Leaves and Roots of Pistia stratiotes as Sorbent Materials for the Removal of Crude Oil from Saline Solutions

The removal and sorption of oil from saline solutions by leaves (L) and roots (R) of Pistia stratiotes are described for the first time. The effects of biomass dose (0.5 and 1.0 g), contact time (30, 60, 90, and 120 min), and initial oil concentration (IOC = 979 ± 9.82, 1,968 ± 8.01, 3,935 ± 40.09, 7,778 ± 196.42, and 15,694 ± 196.41 mg L−1) on removal and sorption (q) were evaluated. Studies included a physicochemical characterization of the biomass. High oil removal (L = 93.71 ± 0.18 % and R = 80.93 ± 0.11 %) and sorption values (L = 2,904.47 ± 4.49 mg g−1 and R = 2,324.38 ± 29.29 mg g−1) were found. Such a high sorption might be related to factors such as a high surface area (128.38 ± 0.61 and 112.62 ± 5.17 m2 g−1, for leaves and roots, respectively), a high degree of relative hydrophobicity in the case of the leaves (71.05 ± 0.71 %), and capillary action. A high correlation was found between IOC and sorption, suggesting that the biomass could adsorb oil at IOCs higher than 15,694 ± 196.41 mg L−1. The Freundlich isotherm model was found to best describe crude oil sorption by leaves and roots of P. stratiotes. These sorbent materials could be good candidates to be used during an oil spill.