Green Synthesis and Characterisation of Iron Oxide-Silica Aerogels and Evaluation of Their Oil Absorption Properties

Chong, Jin Yi (2026) Green Synthesis and Characterisation of Iron Oxide-Silica Aerogels and Evaluation of Their Oil Absorption Properties. Final Year Project (Bachelor), Tunku Abdul Rahman of Management and Technology.

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Abstract

In this study, hydrophobic silica aerogels were heated to impart surface water wettability, evidenced by a change in contact measurement, prior to chemical modification in which superparamagnetic iron oxide were formed in-situ between the pores of silica aerogels. This new composite design allowed the enhancement of their adsorption efficiency, magnetic recoverability, and structural stability. The chemical modification started with the impregnation of iron chloride hexahydrate (FeCl₃·6H₂O) solution into silica aerogels under vacuum conditions, followed by NaBH4 reduction and heat treatment to produce Fe₃O₄-modified aerogels. The physicochemical properties of the materials were characterized using a combination of Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and zeta potential measurements. The results confirmed the amorphous silica framework with the successful incorporation of crystalline Fe₃O₄, and the composite exhibited improved thermal stability, and stable surface charge distribution, when compared to the silica aerogel control. Magnetic susceptibility measurements further demonstrated strong magnetic responsiveness, enabling facile separation from treated water. Performance tests, including oil absorption capacity and batch adsorption experiments, revealed that the iron oxide–silica aerogels exhibited high uptake capacity with recycled cooking oil (8.33 g/g) and silicone oil (8.33 g/g) while retaining their porous structure and hydrophobicity. The combination of lightweight, high surface area, and magnetic recoverability as a whole signify the potential of the Fe₃O₄-Silica aerogel compost as an efficient, recoverable and environmental friendly adsorbents intended for pollution treatment, where hydrophobic pollutants float on top of water systems.