Bio-Based Surfactants in Heritage Conservation: Performance, Challenges and Future Directions.

The conservation field is increasingly seeking environmentally responsible alternatives to petroleum-based surfactants for heritage cleaning applications. This review examines bio-based surfactants-particularly alkyl polyglucosides, rhamnolipids, and mannosylerythritol lipids-as sustainable options for cultural heritage preservation. Performance analysis shows promising but variable results across different applications. Alkyl polyglucosides demonstrate effective soil removal on calcareous stones, while rhamnolipids work well on organic materials when proper pH conditions are maintained. Knowledge transfer from the pharmaceutical and cosmetic industries provides valuable insights, though heritage-specific validation remains limited. The main challenges include inconsistent testing methods across studies, the need for substrate-specific optimization, and concerns about residue retention in porous materials. Rather than completely replacing conventional surfactants, the evidence suggests a more selective approach based on specific cleaning requirements. Future research should focus on developing standardized testing protocols for heritage applications, conducting long-term studies on material compatibility, and adapting quality control frameworks from established industries. Successfully transitioning to sustainable surfactants will require carefully balancing environmental benefits with proven conservation effectiveness, ensuring that green alternatives meet the rigorous demands of cultural heritage preservation.