Eco-friendly sorbents for petroleum and diesel based on macadamia nutshell waste in castor oil-based polyurethane foam for oil spill

Abstract

Abstract Aquatic environments have experienced profound and severe consequences in recent years due to oil spills and chemical leaks in oceanic and river ecosystems. Because of this, several studies have been conducted to develop sustainable adsorbents with hydrophobic characteristics. Thus, the present research focuses on the development of eco-friendly sorbents from macadamia nutshell waste (MW) in castor oil-based polyurethane foam with different proportions of MW (5, 10, 15, and 20 wt%) and a granulometry of 28 mesh to assess the absorption efficiency for different oil types (crude oil CB, crude oil SB, diesel S10, and diesel S500). The eco-friendly sorbents (biocomposites) were characterized by optical microscopy, scanning electron microscopy, density, and contact angle. The pore morphology of sorbents changed to a partial closed-cell structure with a smaller pore size, and biocomposites exhibited a higher contact angle (119.1º ± 0.4). The oil absorption capacities by biocomposites showed maximum sorption of 7.3, 7.1, 5.1, and 3.9 g.g-1 for crude oils (SB and CB), S10, and S500 diesel, respectively. The sorption results showed that the biocomposites showed good removal of heavy oils (crude oil) compared to light oils (diesel S10 and S500). Among the isotherm models used, the Langmuir model demonstrated the most accurate fit and estimated a maximum adsorption capacity of 5.39, 4.23, 3.24, and 2.69 g.g−1 for crude oil CB, crude oil SB, S10, and S500 diesel respectively, using PU+20% MW. Additionally, PU+ 20 % MW showed excellent reusability during 30, 30, 30, and 10 cycles of sorption-desorption for crude oil CB, crude oil SB, S10, and S500 diesel, respectively.