# Valorization of Lavender Agro-Waste into Functional Carbon Materials via Carbonization and Zn2+ Modification

## TL;DR

This study shows how lavender waste can be turned into useful carbon materials by heating and adding zinc ions.

## Contribution

A new method for converting lavender agro-waste into functional carbon materials using carbonization and Zn2+ modification is proposed.

## Key findings

- Zn2+ modification was effective at both 3 and 5 mmol concentrations for biochar obtained at different carbonization temperatures.
- A more uniform zinc ion distribution was observed at 3 mmol, while 5 mmol caused partial particle agglomeration.
- The presence of Zn–O-related interactions was observed, along with degradation of functional groups like O–H and C=O.

## Abstract

This paper proposes a valorization approach for solid lavender residue, a by-product of the essential oil industry. The biomass residue was carbonized at atmospheric pressure and two temperatures (450 °C and 650 °C), followed by solvothermal modification with zinc ions (Zn2+, 3 and 5 mmol). The effects of temperature and Zn2+ incorporation on the elemental composition and morphology of the resulting biochar were examined using X-ray Fluorescence (XRF), Fourier Transform Infrared (FTIR) spectroscopy, and Scanning Electron Microscopy/Energy-Dispersive X-ray Spectroscopy (SEM/EDS) analyses. The applied Zn2+ modification was effective at both concentrations for the biochar obtained at both carbonization temperatures. However, a more uniform metal ion distribution was observed at 3 mmol, while at 5 mmol, a partial particle agglomeration occurred. Progressive degradation of the O–H, C=O, and C–O groups with increasing temperature and the presence of Zn–O-related interactions was observed. The results demonstrated consistent and reproducible trends, suggesting that controlled carbonization combined with Zn2+ incorporation can convert lavender residues into modified carbonaceous materials.