Amoeba-inspired nano-robots for trace low-molecular-weight emerging contaminant removal from water

Trace low-molecular-weight emerging contaminants (LMWECs) in drinking water sources pose chronic health risks but remain challenging to remove using conventional treatment processes. Here, we describe an amoeba-inspired nano-robot (NR_m, where m refers to the molar ratio of Fe:Si), engineered with flexible polymer chains and iron (hydr)oxide nanodomains, for the simultaneous capture and catalytic degradation of 20 representative LMWECs at initial concentrations from 100 ng/L to 1 mg/L in a real surface water. Under optimized operational conditions, NR₁₀ achieved over twice the removal efficiencies compared to conventional water treatment chemicals involving FeCl₃ and polyacrylamide (PAM). The nano-robot autonomously extended polymer "pseudopodia" to bind LMWECs into flocs via hydrophobic association, and used H₂O₂ both as a "propulsion fuel" and as a source of •OH radicals via Fenton-like reactions to accelerate degradation of captured LMWECs. This multi-function mechanism enabled efficient capture and degradation of LMWECs, while reducing toxicity (from "acute" of raw water to "nontoxic" of the treated water) and improving sludge dewaterability. After use, 91% of NR₁₀ could be recovered from flocs, and the recovered nano-robots maintained high LMWEC REs with only ∼2% reduction for each recovery-reuse cycle. NR₁₀ offers a deployable, infrastructure-compatible solution to the growing problem of LMWECs in drinking water.