C
C
Cancer-producing substances
See: Carcinogens.
Carbon
C: non-metallic chemical element. Carbon and its compounds are very common (human bodies 18%); the organic carbon compounds play a central role in all life processes as multifaceted and metabolically active primary components of natural substances.
Carbon dioxide
Inexact: carbonic acid. CO2; colorless, incombustible, slightly acidic smelling and tasting gas. In free state, component of air (0.03%) and in mineral springs (carbon dioxide mineral springs, sparkling water). Heavier than air when bound in the form of carbonates (primarily calcium and magnesium carbonate). Found commercially in liquid form in steel containers (carbonic acid) or solid (dry ice or crushed dry ice). Carbon dioxide is non-poisonous in itself; up to 2.5% in the air is harmless; 4 to 5% has a numbing effect; from 8% upward it is deadly (suffocation). Carbon dioxide is essential to most life forms. The circulation of carbon dioxide in the biosphere is one of the most important processes of nature; it is vulnerable to human interferences, e.g. excessive burning of fossil fuels, which can destabilize the CO2 balance.
Carbon monoxide
Carbon monoxide, CO: gas which is colorless and odorless, not extremely combustible, but inflammable and poisonous even in extremely diluted form (a continual concentration of 0.05% vol. in the air has a fatal impact!). It is lighter than air and is formed by burning carbon or carbon-containing fuels with little oxygen and in the exhausts produced by internal combustion engines. In the blast furnace process, carbon dioxide reduces the oxide to metal. The toxicity of carbon monoxide is primarily due to its strong binding to hemoglobin, which is responsible for oxygen transport. Carbon monoxide poisoning starts with headaches, dizziness, feeling of sickness, nausea, followed by a dazed feeling, unconsciousness and death.
Carcinogenic substances
Also: cancer-producing substances, See: Carcinogens.
Carcinogens
Carcinogenic substances that can produce malignant tumours (cancer) in humans and animals. Carcinogens include naturally occurring substances such as asbestos, aflatoxins in moldy food, methylcholanthrenes as well as components of decomposition products such as benzpyrene in cigarette smoke and coal tar, nitrosamines or synthetic substances such as benzidine, 2-naphthylamine, vinyl chloride and zinc chromate. Classification of a substance as a carcinogen is based either on previous experience with humans or the results of careful animal experiments. The list of the work substances classified as carcinogenic in Germany is included in Appendix II No. 1 of the Working materials ordinance.
Catalysis
Acceleration of a chemical reaction by reducing activation energy using Catalysts. Catalysis changes the reaction speed but not the reaction equilibrium. Types of catalysis:
- Homogenous catalysis: the catalyst has the same physical state as the reacting substances.
- Heterogeneous catalysis: the catalyst is usually solid and the reaction partners are liquid or gaseous.
Many natural processes consist of catalysis in which enzymes are the catalysts (biocatalysts). Catalytic processes play an important role in large technology endeavors.
Catalysts
Substances that have an impact on material conversion without themselves being changed (See: Catalysis). The effect of catalysts can be increased by activators and decreased by catalyst poisons. Catalysts are not only used for many chemical synthesis processes. They are also used to clean car exhaust and industrial emissions. Catalytic converters for car exhaust, which were introduced into mass production in the USA in 1975, consist of precious metals on monolithic catalyst substrates or bulk substrates. They remove nitrogen oxides, hydrocarbons and carbon monoxide from the exhaust (three-way catalytic converters). Catalytic converters are used to purify industrial emissions by reducing the poisonous or odorous organic components from exhaust produced by offset printers, fish meal factories, etc. New DeNOx catalytic converters are used to denitrify power plant exhaust fumes.
Causation
Legally, the connection between doing or refraining from doing and the achieved success; it plays a central role in the discussion surrounding environmental protection in the form of the Polluter pays principle.
Cell
The smallest independent functional and organizational unit capable of reproduction that has all of the characteristics of life. It includes many highly organised structures that are constantly maintained via expenditure of energy. Therefore a cell is constantly exchanging energy and substances with its environment. It can react to changes due to stimulus reactions and it can reproduce. All living organisms are made up of cells and usually go through a singlecell stage at least once in the generation process. Most ball or honey-comb shaped cells are generally microscopic. The average diameter is approximately 0.1 to 0.01 millimeters but nerve cells can reach sizes of over 1 meter and laticifers can be up to several meters long.
Cetane number
Also: cetane rating. Indicates the ignition quality of diesel fuel. It is determined by comparing the ignition quality of the fuel with that of a mixture of methylnaphthalene and cetane.
CHC
See: Chlorinated hydrocarbons.
ChemG
See: Chemicals Act.
