Copper acid corrosion

Materials of Construction. Resistance of alloys to concentrated sulfuric acid corrosion iacreases with increasing chromium, molybdenum, copper, and siUcon content. The corrosiveness of sulfuric acid solutions is highly dependent on concentration, temperature, acid velocity, and acid impurities. An excellent summary is available (114). Good general discussions of materials of constmction used ia modem sulfuric acid plants may be found ia References 115 and 116. More detailed discussions are also available (117—121). For nickel-containing alloys Reference 122 is appropriate. An excellent compilation of the relatively scarce Hterature data on corrosion of alloys ia Hquid sulfur trioxide and oleum may be found ia Reference 122. 

The acid wash test consists of shaking a mixture of 96% sulfuric acid with benzene and comparing the color of the (lower) acid layer with a set of color standards. Other quaUtative tests include those for SO2 and H2S determination. The copper strip corrosion test indicates the presence of acidic or corrosive sulfur impurities. The test for thiophene is colorimetric. 

Dissolved oxygen, water, acid, and metal-ion concentrations can have a pronounced effect on acid corrosion. For example, copper is vigorously attacked by acetic acid at low temperatures at temperatures above boiling, no attack occurs because no dissolved oxygen is present. 

Sulfur dioxide emissions may affect building stone and ferrous and nonferrous metals. Sulfurous acid, formed from the reaction of sulfur dioxide with moisture, accelerates the corrosion of iron, steel, and zinc. Sulfur oxides react with copper to produce the green patina of copper sulfate on the surface of the copper. Acids in the form of gases, aerosols, or precipitation may chemically erode building materials such as marble, limestone, and dolomite. Of particular concern is the chemical erosion of historical monuments and works of art. Sulfurous and sulfuric acids formed from sulfur dioxide and sulfur trioxide when they react with moisture may also damage paper and leather. 

Fig. 19.16 Schematic E — I diagrams of local cell action on stainless steel in CUSO4 + H2SO4 solution showing the effect of metallic copper on corrosion rate. C and A are the open-circuit potentials of the local cathodic and anodic areas and / is the corrosion current. The electrode potentials of a platinised-platinum electrode and metallic copper immersed in the same solution as the stainless steel are indicated by arrows, (a) represents the corrosion of stainless steel in CUSO4 -I- H2 SO4, (b) the rate when copper is introduced into the acid, but is not in contact with the steel, and (c) the rate when copper is in contact with the stainless steel...

Problems with heating coils Internal coil corrosion Note corrosion debris is green hydrated copper carbonate Cu[11IC03 nH20 red cuprous oxide Cu20 /ntemal coil deposition Acid corrosion from soft water. Pinhole corrosion from 02 and C02. Erosion corrosion over 6 ft/s flow. Hard water scale from hard water. 

Zhang XOG, Stimming U. 1990. Scanning tunnehng microscopy of copper corrosion in aqueous perchloric-acid. Corrosion Sci 30 951-954. 

Copper is softer and more ductile than steel and is utilized frequently in the manufacture of pipes and tubing. Copper has good corrosion resistance but will corrode in the presence of nitric acid and other mineral acids. Organic acids do not corrode copper as readily. Dry ammonia does not corrode copper, but the presence of water in ammonia and ammonium hydroxide will corrode copper. Copper resists corrosion in the presence of caustic solutions, but the addition of zinc will increase corrosion rates. Also carbonate, phosphate, and silicate salts of sodium will corrode copper. See FIGURE 9-1. 

In contrast to the situation of a decade ago [3.1). a substantial literature has now accumulated on copper removal by activated carbons. This is not only because of metal recovery from acid mine wastes [176] and acidic corrosion of pipes [33] but also because of increasing industrial contamination of water streams [177-182]. In particular.many wastewaters contain complexing ions such as ethylenedi-aminetetraacetate (EDTA) and the removal of EDTA-chelated copper (and other) ions has been a special focus of attention [45,173,183-186]. 

