plants which are able to extract metals from soil
chosen
TODO salix
TODO vetiver
TODO sorghum
new
chicory
yarrow
parsley
process of extraction is called phytomining
| plant | metal | soil conditions |
|---|---|---|
| alyssum | nickel | ultramafic, serpentine-rich |
| thlaspi | zinc, cadmium, lead, nickel | contaminated or naturally rich |
| brassica juncea | cadmium, chromium, nickel, zinc | contaminated or naturally rich |
| salix | copper, zinc, cadmium, nickel | contaminated or mining sites |
| berkheya coddii | nickel | ultramafic soils |
| hypericum perforatum | nickel, cadmium | contaminated or naturally rich |
| populus | zinc, cadmium | contaminated or naturally rich |
| chrysopogon zizanioides | zinc, cadmium, lead, copper | contaminated or mining sites |
| coriandrum sativum | lead | contaminated soils |
| phytolacca americana | lead | contaminated or mining sites |
| fern | arsenic | contaminated soils |
| sorghum | aluminum | acidic soils, aluminum-rich |
| melastoma malabathricum | aluminum | acidic soils, aluminum-rich |
| amaranthus | copper, arsenic | contaminated or mining sites |
| helianthus annuus | uranium, cesium, strontium | specific areas or contamination |
| bacopa monnieri | chromium | contaminated or naturally rich |
| sesbania drummondii | lead | contaminated or mining sites |
| phragmites australis | zinc, cadmium, lead | contaminated or naturally rich |
| debregeasia longifolia | cadmium, lead, zinc |
To determine the concentration of heavy metals remaining in essential oils after CO2 extraction and in the ash after incineration of phytomining material, we need to consider several factors. Let's break down the processes and the potential outcomes.
CO2 Extraction of Essential Oils
Process Overview
CO2 Extraction: This method involves using supercritical CO2 to extract essential oils from plant material. The process is selective for organic compounds (essential oils), while heavy metals are typically not soluble in supercritical CO2.
Natural Evaporation: Post-extraction, any remaining solvent (CO2) naturally evaporates, leaving behind the essential oils.
Expected Heavy Metal Concentration in Essential Oils
Minimal Presence: Since heavy metals are not soluble in supercritical CO2, the essential oils obtained through this method should have minimal to negligible amounts of heavy metals.
Residual Contamination: Any trace amounts of heavy metals would likely come from contamination during processing or from tiny particulate matter that may co-extract with the oils, but this is usually minimal.
Incineration of Brown Material
Process Overview
Incineration: This involves burning the plant material at high temperatures, reducing it to ash. Incineration is an effective way to concentrate the heavy metals present in the biomass.
Temperature Control: High temperatures (above 500°C) help ensure that most organic matter is combusted, leaving behind inorganic residues, including heavy metals.
Expected Heavy Metal Concentration in Ash
Concentration in Ash: The heavy metals present in the plant material will be concentrated in the ash. The concentration will depend on the initial amount of biomass and the efficiency of the incineration process.
Ash Content: Typically, ash represents a small fraction (about 1-5%) of the original biomass weight. Therefore, heavy metals will be concentrated in this small amount of ash.
Calculation Example
Assumptions
Initial Biomass: 100 kg of plant material
Heavy Metal Content in Biomass: Assume an average concentration of 100 mg/kg (0.01%) of heavy metals in the biomass
Ash Yield: 2% of the original biomass weight
Calculations
-
Total Heavy Metals in Biomass: [ 100 , \text{kg} \times 0.01% = 10 , \text{g of heavy metals} ]
-
Ash Produced: [ 100 , \text{kg} \times 2% = 2 , \text{kg of ash} ]
-
Heavy Metal Concentration in Ash: [ \frac{10 , \text{g}}{2 , \text{kg}} = 5 , \text{g/kg} = 5000 , \text{mg/kg} ]
Summary
CO2 Extraction: The essential oils extracted from the green plant material should contain minimal heavy metals, likely at trace levels that could be considered negligible, assuming good extraction practices and equipment cleanliness.
Incineration: The brown material, when incinerated, will result in ash with a highly concentrated amount of heavy metals. In this example, the concentration could be around 5000 mg/kg, depending on the initial concentration in the biomass and the efficiency of the incineration process.
Practical Considerations
Testing: It's essential to test both the extracted oils and the ash to confirm the actual concentrations of heavy metals.
Regulations: Ensure compliance with local regulations regarding the disposal of ash and the use of essential oils, especially if they are to be used for purposes where heavy metal content is a concern.
Safety Measures: Proper handling and disposal of the ash are crucial to prevent environmental contamination.
By following these guidelines, you can effectively manage the phytomining process and ensure the safe use and disposal of materials containing heavy metals.