Chemical waste water treatment
Treatment of waste water, e.g. with precipitants (See: Precipitation procedure), such as aluminum, iron or calcium salts, which in waste water form hydroxide flocs or poorly soluble compounds. Dissolved or finely dispersed waste water constituents are thereby converted into a separable form and can then be extracted from the water by means of sedimentation, flotation or filtration. This method removes a lot of substances (e.g. phosphates, heavy metals, non-degradable or sparingly degradable organic substances) which cannot be separated entirely or adequately by conventional treatment methods (mechanical and biological purification). Because biologically degradable compounds are also removed by precipitation, this method now enjoys special status in Sweden, Switzerland and partly in Germany, where it is used to relieve overloaded sewage treatment facilities. Another method of chemical waste water treatment is Oxidation of water impurities by hydrogen peroxide.
Chemicals Act
ChemG (full name: "Law on Protection against Hazardous Substances") is of fundamental importance for the chemical industry. It requires that all new substances be tested for toxicological and ecotoxicological properties (See: Toxicology) in accordance with a defined staged plan and also that they be registered before being marketed. Essentially, this law is based on EC Directives, which must also be implemented similarly in the other member states. The ChemG also forms the basis for the Hazardous substance regulations and the Prohibition of Chemicals Ordinance.
Chlorinated hydrocarbons
Abbreviation: CHC. Chlorine-containing organic compounds, which also contain agents from pesticides and plant protection agents and from numerous technical solvents from other areas.
Chromates
Salts of chromic acid HCrO4 are derived from chromium trioxide CrO3. Were used as corrosion preventives (pigments). Zinc chromate, calcium chromate, chromium (III) chromate are classified as carcinogenic substances.
Cleaning agent
Preparations made of tensides, softening agents, solvents, etc. for household purposes (kitchen, bath, kitchenware), industrial cleaning purposes (car, engine) and cleaning in the food industry (e.g. drink bottles). Used in the paints industry to clean surfaces before painting or for cleaning stubborn stains from painted surfaces (paint cleaner).
Cleaning stages
Mechanical, biological, chemical and physio-chemical cleansing of Waste water.
Climate
The average condition of meteorological phenomena determined by climate factors and climate elements, cosmic influences and their interrelations over a longer period of time as opposed to weather. Regional allocation of climate types produces various different climate zones, which themselves can be subdivided into climate provinces. Depending on the size of the observed area, distinction is made between:
- Macro climate: the actual climate used to determine the climate zones
- Micro climate: the climate of the smallest spaces, determined by the layer of air closest to the earth
Climate changes
Climate changes taking place in geological periods of time. These can be limited to certain regions (e.g. as a result of changed distribution of land and water) or global (e.g. resulting from cosmic influences). Whether CO2 emissions and accumulation in the upper atmosphere and emissions of dust affect the global incoming and outgoing radiation ratio, thereby leading to climate changes, is disputed.
Closed Substance Cycle & Waste Management Act
This act, which was ratified on October 7, 1996, replaces the Waste Management Act of 1986. The body of rules underlying the Closed Substance Cycle & Waste Management Act consists of seven decrees and one guideline.
- Decree pertaining to introduction of the European Waste Catalog (EWC)
- Decree pertaining to specification of waste that requires special monitoring.
- Decree pertaining to specification of recycling waste that requires monitoring
- Decree pertaining to provision of proof
- Decree pertaining to transportation authorization
- Decree pertaining to waste management concepts and waste balance sheets
- Decree pertaining to specialized disposal companies
- Guideline pertaining to the activity and recognition of disposal associations
Coagulation
Discharge of the electrical potential of colloids by the addition of oppositely charged particles.
Cohesion
The coherence of a single type of molecules caused by cohesive forces (electrical exchange forces of the electrons); especially strong in solids and liquids. Can be derived from the gas law in the case of real gases.
Colloid
Combustion gases
The exhaust gases resulting from burning fuels in industrial and household ovens or in internal combustion engines.
Contamination
Pollution caused by transportation of chemical, microbial or radioactive substances. See: Decontamination.
Corrosion
Surface destruction (rusting, etc.) due to effect of aerosols or water forming local elements (chemical and electrochemical reactions). Corrosion resistance is the degree to which a substance can withstand corrosion. The main method of protecting against corrosion consists of applying coatings or protective layers to the objects to be protected. Cathodic corrosion protection is gaining importance (cathodic protection). The corrosion caused upon storing heating oil in steel tanks represents a special case because the sulfur in the heating oil is converted to sulfuric acid, which causes the corrosion.
Crude oil
Petroleum or mineral oil. A naturally occurring mixture of various hydrocarbons (alkanes, alkenes, naphthenes and aromatic compounds), practically insoluble in water. There is no universally accepted theory concerning the formation of crude oil. It is still unclear as to whether crude oil is formed organically or inorganically and whether it formed in primeval times or more recently. Geophysical methods (geophysics of oil) are used in the search and exploration of possible crude oil reserves: these methods can be gravimetric, magnetometric or seismological. Oil drilling is not only performed on land, but increasingly on offshore drilling platforms, jack-up rigs and drill barges in shallow continental shelf areas.