Bleaching earth

I started researching what made fullers earth so effective at bleaching after I saw the absolutely ridiculous prices on carbon chemistry, I hope you all find the information to be useful.

Fuller’s earth is any clay material that has the capability to decolorize oil or other liquids without chemical treatment. Fuller’s earth typically consists of palygorskite, attapulgite, or bentonite.

“attapulgite, sepiolite, and bentonite have common properties and they all can be used as bleaching earth. However, attapulgite and sepiolite may be used as a natural bleaching earth, which does not require acid activation. Bentonite is an acid activated bleaching earth because the necessary surface area and porosity have to be created by an acid treatment (Murray, 2007). On the NOP National List, bentonite is a nonsynthetic allowed substance listed under 7 CFR §206.605.
Acid activation enhances properties already present in the clay. Sulfuric acid is most commonly used in the activation process but hydrochloric acid is also effective. The acid treatment increases the surface area and pore volume thus improving the clays performance in removing color pigments and impurities from vegetable oil and animal fat. Although acid activated bleaching earth is often more effective, it is also more costly.”

Attapulgite TR.pdf (323.6 KB)

“Attapulgite is a magnesium aluminum silicate clay of very fine particle size. It is also known as Fullers Earth and is closely related to Sepiolite mineral. Unlike bentonite (or montmorillonite) attapulgite crystals are needle shaped (acicular) rather than flat or flake-like. Like bentonite they disperse well to thicken, suspend and gel suspensions without flocculation problems.”

The fact that attapulgite has needle like crystals means that it will lend itself very well to filtration by a filter media.

Edit: added more info and a link
Edit:2: Tried to make it look neat.


I’ve highlighted what I thought was interesting. Aside from the quoted questions

Evaluation Question #9: Is the petitioned substance to be used primarily as a preservative? (From 7 CFR § 205.600 (b) (4).)
By definition, bleaching is the physical and chemical interaction of a sorbent (bleaching clay) with oil or fat to improve its quality in the edible oil processing. It refers to removing impurities from a given oil through the addition and subsequent removal of bleaching sorbents (such as attapulgite). The impurities, in the spent bleaching earth, may contain oxidation products, color pigments, phospholipids and glycolipids, metal traces, soaps, and contaminants (such as pesticides). No information was identified to suggest that attapulgite is used primarily as a preservative

Evaluation Question #10: Is the petitioned substance to be used primarily to recreate or improve flavors, colors, textures, or nutritive values lost in processing (except when required by law, e.g. vitamin D in milk)?(From 7 CFR § 205.600 (b) (4).)

The function of a bleaching clay is to remove undesirable by-products (impurities) for the vegetable oil and animal fat, thus improving the appearance, flavor, taste, and stability of the final product (Zschau, 2000). Duff (1991) has reported that adsorptive bleaching removes all gross impurities such as meals, metal contaminants (e.g. iron or copper), and any soaps left over from alkali refining. In addition, it removes peroxides and some of the secondary products of oxidation. But it does a poor job for removing pigments (e.g. chlorophyll, gossypol, and carotene) and gums. Hastert (1991) has indicated that attapulgite is not ordinarily used for vegetable oil adsorption because of its limited decolorizing ability. It is more likely to be used in treating meat fats which require little color removal.

Duff and Hastert both state that attapulgite clay has a limited ability for color removal. So if there’s anything to take away from this it’s that cheap acid activated bentonite clay is more effective at removal of pigments but attapulgite clay is effective at removing soaps and phospholipids that occur after alkali refining which means that it may find itself in an effective remediation procedure for removing pesticides such as green cleaner.
Green cleaner is primarily made up of sodium lareth sulfate and soybean oil which would be easy enough to remove it from an extract solution with the addition of potassium hydroxide to react with the soy ran oil followed by mixing with attapulgite clay for subsequent filtration.

Bleaching efficiency improves when operating pressure in the bleacher is run between 50 to 125 mmHg (absolute). Reduced pressure allows for a smooth water evaporation rate resulting in increased efficiency for removal of phospholipids, chlorophylloids, and some red pigments. Reduced pressure also minimizes interaction of oil and air resulting in lower peroxide values, anisidine values, and bleached oil color.

Bleaching efficiency is highly dependent on the interaction between vacuum, moisture and temperature. Bleaching clay has an attraction/affinity for polar compounds including water. Maintaining adequate moisture levels in the bleacher throughout the bleaching process affords better removal of soaps, phospholipids and chlorophyll due to bleaching clay’s affinity for these compounds. More specifically, phospholipids and soaps are more readily removed from fats and oils when properly hydrated.

