Development of hydrophobic polyurethane/castor oil biocomposites with agroindustrial residues for sorption of oils and organic solvents.

Since pollution of aquifer sources by organic compounds is a threat to the environment and humans, technology's constant advancement in developing sustainable adsorbents using renewable resources with hydrophobic characteristics has become increasingly attractive. In this study, we developed and characterized castor oil-based polyurethane biocomposites reinforced with malt and/or acerola residues for adsorption/separation of various organic oils/solvents. The residues evidenced biocomposite flexibility, increase in adsorption capacity for all organic oils/solvents, with a maximum of 3257.8 ± 55.6% for chloroform in 60 min and hydrophobicity (144 ± 0.2°) in acidic, saline and alkaline environments, and when exposed to UV radiation. These biocomposites can be quickly and repeatedly recovered by simple hand-tightening and solvent release systems (10 times) and vacuum suction filtration (20.5 ± 0.9 s/10 mL). Through the pseudo-first order (PPO) and pseudo-second order (PSO) kinetic models, the engine oil adsorption capacity increased with time from 746.7 ± 77.4% (60 min) to 928.6 ± 16.7% (90 min). These bio-composites are prototypes to be used with malt and acerola bagasse residues, becoming a reference for future works, produced in a sustainable way, with high potential for application in treatment of effluents with organic pollutants.