Plants Produce Oxygen

Green plants produce oxygen by the reaction below. If a rosebush produces 50.5 L of oxygen at 27.0°C and 101.3 kPa, how many grams of glucose, CgHj Og, did the plant also produce ... 

This conversion process, photosynthesis, was observed by Priestley in 1772. He observed that when a plant and an animal were kept together in an airtight jar, both lived but when kept separately, both died. Later, investigators realized that the plants produce oxygen, while the animal exhales carbon dioxide and water vapor. To be complete, this miniecosystem requires complimentary processes. 

Reactions involved in photosynthesis are very complicated, and of multiple steps, but oxygen comes from the decomposition of water. So plants produce oxygen, which animals consume, and a steady state has been established. And so, the current 21% figure (oxygen in the air) seems to be more or less constant (see also Chap. 3). 

A whole bunch of bewigged European scientists solved the puzzle piece by piece over a period of about 100 years. In 1780, the English chemist Joseph Priestley found that plants could restore air which has been injured by the burning of candles . He used a mint plant, and placed it into an upturned glass jar in a vessel of water for several days. He then found that the air would neither extinguish a candle, nor was it all inconvenient to a mouse which I put into if. In other words, he discovered that plants produce oxygen (luckily for the mouse ). 

Fourthly living things do not just respond to the climate—they affect it as well. Plants consume carbon dioxide and produce oxygen through photosynthesis. Earthbound plants take carbon dioxide directly from the air drifting photosynthetic micro-organisms called phytoplankton use carbon dioxide dissolved in water. 

The reactor conversion is 20% and selectivity 80%. Find the heat removal rate from a plant producing 100 tons per day of ethylene oxide (see Table 6.16). Excess oxygen of 10%... 

Botrytis cinerea is responsible for gray mold disease in more than 200 host plants. This necrotrophic fungus displays the capacity to kill host cells through the production of toxins and reactive oxygen species and the induction of a plant-produced oxidative burst. Thanks to an arsenal of degrading enzymes, B. cinerea is then able to feed on various plant tissues (Choquer and others 2007). 

Primary organics are emitted to the atmosphere by industrial sources (oil refineries, chemical plants, producers and users of solvents and plasticizers), vehicles (as a result of incomplete fuel combustion, oxygenated degradation products of lubricating oil, polymers from tires), and agricultural activities (use of pesticides). An exhaustive literature survey is beyond the scope of this section, but can be found in Air Quaiity Criteria for Particulate Matter many useful references are also available. 

Two bioassays are employed to evaluate the effect of samples on terrestrial life forms. For gas samples, the plant stress ethylene test is presently recommended. This test is based on the well-known plant response to environmental stress release of elevated levels of ethylene (under normal conditions plants produce low levels of ethylene). The test is designed to expose plants to various levels of gaseous effluents under controlled conditions. The ethylene released during a set time period is then measured by gas chromatography to determine toxicity of the effluent. For liquid and solid samples, a soil microcosm test is employed. The sample is introduced on the surface of a 5 cm diameter by 5 cm deep plug of soil obtained from a representative ecosystem. Evolution of carbon dioxide, transport of calcium, and dissolved oxygen content of the leachate are the primary quantifying parameters. 

Photosynthesis and respiration help to maintain the concentrations of oxygen and carbon dioxide in the atmosphere. Respiration is the process by which carbohydrates (most commonly glucose) are broken down for the release of energy needed for life processes. Photosynthesis uses carbon dioxide and produces oxygen. Respiration does the opposite—it uses oxygen and produces carbon dioxide. Plants and algae carry on photosynthesis, while animals carry... 

Designers also face the choice of capacity of an oxygen plant. Costs per unit weight of oxygen made are lowered as the capacity of the plant goes up. For example, a plant with a capacity of 2000 tons (1800 metric tons) per day will produce oxygen at approximately 50% of the cost per nnit weight as a plant with a 200-ton (180-metric ton) capacity per day. 

Priestley also researched relationships among plants, air, and animals. He observed the respiration of plants, by which they take in carbon dioxide and produce oxygen. His observation helped others understand the process. He observed green matter , which now we know as photosynthesis. 

Five major U.S. chemical firms are now producing oxygenation systems for sewage wastewater treatment, in what the industry feels could become oxygen s largest market (Ref. 12). Membrane systems could economically compete with conventional technologies in the smaller plants. 

---