The above link goes very in dept on the optimization of the parameters affecting bleaching.

Edit: added quote to make it look neat.


Good work. I’ve been wanting to do a little research on the different bleaching clays and what makes them work. I might have to do a test between the lower priced clays you can find on ebay/amazon and the higher priced versions.


@JacobsLadder I was thinking the exact same thing after reading all the info @ScoobyDoobie posted . I think this calls for a test of low vs high price bleaching clays.

Great informative post @ScoobyDoobie. I wouldnt call Carbon Chemistry T5 ridiculously over priced cause research and development takes time and money, but finding a cheaper alternative would be awesome.

Thanks again for this cause i was just about to buy some bentonite clays.


This product works great for me… @JacobsLadder @Killa12345


We launched T41 for pesticide degradation prior to adsorption with Mag-Sil PR. The industry being what it is, people threw it in the boiling flask and got some color reduction (perhaps due to carbon content and pH) and when adding too much…isomerization (definitely due to pH).

T41 has its place, T5 is modified bentonite sans acid activation that is oriented towards collecting colloidal impurities.

We sell hardwood carbon specifically for color. Our prices on ENGINEERED clay, silica 60, alumina, Mag-Sil PR, etc are hard to beat in bulk, our primary sales method.

If cosmetic bentonite works for you then by all means pursue that! We launched these clays for purposes that they were designed for.

Edit: We aim to sell the stuff that is relatively hard to acquire at volume. You’ll notice we sell Alumina and T5 instead of DE and Celite 545. You can get DE almost anywhere and Celite 545 is available from Grainger in bulk.


I’m not sure if cosmetic bentonite would be suitable because I don’t know if they perform an acid activation step on bentonite that will be used for cosmetics.

I’m certainly seeing now that a lot of thought went into carbon chemistry’s absorbent lineup, I very much appreciate your response.

Edit: This is an Ebay supplier of cheap acid activated bentonite sourced in the USA.

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T5 is Tonsil?

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We are their distributor in North America. Whenever people email them it gets forwarded to us. @CosmicBandit


Theres a bit more that goes into activating a bleaching clay but give that stuff a shot and let me know how it goes.

That stuff is $18/half pound…which comes out to ~$72/kg. Its not really much cheaper than T41 and has no carbon, definitely more expensive than T5.


One question: When you talk about bentonite and isomerization, how is it even possible? The pH of Bentonite is about 9, how can it make the solution go acidic? Or did I just misunderstand something?

Does that mean that T5 has also high pH or is it just neutral?

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T5 has a pH value of 6-7.

T41 is acid activated (pH 3) which leaves lewis acid sites on the clay structure. @yo_mama


So with bentonite it is possible to adjust the pH of your product? Means: If I have a disbalance (pH) in my product i can manipulate it with different types of bentonite depending on their different pH?


Correct. Furthermore, because T41(pH 3) and MagsilPR(pH 9) are meant to be used together…you can neutralize during processing.


What would tou suggest dor color remediation with out alot of isomerizarion ro d8. Either in rhe flask or as nust a dimteation aid. Love all tour peoducts and rhe knowledge tou fibe out is priceless. Thank you


Remember that your sources of color vary (chlorophyll, phenol, oxidized terps, oxidized lipids, etc). For chlorophyll and lipids T5 and carbon works great, alumina helps too. A tight fractional distillation helps with phenol and oxidized terps.

An important lesson on isomerization is that it is a redox reaction for THC and so a function of heat and energy transfer (pH). We only ever advise scrubbing at about 90c max, and avoid excessive acidity. Putting absorbent in the flask makes them too effective, so you would expect isomerization to a certain extent without reducing absorbent load.

Note: I try to be as intelligent as possible but there may be variables in your process that makes your results differ from what I’m saying.


After doing some more research and reading that some bentonite clays are known to contain lead, I think it’s best to just get your bleaching clay from a trusted source like carbon chemistry.


That reminds me…T5 is also engineered for heavy metal remediation. We have a client in another industry that uses it for mercury and arsenic remediation during prep phase.


That’s great you’ve produced a product that is mixed and Rtu for processing. I’ve used a mix that seemed to work well for me as far as removing color. The mix I used goes as follows;
Bentonite clay 9%
Celite 545 3%
Activated carbon 6%

I’d love to check out your mix though. I’ll be placing an order :call_me_hand:t2:


can you provide me with the info to procure the products you provide? ty my friend