Copper Corrosion Control Research Articles

Lead and Copper Research

The Lead and Copper Rule (LCR) was enacted in the United States more than 25 years ago, and the water industry is now anticipating a proposal from the US Environmental Protection Agency (USEPA) to update those regulations in early 2019. The anticipated LCR revisions, along with recent and highly publicized drinking water lead events, have resulted in renewed interest in drinking water lead levels. In response, this special focus issue of Journal AWWA is dedicated to presenting current information on lead and copper in drinking water. Much has been learned about lead and copper corrosion control over the past two decades or so, thanks to research by academic and governmental investigators (especially at USEPA itself) and the practical experiences of water professionals at countless drinking water utilities. For example, little was known about the importance of particulate lead relative to soluble lead 25 years ago. Drinking water sampling strategies focused on first draw according to the LCR, yet now we understand the value of alternative sampling approaches to address different lead and copper objectives. Parameters such as the Langelier saturation index and calcium carbonate precipitation potential were previously considered viable lead corrosion control assessment options in the original guidance, yet their value is now questioned as they may actually prove misleading for lead control. The role that orthophosphates play in lead corrosion control compared with polyphosphates is better appreciated even if it is still not well understood. The role of pipe age in copper mineralogy and solubility has been explored, as has the connection between pipe scale analysis findings and metal release to drinking water, and corrosion mechanisms and making corrosion treatment changes are better understood. Despite recent progress, there is still much to learn. Research on lead and copper in water systems and their effects on human health is ongoing. As demonstrated by the original research published in this special issue of Journal AWWA, the drinking water industry seeks to further reduce lead and copper in drinking water. Special thanks goes to all of the authors who contributed to this issue of the Journal. Feature articles begin with a review by Cornwell (page 30) on how well the water industry has reduced lead levels since the LCR with a focus on current national levels. McTigue et al. (page 38) review AWWA's new standard on lead service line replacement. And Burlingame et al. (page 44) focus on utility efforts to help reduce lead in schools. There are several peer-reviewed research articles in this issue, as well, including the article by Roth et al. (page 15) on how blending source waters affects lead corrosion—an often-forgotten issue. The article by Deshommes et al. (page 28) discusses lead service line management and public perception. Lytle et al. (page 26) describe a model they developed based on laboratory and field data for estimating the impact of orthophosphate dose on copper reduction. Williams et al. (page 27) present details on what they have learned in designing a pipe rig system to evaluate corrosion control on harvested lead pipes. Finally, Bradley and Horscroft (page 29) describe their approach to using historical LCR and water quality data to evaluate corrosion control effectiveness.

Water Quality Parameters Affect Corrosion Control

Research has shed new light on the effects of treatment changes on lead and copper corrosion control.

Effect of benzotriazole on corrosion inhibition of copper under flow conditions

The corrosion inhibition of benzotriazole on the copper surface is often investigated in static environment. The evidence for the protection of copper in dynamic flowing environment is limited. Hence, we investigated the corrosion control of copper in 3.5% NaCl solution in the presence of benzotriazole by a rotating cage. The flow test was carried out at different velocities 0.5–3.0m/s (100–700rpm). Copper showed accelerated corrosion activity with respect to the increase in the velocity in 3.5% NaCl test solution. However, benzotriazole added to the test solution reduced the corrosion attack on the copper. This clearly shows the adsorption of inhibitor on copper surface resulted in decreasing the mass loss by 4–5 times. The surface property was examined by using a scanning electron microscopy, atomic force microscopy and contact angle measurements. Adsorption of benzotriazole on copper surface follows the Langmuir adsorption isotherm.

Corrosion control of copper in 3.5 wt.% NaCl Solution by Domperidone: Experimental and Theoretical Study

Inhibition of copper corrosion in 3.5wt.% NaCl solution by domperidone was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The experimental results revealed that domperidone was an anodic inhibitor with a maximum achievable inhibition efficiency of 94.2%. The results of SEM and AFM studies further confirmed the inhibition action of domperidone. Quantum chemical calculation and the molecular dynamics (MD) simulation showed that the domperidone molecule could be adsorbed on copper surface through the imidazolidinone ring, benzene ring and N atom of hexaheterocyclic. Adsorption of domperidone was found to follow the Langmuir adsorption isotherm.

Consider Aeration and Chemical Alternatives for Copper Corrosion Control

Several factors drive the need to reduce copper in water systems. However, because those drivers aren't the same for all systems, several options for reducing copper and resulting corrosion are available.

