Inhibitors chemicals used

The most significant commercial use of o- IDA is in the manufacture of tolytria2oles. Tolytria2oles are used as corrosion inhibitors, chemical intermediates, photographic chemicals, and catalysts (16). Other uses for o- IDA include polyols (13,54) and antioxidants (54). 

Scale Inhibitors. When scaling conditions exist, scale inhibitors can be used to control the scaling tendencies, and keep metal surfaces free of scale deposits. Scale inhibitors are chemicals that interrupt and deform the normal crystalline growth pattern of carbonate scales. The three most commonly used classes of scale-inhibiting chemicals used in drilling fluid are [191,197] ... 

Following a brief discussion of inhibitor classifications and of types of chemicals used as inhibitors, the principles and practice of inhibition are... 

A difficulty arises in describing the precise chemical nature of many inhibitor formulations that are actually used in practice. With the advancing technology of inhibitor applications there are an increasing number of formulations that are marketed under trade names. The compositions of these are, for various reasons, frequently not disclosed. A similar problem arises in describing the composition of many inhibitor formulations used in the former Soviet Union. Here the practice is to use an abbreviated classification system and it is often difficult to trace the actual composition, although in many cases a judicious literature search will provide the required information. 

Inhibitors may be classified according to their solution properties as either oil-soluble inhibitors, water-soluble inhibitors, or dispersible inhibitors. Chemical inhibitors act as film formers to protect the surface of the pipeline. Corrosion inhibitors, used for the protection of oil pipelines, are often complex mixtures. The majority of inhibitors used in oil production systems are nitrogenous and have been classified into the broad groupings given in Table 11-4. Typical corrosion inhibitors are shown in Table 11-5. For details, see also Chapter 6. 

The major objective of this presentation is to illustrate how an environmental risk assessment of a chemical can be made using mathematical models which are available at the present time. CGA-72662, a CIBA-GEIGY insect growth inhibitor, is used as an example to show how a risk assessment can be carried out using the SWRRB runoff model coupled to the EXAMS fate model. 

Corrosion inhibitors are used to reduce the corrosion of surface equipment, surface casing, and the drill string by drilling and well treatment fluids. Many different corrosion inhibitors have been used. These include amine salts such as ammonium sulfite -bisulfite blends, zinc carbonate, zinc chromate, hydrated lime, fatty amine salts of alkylphosphates, cationic polar amines, ethoxylated amines, and tertiary cyclic amines. Commercial products are usually proprietary blends of chemicals. 

Because of the relatively low cost of many of the chemicals used in drilling fluids, development of more cost effective additives is a major challenge. However, improved high temperature polymers, surfactants, and corrosion inhibitors are under development in many laboratories. 

A remaining crucial technological milestone to pass for an implanted device remains the stability of the biocatalytic fuel cell, which should be expressed in months or years rather than days or weeks. Recent reports on the use of BOD biocatalytic electrodes in serum have, for example, highlighted instabilities associated with the presence of 02, urate or metal ions [99, 100], and enzyme deactivation in its oxidized state [101]. Strategies to be considered include the use of new biocatalysts with improved thermal properties, or stability towards interferences and inhibitors, the use of nanostructured electrode surfaces and chemical coupling of films to such surfaces, to improve film stability, and the design of redox mediator libraries tailored towards both mediation and immobilization. 

Uses. In the preparation of azo dyes corrosion inhibitor chemical intermediate... 

Uses. A high-production-volume chemical used in manufacture of epoxy-phenolic resins (protective linings for food and beverage cans) monomer for polycarbonate resins (used in food contact materials such as returnable beverage bottles, infant feeding bottles, plates, and mugs) antioxidant in PVC plastics inhibitor of end polymerization in PVC plastics... 

Various chemicals like demulsifiers, scale inhibitors and corrosion Inhibitors arc used. Points of Injection for these chemicals are shown in tne process flow diagram. 

It should be noted that there is a kinetic isotope effect on the normal reaction (9.11) when the a-deuterated compound is used as the substrate. A similar effect is found when the deuterated suicide inhibitor is used. Thus, both reactions involve a proton transfer in the rate-determining step of the reaction. It has also been shown that a sample of the allenic intermediate that is prepared chemically does in fact irreversibly inhibit the enzyme.18... 

Oxygen, carbon dioxide and various chemicals used to reduce scaling can cause corrosion. Corrosion control is provided largely by the use of inhibitors such as chromates, polyphosphates, silicates and alkalies. 

In order to more properly understand the role and benefits of modern inhibitor chemicals, it is useful to review some examples of the more important types of original chemical inhibitors and treatment programs, especially as many of these are still being used today, albeit in an amended form by the incorporation of phosphonates and polymers, which have enhanced their performance. 

The presence of polyphosphate detergent in the cleaning formulation (some of which will revert to orthophosphate) will, under most circumstances, lead to passivation of the clean metal surfaces. Additionally, as part of the water treatment program start-up procedure, it may prove useful to supplement this initial passivation with 2 to 3x the normal reserve of maintenance inhibitor chemical treatment for a period of 1 to 2 weeks. 

Other approaches attempted to overcome the obstacle of poor GI absorption of macromolecules include the use of enzyme intestinal inhibitors, chemical derivatization, prodrugs,... 

It is also possible to block GA synthesis chemically using inhibitors such as AMO-l6l8 (68), or the quaternary ammonium iodide compound in Figure 11 X 9,70), which block ent-kaurene formation. 

Fire-retardant chemicals used by the commercial wood-treating industry are limited almost exclusively to mono- and diammonium phosphate, ammonium sulfate, borax, boric acid, and zinc chloride (4,8). It is believed that some use is also made of the liquid ammonium polyphosphates (9). Some additives such as sodium dichromate as a corrosion inhibitor are also used. Aqueous fire-retardant treatment solutions are usually formulated from two or more of these chemicals to obtain the desired properties and cost advantages For leach-resistant type treatments, the literature shows that some or all of the following are used urea, melamine, dicyandiamide, phosphoric acid, and formaldehyde (10-12) ... 

Therapeutic Function Enzyme, Wound adhesion inhibitor Chemical Name Enzyme used to prevent wound adhesions Common Name -... 

Y3. Yamamoto, N., Nagasawa, Y., Sawai, M., Sudo, T., andTsubomura, H., Potentiometric investigations of antigen-antibody and enzyme-enzyme inhibitor reactions using chemically modified metal electrodes. J. Immunol. Methods 22, 309-317 (1978). 

The most significant impurities in the feed streams to a typical alkylation unit are ethylene, dlolefins, sulfur compounds and water. Corrosion Inhibitors and other chemicals used in upstream processing can also be present in some cases, and these can have harmful effects. The amount of each iaqiurlty that reaches the alkylation reactor varies considerably from refinery to refinery. If accurately determined and properly accounted for, these impurities can explain an appreciable percentage of the acid make-up reported by various operating units. The impurity data shown in Table I can be used to evaluate the merit of Improved upstream process control and/or more efficient feed pretreatment methods. 

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