Understanding the aggregation behavior of engineered nanomaterials (ENMs) in aqueous environments is essential to understanding their fate, transport, and toxicity. Because naturally occurring colloids will likely be present at much higher concentrations than ENMs in environmental systems, heteroaggregation and attachment with these natural colloids could significantly influence ENM fate and impact on water bodies. This study investigated the heteroaggregation and attachment between hematite (α-Fe2O3) and citrate-capped gold nanoparticles (Cit-AuNPs) in 1 mM KCl. The influence of Cit-AuNP concentration was investigated at pH 6 and pH 8. Attachment was quantified by separation of hematite and hematite-Cit-AuNP aggregates from
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