Activated charcoal is nothing short of a natural miracle when it comes to water filtration.
Extremely porous (we’re talking microns) and with a large surface area, it is excellent at filtering out contaminants and toxins.
It is definitely something that anyone who takes emergency preparedness seriously should know how to make, which is why we’ve put together the following guide on how to make activated charcoal.
Step-by-Step Guide to Making DIY Activated Charcoal
Step 1: Gathering the Right Materials
Essentially, when you’re making activated charcoal, you’re carbonizing wood. To do this properly, you will, of course, need the wood (preferably hardwood like oak, hickory, or any dense variety).
You’ll also need a metal drum or a large fire-safe container with a lid, a small shovel or stirring stick, some water, calcium chloride (or lemon juice) for chemical activation, a fine mesh sieve or cheesecloth, and protective gear (gloves, goggles, and a mask).
If you’re unfamiliar with calcium chloride, it’s a common chemical compound used in activities like winemaking, home brewing, and cheese making. It can also be used to treat and clean water.
A 2 lb bag of it costs around 17 bucks on Amazon, but you can find it pretty much everywhere.
Potential Pitfalls on Step 1
One mistake I see a lot of people make during the initial stage of making activated charcoal is choosing the wrong wood. Avoid softwoods like pine and spruce, as they contain too many resins that interfere with the carbonization process.
Also, whenever possible, wear protective gear to avoid burns or inhaling harmful fumes.
Step 2: Carbonize the Wood
Carbonization is the process of converting organic matter into carbon through what is called destructive distillation. If you want to read more about how carbonization works, check out this Wikipedia article, it’s actually quite interesting.
During this step, start by cutting the hardwood into small pieces to increase the surface area.
Then, place the hardwood in a metal drum or container with a lid that allows some airflow to keep the fire burning but isn’t completely open.
The objective here is to create a low-oxygen environment to slowly char the wood (a process called pyrolysis).
You will need to heat the drum over the fire for several hours, aiming for temperatures between 600°F and 900°F (315°C and 480°C). The wood slowly turns into charcoal as volatile compounds are driven out.
Once the wood has fully carbonized, it should be black and brittle. Remove the container from the heat and let it cool. What you’ve got now is basic charcoal.
Potential Pitfalls on Step 2
People tend to mess up step two by not achieving a high enough temperature. If the temperature isn’t in the range we mentioned above, the wood won’t fully carbonize, resulting in lower-quality charcoal.
You should also be careful not to introduce oxygen too early. If you open the lid too soon, it can lead to combustion rather than slow carbonization, which will burn the charcoal entirely (i.e., you won’t actually have any activated charcoal).
Step 3: Crushing the Charcoal
Once the charcoal has cooled, break it down into smaller pieces. You can use a hammer or a similar tool to crush it into granules or even powder form (the finer, the better for filtration).
Pass the crushed charcoal through a fine mesh sieve to get a consistent particle size.
Potential Pitfalls on Step 3
The only way to go wrong on step 3 is by making granules that are too big. If they aren’t small enough, the surface area will be reduced, which limits the charcoal’s effectiveness for adsorption.
Aim for fine granules to maximize filtration ability, and you will end up with cleaner, better-tasting water.
Step 4: Activating the Charcoal
This is where the rubber meets the road. If you’re making activated carbon for water filtration, it’s helpful to understand what the activation process is and what it accomplishes.
Here is a conversation between chemists in a Reddit thread on the topic:
“The smooth floor is normal charcoal, the rough one is the activated one.”
Activating it, then, is, in simple terms, making it porous and increasing the surface area so that it can effectively absorb toxins and contaminants.
To activate charcoal, prepare an activating solution by dissolving calcium chloride (use about a 1:4 ratio of calcium chloride to water) or lemon juice (if calcium chloride isn’t available) in water.
Then, submerge the crushed charcoal in the solution and let it soak for up to 24 hours. What you’re doing here is chemically activating the charcoal by opening up the pores, which dramatically increases the surface area for absorption.
After you’ve soaked the charcoal, drain the excess solution and thoroughly rinse the charcoal in clean water.
Potential Pitfalls on Step 4
If you don’t go through the activation step, the charcoal will have far fewer active sites to trap contaminants.
Furthermore, if you rush the soaking process and don’t leave it for a full 24 hours, you will end up only partially activating the charcoal, which, again, limits its filtration ability.
Step 5: Drying and Final Preparation
You’re just about done.
