Transforming marine waste into valuable resources: morphological and structural characterization of crab shell particles for composite applications

This study investigates the utilization of crab shell waste as a novel reinforcement material in composite applications, addressing growing concerns about environmental sustainability and material innovation. While previous research has focused on extracting individual compounds such as chitin and calcium carbonate (CaCO₃) from crab shells for biomedical and water purification uses, this study explores the direct application of crab shell particles in their raw and carbonized forms for composite reinforcement. Crab shells were processed into particles in both natural and carbonized states. A suite of advanced material characterization techniques, such as Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDS), X-ray Fluorescence (XRF), X-ray Diffraction (XRD), and Fourier-Transform Infrared (FTIR) Spectroscopy, were employed to analyze their surface morphological, structural, chemical, and functional properties. XRF analysis revealed that key elements such as calcium (Ca), silicon (Si), aluminum (Al), oxygen (O), iron (Fe), and phosphorus (P) were present, with dominant oxides being CaO, SiO₂, Al₂O₃, and P₂O₅. Carbonized samples showed higher concentrations of Ca and CaO. SEM images displayed nodular and rod-like crystalline microstructures, suggesting a heterogeneous morphology conducive to mechanical interlocking in composites. FTIR spectra identified functional groups including hydroxyl (O–H), carbonyl (–C = O), alkene (C = C), and amine (–NH₂), while XRD confirmed calcium carbonate as the primary crystalline phase. The study demonstrates the feasibility and advantages of using crab shell waste, particularly in its carbonized form, as a sustainable and effective reinforcement material for composites. This approach not only valorizes marine bio-waste but also supports environmentally responsible manufacturing practices. The findings pave the way for further development of bio-based composite materials with reduced environmental impact.