Safety Commission Consumer Products Copper (Cu) Corrosives Corticosteroids Cosmetics and Personal Care Products Cotinine Coumarins Creosote Cresols Cromolyn Cumene Cumulative Risk Assessment Cyanamide Cyanide Cyanogen Chloride Cyclodienes Cyclohexamide Cyclohexane Cyclohexene Cyclophosphamide Cyclosporine Cyfluthrin Cypermethrin Cysteine Cytochrome P-450 "2,4-D (2,4-Dichlorophenoxy Acetic Acid)" Limonene Dalapon DDT/DDE/DDD Decane DEBT (Diethyltoluamide) DEE Deferoxamine DEHP (Di-Ethyl Hexyl Phthalate) Delaney Clause Deltamethrin Deodorants Detergent Developmental Toxicology Dextromethorphan Diazepam Diazinon Diazoxide Dibenzofuran " Dib enz [a, h] anthracene" Dibromochloropropane Dibutyl phthalate Dicamba Dichlone Dichlorobenzene Dichloroethanes "Dichloroethylene, 1,1-"... 

For applications requiring corrosion-resistant alloys, either low-carbon or stabilized stainless steels such as Type 321 SS are normally selected. Sensitization-induced polythionic acid corrosion is a concern in such applications. High-nickel alloys and copper-based alloys often corrode rapidly in the presence of high-temperature sulfur compounds. 

DIUROL 5030 (61-82-5) Substance acts as a weak base to form salts in contact with acids. Corrosive to iron, aluminum, copper, and copper alloys. 

PHENYLHYDRAZINE HYDROCHLORIDE or PHENYLHYDRAZINE MONOHYDROCHLORIDE or PHENYLHYDRAZINIUM CHLORIDE (59-88-1) Combustible solid (flash point about 194 F/90°C). Dust or powder forms explosive mixture with air. A strong reducing agent Reacts violently with strong oxidizers, alkalis, ammonia, ammonium persulfate, bromine dioxide, lead dioxide, nitric acid, perchlorates, permanganates, peroxides, sulfuric acid. Incompatible with alkali metals, chromates, copper salts. Corrosive to metals, nickel. 

Carbon steels and stainless steels are the most common construction materials for equipment used in the manufacture, storage, and transportation of sulfuric acid. Anodic protection was successfully used to control the corrosion of the various equipments made of these materials in this acid over a wide range of temperatures. While the corrosion rates of carbon steels in sulfuric acid are mainly functions of temperature, velocity, and acid concentration and purity, particularly the iron content, these rates are greatly affected by minor alloying elements in steel, particularly copper. The corrosion rates of steel in 77 to 100% concentrations are in the range of 20 to 40-mils per year (mpy) at 24 °C [14]. 

Copper possesses good corrosion resistance primarily because it is relatively noble (corrosion resistant by immunity), and it is most suitable for reducing environments. The potential range where the material is active in aqueous solutions (Figure 10.1) is so high that reduction of hydrogen ions is not a possible cafliodic reaction. Therefore, copper is immune for example in oxygen-free sulphuric acid. Corrosion can only occur if there is some other oxidizer present that causes a cathodic reaction. 

Copper exhibits a good corrosion resistance in air, as well as in hot and cold water, provided the flow velocity does not exceed a certain value (Chapter 10). The standard potential of copper is more noble than that of hydrogen. Therefore, in the absence of oxygen, copper resists corrosion even in acid environments. The potential-pH diagram of Figure 12.10 illustrates this behavior. 

C.2.2 4.9 g sodium cyanide (NaCN) Reagent water to make 1000 mL 1 to 3 min 20 to 25°C Removes copper sulfide corrosion products that may not be removed by hydrochloric acid treatment (C.2.1). 

Determination of resistance to intergranular corrosion of stainless steels—Part 2 Ferritic, austenitic and ferritic-austenitic (duplex) stainless steels—Corrosion test in media containing sulfuric acid Corrosion of metals and alloys— Determination of dezincification resistance of brass Copper alloys— Ammonia test for stress corrosion resistance Corrosion tests in artificial atmosphere—General requirements... 

The hydrogen ions cause acidic corrosion of both iron and copper alloy surfaces in the steam condensate system. The simplified corrosion... 

Hydrofluoric acid, hydrogen fluoride and fluorine are less corrosive to many metals and alloys than their own halide counterpart. The nickel-copper alloys, typified by Monel alloy 400 have excellent resistance to hydrofluoric acid corrosion. Stainless steels, such as 316, suffered severe transgranular corrosion. Table 9.23 summarizes the corrosion resistance of nickel alloys and stainless steels in anhydrous hydrogen fluoride [37]. The weakness of stainless steel to anhydrous hydrogen fluoride corrosion is shown in Table 9.23. 

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