The Effect of pH on Copper Corrosion

Introduction

The element copper is a necessity for humans, people need to have a small amount of copper in their diet. “On average, most people will eat and drink about 1,000 micrograms (μg) of copper per day” (Winter M. 2009). Copper is essential for a human to stay healthy, although too much copper can be harmful. Most people receive a majority of copper in the water that they drink. Copper appears in water because water is corrosive and when there are pipes that carry strong flows of water, the pipes corrode. When water has a low pH, it tends to corrode pipes as well. Due to the acidity in water, copper pipes corrode, leading to a large amount of copper in drinking water. Common identifiers of copper in water include blue tints in water, metallic tastes, or has a distinctive odor to it. When copper and acids react, copper turns green. This happens because when copper responds to different elements, it creates a chemical reaction copper is turned green. The Statue of Liberty has turned green over time due to acid rain. Acid rain is caused by humans polluting water systems. The acidic rain-when in contact with copper-turns the original color of copper to a dull, green color. Copper corrosion is affected greatly by the pH of a solution.

Previous and current research

Copper tends to be more corrosive when liquids have a lower pH; higher acidity. Research has been done that states that when water is more acidic it tends to corrode pipes. Citizens in Cleveland have noticed that their water supply from Lake Erie has discoloration in it. The people have noticed that their water is slightly brownish/yellowish. “The raw water’s pH, a measure of acidity or lack thereof, had plummeted, nearing a level in which it would be acidic.” (Tony Briscoe. 2019). Scientists in the area notice that the water’s pH has gone down because of this new found lower pH. The scientists conclude that the water is turning brown because it was corroding the metal pipes that carry the water to a person’s house. “If the pH goes bad too long, the protective coating can start to break down, and you can start to get leads in the drinking water.” (Margevicius. 2019). Another scientist states that if pH has gone bad, it can lead to the destruction of the coating on the copper pipes. This protective coating helps the copper pipes so that the pipes do not corrode as quickly as they might if there was no coating. Another reason for protective coating on copper pipes is to reduce lead poisoning. Lead poisoning can occur because the protective coating on the pipes that the water is brought in on is starting to dissolve due to the acidity of the water. The water is too corrosive for the protective coating on the pipes to have any sort of benefit of protecting the pipes. “Many communities nationwide use zinc orthophosphate.” (Water Research Foundation. 2016). Another thing that people have started using to eliminate copper corrosion is the use of zinc orthophosphate. Many copper pipes have zinc orthophosphate because it is used to reduce the amount of corrosion from copper pipes, but zinc orthophosphate is expensive. Scientists are figuring out how they can use orthophosphoric acid to protect pipes instead of using zinc orthophosphate. Research is still being done on the effect of pH on corrosion due to the severity of the issue that will eventually be a worldwide problem.

Impact of topic

The effect of pH on corrosion impacts people, drinking water, pipes, and anything else that is made of copper. Corrosion is very harmful, especially when metal pipes are corroded away and the pieces of metal are broken down into one’s drinking water. Highly acidic water causes the copper pipes that carry the water that people drink to corrode. The leading impact of pH on copper corrosion is how healthy one’s drinking water is. “Copper corrosion in residential plumbing installations can lead to an increase in copper concentration in drinking water as well as leakages.” (Jay Dartmann. 2019). Additionally to impacting the cleanliness of drinking water, the effect of pH on copper corrosion also affects how the pipes function. The acidic water damages the pipes and causes microscopic holes in the pipes that leak water. Eventually these tiny holes grow over time and become bigger. The bigger the holes in the pipes are, the more damage the acidic water is going to do. When the pipes are damaged, then they will no longer carry water from one place to another. The acidity in the water breaks down the pipes and causes destruction, creating holes in the pipes. PH has a major impact on copper corrosion.

Additional research

Additional research that needs to be done about the effect of pH on copper corrosion is just how acidic is too acidic. It would be beneficial if scientists knew exactly how much acidity in water would be safe before the water is too dangerous to drink. More research also needs to be done about how to make the copper pipes stronger. Copper is a strong, dependable, durable metal, but in order to have less corrosion on copper pipes scientists must figure out what kind of metal is one hundred percent corrosive resistant so that people no longer need to worry about drinking metal, lead, or any other type of poisonous substance that could cause sickness or fatality. More research needs to be done in order to identify if basic solutions are corrosive the same way as alkaline substances. Acidity plays a big role in copper corrosion, but people do not know if bases impact the pipes in the same way. Studies must be done in order to determine if basic substances could possibly be more corrosive than acidic substances. Much research has been done about why and how pH levels affects copper and how different levels affect copper differently, but not much research has been done on how to fix these problems. The best solution to this problem is to experiment with different pH levels and determine which type of metal will be the least likely to corrode when dealing with acidic metals.

Conclusion

Copper corrodes when water or any type of solution has a pH level lower than 7. The reason that copper corrodes with lower pH levels is because acids are stronger than bases and corrode copper easilier. Bases such as milk, soap and baking soda do not corrode metals as effortlessly as acids do. This is because “Acids give off H+ (Hydrogen) ions in water; bases give off OH- (Hydroxide) ions in water.” The reason that acids give off hydrogen is because acids give protons when reacted with water molecules. Bases give off OH- ions when reacting with water. Acid water effects copper pipes because acidic water corrodes and breaks down to copper, so that people are potentially drinking little pieces of copper. Small amounts of copper are safe to consume, but in huge quantities, eating copper is quite dangerous. Improving copper structures such as buildings, statues, and pipes would help safen and refine the world.