Development Of A New Kind Of Corrosion Inhibitor For Hydrochloric Acid Cleaning Of Galvanizing Equipment

Galvanized equipment existed in natural environment and corrosive environment has super antiseptic property, which is widely used in foodstuff, chemical industry,petroleum and so on for facility cladding and anode protecting,especially in the industry of aquaculture refrigerator equipment, ood processing industry evaporative condenser etc. But in practical application, the surface of galvanized equipment always generates a large number of scale depositing on account of environmental medium, which will effect the work efficiency seriously, cause enormous financial loss and production decline. The best way to clean the depositing is using chemical cleaning, and hydrochloric acid is the most universal freshener.The zinc metal has active quality, low standard electrode potential, higher than a kite skyscraping acid reaction equilibrium constant, so it is prone to happen chemical reaction with Acid. The key is the addition of the valid corrosion inhibitor. At present, the report of the zinc corrosion inhibitor in China is rare, especially the corrosion inhibitor of the hydrochloric acid media still has quite a lot shortage.While in practical application, the demand of the corrosion inhibitor is increasing. Therefore,it is important to develop the new pattern zinc corrosion inhibitor, above all the corrosion inhibitor in hydrochloric acid solution.The paper uses the weight loss method, selecting from hundreds of chemical, and screens out slow-release effective for zinc in hydrochloric acid media, which is a reference for preparing composite corrosion inhibitor. The research finding of single-package thermodynamic property on salicylaldehyde, which is screned out as the good corrosion inhibition. The salicylaldehyde thermodynamics adsorb adsorption accord with Langmuir law of adsorption. The thermodynamic parameter of corrosion inhibitor show that enthalpy change, entropy change and free energy less than zero. In other words, the thermodynamics adsorption of the corrosion inhibitor is spontaneous, exothermic process of entropy decreasing. But in the condition of high temperature, free energy is great, which increases rate of corrosion.The corrosion inhibitor filtrated as single-package, went through hundreds of experiment design to develop three kinds of composite corrosion inhibitor which has good corrosion inhibition affection. Using the orthogonal test, the best optimum proportion is determined. Finally JZA-1、JZA-2 �'� JZA-3 as three kinds of metal zinc corrosion inhibitor of new Hydrochloric acid medium are successfully developed.Using the weight loss method, the paper researches the corrosion inhibition performance of the three corrosion inhibitions and its anti-interference ability to acid rate, temperature and time. The researches show that the three corrosion inhibitions have excellent function. Particularly JZA-1 �'� JZA-2, when the corrosion rate of galvanized layer declines to less than 0.2 g·m-2·h-1 under the condition of routine cleaning, it doesn’t happen to nonuniform corrosion phenomenon.The antijamming capability of the three corrosion inhibitor is good, even in the acidity up to 10 percent or the temperature up to 60 degree it is valid. The slow-release effect become good with the time long.According to the electrochemistry research to the three corrosion inhibitions, it is founded that compared with the condition of no corrosion inhibition, the corrosion electric current obviously declines when it adds corrosion inhibition.So JZA-1 is mixed type corrosion inhibitor, and JZA-2、JZA-3 are anode type.