Ultrasound-Assisted Extraction of Saponins from Beet Leaves for Soil Decontamination

The traditional consumer society based on oil and petroleum products has increased the number of cases of total petroleum hydrocarbon (TPH) soil contamination worldwide. It is vital to proceed with the treatment and requalification of these affected areas using cost-effective and environmentally sustainable methods. This work presents a sustainable approach to soil remediation using soil washing with saponins extracted from beet leaves, a subproduct from the food industry. Two different methods were evaluated to extract saponins from beet leaves: (i) the traditional method, maceration with 50% (v/v) methanol/water and 50% (v/v) ethanol/water, followed by the n-butanol partition, and (ii) ultrasound-assisted extraction using an aqueous ethanolic solution of saponins. The second method was selected to carry out soil decontamination optimization using STATISTICA software, since it obtained better yields and is a more environmentally friendly method, where 75% (v/v) ethanolic solution, liquid/solid ratio (L/S) of 10 mL/g, and contact time of 30 min. The crude extracts obtained in Method 2 were used to prepare washing solutions for soil remediation, obtaining an efficiency of (90.40 ± 1.40)% (m/m) in TPH removal.