Self-cleaning hydrophobic interconnected porous silica derived from bagasse ash for oil spill remediation

Abstract

Oil spill remediation presents a significant environmental challenge. The remediation process must minimize impacts on the surrounding ecosystem. Utilizing conventional chemical dispersants to commonly remediate oil spills may pose risks, as they might not prevent secondary pollution and can increase the environmental burden on coastal and marine life. This study explores the sustainable valorization of bagasse ash into hydrophobic, porous silica adsorbents for oil spill remediation in a simulated, relevant seawater environment. Mesoporous silicas with varying pore architectures were synthesized and surface-modified with trimethylchlorosilane (TMCS) to improve hydrophobicity. Among these, TMCS-modified mesocellular silica (MS) showed the highest diesel oil adsorption capacity (4.33 g oil g⁻¹), which was 1.8–2.5 times greater than TMCS-modified MCM-41 and MCM-48. This performance is attributed to its wormhole-like, interconnected mesoporous structure, large pore volume (1.40 cm³g⁻¹), and enhanced surface hydrophobicity. Given the possibility that oil-adsorbed materials may leak during the removal or cleanup process at sea, adsorbents were functionalized with Ti, Zn, and Ti–Zn to enhance their photocatalytic ability and minimize environmental impact. Although the incorporation of metal oxides slightly reduced oil uptake, it improved the self-cleaning function through photocatalytic degradation of the adsorbed oil. TMCS/Ti–Zn/MS adsorbents exhibited the photocatalytic degradation efficiency (up to 30.18%) due to the synergistic effect between TiO₂ and ZnO. They exhibited lower environmental impacts than the commercial dispersant Corexit 9500, with 3.2 times lower climate change impact and 5.8 times lower ozone depletion potential. This research offers a high-performance, environmentally sustainable alternative for marine oil spill remediation.