Lecture 4 - impact of nano on environment

Question 1

Settling out of nanomaterials

Answer 1

Particles settle on very long time scale, like Brownian motion, so very random, continuous and depends on size and density

Question 2

Agglomeration

Answer 2

small particles or individual entities come together to form larger clusters or aggregates.

Question 3

Adsorption

Answer 3

surface phenomenon in which molecules or particles from a fluid (gas or liquid) adhere to the surface of a solid or liquid material

Question 4

Solution/dissolution

Answer 4

mixing and dispersal of one substance (the solute) within another substance (the solvent) to create a homogeneous mixture

Question 5

Predicting behaviour of nanomaterials.

Answer 5

Assess:
1. Rate of dispersal/agglomeration in media
2. Rate of interaction with environmental constituents
3. Rate and form that nanomaterial will be presented to environmental receptors

Question 6

Nano Zero valent Iron

Answer 6

Nanosized zero valent iron (nZVI), Fe0
Metallic iron oxidizes to donate electrons to other compounds
Used to treat/convert chlorinated volatile organic compounds (CVOCs) which are known carcinogens

Question 7

How nZVI work

Answer 7

CVOCs in ground water or soil diffuse into emulsion particles
CVOCs dechlorinated to produce non-halogenated hydrocarbons like ethene and ethane
Vegetable oil component promotes biological reductive dechlorination of residual CVOCs

Question 8

Catalytic converters

Answer 8

Use metals to convert harmful emissions into harmless ones.
Problem: heat from the exhaust causes migration and agglomeration of metal to reduce efficiency
Mazda’s new nanocatalytic converter embeds the nanocatalysts reduces the amount of metals used in a converter by 70 to 90%.