Neem Extract Antimicrobial Textile Treatment

Neem (Azadirachta indica) extracts containing azadirachtin, nimbidin, and nimbidol are applied to cotton textiles at 2–8% owf via pad-dry-cure (100–120°C) or exhaustion at pH 5–6. Nimbidin concentration of 0.5–2.0% owf achieves 2–3 log reduction against S. aureus and E. coli (AATCC TM100). Additional insect-repellent activity against Aedes aegypti (mosquito) exceeds 80% protection for 20 washes (WHO method). Mordanting with alum (5% owf) or tannic acid (3% owf) improves wash fastness by creating coordinate bonds with fiber hydroxyl and amine groups. Slight yellowing (ΔE 3–5) is managed by combination with optical brighteners. GOTS-permitted natural biocide; cost of $0.05–0.15/m² makes neem competitive with synthetic alternatives for organic cotton markets.