Pineapple waste biosurfactant: sustainable soil clean up via optimization, characterization and sorption kinetics

Pineapple waste is a low-cost agro-industrial waste with promising applications in biosurfactant production and alternative non-toxic chemical surfactants. For its use to be viable for commercial purposes, the production as well as the performance of the biosurfactant produced, must be studied; specifically, the functionality of the biosurfactant product can be verified from its surface-activity characteristics. The present study investigated the optimum culture medium of biosurfactant derived from pineapple waste (BPW) as the main carbon source using Acinetobacter calcoaceticus for fermentation and kinetic modelling was performed. The fermentation process was first optimized using the Plackett–Burman and Box–Behnken statistical designs to obtain the maximum yield at optimum conditions. Four significant variables had the most influence on the optimization process (temperature, pineapple waste, agitation, and incubation period), with a maximum biosurfactant yield of 3.09 mg/mL. The kinetic studies revealed that the biomass growth and biosurfactant behaviour best fitted the Mercier model, while the substrate utilization was best represented by the Leudeking-Piret. To understand the behaviour of the biosurfactant towards pyrene, sorption kinetic modelling was performed. The Freundlich isotherm model for adsorption and the pseudo-second-order model for desorption were most effective at describing the biosurfactant sorption behaviour in the soil–surfactant system. The results of this study suggested that it is feasible to produce biosurfactants using pineapple waste as the primary carbon source through fermentation and can be used effectively for soil remediation against oil pollution.