Process for treating aqueous systems

Abstract

In-situ bromination of aromatic azoles using ppm levels of one or more brominating agents prior to forming a film on a metal surface in an aqueous system and treating deposited unexpectedly effective in improving the chlorine resistance and the corrosion inhibition of the bromine treated aromatic azoles.

We claim:  
     
         1 . A process for inhibiting metal corrosion in an aqueous system comprising the steps of pre-mixing an aqueous solution of one or more aromatic azoles with one or more brominating agents, wherein the total concentration of bromine present expressed as chlorine is between 0.1 to 20 ppm; and adding the bromine treated aromatic azole to the aqueous system.  
     
     
         2 . The process of  claim 1  wherein the concentration of bromine present expressed as chlorine is between 1 to 5 ppm and wherein the bromine treated azole is added to the aqueous system with one or more water treatment additives selected from the group consisting of scale inhibitors, biocides, dispersants, de-foamers, fluorescent tracer compounds, other corrosion inhibitors and combinations thereof.  
     
     
         3 . The process of  claim 1  wherein the aromatic azole is selected from the group consisting of tolyltriazole, benzotriazole, butyl benzotriazole, sulfonotolyltriazole, carboxybenzotriazole, 2-mercaptobenzothiazole, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotrizole-1-methanamine and combinations thereof and wherein the metal is selected from the group consisting of copper, copper alloys, carbon steels, aluminum, aluminum alloys, stainless steels and combinations thereof.  
     
     
         4 . The process of  claim 1  wherein the brominating agent is selected from the group consisting of hypobromite, bromine, alkaline solutions of bromine, bromonium ions, bromine complexes (e.g. Lewis acid complexes with aluminum anions), hypobromous acid, mixtures of NaBr and NaOCl, dibromonitrilopropionamide, bromodichlorohydantoin, 1,2-dibromo-2,4-dicyanobutane, 2-bromo-2′-nitrostyrene, 2-bromo-4′-hydroxyacetophenone, 5-bromo-2-nitropropane-1,3-diol, 5-bromo-5-nitro-1,3-dioxane, 1-bromo-3-chloro-5,5-dimethylhydantoin, 3-bromo-1-chloro-5,5-dimethylhydantoin, 1-bromo-3-chloro-5-ethyl-5-methylhydantoin, 3-bromo-1-chloro-5-ethyl-5-methyl-hydantoin and combinations thereof.  
     
     
         5 . A process for inhibiting metal corrosion in an aqueous system comprising the steps of contacting a film comprising one or more aromatic azoles covering a metal surface with one or more brominating agents in-situ, wherein the total concentration of bromine present expressed as chlorine is between 0.1 to 20 ppm; and exposing the bromine treated film in contact with the aqueous system to an oxidizing halogen.  
     
     
         6 . The process of  claim 5  wherein the concentration of bromine present expressed as chlorine is between 1 to 5 ppm and the oxidizing halogen is chlorine; wherein the brominating agent is selected from the group consisting of hypobromite, bromine, alkaline solutions of bromine, bromonium ions, bromine complexes (e.g. Lewis acid complexes with aluminum anions), hypobromous acid, mixtures of NaBr and NaOCl, dibromonitrilopropionamide, bromodichlorohydantoin, 1,2-dibromo-2,4-dicyanobutane, 2-bromo-2′-nitrostyrene, 2-bromo-4′-hydroxyacetophenone, 5-bromo-2-nitropropane-1,3-diol, 5-bromo-5-nitro-1,3-dioxane, 1-bromo-3-chloro-5,5-dimethylhydantoin, 3-bromo-1-chloro-5,5-dimethylhydantoin, 1-bromo-3-chloro-5-ethyl-5-methylhydantoin, 3-bromo-1-chloro-5-ethyl-5-methyl-hydan-toin and combinations thereof; and wherein the bromine treated azole is added to the aqueous system with one or more water treatment additives selected from the group consisting of scale inhibitors, biocides, dispersants, de-foamers, fluorescent tracer compounds, other corrosion inhibitors and combinations thereof.  
     
     
         7 . The process of  claim 5  wherein the metal is selected from the group consisting of copper, copper alloys, carbon steels, aluminum, aluminum alloys, stainless steels and combinations thereof and wherein the aromatic azole is selected from the group consisting of tolyltriazole, benzotriazole, butyl benzotriazole, sulfonotolyltriazole, carboxybenzotriazole, 2-mercaptobenzothiazole, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotrizole-1-methanamine and combinations thereof.  
     
     
         8 . A process of inhibiting metal corrosion in an aqueous system including one or more aromatic azoles comprising the step of adding one or more halogenating agents, wherein the total concentration of halogen present in the aqueous system and expressed as chlorine is between 0.1 to 20 ppm.  
     
     
         9 . The process of  claim 8  wherein the aromatic azole is selected from the group consisting of tolyltriazole, benzotriazole, butyl benzotriazole, sulfonotolyltriazole, carboxybenzotriazole, 2-mercaptobenzothiazole, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotrizole-1-methanamine and combinations thereof and wherein the halogenating agents are selected from the group consisting of fluorinating agents, brominating agents, iodinating agents and combinations thereof.  
     
     
         10 . The process of  claim 8  wherein the metal is selected from the group consisting of copper, copper alloys, carbon steels, aluminum, aluminum alloys, stainless steels and combinations thereof.