Inhibitors continued test methods

In order to determine the effect of chemical additives on corrosion, an actual corrosion process must be taking place, so that the inhibitor test and the corrosion test are inseparable. The fact that many variables affect a corrosion process means that numerous different inhibitor tests are available. Although additive concentration is generally low, the type of system, whether once-through or recirculating, or the method of treatment, continuous or batch-wise, will determine, not only the test method, but also the inhibitor concentration required. 

Simple methods for almost all other inhibitor component species are notoriously inaccurate, and therefore of limited validity. Phosphonates, for example, have been a mainstay of almost all inhibitor programs for 20 years or more, and yet the accuracy of the various field methods available for phosphonate testing continue to be viewed (quite rightly) with... 

The test kit is based on immunoassay techniques and the method takes about 10 minutes to provide an analysis. A unique tag, permanently attached to the polymer, changes the color of special test strips exposed to ppm levels of polymer. The strips indicate the amount of tagged polymer that is present, without interference from other additives and contaminants. This technology is not currently available for continuous inhibitor detection, but given the importance of AH Organic Programs, there is little doubt that further developments will take place. The Water Additives Division of Great Lakes Chemical Corp. have also recently introduced a similar simple and accurate immunoassay test for the detection of Belclene 200 antiscalent. 

This method (Fig. 9.5 B) was designed to test whether any inhibition reaction occurred in the presence of a water-insoluble substrate during lipase hydrolysis. Lipase was injected into the reaction vessel of a pH-stat containing the emulsified substrate maintained under vigorous stirring. The inhibitor was injected a few minutes after lipase addition. Lipase activity was then continuously recorded (Fig. 9.5 B). 

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