Summary
This PRISMA-guided scoping review of 62 studies (2019–2025) evaluates biochar-based sorbents for microplastic removal from water. While laboratory studies consistently report >90% removal efficiency, performance deteriorates substantially in realistic environmental conditions (wastewater, surface water) due to interference from dissolved organic matter, ionic competition, and particle heterogeneity. The review highlights critical gaps in methodology and field validation, essential for translating biochar from a laboratory promise to a deployable water treatment technology.
Regional applicability
Findings are internationally applicable and directly relevant to United Kingdom water treatment and wastewater management policy, particularly where microplastic contamination of drinking water and aquatic environments is an emerging regulatory concern. The emphasis on field-scale validation and standardised testing protocols aligns with UK environmental quality standards and drinking water safety frameworks.
Key measures
Microplastic removal efficiency (%), biochar feedstock types, pyrolysis conditions, surface modifications (magnetisation, surfactant-coating, chemical activation), removal mechanisms (electrostatic attraction, hydrophobic interactions, π–π stacking, physical entrapment), performance in laboratory versus complex matrices (wastewater, surface water)
Outcomes reported
The scoping review synthesised 57 experimental and 5 review studies on biochar-based materials for microplastic removal, finding high laboratory removal efficiencies (>90%) but significant performance decline in complex environmental matrices. The review identified critical methodological gaps including narrow polymer typologies, lack of standardised testing protocols, and limited field-scale validation.
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