How do you remove salt from seawater? For centuries, this question has baffled sailors stranded at sea and students stranded at scientific fairs. The answer is simple - evaporation. When you make seawater evaporate (either naturally or by artificial heat), only the water forms water vapor; salt will be left behind. With this knowledge, it's fairly easy to separate salt from water with the common types of ingredients you might have at home.
Step
Method 1 of 3: Conducting a Basic Evaporation Experiment
Step 1. Heat water and add salt to make brine
It's easy to see the principles of evaporation at work by performing this simple experiment. To get started, all you need is a little regular table salt, tap water, a saucepan, some black construction paper or sugar paper, and a stove. (Construction/sugar paper is a kind of thick colored paper with a slightly rough and uneven surface texture, usually used for making crafts, designs, or models.) Add a few cups of water to a saucepan and place the pot on the hot stove. Wait for the water to heat up - it doesn't need to boil, but the hotter the water, the faster it will dissolve the salt.
The reason hot water is the best for dissolving salt (and other chemicals) has to do with the movement of the molecules that make up the water. As the water heats up, these molecules move faster, hitting more salt molecules and destroying the salt crystals
Step 2. Add salt until the salt is no longer dissolved
Continue adding small spoonfuls of salt and stirring to dissolve it. Eventually, you'll reach a point where the salt won't dissolve anymore, no matter how hot the water is. This is called the saturation point of water. Turn off the stove and cool the water slowly.
When the water reaches its saturation point, it is no longer able to dissolve the salt at the molecular level - so much salt has dissolved that it no longer has any chemical potential to destroy the new salt crystals
Step 3. Spoon the water onto the dark construction paper
Using a ladle or ladle, pour some of your brine onto a sheet of dark construction paper. Place this paper on a plate to prevent water from seeping onto the countertop or the countertop below. Now, all you need to do is wait for the water to evaporate. This process will be slightly faster if you leave the paper somewhere in the sun.
Don't throw away your leftover brine - there are lots of things you can do with it. For example, you can use it to boil eggs, boil potatoes, preserve spinach, and even help you peel beans
Step 4. Wait for the salt to form
When water evaporates, it will leave very small salt crystals. These crystals will appear as small, shiny, white or clear flakes on the surface of the paper. Safe! You just separated the salt from the water.
You can take a pinch of salt off your paper to season your food - it should be perfectly safe to eat. But, be careful not to put any pieces of paper in your food
Method 2 of 3: Making a Flute Tool
Step 1. Begin to boil a pot of brine
The simple experiment above shows how to get salt from water. But what if you also want to store less salty water? Distillation or distillation is the answer. Distillation is the process of heating a liquid to separate it from the other chemicals dissolved in it, then collecting its condensation, which is completely "pure". In this case, we'll start by making a few glasses of brine (see above for instructions) and heating it to a boil on the stove.
Step 2. Place the lid on the pan at a slight angle
Next, find a lid for your pot (the lid doesn't have to be exactly the same size). Balance the lid over the pan so that part of the lid hangs over the rim of the pan. Try to adjust the lid so that the part that hangs over the edge of the pot is the lowest point of the lid. Watch as dew forms on the underside of the cap and begins to drip down.
When the brine boils, the water (without the salt) will turn to steam and rise to the top of the pot. When the steam hits the lid, the steam will cool slightly and form liquid dew (water) on the bottom of the lid. This water does not contain salt, so all we need to do is collect it to get salt-free water
Step 3. Let the water collect in a bowl
As the water flows downwards, condensation on the bottom of the cap will naturally collect at the lowest point of the cap. Once enough dew has gathered here, the dew will start to form droplets and fall. Place a bowl under this holder to catch any drops of distilled water as they fall.
If you wish, you can also place a long, slender metal or glass object (such as a stirring rod or thermometer) from the bowl to the lowest point of the lid - the water will flow down through this object into the bowl
Step 4. If needed, repeat
As the brine in the pot boils, more and more of the distilled water will collect in your bowl. This water has lost a lot of salt in it. However, in some situations, a little salt is still left. In this case, you may want to do a double distillation - boil the distilled water you've collected in the same way you boil the brine to remove any remaining salt.
Technically, this water is safe to drink. However, unless you're sure that the lids of the pots and bowls you collect the water in (and slim metal or glass rods, if you're using one) are clean, you probably don't want to drink them
Method 3 of 3: Using Less-Used Ways
Step 1. Use reverse osmosis (RO)
The method above is not the only way to separate salt from water. This is the easiest way for most people who work at home. It is also possible to separate salt from water in other ways that require special ingredients. For example, a technique called reverse osmosis can remove salt from brine by forcing water through a permeable membrane. This membrane acts as a filter, allowing only water molecules to pass and retaining dissolved contaminants (such as salt).
Reverse osmosis pumps are usually sold for domestic use, but are also often used for recreational purposes such as camping. Pumps may cost a fortune, usually a few hundred thousand or a million
Step 2. Add decanoic acid
Another way to separate salt and water is through a chemical reaction. For example, studies have shown that mixing salt water with a chemical called decanoic acid is a reliable way to remove salt. After adding the acid and slightly heating, then cooling, the salt and other impurities "leave" from the solution (that is, harden and sink to the bottom). When the reaction is complete, the water and salt are in two completely separate layers, making it easy for us to extract the water.
Decanoic acid is available at chemical stores - usually around IDR 350,000 – IDR 500,000 per bottle
Step 3. Use electrodialysis
Using electrical power, it is possible to remove particles such as salt from water. This is done by dipping the negatively charged anode and positively charged anode into water and separating them with a porous membrane. The electric charges from the anode and cathode essentially attract dissolved ions (such as the ions that make up salt) toward the anode and cathode like a magnet, leaving completely pure water.
Note that this process does not remove bacteria or other contaminants from the water, so further action must be taken to obtain water that is drinkable in this way in the forest. However, recent research is promising, suggesting new techniques that do kill bacteria as part of the process
Tips
Don't use sea water if you don't have to. In addition to salt, seawater also contains minerals, organic matter, and other contaminants, which can make it difficult for seawater to be completely purified
Warning
- Be careful every time you boil water on the stove. If you must touch the pan, be sure to use oven mitts or a towel to protect yourself.
- Don't drink salt water if you get lost in the wilderness. Our bodies need more water to get rid of salt than the water it produces from salt water, so salt water can make a person much more dehydrated.
