Guadua angustifolia biochar/TiO₂ composite and biochar as bio-based materials with environmental and agricultural application

Globally, the companies that make commercial use of bamboo culms produce different kinds of solid waste rich in lignocellulosic biomass, which in some cases is not used and is discarded in landfills or incinerated in the open air; losing the possibility of recovering them and using them in other productive sectors. The research objective were to produce a biochar from Guadua agustifolia Kunth sawdust, evaluate its potential environmental and agricultural use, obtain a biochar/TiO₂ composite to inactivate Escherichia coli and use the biochar as a soil conditioner in medicinal plants producing phenolic compounds and flavonoids. Biochar composite (produced at 300 °C for 1 h) involved TiO₂ at 450 °C for 1 h for inactivation of E. coli (initial concentration: 6.5 ± 0.3 Log₁₀ CFU mL^{− 1}). For agriculture, 2% biochar was used to evaluate B. pilosa L. and G. angustifolia plant growth for 90 days. The biochar/TiO₂ composite had a high photocatalytic activity on E. coli, generating a final count of 1.97 ± 0.2 Log₁₀ CFU mL^{− 1} after 60 min. Biochar (2%) increased the total phenol and flavonoid content in the medicinal plant B. pilosa L. and total phenols in G. angustifolia, tested at the nursery stage. This study provides new information on the conversion and use of G. angustifolia sawdust as an alternative for new bio-based materials with environmental and agricultural applications. In addition, obtaining biochar and composite could positively impact the bamboo production chain in Colombia because of renewable and globally accepted alternatives that help capture gaseous emissions causing the greenhouse effect.