Green Criteria for Metals Removal
- Large molar /weight excesses of reagents should be avoided if possible.
- The green hierarchy for metals
- Simple inorganic reagents/extraction solutions
- Organic reagents like amines, sulfides
- Activated carbons
- Organophosphines
- Functionalised scavenger resins/polymers
- Techniques that require large volumes of solvent(s) should be avoided. When choosing solid scavengers, excessive absorption of the product should be avoided if possible.
- For precious metals, the recovery methodology should generate a waste suitable for recycling and recovering the metal.
- Generation of large volumes of liquid waste containing very dilute concentration of precious metals should be avoided.
- Oxidative methods should use low impact oxidants like air, hydrogen peroxide, bleach etc.