Part 3 Flashcards
What are fuel additives used for?
Additives can be used to reduce the total mass of particulate matter, and reducing CO, NOx and SOx emissions.
What are Cerium oxide NPs used for?
Added to fuel to improve performance by:
- soot burn within the combustion cycle
- Oxidising carbon deposit build up within the engine, improving performance and better fuel economy.
What is the transformation of Cerium during combustion?
Undergoes transformation from CeO2 (+4) to Ce2O3 (+3) SEE NOTES.
Why do combustion chamber deposits lower efficiency?
Regular atomisation produces large drops of fuel which promotes Incomplete combustion, increasing harmful emissions and promotes buildup of combustion chamber deposits. Deposits act as thermal insulators, raising combustion temperatures and increasing NOx emissions.
What effect does F2-21 additive have on fuel combustion?
F2-21 creates millions of tiny nano-clusters in the fuel. These nano-clusters explode just before and during combustion, increasing turbulence and generating smaller fuel droplets. Smaller fuel droplets vaporize completely, leaving no unburned fuel residue. This results in more complete combustion, which increases power and improves mileage.
What effect do NPs have on combustion chamber deposits?
Exploding NP clusters help break down and disintegrate combustion chamber deposits, as well as prevent future build up.
How can NMs be used for carbon capture?
Use of amines to capture CO2, as these can form stable carbamates and bicarbonates.
How can NMs be used for water purification?
Coating Fe3O4 magnetic NPs with humic acid for high efficient removal of heavy metals in water
What is the mechanism for batch synthesis of NPs?
A rapid increase in the concentration of free monomers in solution. The monomer undergoes burst nucleation which significantly reduces the contraption of free monomers in solution. After this point, almost no nucleation occurs due to the low concentration of monomers after this point. Following nucleation, growth occurs.
How do you synthesise a semiconductor NP?
(1) TOPO is dried and degassed in a reaction vessel by heating, whilst periodically flushing with argon.
(2) Heat is removed first from the reaction vessel. Then a mixture is quickly injected ti the vigorously stirring reaction flask.
(3) the temperature is gradually raised and maintained for a period of time to produce a series of NP sizes.
Give the limitations of batch synthesis of NPs
Batch to batch variation due to temperature gradient, concentration gradient etc, pH, reactant concentrations. Poor reproducibility.
Hard to discern between nucleation and growth stages
Low yield
High cost, bottle neck of batch processing.
Give the advantages of Microfluidic synthesis of NPs
Fast heat transfer due to their large interfacial surface area-to-volume ratio, efficient and homogenous mixing.
Precise control over reaction conditions, including temperature
Production time is independent of the process scale.
Distinct stage of nucleation and growth
Can be used to produce ultra small nanoparticles.
What are the main pathways for NP exposure?
Inhalation
Digestion
Dermal exposure
Why is inhalation of NP a risk to health?
- Ultra-small NPs showed efficient delivery to the alveoli, but generally show low retention in the lungs due to rapid penetration into the bloodstream.
- Larger particles settle in upper airway and removed by e.g. mucus, coughing etc.
- Smaller nanoparticles penetrate deeper into the alveolar region
- NPs less than 100 nm start to behave more like a gas, they begin to diffuse in the body. The have the ability to penetrate the lungs and enter to bloodstream.
What are the effects if NPs enter the blood stream?
It allows them to be engulfed by cells and accumulate in organs like the heart, kidney, liver etc. In addition, some of these materials can also damage DNA and cause cancer.
