) formulation for Islamic najis cleansing and its antibacterial activity against bacteria from dog’s saliva

This present work describes the optimization of bentonite self-foaming clay soap (SFCS) using Box Behnken design. The experimental design of formulation bentonite SFCS consists of the amount of clay bentonite (X1, %), Sodium Lauryl Sulphate (SLS) (X2, %), potassium cocoate (X3, %) and cocamidopropyl betaine (X4, %) as independent variables while the dependent or response variable (Y) are zeta potential (Y1, mV), viscosity (Y2, cps) and foamability (Y3, cm). Experimental data (X, Y) were analyzed with ANOVA to produce a polynomial regression model of responses. The antibacterial activity was examined on Proteus mirabilis which was isolated from dog's saliva. Significant models of 3 responses (P <0.05) were resulted, following quadratic model for viscosity, reduced 2FI model for foamability, and linear model for zeta potential. The obtained optimized formula is at clay bentonite 5 %, SLS 2.20 %, potassium cocoate 1 %, and cocamidopropyl betaine 1 %. Antibacterial effectivity test showed the percent reduction of SFCS-bentonite is significantly higher (99.401%) than its original liquid clay soap (98,204%) and the soap without clay bentonite (73,054%). It can be concluded that the SFCS-bentonite can be optimized using Box Behnken design and can be developed as Islamic najis cleansing.