Cactus-inspired bio-derived superhydrophobic anti-corrosive hybrid coating: A sustainable fluorine/silane-free approach for multifunctional oil-water separation

Abstract

The rapid rise in demand for environmentally friendly technologies, and the shift toward a sustainable, fluorine/silane-free approach is critical for driving groundbreaking advancements in environmental remediation solutions. This study reports the synthesis and comprehensive characterization of a multifunctional foam featuring exceptional superhydrophobic and superoleophilic properties, tailored for advanced anti-corrosion, self-cleaning, and oil-water separation applications. Utilizing chicken eggshell waste, we developed a sustainable, fluorine/silane-free coating by first synthesizing functionalized calcium carbonate (FCC) with a cactus-like micro/nanostructure. This FCC exhibited a core-shell structure with a crystalline core and an amorphous calcium carbonate shell. We then fabricated the r-AC-FCC-coated foams using dip-coating and reduction techniques. The r-AC-FCC coating demonstrated outstanding anti-corrosion performance, particularly in saline conditions, with an inhibition efficiency surpassing 80 % and significant corrosion rate reductions in acidic and alkaline environments. The foam achieved a remarkable oil-water separation efficiency of 97 %, showcasing an impressive oil adsorption capacity of 12-65 g/g. Enhanced mechanical properties of r-AC-FCC coated foam were noted, with compressive strength and modulus of elasticity improved by 69 % and 119 %, respectively. The foam also exhibited superior self-cleaning performance and maintained high efficacy over multiple reuse cycles. Biocompatibility tests indicated effective oily wastewater treatment, significantly improving mung bean germination rates. This innovative foam leverages the optimal synergy between surface roughness and energy, underpinned by FCC's hierarchical nanostructures and robust r-AC anchoring, offering a powerful, sustainable solution for environmental remediation and material protection.