Diesel removal in non-aqueous phase by fibres from Calotropis procera: kinetic, isothermal and sorption potential evaluation.

Calotropis procera fibres have been proposed for free-phase diesel removal in case of spillage into groundwater. For this, characterizations were carried out using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FEG-SEM), wettability and contact angle measurements. Sorption oil capacity, kinetic, isothermal and recycling behaviour were evaluated. For initial optimization of the oil sorption capacity, an experimental design (DOE) was applied, with the optimized condition being 60 g L-1 of diesel in water and 0.01 g of fibre. Then, the results clearly indicated that the fibres have a hydrophobic and oleophilic character, quickly reaching more than 71.43 g g-1 of diesel sorption, according to the adjustment (R² > 0.99) of the pseudo-second order and Langmuir models, governed by absorption mechanisms. It should also be noted that at the end of 8 reuse cycles, the fibre presented a total accumulated sorption capacity of about 252.6 g g-1 of diesel. Furthermore, a laboratory-scale experiment was carried out to remove diesel from groundwater in gas station areas, the fibre removed 98.55% to 99.97% of removal efficiencies were achieved of the free phase over time. Therefore, the material demonstrates excellent characteristics for removing diesel spills in groundwater due to its fast, high and stable removal capacity.

Combined Treatment (Alkali + Thermal) of Calotropis procera Fiber for Removal of Petroleum Hydrocarbons in Cases of Oil Spill.

The objective of this study was to evaluate the Calotropis procera fiber treated with NaOH combined with heat treatment as sorbent material for removal of petroleum and derivatives in cases of oil spill. The effects of oil viscosity, fiber/oil contact time, and the type of sorption system (oil and oil/water) were evaluated by experimental planning. The fiber obtained was characterized by Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM-FEG), thermogravimetric analysis (TG/DTG), contact angle, and wettability. The fiber treated by combining NaOH and heat treatment (CPNaOHT) exhibited a large structure with an internal diameter of 42.99 ± 3.98 µm, roughness, and hydrophobicity on the surface with a contact angle of 101 ± 2°. The sorption capacity of oil ranged from 190.32 g/g to 98.9 g/g. After five cycles of recycling, the fiber still maintains about 70% of its initial sorption capacity and presented low liquid desorption (0.25 g). In this way, it can be used as an efficient sorbent to clean up spills of oil and oil products.