Here are some information about the PAH content of oils and their treatment with activated carbon.

Please note that this information is not based on specific research, but mostly on industrial experiences by our customers: its application in your process must take into account the different process conditions and feedstock processed.

The following data have been obtained by treating olive kernel oil and seed oils, specifically sunflower oil, with our Activated Carbon 125 and 125/30.

Detection and treatment of PAH are also performed on other oils, e.g. grapeseed coconut oil, but volumes of these oils are much smaller than those of sunflower oil.

   Take a look a the PAH Matrix

The effective dosage of activated carbon may vary by great extent among different batches of oil, even of the same origin. In fact, the concentration and composition of PAH in the oil depend strongly on the conditions in which seeds have been stored and dried, as well as on the extraction process and on the oil's storage conditions. Different batches of seed oil show PAH content (measured as benzo[a]pyrene) between 3 and 300 ppb, whilst values of 500 ppb, 1000 ppb and more have been detected in olive kernel oils.

In practice, we could see that oils containing about 30 ppb of PAH (benzo[a]pyrene) can be treated successfully with 0.1-0.2% of activated carbon to reduce the PAH (benzo[a]pyrene) level below 1 ppb, whilst in oils with higher PAH (benzo[a]pyrene) content the level after treatment did not go below 5 ppb, even with 0.5% activated carbon.

For this reason, refiners tend to dilute high-PAH-oils with batches containing very low levels, thus reducing the average value to about 30 ppb and making the treatment technically and economically effective.

Alternatively, or additionally, a "double treatment" proved effective: this process consists of a first step with (bleaching clay and) 0.3-0.5% activated carbon, followed by a second step with (little bleaching clay and) 0.1-0.2% activated carbon. In the second step the bleaching clay is necessary to avoid filtration problems, because activated carbon alone does not form a good enough filter cake, and could pass through the filter mesh into the refined oil.

Efficacy of the treatment is directly proportional to contact time: the longer the contact time, the better the PAH removal.

Temperature does not seem to have a dramatic influence (at least in the most common process conditions).

Hoping that the above is clear and that it will be useful to you, please contact us for any further information or product request.