What is NOx titration?

What is NOx titration?

NOx titration: Elevated ozone in polluted regions is usually due to the ozone production sequence shown above. However, at nighttime and in the immediate vicinity of very large emissions of NO (e.g. power plants), ozone concentrations are depressed through the process of NOx titration.

What is photolysis of ozone?

Ozone photolysis is the source of the O(1D) atoms in the lower atmosphere. Here, we call the probability of the formation of an O(1D) atom in the photolysis of a single ozone molecule at a given photolysis wavelength the “O(1D) quantum yield”.

Is NOx a VOC?

Ozone is not emitted directly into the air, but is created when its two primary components, volatile organic compounds (VOC) and oxides of nitrogen (NOx), combine in the presence of sunlight. VOC and NOx are often referred to as ozone precursors, which are, for the most part, emitted directly into the atmosphere.

Does photolysis produce ozone?

An example of an endothermic reaction is the photolysis of oxygen molecules to form ozone, since this reaction requires the energy of UV photons. The reactions of O3+O to form the two oxygen molecules is exothermic since it gives off energy.

Why does ozone increase when NOx decreases?

However, substantial increases in non-peak O3 concentrations were associated with NOx decreases, which were driven by two mechanisms. First, decreasing NOx reduces the amount of O3 quenched through NOx titration, leading to an apparent increase in O3 concentrations, especially during the night and wintertime.

Does lowering the NOx concentration lower the production of ozone explain?

The only important tropospheric source of ozone is the photolysis of NO2 (Reactions 6.1 and 6.2), so that decreasing the available NOx leads directly to a decrease in ozone.

What is photolysis in atmosphere?

Photolysis in the atmosphere Photolysis occurs in the atmosphere as part of a series of reactions by which primary pollutants such as hydrocarbons and nitrogen oxides react to form secondary pollutants such as peroxyacyl nitrates. See Photochemical smog.

What do you understand by photolysis?

photolysis, chemical process by which molecules are broken down into smaller units through the absorption of light.

How does ozone form from NOx?

In the earth’s lower atmosphere, ground-level ozone is considered “bad.” “VOC + NOx + Heat + Sunlight = Ozone. Motor vehicle exhaust and industrial emissions, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC, that help to form ozone.

What is photolysis frequency?

The photolysis frequencies are calculated by the following formula: j=λ2∫λ1F(λ)σ(λ,T)φ(λ,T)dλ. F(λ) is the actinic flux dependent on wavelength.

How do I lower my NOx emissions?

The best way to minimize NOx formation is to reduce flame temperature, reduce excess oxygen, and/or to burn low nitrogen-containing fuels.

Where does photolysis occur?

chloroplasts
Photolysis of water occurs in the thylakoids of cyanobacteria and the chloroplasts of green algae and plants.

How does photolysis happen?

Photolysis (also called photodissociation and photodecomposition) is a chemical reaction in which an inorganic chemical (or an organic chemical) is broken down by photons and is the interaction of one or more photons with one target molecule.

Where does photolysis take place?

chloroplast
This part of photosynthesis occurs in the granum of a chloroplast where light is absorbed by chlorophyll; a type of photosynthetic pigment that converts the light to chemical energy. This reacts with water (H2O) and splits the oxygen and hydrogen molecules apart.

Who discovered photolysis?

The technique, which was developed by the English chemists R.G.W. Norrish and George Porter in 1949, consists of subjecting a gas or liquid to an intense burst of light lasting a few microseconds or milliseconds, followed by a second, ordinarily less intense flash.