How is salt obtained from salt water? For centuries, this question has engaged sailors and science students. The answer is simple - evaporation. When you let the salt water evaporate (through natural or artificial heat), only the water evaporates - the salt remains. Thanks to this knowledge, it is quite simple to separate the salt from the water using common means that you have at home.
Steps
Method 1 of 3: Perform a Basic Experiment
Step 1. Heat the water and add salt to obtain salty water
It is easy to see the principles of evaporation in action with this experiment. To start, what you need is plain salt water. That, sink water, a frying pan, a small black cardboard, and a stove. Add a couple of cups of water to the pan and place it on the stove. Wait for the water to heat up - it does not need to boil, but the hotter it is, the faster the salt will dissolve.
The reason why hot water is better for dissolving salt (and other chemical agents) has to do with the motion of the molecules that make up the water. When the water becomes hot, these molecules move faster, hitting the salt molecules and dissolving it
Step 2. Add salt until it no longer dissolves
Keep adding small spoonfuls of salt and try to dissolve it. Eventually, you will reach a point where the salt no longer dissolves, no matter how hot the water is. This is called the water saturation point. Turn off the heat and let the water cool down a bit.
When the water reaches its saturation point, it no longer has the ability to dissolve salt molecules - so much salt has been dissolved that there are no more molecules available to dissolve more
Step 3. Pour some salt water on the black card
Using a spoon or a ladle, pour a little salted water onto the black cardboard. Place the card on a plate to avoid soiling the surface underneath. Now, all you have to do is wait for evaporation. This process will be quicker if you leave the card in the sun.
Don't waste your leftover salt water - there are a thousand things you can use it for. For example, you can boil an egg, some potatoes, store some spinach, and even help you peel the peanuts
Step 4. Wait for the salt to form
As the water evaporates, it should leave behind some small salt crystals. These should have the appearance of small white and shiny flakes on the surface of the sheet. Congratulations! You have just separated the salt from the water.
Feel free to use some of the salt on the cardboard to flavor your foods - it should be perfectly edible. But be careful not to have paper scraps in your food
Method 2 of 3: Building a Distiller
Step 1. Start by boiling a pot of salted water
The previous experiment showed how to get salt from water, but what if you also want to preserve distilled water? The answer is distillation. It is the process of heating a liquid to separate it from the other chemicals in it, then collecting the condensation, which should be relatively "pure". In this case, we'll start brewing a couple of cups of salted water (see above for instructions) and heat it to boil.
Step 2. Place a lid slightly apart
Next, find a lid that fits your pot (it doesn't have to be perfect). Place it so that it partially leaves the pot uncovered. Try to position it so that the protruding part of the pot is at an angle. Watch the condensation begin to form on the lid and run off.
While the water is boiling, the water (without salt) will turn into steam and will rise from the pot. When it hits the lid, condensation (water) will form on the bottom surface of the lid. This water does not contain salt, so that's all we have to do to get distilled water
Step 3. Collect the water in a cup
Since the water flows downwards, the condensation on the lid will go to its lowest point. Once a certain amount of condensation collects there, it will start to form droplets and run off. Place a cup under this point to collect it.
If you want, you can also place a metal or glass object under the lid (such as a wand or a thermometer) from the cup towards the lowest point of the lid - the water will flow along this object from the lid into the cup
Step 4. Repeat if necessary
As the salt water boils in the pot, more and more distilled water should collect in the cup. This water will be devoid of most of the salt. However, in some situations, a small percentage of the salt may remain. In this case, you could carry out a double distillation - boil the already partially distilled water and collect the condensate again.
Technically, this water should be drinkable. However, unless you are sure of the cleanliness of the starting water, the pot and the cup (and the metal or glass object), you should not drink it
Method 3 of 3: Using Uncommon Methods
Step 1. Use reverse osmosis
The previous methods are not the only way to separate the water from the salt, they are simply the simplest methods to use at home. It is also possible to separate the salt from the water using specific materials. For example, a technique called reverse osmosis can remove salt from water by forcing the passage of water through a membrane. This membrane acts as a filter, allowing only the water molecules to pass and retaining other substances (such as salt).
Reverse osmosis pumps are used in some cases for residential purposes, but often also for recreational purposes, such as camping. Pumps can be quite expensive, usually several hundred dollars
Step 2. Add some decanoic acid
Another way to separate salt from water is through chemical reactions. For example, research has shown that treating water with a chemical called decanoic acid is a reliable way to remove salt. After adding the acid and heating a little, then cooling, the salt and other impurities will separate from the solution (solidifying at the bottom). When the reaction is complete, the water and salt will form two separate layers, making it easy to remove from the water.
Decanoic acid can be found in chemical reagent stores - usually for € 30-40 per pack
Step 3. Use electrodialysis
Using the power of electricity, it is possible to remove the salt particles from the water. It is carried out by submerging a negative anode and a positive cathode in water and separating them through a porous membrane. The electric charge of the anode and cathode essentially "pushes" the dissolved ions (such as those that make up the salt) towards them like magnets, leaving relatively pure water.
Note that this process does not necessarily remove bacteria or other contaminants from the water, so further treatments will be required to obtain drinkable water after using this method. Recent research has been promising, and has suggested new techniques in the process kill bacteria
Advice
Don't use sea water unless you are required to. In addition to salt, it can also contain minerals, organic matter, and other contaminants that make it difficult to purify it completely
Warnings
- Be careful every time you boil the water on the fire. If you have to touch a hot pot, be sure to use kitchen gloves.
- Don't drink sea water if you are offshore. Our bodies need more water to dispose of the salt dissolved in it, so salt water makes us even more dehydrated.
