A review: Analytical and catalytic evaluation of eggshell-based materials for the removal of volatile organic compounds

Volatile organic compounds (VOCs) are among the major atmospheric pollutants due to their toxicity, persistence, and potential carcinogenic effects. Catalytic oxidation is considered one of the most efficient techniques for VOC removal; however, the high cost and limited sustainability of conventional catalyst supports have encouraged the development of alternative low-cost materials. Eggshells, an abundant agricultural waste primarily composed of calcium carbonate, have recently attracted attention as natural catalyst supports due to their porous structure, thermal stability, and chemical reactivity. This systematic review investigates recent advances in the application of eggshell-based materials in catalytic oxidation processes for VOC abatement from an analytical chemistry perspective. Relevant studies were selected according to predefined inclusion and exclusion criteria. Information regarding catalyst synthesis methods, calcination conditions, catalyst composition, physicochemical properties, analytical evaluation, and catalytic performance was critically reviewed. Various analytical and characterization techniques, including FTIR, SEM, TEM, XRD, BET, TGA, ICP-OES, and GC-MS, were employed to evaluate catalyst morphology, elemental composition, surface properties, and VOC degradation products. The reviewed studies demonstrated that eggshell-supported catalysts modified with Ag, Co, Pt, and MnO₂ nanoparticles achieved VOC removal efficiencies of 90-100% at relatively low operating temperatures (100–280 °C). Among the synthesis approaches, wet impregnation was identified as a simple, scalable, and effective method. The catalysts also exhibited high thermal stability and resistance under different humidity and pollutant conditions. Overall, eggshell-derived catalysts are sustainable and cost-effective materials for environmental analysis, VOC monitoring using GC-MS, air pollution control, and industrial VOC treatment.