Interlayer and surface chemistry mechanisms in the removal of emerging mycotoxins – alternariol and enniatin B – by organically and thermally modified smectites

Abstract

This study investigated the adsorption performance of differently modified smectite-based materials toward the emerging mycotoxins: alternariol (AOH) and enniatin B (ENN B), under aqueous and simulated gastric conditions. The results demonstrated that mycotoxin removal efficiency is strongly governed by smectite type and targeted modification strategy. AOH adsorption was most effective on organo-modified smectites, particularly hexadecyltrimethylammonium (C16)-modified materials, where dense alkyl chain packing and interlayer hydrophobization promoted diffusion-driven uptake. In contrast, ethyl lauroyl arginate (LAE®) and cocamidopropyl betaine (CPB) modifications showed lower efficiencies due to steric effects and reduced charge neutralization. Vitamin B1-modified Na-smectite outperformed Ca-smectites owing to higher ion-exchange efficiency and modifier-to-CEC ratios. Adsorption isotherms for AOH were linear in both acidic aqueous media and simulated gastric fluid, indicating the predominance of hydrophobic interactions with limited pepsin interference for C16-modified materials. ENN B removal was enhanced by Mg2+ ion exchange and thermal treatment at 300–500°C, which reduced layer charge, generated hydrophobic domains and Lewis acid sites, yielding adsorption efficiencies up to ∼80 %. Excessive calcination (700°C) diminished adsorption due to dehydroxylation and partial amorphization. While hydrophobic interactions dominated ENN B uptake, ion–dipole and hydrogen-bonding interactions likely contributed. Dual-component experiments revealed selective and adsorbent-specific affinities of AOH and ENN B. Importantly, adsorption efficiencies were independent of specific surface area, emphasizing the decisive role of smectite interlayer and surface chemistry.