Both nanoplastic and iron mineral types determine their heteroaggregation: Aggregation kinetics and interface process

Area of Science:

• Environmental Science
• Environmental Chemistry
• Materials Science

Background:

• Nanoplastics (NPs) are emerging environmental contaminants.
• NPs inevitably interact with iron minerals (IMs) in aquatic environments.
• These interactions influence NP transport, fate, and ecological impact.

Purpose of the Study:

• To investigate the heteroaggregation kinetics of four NPs with hematite and magnetite.
• To elucidate the interfacial interaction mechanisms between NPs and IMs.
• To assess the impact of pre-homoaggregation on NP-IM heteroaggregation.

Main Methods:

• Batch heteroaggregation kinetics experiments.
• Utilized four types of NPs: PMMA, PS-Bare, PS-NH2, and PS-COOH.
• Used two IMs: hematite and magnetite.

Main Results:

• Heteroaggregation was dependent on both NP type and IM type.
• NPs showed stronger heteroaggregation with hematite than magnetite.
• Specific interactions included hydrogen bonding, complexation, hydrophobic, cation-π, and electrostatic forces, with electron transfer observed.
• Pre-homoaggregation affected subsequent heteroaggregation, and IM homoaggregates could be disrupted by certain NPs.

Conclusions:

• NP-IM interactions are complex and influence NP environmental behavior.
• These interactions can affect elemental cycles, particularly the iron cycle.
• Understanding these processes is crucial for assessing the ecological risks of nanoplastic pollution.