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Real-time quantification of nanoplastics deposition in nanofiltration using laser-induced breakdown detection (LIBD)
Tyler A Malkoske1, Minh N Nguyen1, Susanne Erpel2
1Institute for Advanced Membrane Technology (IAMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany.
Water Research
|July 6, 2026
Summary
Laser-induced breakdown detection (LIBD) quantifies nanoplastic (NP) deposition and release during nanofiltration (NF). High fluxes cause significant NP cake formation, while backwash effectiveness varies with deposit thickness.
Area of Science:
- Environmental Science
- Water Treatment Technology
- Materials Science
Background:
- Nanoplastics (NPs) pose environmental risks, and their removal via nanofiltration (NF) is crucial.
- NP deposition on NF membranes can impair filtration performance and resist cleaning.
- Understanding NP-membrane interactions is vital for effective water purification.
Purpose of the Study:
- To quantify nanoplastic particle deposition and release during bench-scale nanofiltration.
- To investigate the influence of permeate flux on NP deposition and cake layer formation.
- To evaluate the effectiveness of backwash in removing deposited NPs and identify release mechanisms.
Main Methods:
- Coupling laser-induced breakdown detection (LIBD) in-line with a bench-scale NF system.
- Filtration experiments using polystyrene (PS) particles and weathered NPs at environmentally relevant concentrations.
- Analysis of particle deposition and release under varying permeate and backwash fluxes.
- Theoretical analysis of hydrodynamic and intermolecular forces governing NP transport.
Main Results:
- LIBD successfully quantified PS particle and NP deposition and release during NF and backwash.
- High permeate fluxes (>100 L/m².h) led to 50-100% NP deposition, forming thick cake layers.
- Low permeate fluxes (<50 L/m².h) resulted in insignificant NP deposition.
- Backwash effectiveness showed limited improvement with increased backwash flux, with release mechanisms dependent on deposit thickness (complete release vs. cake fracturing).
- Irreversible deposition was observed for weathered NPs.
Conclusions:
- LIBD is a powerful tool for studying NP transport in membrane filtration systems.
- NP deposition and cake formation are highly dependent on operating flux.
- Backwash efficiency is limited, especially for thicker NP deposits.
- Further research should consider NP aggregation and polydispersity for precise quantification.