Culture dependent and independent analyses of bacterial communities involved in copper plumbing corrosion

This study used culture-dependent and culture-independent approaches to characterize bacterial communities in copper plumbing corrosion and to assess biofilm formation and copper resistance of heterotrophic bacteria isolated from copper pipes. Water and copper pipes were collected from a cold-water household distribution system affected by 'blue water' corrosion and presenting biofilm formation. Corrosion-promoting ageing experiments were performed with conditioned unused copper pipes filled with unfiltered and filtered sampled water as nonsterile and sterile treatments, respectively. During 8 weeks, stagnant water within the pipes was replaced with aerated fresh water every 2 or 3 days. Total copper and pH were determined in sampled water, and copper pipe coupons were cut for microscopic analyses. Biofilms were extracted from field and laboratory pipes, and total DNA was isolated. Bacterial communities' composition was analysed by terminal restriction fragment length polymorphism (T-RFLP) and clonal libraries of 16S rRNA genes. Heterotrophic bacterial isolates were obtained from water and biofilm extracts and characterized in terms of biofilm formation capacity and copper minimum inhibitory concentration. The results indicated that copper concentration in stagnant water from nonsterile treatments was much higher than in sterile treatments and corrosion by-products structure in coupon surfaces was different. Multivariate analysis of T-RFLP profiles and clone sequencing showed significant dissimilarity between field and laboratory biofilm communities, and a low richness and the dominant presence of Gamma- and Betaproteobacteria in both cases. Several bacterial isolates formed biofilm and tolerated high copper concentrations. The study demonstrates microbially influenced corrosion (MIC) in copper plumbing. Gamma- and Betaproteobacteria dominated the corroded copper piping bacterial community, whose ability to form biofilms may be important for bacterial corrosion promotion and survival in MIC events. The characterization of micro-organisms that influence copper plumbing corrosion has significant implications for distribution system management and copper corrosion control.

Corrosion control of copper in nitric acid solutions using some amino acids – A combined experimental and theoretical study

Inhibition performance of three amino acids, namely l-methionine (MIT), l-methionine sulfoxide (MITO) and l-methionine sulfone (MITO2), as corrosion-safe inhibitors for copper surface in 1.0 M nitric acid was investigated by weight loss, dc polarization and ac impedance techniques. A significant decrease in the corrosion rate of copper was observed in the presence of the investigated compounds. The reactivates of the compounds under investigation were analyzed through Fukui functions, to explain their inhibition performance. Simulation techniques incorporating molecular mechanics and molecular dynamics were used to simulate the adsorption of l-methionine derivatives, on copper (1 1 1) surface in nitric acid.

Evaluation of the effect of dosage, pH and contact time on high-dose phosphate inhibition for copper corrosion control using response surface methodology (RSM)

The response surface methodology (RSM), particularly Box-Behnken design model, was used in this study to obtain the optimum operating conditions for reduction of copper corrosion by-product release using high-dose polyphosphate inhibition. Furthermore, the RSM was also applied to study the main and interactive effects of the parameters investigated. Both analysis of variance (ANOVA) and coefficient of determination ( R 2) showed that the RSM approach was appropriate for the optimization of high-dose polyphosphate inhibition. The main effects of polyphosphate dosage and pH were found significant in reducing copper release using high-dose polyphosphate whereas the effect of contact time was less significant. In terms of interactions between the effects, the relation between polyphosphate dosage and the pH was the most significant. The optimal polyphosphate dosage, pH and contact time were found to be 22–28 mg/L of polyphosphate as P, 9–10, and 36 h, respectively. The highest total copper release reduction was estimated as 95.86% under the optimum condition. Surface analysis using both SEM–EDX and XRD discovered that cupric phosphate was present on the copper surface treated with high-dose polyphosphate inhibition. This implied that cupric phosphate could be responsible for the reduction of copper release by forming a protective layer.

Surface protection of copper in acid medium by azoles and surfactants

The influence of derivatives of 1,2,4 triazole, 3-amino 1,2,4-traizole (ATA), 3-amino 5-mercapto 1,2,4 triazole (AMT) and 3-amino 5-methylthio 1,2,4 triazole (AMTT) and ionic surfactants cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) on the corrosion control of copper in acidic solution was investigated by gravimetric and electrochemical methods. The combined effect of triazoles and surfactants was also evaluated. Electrochemical parameters like corrosion potentials corrosion current density, corrosion rates and inhibition efficiencies were determined. The results reveal the fact that of all triazoles AMTT shows best inhibition and anionic surfactant SDS protects the surface better than the cationic surfactant CTAB. The polarisation data reveal that all inhibitors behave as a mixed type inhibitor. Adsorption of these inhibitors on the surface of copper is found to obey the Langmuir adsorption isotherm. A marked inhibition synergism effect is shown by all the combinations of triazole and surfactant.

