Zinc is a metallic element that is essential to human health as a micronutrient. However, large amounts of zinc can be toxic to human and environmental health. Acute adverse human health effects of high zinc intake include nausea, abdominal cramps, vomiting, loss of appetite, diarrhoea, and headaches. Zinc may contaminate drinking water if stored in metal containers or flow through pipes coated with zinc to resist rust. Galvanized roofs are a common source of zinc in stormwater. Zinc is also released into the environment through tire wear. Vetiver (Chrysopogon zizanioides) is a C4 grass widely used to extract essential oils from its dense root system, which are commercially used in perfumes and cosmetics. Vetiver biomass after oil extraction is treated as waste and is disposed of in landfills. Biochar is a rich organic carbon source and can be a promising adsorbent for metal and organic contaminants. This study investigates the adsorption potential of zinc onto biochar generated from spent vetiver biomass used for oil extraction. Shoots and roots of spent vetiver were pyrolyzed at 300, 500, and 700oC for 30, 60, and 120 minutes. Biochar yield from shoots was significantly lower (12–23%) than roots (32–56%). The BET surface area was 1–6 m2/gm for the shoots and 24–308 m2/gm for the roots. Adsorption isotherm studies were conducted using zinc nitrate as the source of zinc, for a range of concentrations from 0–100 mg/L onto biochar generated from vetiver roots. After 24 hours of equilibration, supernatant samples were filtered through a 0.45-µm syringe filter and analyzed for Zn using ICP-OES. Better fit was obtained using the Langmuir isotherm model (R2=0.98) compared to the Freundlich isotherm (R2=0.93). The Zn adsorption capacity of biochar increased with increasing pyrolysis temperature.

Sustainable reuse of spent biomass for environmental remediation: Vetiver root biochar adsorbs Zinc

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.