Chemical agents dispersal

The physical transport of oil droplets into the water column, called dispersion, is often a result of water surface turbulence but may also result from the application of chemical agents (dispersants). These droplets may remain in the water column or coalesce with other droplets and gain enough buoyancy to resurface. Dispersed oil tends to biodegrade and dissolve more rapidly than floating slicks because of high surface area relative to volume. Most of this process occurs from about half an hour to half a day after the spill. 

Toxicity follows exposure to chemical agents dispersed as solids, liquids, aerosols, or vapor (Table 23.1). CW agents have characteristics that make them uniquely suited to warfare. In addition to their extreme toxicity, their chemical structures are simple, and the manufacturing processes for most are relatively uncomplicated and inexpensive. Cyanide and phosgene are manufactured in large quantities for use in industry and are shipped in bulk by truck or train. 

Non-persistant - Non-persistent chemical agents disperse rapidly after release and present an immediate, short duration hazard. 

Styrene—maleic anhydride copolymer [9011-13-6] engineering thermoplastics, paper treatment chemicals, floor poHshes, emulsifiers, protective coUoids, antisoil agents, dispersants... 

Vapor pressure Volatility 11,100 mmHg at 20°C. This high vapor pressure means that SA is difficult to liquefy and to store. 30,900,000 mg-min/m3 at 20°C. This by far the highest volatility found among the compounds considered for tactical use as chemical agents. This fact, coupled with a relatively low latent heat of vaporization, qualifies SA as the most rapidly dispersing chemical agent. 

Containment structures for chemical munitions should be designed to contain both the forces of explosion and the agent dispersed by the explosion. 

APEOs are used in domestic and industrial applications. They are applied as detergents, emulsifiers, wetting agents, dispersants or solubilisers. APEO derived from nonylphenol (NP), i.e. nonylphenol ethoxylates (NPEOs) comprises about 80% of the total market volume, while octylphenol-derived surfactants (OPEOs) account for 15-20%. Because of the persistence and toxicity of some degradation intermediates, their use has been reduced in several countries either through voluntary bans by the chemical industry or by legal regulations. However, excellent properties in combination with comparably low production costs hampers their complete replacement with other more environmentally acceptable alternatives. 

Salvin, V. S., and R. A. Walker. Service fading of disperse dyestuffii by chemical agents other than the oxides of nitrogen. Textile Res. J. 25 571-584, 1955. 

The time-resolved studies of the cluster formation achieved by pulse radiolysis techniques allow one to better understand the main kinetic factors which affect the final cluster size found, not only in the radiolytic method but also in other reduction (chemical or photochemical) techniques. Generally, reducing chemical agents are thermodynamically unable to reduce directly metal ions into atoms (Section 20.4) unless they are complexed or adsorbed on walls or dust particles. Therefore, we explain the higher sizes and the broad dispersity obtained in this case by in situ reduction on fewer sites. A classic... 

Therefore, atomization of liquids and control of droplet formation by means of ultrasonics has potentially important applications for propulsion systems and the dispersal of chemical agents, as well as for the creation of mists and fogs... 

Riot Control, Chemical Agents for. Irritants, which affect the mucous membranes of the eyes and the respiratory system, are used in riot control to disperse crowds. Chloroaoetophenone... 

Once chemical agents are fully dispersed, they do not tend to persist in the environment because of their high chemical reactivity, particularly with water (hydrolysis). However, in extremely dry desert climates, they can persist for considerable periods of time (U.S. Army, 1988). The major environmental degradation products of nerve and mustard agents have recently been assessed and their persistence and toxicity evaluated. A potential hydrolysis product of VX (S-(2-diisopropylaminoethyl) methylphosphonothioic acid [EA-2192]) is a degradation product expected to display a high level of mammalian toxicity. Some mustard partial hydrolysis products are also toxic (Munro et al., 1999). 

The job of a chemical munition is to create a toxic environment over as much of the target as is compatible with the toxicity of its charge. It must convert its bulk load either into an even distribution of liquid or solid particles, or into a cloud of vapour, or into both. It must, additionally, do this in a certain time. These are strict demands, and they are made more severe by the diversity of chemical agents now in stockpiles. Each agent has a combination of physical characteristics and toxic behaviour that is unique but, nevertheless, all munitions work on the same basic principle they cause the transfer of energy from a store, generally an explosive, to the chemical load. The simplest chemicals to disperse are the volatile, non-persistent ones such as phosgene the hardest ones... 

---