Pilot-scale production of functionalized nanoclays for sustainable agricultural applications: process scale-up and optimization

Abstract

This study presents the pilot-scale development of environmentally friendly agro-inputs based on natural bentonite functionalized with chitosan (Q) and salicylic acid (SA), based on successful previous laboratory-scale formulations. Comprehensive physicochemical, morphological, and thermal characterization tests were carried out in order to evaluate how pilot-scale adjustments influenced the structural and functional properties of the nanoclays compared to their laboratory-scale counterparts. The pilot-scale optimizations of the Bentonite-chitosan (Bent-Q) system presented the most significant potential for cost reduction, which is crucial for market adoption. Key optimizations include increasing the initial bentonite concentration by 2.5-fold, reducing the reaction time by 83%, and lowering the reaction temperature to ambient conditions. Biological efficacy tests on tomato plants (Solanum lycopersicum), a globally significant horticultural model, confirmed the activity of the functionalized nanoclays. The optimal scaled-up Bent-Q formulation triggered an increase of 66% in chitinase enzyme (PR3) as a marker for induced defense response in tomato seedlings demonstrating its elicitor activity. Besides, seeds pre-treated with both optimal scaled-up Bent-Q and Bent-SA showed an increase in the germination index of between 100 and 200% compared to the control with water and improved salt tolerance, highlighting their priming effect.