Bentonite-PDMS composite foams for oil spill recovery: Sorption performance and kinetics

The aim of this article is the synthesis and characterization of bentonite-filled siloxane foams for oil spills recovery. Composite foams at varying filler content in the range 35–45 wt% were investigated. The sorption kinetics and capacity of composite foams in different oils (e.g., kerosene, virgin naphtha, pump oil) were assessed. As a reference, water absorption capacity was also evaluated. Among all, the composite foam filled with 40 wt% bentonite (B-40 batch) shows the lowest affinity with water and good absorption capacity with oils (mainly light oils) reaching an absorption capacity at saturation equal to 10.3 and 518.2 wt% in water and virgin naphtha, respectively. Furthermore, isothermal absorption curves were analyzed using three kinetic models: pseudo-first order, pseudo-second order, and Elovich models. The equilibrium isotherm fitting results were optimal using the pseudo-second order model, indicating that chemisorption phenomena play a key role in the speed of the absorption phase for these PDMS-based composite foams. Finally, a correlation was addressed between morphology, foam microstructure, absorption capacity, and kinetics.