It is important to safely dispose of acids that have a very low pH level (<2). They can be disposed of in the standard sewer system if they do not contain dissolved heavy metals or other toxic substances and the pH is neutralized to a less acidic level (between 6, 6 and 7, 4). However, if heavy metals are present, you should treat this solution as a hazardous waste and dispose of it through the proper channels.
Method 1 of 3: Work Safely
Step 1. Review the Acids section on the International Chemical Safety Sheets
These sheets provide you with all the relevant safety information on the handling and storage of a chemical product. You can look up the exact name of the acid in question in the online database so that you get all the relevant information.
Step 2. Wear the proper protective gear
When handling acids (or any other powerful chemicals), it is very important that you wear safety glasses, gloves, and a lab coat. You must wear safety glasses to avoid splashing and protect the sides of your eyes. Gloves and lab coat protect your skin and clothing.
- Gloves must be made of plastic or vinyl.
- You should tie your hair up if it is long to prevent it from inadvertently coming into contact with acid.
Step 3. Work in a well-ventilated area or with a chemical fume hood
The fumes released by acid are toxic. If possible, you should use a fume hood to limit your exposure to this substance. If you don't have access to one, you should open all the windows and ventilate the area with a fan.
Step 4. Locate the nearest tap water supply
In case the acid comes into contact with the skin or the eyes, you should wash with plenty of water for at least 15 minutes. Then you should seek medical attention immediately.
- If splashes get into your eyes, keep your eyelids open and move your eyes up and down and side to side to clean them properly.
- If any splashes land on your skin, you should soak the affected area in water for a full 15 minutes.
Method 2 of 3: Dispose of Acids at Home
Step 1. Get a container that will not deteriorate when you add the acid
Most strong acids degrade glass and metal, but they do not react with plastics. There are many different types of plastics, so make sure you get the right container for the acid you have. The acid must be stored in such a container, but you need a second container to dilute and neutralize it.
- You want to make sure the container can hold at least twice the amount of acid you have. This way, you will have enough space to dilute and neutralize it.
- Be very careful not to spill the acid if you have to transfer it to a larger container.
Step 2. Place the empty container in a bucket of ice
By diluting and neutralizing a strongly acidic solution, a great deal of heat is released. You should place the empty container in a bucket of ice to limit the chance of burning or melting it.
Step 3. Dilute the acid with water
If you have a highly concentrated acid, you must first dilute it with water. This step can be dangerous, so you must follow all instructions very carefully. Use cold water to prevent the solution from boiling and splashing. Add water to the empty container. Then add the acid slowly to the water and pay close attention to the temperature of the container while you do this.
- The amount of water you need to dilute the acid depends on the concentration of the solution. The more concentrated it is, the more water you will need. You can calculate the exact amount by following the steps in the article on how to dilute an acid.
- You should never put the water directly on the acid, as it can cause the water to boil quickly and cause the acid to splatter.
- Be very careful not to spill the acid as you dilute it.
Step 4. Test the pH of the acid with litmus paper or pH indicator paper
You can find this type of paper at a science lab supplies catalog or at a pool accessories store. To determine how much neutralizing solution you need, you must know the pH of the acid you are going to neutralize.
- Dip one end of the litmus paper into the solution. The paper will change color depending on the pH level.
- Remove the paper and compare the color with the chart that comes on the package. The color that matches the paper is the pH of the solution.
- The lower the pH level of the acid, the more neutralizing the solution you need should be.
Step 5. Make a neutralizing solution
Solutions such as sodium hydroxide or magnesium hydroxide are considered basic and serve to neutralize acids. Sodium hydroxide is also known as caustic soda, while magnesium hydroxide is the main ingredient in milk of magnesia. You can buy both substances in any store.
- You must follow the instructions that come on the caustic soda container to make your sodium hydroxide solution.
- You don't need to alter the milk of magnesia, as you can use it directly to neutralize the acid.
Step 6. Neutralize the dilute acid
Basic solutions react when they come into contact with acid solutions and neutralize them producing water and salt. You should add the basic solution little by little over the diluted acid and stir gently as you do it. Pay close attention to the temperature of the container and be careful not to splash the solution.
Step 7. Test the pH frequently
You should periodically check the pH level with litmus paper to make sure you don't go over the target range of 6, 6 to 7, 4. Keep adding the saline solution slowly until you reach the desired neutral range.
- As an alternative, you can use a universal indicator solution. The liquid will change color according to the pH level. Add the saline solution until the indicator changes to the color around the 7.0 range.
- If you go over the neutral range, you should slowly add a dilute acid solution to bring the pH level down to at least 7.4.
Step 8. Flush the solution down the drain
You can safely dispose of the neutralized solution down the drain while running the cold water. You should let the water run for at least 30 seconds after you empty the container.
Method 3 of 3: Dispose of Acid Containing Dissolved Heavy Metals
Step 1. Get a container that will not deteriorate when you add the acid
Most strong acids degrade glass and metal, but do not react with plastics. There are many different types of plastics, so make sure you get the right container for the acid you have. Acid should be stored in such a container, but be sure not to fill it completely to avoid spillage.
Step 2. Determine the contaminants in the acid
Heavy metals such as cadmium, zinc, copper, mercury, and lead are considered toxic and should not be added to the water system. In addition, there are other inorganic compounds that are also considered toxic or corrosive and should not be flushed down the drain either.
If you have different containers of the same acid with different dissolved compounds, you should keep them in separate containers, as they must be disposed of separately
Step 3. Contact a hazardous waste collection service near your location
If you are in college or work in a laboratory, there is a department that handles the proper disposal of hazardous waste. If you don't have this option, you can contact a local organization to help you with the removal process.
- If you consume too much milk of magnesia, your stomach acid can become basic.
- If you are trying to dilute the acid, make sure to add it to the water and not the other way around. If the acid has a high enough concentration, it will start to release a lot of heat if you add the water to it.
- Certain types of acid are highly corrosive and can damage anything weak they come in contact with.