Evaluation of inhibitors and biocide on the corrosion control of copper in neutral aqueous environment

Polarisation and impedance measurements were performed on copper in neutral aqueous solution with and without inhibitors and biocide. The inhibitors used were 3-benzylidene amino 1,2,4-triazole phosphonate (BATP), 3-cinnamalidene amino 1,2,4-triazole phosphonate (CATP), 3-salicylalidene amino 1,2,4-triazole phosphonate (SATP) and 3-paranitro benzylidene amino 1,2,4-triazole phosphonate (PBATP). Effect of inhibitors and biocide against the corrosion of copper in neutral aqueous solution has been studied. Results elucidate the minimal interference between biocide and inhibitors system. Surface evaluation techniques like FT-IR, XRD and EDXA were used to determine the nature of the protective film formed on the metal surface.

Corrosion inhibition of copper by new triazole phosphonate derivatives

New corrosion inhibitors, namely 3-vanilidene amino 1,2,4-triazole phosphonate (VATP) and 3-anisalidene amino 1,2,4-triazole phosphonate (AATP) were synthesised and their action along with biocide on corrosion control of copper in neutral aqueous environment has been studied. Potentiodynamic polarisation measurement and electrochemical impedance spectroscopy (EIS) has been employed to analyse of their inhibition behaviour. VATP showed better protection over the other inhibitors used. The dissolution of copper in presence of VATP and AATP with biocide mixture is negligible compared to blank. A combination of electrochemical methods and surface examination techniques are used to investigate the protective film and explain the mechanistic aspects of corrosion inhibition.

Corrosion inhibition of copper by new triazole phosphonate derivatives

New corrosion inhibitors, namely 3-vanilidene amino 1,2,4-triazole phosphonate (VATP) and 3-anisalidene amino 1,2,4-triazole phosphonate (AATP) were synthesised and their action along with biocide on corrosion control of copper in neutral aqueous environment has been studied. Potentiodynamic polarisation measurement and electrochemical impedance spectroscopy (EIS) has been employed to analyse of their inhibition behaviour. VATP showed better protection over the other inhibitors used. The dissolution of copper in presence of VATP and AATP with biocide mixture is negligible compared to blank. A combination of electrochemical methods and surface examination techniques are used to investigate the protective film and explain the mechanistic aspects of corrosion inhibition.

Copper corrosion control in the Netherlands

Copper is the most commonly used material for pipes in domestic installations in the Netherlands. Depending on the composition of the water the copper pipes can add a significant amount of copper to drinking water. In the new European Drinking Water Directive (98/83/EC) the parametric value for copper in drinking water is decreased from 3 to 2 mg/l. The new directive also stipulates that copper levels should be determined on the basis of a sample ‘taken at the consumers' tap’ representative of the weekly average intake by humans. Harmonisation of monitoring protocols for copper in the European member states is necessary. In the Netherlands about 45% of the drinking water is already softened or de-acidified in order to decrease copper concentrations in drinking water. In the Netherlands two new treatment techniques have been studied for their impact on copper release; these are Reverse Osmosis (RO) and the addition of inhibitors. Copper pipe rig tests have shown that RO treatment decreases copper release. Split treatment of water with RO reduces copper solubility of drinking water through a decrease in both total inorganic carbon (TIC) and sulphate level. Remarkable was the relatively small decrease in copper release after split treatment with RO, compared to previous experiences in the Netherlands, suggesting an effect of natural organic matter. A new promising technique in the Netherlands is the addition of the inhibitor carbonate-activated silicate. At the test sites, the reduction in copper solubility due to the use of carbonate-activated silicate was 15 to 35%.

Evaluation of lead and copper corrosion control techniques

The University of South Carolina has been involved in numerous studies to evaluate lead and copper corrosion control strategies for low hardness, low alkalinity waters found in South Carolina. This article discusses the results of three batch studies where the effects of pH and alkalinity adjustment, phosphate inhibitor addition, and silicate inhibitor addition on lead and copper corrosion mitigation were investigated. These studies indicate that all of these strategies reduce lead corrosion. Phosphate inhibitor addition, and pH and alkalinity adjustment were more effective than silicate inhibitor addition for the water quality investigated.

Lead and copper corrosion control

Abstract EPA sponsored a three year project in which researchers at the University of South Carolina performed comprehensive treatment and distribution system monitoring studies for several communities in South Carolina. The primary objective was to provide insight to state regulators and water suppliers on appropriate corrosion control strategies. This paper presents: (1) a comparison of the use of a batch‐mode (fill‐and‐draw) system to a continuous flow pilot system in performing corrosion treatability studies, (2) an evaluation of a method for measuring corrosion rates in copper plumbing systems by gravimetric weight‐loss, and (3) an evaluation of the treatment effectiveness of several chemical treatment alternatives. Two months were requires to establish relatively stable operation in the continuous‐flow pilot system, after which another two to three months were necessary to obtain reliable data from evaluation of treatment method efficiency. At lease one month was required to stabilize the operation ...