Has anyone else been wondering what difference really is between bleach and oxygen bleach? I tried powdered oxygen bleach for the first time this summer and was blown away. I am afraid of handling chlorine bleach so even when I had it in the cupboard I never actually end up using it. But what is really the difference between the two? Why do people say oxygen bleach is greener?
What is chlorine bleach?
To start with, what is chlorine bleach? What we think of when we say “bleach” is sodium hypochlorite, diluted with water to around a five percent concentration. This ~5% mix is what is on store shelves.
What is oxygen bleach?
Oxygen bleach, on the other hand, comes in a powdered form. The powder is usually around 65% sodium percarbonate and 35% sodium carbonate (aka washing soda). Sodium percarbonate is itself a compound of washing soda and hydrogen peroxide.
Why use oxygen bleach over plain old hydrogen peroxide?
Oxygen bleach is undoubtably more expensive than hydrogen peroxide, which is another “green” solution for bleaching. Why not just use the peroxide if that’s what’s in oxygen bleach anyway? The hydrogen peroxide that is released when oxygen bleach meets water is much more concentrated. It’s been my experience that oxygen bleach removes stains much better than the 3% hydrogen peroxide solution you get at the drug store.
So how do bleaches work?
Both chlorine and oxygen bleach work via the chemical reaction of oxidation (the process of losing electrons – this shows up all over the place in chemistry). The power of the oxidation reaction breaks the bond between the stain and your clothes, and that is why it is so useful. The reaction of chlorine bleach is much stronger, however – so much stronger that it can breaks down not only the bonds in the stains but also in the fabric dye and even the fabric itself! This is why, despite the fact that the chlorine bleach sold on shelves is only a 5% concentration, this is still very powerful and most instructions say to dilute it further before using it.
It’s also worth noting that the oldest bleach of all is sunlight – it does not happen via the chemical reaction of oxidation but rather the physical force of ultraviolet light can cause the same breaking down of the dyes in the fabric, so we still say sunlight “bleaches”.
Unlike chlorine bleach, which is caustic, oxygen bleach is safe to handle for normal laundry use. Don’t go eating it or rubbing it in your eye, obviously, but I stick my hands in water that I’ve dissolved oxygen bleach in and just wash my hands after and I’ve never been irritated by it. Contact with bleach that has been further diluted out of the store bottle may not be an emergency but extended contact or contact with bleach at higher concentrations can cause tissue damage.
Why can’t you mix chlorine bleach?
Another reason to be careful with chlorine bleach is that it is much more reactive with other household cleaners. We know that chlorine bleach is made of sodium hypochlorite, which has the chemical makeup NaClO. This means the molecule is composed of a sodium, a chlorine and an oxygen atom bonded together.
Mixing chlorine bleach with other common household cleaners has the potential to result in the release of the chlorine atoms as chlorine gas, which is toxic enough that it was used in large concentrations as a weapon of war in WWII. Any acidic cleaner, like vinegar, mixed with chlorine bleach will produce chlorine gas. Additionally, mixing chlorine bleach with amines like ammonia or urine can produce nitrogen trichloride gas, which can cause lung injury. These potential reactions are why labels always say not to mix bleach with other cleaners, because without understanding chemistry and knowing all the ingredients most of us cannot predict what will happen.
Does bleach leave “toxic residue”?
Keeping in mind that I don’t have a chemistry degree, but as far as I can tell when people talk about bleach being toxic they are referring to the potentially toxic products of chemical interactions. My understanding is that both chlorine and oxygen bleach, used correctly, eventually break down into relatively harmless substances, like hydrogen peroxide, lye, water and oxygen. However there’s always a possibility that pouring chlorine bleach down the drain when it has not yet exhausted its reactive potential will mix with other substances down the line in potentially dangerous ways so it’s better not to do it, I’d say.
In case you’re into the details sodium percarbonate (aka oxygen bleach) breaks down into washing soda (Na2CO3) and hydrogen peroxide (H2O2) when it reacts with water. Hydrogen peroxide then further decomposes into water and oxygen.
(2 Na2CO3·3 H2O2) + H2O → 2 Na2CO3 + 3 H2O2
H2O2 → H2O + ½ O2
Bleach in water, on the other hand, decomposes into hypochlorous acid (HOCl) and sodium hydroxide (NaOH, aka lye).
Na(OCl) + H2O → 2 HOCl + NaOH
Are there disadvantages of oxygen bleach?
Oxygen bleach reportedly works best on organic stains (as opposed to grease or synthetic stains). Oxygen bleach is also more expensive than chlorine bleach and can’t do double duty as a disinfectant the same way as chlorine bleach or hydrogen peroxide can.
How I use oxygen bleach
For spot treatment I fill a small tub with boiling water and dissolve a half a cap of oxygen bleach powder in it. I then submerge the item and leave it overnight. Oxygen bleach does need a little more time and hot water to work than chlorine bleach, so that’s why I go through the trouble of boiling the water and soaking it overnight. The next day I dump the water out and the item goes straight in the wash with a full load.
For regular loads of whites I have a top-loading washing machine so I put it all in, switch it to the hot water setting and let it fill enough to cover all the clothes. While it is filling I put in a full capful of oxygen bleach powder and stop the machine before it starts the agitation cycle. I close the lid and let the load soak in the hot water for a couple hours, then I come back down, add detergent and let the cycle finish.
So, Do we need to be careful with bleach? Absolutely, but do we need to be afraid of it? No. Looking into this really helped demystify bleach for me. Having separated fact from fiction, I feel I can make an informed decision that I only want to use oxygen bleach in our house. I hope it helps you too!