Nano-Enabled Sustainable Corrosion Inhibitors from Agricultural Biomass: Adsorption Behaviour and Industrial Applications

Agricultural biomass is increasingly being transformed from a waste-management burden into a feedstock for sustainable corrosion-control materials. Concerns about the toxicity, persistence, cost, and environmental impacts of conventional inhibitors have stimulated interest in bio-based alternatives, while nanotechnology offers opportunities to improve surface area, dispersion, and interfacial properties. This review critically examines agricultural-biomass-derived nanomaterials for corrosion inhibition, focusing on mild and carbon steels in acidic and saline environments. Using a feedstock–nanoarchitecture–adsorption–interface–application framework, the review explores agricultural residues, including rice husk, fruit peels, mango kernels, and plantain residues, as sources of silica, calcium-containing materials, porous carbon, carbon dots, and polyphenolic extracts. Their protective mechanisms involve physical adsorption, chemisorption, electrostatic interactions, donor–acceptor interactions, surface complexation, and barrier-film formation. Langmuir, Temkin, Freundlich, and related isotherms support adsorption analysis, although fitting a single model does not establish a unique mechanism. Gravimetric measurements, electrochemical impedance spectroscopy, potentiodynamic polarization, and surface characterization provide complementary evidence, while density functional theory, molecular dynamics, and Monte Carlo simulations clarify molecular interactions. Reported studies demonstrate promising laboratory inhibition efficiencies. However, translation into industrial applications remains limited by feedstock variability, nanoparticle aggregation, reproducibility, toxicity, scalability, process compatibility, limited field testing, and incomplete life-cycle assessments. This review proposes a qualification pathway integrating raw-material standardization, nanoscale quality control, mechanistic validation, realistic corrosive environments, continuous-flow testing, and life-cycle assessment. Ultimately, successful development requires balancing inhibition efficiency with safety, reproducibility, manufacturability, and demonstrated performance under industrially relevant conditions.