Now all you need to do is spread the activated charcoal out on a clean surface or in a pan to dry. You can let it air dry for a few days or place it in an oven at low heat (around 200°F, or 90°C) to speed up the process.
Once everything is completely dry, store the activated charcoal in an airtight container to prevent moisture from deactivating it.
Potential Pitfalls on Step 5
I’ve made the mistake of storing activated charcoal in a humid environment before, and I’ve had to get rid of a batch.
Activated charcoal, as we’ve tried to drive home throughout this article, is very porous and will quickly absorb moisture from the air if not properly sealed.
You should also make sure that you’re drying it for a long enough period of time. Wet charcoal is not only less effective, but it can also result in bacterial growth, which is counterproductive for water filtration.
You can test the dryness with your hands – it should feel bone dry.
Step 6: Using Your Activated Charcoal for Water Filtration
Now it’s time to actually use your homemade activated charcoal.
Place the activated charcoal in a filter housing, such as a mesh bag, cheesecloth, or between two layers of fine gravel in a water filter setup.
Then, pass water slowly through the charcoal. It will adsorb chemicals, bad odors, and some dissolved compounds.
Potential Pitfalls on Step 6
It is important to keep in mind that activated charcoal does not kill bacteria, viruses, or protozoa. To ensure safe drinking water, you need to pair activated charcoal filtration with other purification methods like boiling, UV light, or chemical disinfectants.
And, as always, filter out debris and sediment before passing water through the charcoal filter to avoid clogging and reducing filtration efficiency.
5 Nifty Ways to Use Your Activated Charcoal
Did we mention activated charcoal was a miracle substance?
Your freshly created activated charcoal, which should have an indefinite shelf-life provided you store it properly, has myriad different everyday and emergency preparedness uses. Below are some things you can use it for in addition to water filtration.
1. Air Purification
Activated charcoal isn’t just good at filtering toxins, odors, and pollutants out of water, but the air you breathe as well.
You can place some small sachets or containers of the charcoal in different areas of your home – kitchen, bedroom, near pet areas – to help neutralize odors. You can also use it in your car or refrigerator to adsorb bad smells.
Just make sure the charcoal stays dry to retain its adsorbing abilities.
2. Emergency Detox Treatment
In an emergency situation, or if you are living off the grid, and quick access to professional medical care is not an option, activated charcoal can be used in emergencies for accidental ingestion of toxins.
Activated charcoal binds to certain chemicals and prevents absorption in the stomach.
If you suspect poisoning (non-caustic or non-corrosive substances only), mix a small amount of activated charcoal with water and drink it. It can help slow down toxin absorption while waiting for medical attention.
The results from a study done in 2019 conclude that:
“The administration of activated charcoal is indicated to treat moderately severe to life-threatening intoxication. It should be carried out as soon as possible, within the first hour of the ingestion.”
We should emphasize that you should always consult a medical professional immediately before using it for poisoning and do not use it for strong acids, alkalis, or petroleum-based toxins.
3. Teeth Whitening/Oral Health
The teeth whitening capabilities of activated charcoal have been known for a long time – both in dentistry and by human societies around the world.
Using activated charcoal can help whiten teeth by removing surface stains and can bind to toxins and bacteria in the mouth, promoting oral health.
Simply dip a wet toothbrush into fine activated charcoal powder and gently brush your teeth for a minute or two. Rinse thoroughly afterward. It can also be added to toothpaste for regular use.
Just be careful because charcoal is mildly abrasive and can wear down enamel with overuse – leading to more serious issues.
4. Soil Amendment for Gardening
Another reason to always have some activated charcoal on hand – whether you’re interested in emergency preparedness or not – is that it’s a great garden aid.
Activated charcoal can improve soil health by retaining nutrients, improving drainage, and neutralizing toxins in the soil.
Mix activated charcoal into your garden soil or potting mix at a ratio of about 5-10% charcoal to soil. This will help retain moisture and nutrients while also absorbing harmful substances like pesticides and heavy metals.
Just FYI, finely ground charcoal will distribute more evenly throughout the soil.
Number 5: Preserving Food
Yet another emergency preparedness angle for activated charcoal: you can also use it to help preserve food.
Activated charcoal can extend the shelf life of perishable foods by adsorbing moisture and odors that contribute to spoilage.
All you need to do is place small pouches or containers of charcoal in your refrigerator or pantry near foods prone to going bad – fruits, vegetables, bread, etc. This helps maintain a fresher environment by adsorbing ethylene gas, which accelerates ripening.
Just make sure the charcoal doesn’t come into direct contact with the food, as it can leave a residue or affect the taste.
