Harmful gases examples

A chemical reactivity hazard, as the term is used in this publication, is a situation with the potential for an uncontrolled chemical reaction that can result directly or indirectly in serious harm to people, property or the environment. The uncontrolled chemical reaction might be accompanied by a temperature increase, pressure increase, gas evolution or other form of energy release. It need not be explosive to result in serious harm. For example, gases evolved from a chemical reaction can be flammable, toxic, corrosive, hot, or can pressurize an enclosure to the point of rupture. 

Liquid Dispersion Spray columns are used with slurries or when the reaction product is a solid. The absorption of SO9 by a hme slurry is an example. In the treatment of phosphate rock with sulfuric acid, offgases contain HF and SiF4. In a spray column with water, solid particles of fluorosilic acid are formed but do not harm the spray operation. The coefficient /cl in spray columns is about the same as in packed columns, but the spray interfacial area is much lower. Considerable backmixing of the gas also takes place, which helps to make the spray volumetri-caUy inefficient. Deentrainment at the outlet usually is needed. 

The selectivity of the catalyst is of major importance in the case of chlorinated VOCs the oxidation products should not contain even more harmful compounds than the parent-molecule, for example, formation of dioxins should be avoided. In addition, the minimization of CI2 and maximization of HCl in a product gas should be achieved [61]. These are just a few examples of why researchers are continuing the search for VOC oxidation catalysts as well as new reactor concepts. The new possibilities include, for example, utilization of nanosized gold catalysts in the oxidation of sulfur-containing VOCs and microwave-assisted processes where combination of adsorption and oxidation is used in low-concentration VOC oxidation [62, 63]. 

Chemicals, unfortunately, don t sort themselves out into neat groups that behave the same way in the human body. Just because one chemical has much the same structure as another, it doesn t necessarily behave the same way as the other. What we want to know is which ones are toxic, that is, capable of causing bodily harm and how much harm they can cause. Unfortunately, we can t always do that just by looking at the chemical structure. Carbon monoxide, for example, which is a chemical combination of the soot called carbon and the gas called oxygen, is a poisonous gas which, when inhaled into the body, limits the amount of life-giving oxygen that can be... 

Is obtaining or harnessing the fuel harmful to the environment For example, oil wells and strip coal mines destroy habitat. Natural gas pipelines, shown in Figure 5.20, are visually unappealing. They also split up habitat, which harms the ecosystem. 

Fuel processing is defined in this Handbook as the conversion of a commercially available gas, liquid, or solid fuel (raw fuel) to a fuel gas reformate suitable for the fuel cell anode reaction. Fuel processing encompasses the cleaning and removal of harmful species in the raw fuel, the conversion of the raw fuel to the fuel gas reformate, and downstream processing to alter the fuel gas reformate according to specific fuel cell requirements. Examples of these processes are ... 

Sny material in the atmosphere that is harmful to health is defined as an air pollutant. One major source of air pollutants is volcanoes. The largest volcanic blast of the 20th century, for example, was the 1991 eruption of Mount Pinatubo in the Philippines, which released 20 million tons of the noxious gas sulfur dioxide, S02. As Figure 17.7 shows, this sulfur dioxide managed to travel all the way to India in only 4 days. 

The problem is exacerbated in large and crowded communities. For example, there are well over 50 hospital incinerators in New York City. Most local hospital incinerators are not equipped with acid-gas scrubbers, which convert harmful airborne substances into harmless calcium salts. Nor are most incinerators equipped with electrostatic precipitators to capture particles that have adsorbed toxic flue gases. 

Catalytic converter A device for converting dangerous exhaust gases from cars into less harmful emissions. For example, carbon monoxide gas is converted to carbon dioxide gas. 

In recent years, many of the technologically outdated methods of 40 CFR Part 136 have been upgraded to incorporate the latest advances in instrumental analysis. For example, capillary chromatographic columns with superior compound resolution replaced obsolete packed columns in gas chromatography (GC) and GC/MS analytical methods Freon 113, a chlorofluorocarbon harmful to the environment, was phased out as the extraction solvent in oil and grease analysis and replaced with hexane in Method 1664 (EPA, 1999b). 

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