Advancements in essential oil-based emulsions: Eco-friendly alternatives to conventional agrochemicals

Conventional agrochemicals are effective but raise concerns about toxicity, persistence, and environmental safety. Essential oils (EOs), owing to their inherent antimicrobial, insecticidal, and antioxidant properties, have emerged as natural alternatives; however, their high volatility and instability limit direct application. Emulsion-based delivery systems, particularly nanoemulsions (NEms) and Pickering emulsions (PEms), provide effective strategies for stabilising and controlling the release of EOs. This review highlights recent advances in EO emulsions, emphasising plant-based surfactants, biosurfactants, and nanoparticles as green stabilisers, alone or in synergy with conventional emulsifiers. Theoretical aspects of colloidal stability, mechanisms of destabilisation, and the role of electrostatic, steric, and non-DLVO forces are discussed. Applications of EO emulsions as agrochemicals are presented, focusing on their improved wettability, adhesion, washing resistance, and sustained release. Finally, current challenges in large-scale production, regulatory standardisation, and field-level validation are outlined and provide future perspectives on establishing EO emulsions as sustainable next-generation agrochemicals.