Sustainable utilization of peanut shells: Global trends, technologies, and future perspectives

Peanut shells are an abundant lignocellulosic by-product generated in large quantities by the global peanut processing industry and are increasingly recognized as a valuable secondary resource. This review provides a system-oriented assessment of their sustainable utilization, including physicochemical properties, processing routes, environmental applications, and high-value material and energy uses within circular bioeconomy frameworks. Peanut shells show strong potential as precursors for adsorbents, biochar, activated carbon, biocomposites, biochemicals, and bioenergy products, particularly in contaminant removal, carbon material production, and lightweight construction materials. Recent advances in nanotechnology, biotechnology, and digital process optimization further expand their applicability toward multifunctional materials and integrated valorization pathways. However, large-scale implementation remains limited by feedstock variability, lack of process standardization, incomplete techno-economic validation, and insufficient assessment of long-term environmental performance and technology readiness, which currently restrict the transition from laboratory-scale studies toward reliable industrial implementation. The review indicates that integrated valorization strategies represent a long-term development direction with high theoretical potential; however, their industrial implementation remains limited by insufficient demonstration-scale validation, techno-economic evidence, and process integration studies. Overall, peanut shells represent a versatile biomass resource with growing relevance for sustainable materials engineering, environmental technologies, integrated biorefinery concepts, and future circular bioeconomy systems.