Volatile Organic Compounds VOC

VOC s are emitted from chemical processes either controlled or uncontrolled. Control techniques are provided in the following sections. Emission can also result from the incomplete combination of organic constituents and conversion of certain constituents present in the raw material, auxiliary fuel, and/or combustion air. 

Inorganic pollutants, such as HCL, HF, NO, SO, are also formed as a result of incomplete combustion. Inorganics include  

Particulates emissions are strongly influenced by the chemical composition of the raw material and the auxiliary fuel, type of combustion process, the operating parameters, and the air pollution control system. Most of the pollutants of concern, other than VOC and inorganics, are collected as particulates. 

A volatile compound is a material that at ambient temperatures or under the influence of heat is capable of being vapourised or becoming a gas, i.e., solvents involved in paints. Some materials indoors may continue to generate VOC over many years (ageing), the concentration of which varies with time, variation in temperature, airflow and volume of the house. Possible sources of VOC indoors are outlined in Section 12.1.2.2. 

2 Some Toxic Chemicals that Can be Found Indoors 

As an exception, radon is added to the list because of its importance, however, it is still not well known yet. Although radon is not directly related to construction materials, it exists in houses and it can be eliminated by certain construction techniques. 

Benzene Mainly causes dizziness, headache, vomiting, drowsiness and 

Chronic exposure if in contact with the eyes neuritis, atrophy, visual impairment, oedema and cataracts, it can cause depression, bone marrow depression, leukemogen headaches, anorexia, nervousness, weariness, anaemia, pallor, reduced clotting, marrow damage and finally leukemia. Deliberate inhalation of benzene vapours (glue sniffing) can kill directly. 

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The removal of volatile organic compounds (VOC) from air is most often accompHshed by TSA. Air streams needing treatment can be found in most chemical and manufacturing plants, especially those using solvents. At concentrations from 500 to 15,000 ppm, recovery of the VOC from steam used to regenerate activated carbon adsorbent thermally is economically justified. Concentrations above 15,000 ppm ate typically in the explosive range and... 

Nltropropane. As much as 9100 t of 2-nitropropane once were consumed for use in coatings annually. Concern about toxicity and a general movement to low volatile organic compound (VOC) coatings have resulted in almost the complete disappearance of this use for 2-nitropropane. However, derivatives such as 2-meth5l-2-nitro-l-propanol (used in tire cord adhesive) and 2-amino-2-methyl-l-propanol (a pigment dispersant and buffer), have served as an outlet for 2-nitropropane production. 

Growing concerns over solvent costs and atmospheric poUution from solvent-home coatings necessitate low volatile organic compounds (VOC)... 

For aqueous inks, the resins are water- or alkali-soluble or dispersible and the solvent is mosdy water containing sufficient alcohol (as much as 25%) to help solubilize the resin. To keep the alkah-soluble resin in solution, pH must be maintained at the correct level. Advances include the development of uv inks. These are high viscosity inks that require no drying but are photocurable by uv radiation. In these formulations, the solvent is replaced by monomers and photoinitiators that can be cross-linked by exposure to uv radiation. The advantage of this system is the complete elimination of volatile organic compounds (VOC) as components of the system and better halftone print quaUty. Aqueous and uv inks are becoming more popular as environmental pressure to reduce VOC increases. 

In 1990, a test using scrap tires (2x2 in. I DE) to generate steam for electricity was conducted at the Elexsys plant. The I DE replaced 20% of the plant s coal. Results showed that IDE is an environmentally sound fuel. Particulate emissions were reduced by the lower ash content of IDE, volatile organic compounds (VOC) were reduced because of more efficient burning of I DE compared to coal, and carbon dioxide emissions were reduced because I DE contains half the fixed carbon found in coal. Nitrogen oxide, chlorine emissions, and metals were also reduced, and ferrous metals and dioxins were nondetectable (7). 

Some of the methods used for deterrnination of organic pollutants in the environment foUow (118). The most notable are polyaromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). 

The copolymers are insoluble in water unless they are neutralized to some extent with base. They are soluble, however, in various ratios of alcohol and water, suggesting appHcations where deUvery from hydroalcohoHc solutions (149) but subsequent insolubiUty in water is desired, such as in low volatile organic compound (VOC) hair-fixative formulations or tablet coatings. Unneutralized, their Ts are higher than expected, indicating interchain hydrogen bonding (150). 

In 1966, the Los Angeles Air Pollution Control Board designated trichloroethylene as a photochemically reactive solvent that decomposes in the lower atmosphere, contributing to air pollution. In 1970 all states were requited to submit pollution control plans to EPA to meet national air quaUty standards. These plans, known as State Implementation Plans (SIPS), controlled trichloroethylene as a volatile organic compound (VOC). They were designed to have each state achieve the National Ambient Air QuaUty Standard (NAAQS) for ozone. The regulations were estabUshed to control the emission of precursors for ozone, of which trichloroethylene is one. 

Supercritical Atomization. Atomization can be obtained by mixing a supercritical fluid (SCF) with the material to be atomized. This process reduces volatile organic compound (VOC) emissions as the SCF acts as a solvent and replaces some of the hydrocarbon solvents in the material (see... 

Method 25 applies to the measurement of volatile organic compounds (VOC) as nonmethane organics (TGNMO), reported as carbon. Organic particulate matter will interfere with the analysis, and, therefore, in some cases, an in-stack particulate filter will be required. The method requires an emission sample to be withdrawn at a con-... 

Provide annual estimates of all point and fugitive emission sources (tons per year) of hazardous substances, volatile organic compounds (VOCs), heavy metals and fossil fuel products (for example, NOx and SOx) that are released to the environment. 

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