Ecotoxicity assessment of magnetic trimethyl chitosan nanomaterials for the treatment of glyphosate- and AMPA-contaminated water.

Glyphosate (GLY) and its main degradation product, aminomethylphosphonic acid (AMPA), are frequently detected in aquatic environments due to their extensive use and incomplete removal by conventional wastewater treatment processes. Magnetic nanosorbents have emerged as promising nanomaterials (NMs) for water remediation, although their environmental safety remains insufficiently understood under controlled co-exposure and worst-case scenarios. In this study, trimethyl chitosan-functionalized magnetic (Fe₃O₄@SiO₂/SiTMC) NMs were evaluated for the removal of GLY and AMPA from ultrapure water and wastewater, and their ecotoxicological effects were assessed using Danio rerio embryos under three exposure scenarios: NMs alone, NMs after GLY or AMPA adsorption, and simultaneous exposure with phenmedipham (PHE). In ultrapure water, Fe₃O₄@SiO₂/SiTMC NMs showed high removal efficiency for GLY and lower, yet still substantial, removal of AMPA, whereas adsorption performance decreased markedly in wastewater, highlighting the influence of matrix complexity on nanosorbent efficiency. The NMs alone did not induce relevant toxicity up to 250 mg/L, and only minor effects were observed after their use in GLY and AMPA adsorption assays. In contrast, co-exposure with PHE increased embryo toxicity and behavioral effects, suggesting that the NMs may alter the bioavailability of co-occurring contaminants. These findings demonstrate that Fe₃O₄@SiO₂/SiTMC NMs are promising for herbicide-contaminated water treatment but also indicate that their hazard profile may change in multi-contaminant systems, underscoring the need for ecotoxicological assessment under simulated co-exposure scenarios.