Isothiazolone, biocide

Collier, P. J., Ramsey, A J., Austin, P. Sc Gilbert, P. (1991) Uptake and distribution of some isothiazolone biocides in Escherichia coli and Schizosaccharomyces pombe NCYC 1354. Int J Pharm, 66, 201-206 [and preceding two papers]. 

Bronopol Good antibacterial activity Indirect food contact approvals Not a sensitiser Acceptable environmental profile Fast kill rate Excellent in combination with isothiazolone biocides Performance gap against yeast Poor heat and alkali stability Less cost effective than CIT/MIT... 

Formaldehyde Donors Good antibacterial activity Fast kill rate Good heat and alkali stability Cost effective Excellent in combination with isothiazolone biocides Formaldehyde itself is a sensitiser Performance gap against yeasts fungi... 

Williams, Terry M., The Mechanism of Action of Isothiazolone Biocides, paper presented at the 2006 NACE Corrosion Conference, San Diego, California, paper number 06090,2006. 

Williams TM (2006) The mechanism of Action of isothiazolone Biocides, Paper No. 06090, CORROSION 2006, NACE International, USA... 

Jacobson A, Williams TM (2000) The Environmental Fate of Isothiazolone Biocides, Chimica Oggi, Yol. 18, No. 10, pp. 105-108... 

A. B. Downey, G. L. Willingham, and V. S. Frazier. Compositions comprising 4,5-dichloro-2-N-octyl-3-isothiazolone and certain commercial biocides. Patent EP 680695, 1995. 

J. C. Hsu. Synergistic microbicidal combinations containing 3-isothiazolone and commercial biocides. Patent US 4906651, 1990. 

While starches are commonly used, they are relatively poor viscosifiers. Acids and bacterial enzymes readily attack the acetal linkages resulting in facile depolymerization. Both formaldehyde and isothiazolones have been used as starch biocides (17). Development of improved high temperature water viscosifiers for drilling and other oil field applications is underway. For the... 

Isothiazolone has also been used as a non-oxidizing biocide for RO applications. However, the residence time required is much longer than for DBNPA. For example, a dosage of 50 to 100 ppm requires a 4-hour contact period. Thus, isothiazolone is not recommended for shock feed or continuous feed, but is recommended for cleaning events. Isothiazolone is more effective than DBNPA in high-organic waters. 

Since various industrial products have known spoilage problems as mentioned above, the use of Biocides is essential. Industrial preservation has revolved around the use of isothiazolone (IT) and formaldehyde donor (FD) biocides. 

Non-oxidizing biocides include a variety of organic compounds such as glutaraldehyde, quarternary ammonium salts (QUATS), isothiazolones etc. These compounds are less critical in terms of corrosion because they do not accelerate the cathodic partial reaction. Many of them are active over a wide range of pH and temperatures. THPS, a water soluble organic compound, has been found particularly effective for preventing microbial corrosion due to SRB in oilfields [33]. Biocide... 

Effect of combination of non-oxidizing biocides. Experimental study shows that the combination of nonoxidizing biocides was more efficacious in biofilm control than biocides when used alone (Figure 9). Simultaneous use of isothiazolones (4 ppm) and quaternary ammonium compound (12 ppm) demonstrated better biofilm control than either isothiazolones or quat alone. This biocidal combination controlled biofilm (based on HTR data) for about 27, 30, and 32 hours after three consecutive treatments. The biofilm DO response was much more significant than any separately tested biocide and was similar to the test when isothiazolone was used together with oxidizing biocide. These laboratory results confirmed practical (field) evidence that combinations of biocides affect biofibns more effectively than biocides used alone. 

Preservation of a water-based packer fluid. The role of the biocide in a packer fluid is to prevent the degradation of the organic polymer and to prevent the growth of potentially harmful microorganisms once the fluid is in the annular space. The biocide should have long lasting preservative qualities, be compatible with the other components of the fluid, and be tolerate of the conditions it will see once the fluid is in-place. Commonly used biocides include quaternary ammonium compounds, glutaraldehyde and isothiazolone. 

Stabilizers 2,4-di-tert-butylphenol, 4,5,-dichloro-2-n-octyl-4-isothiazolone-3-one biocide, 2-n-octyl-4-isothiazolin-3-one, chitosan, gold nanoparticles, grafted 2,2,5,5-tetramethyl-imidozalidin-4-one, nonylphenol disulfide, silver nanoparticles ... 

The following sections discuss the primary biocide used today, chlorine, and alternative physical and chemical techniques to address membrane biofouling control. The most common alternative techniques examined here include chloramine, chlorine dioxide, ozone, UV, and non-oxidizing biocides such as DBNPA and isothiazolone. Table 8.12 summarizes advantages and limitations of these techniques (adapted from Kim, 2009). It is important to note that some of these biocides/disinfectants can contact the membranes, and others must be removed or destroyed before the water is introduced to the membrane system itself. 

It is likely that isothiazolones act similarly to phthalimide biocides, interfering with enzymatic metabolism of nutrients. Isothiazolones are toxic to aquatic life, and should not be used in liners for ponds for raising of hsh or plants, or in agricultural hlms. 

---