Optimization of evaporative extraction of natural emulsifier cum surfactant from Sapindus mukorossi—Characterization and cost analysis

Abstract

In the recent world, biosurfactants have gained much research interest because they are eco-friendly and non-toxic in nature. The detergency of a naturally available biological surfactant (soap nut) has been compared with that of a surface-active petroleum waste-derivative (2-hydroxybiphenyl) (2-HBP)112-hydroxybiphenyl – 2-HBP. and a widely used commercial surfactant (Ezee). Surface tension (ST),22Surface Tension – ST. critical micelle concentration (CMC)33Critical Micelle Concentration – CMC. and emulsification index (E-24 index)44Emulsification Index – E-24 index. are the three principal properties that have been investigated. Moreover, E-24 index and yield for soap nut have been optimized as a function of extraction time and temperature by central composite design (CCD)55Central composite design – CCD. in response surface methodology (RSM)66Response surface methodology – RSM. using Design Expert Version 8.0.7.1 (StatEase, USA). The optimized emulsification index is observed to be 88.042% at 100°C and 12.02min, which is higher than that of 2-hydroxybiphenyl (64%) and Ezee (79.6%). The maximum achievable yield of the soap nut extract at this temperature and time is 31.21% (g extract/g of raw pulp of soap nut). The E-24 index of soap nut extract under optimum conditions of evaporative extraction routeis comparable to the E-24 index of extract from Soxhlet extractor.It has been observed that optimally extracted soap nut solution has a CMC of 23kg/m3, whereas the values of CMC of 2-HBP and Ezee are 0.2kg/m3 and 250kg/m3 respectively. A cost analysis based on the production cost of soap nut extract and the market price of 2-HBP and Ezee suggests that the price of surfactants varies inversely with their CMC value and hence, lesser amount of costlier surfactant is required for the reduction of surface tension in the same extent. The soap nut extract is the best product among the three for the purpose of emulsification, particularly suitable in food and pharmaceutical industries.