Synthetic vs. mineral oils definition

The difference between what is called synthetic oil and mineral oils is not clear-cut. It ought to be so that synthetic oils are purely of synthetic origin. Nonetheless a court case between Mobil Oil and Castrol ruled that some refined mineral oils can be designated synthetic oils too. The case can be found at the link proveded below. Search for 3526 then the case can be found.

CASTROL, INC. (Castrol Syntec Synthetic Motor Oil), Report #3526, NAD/CARU Case Reports (March 1999)

Other notes on mineral oils

Engine oils ensure that the engine is lubricated during use, but also that metal particles from the internal surfaces of the engine are transported into the oil sump (oil pan). In addition, the oil also transfers heat from the the hottest parts of the engine (to cool them).

Additives in lubricating oils can be divided into 

1) Additives that modify the physical properties

2) Additives that modify the chemical properties

In Group 1 include additives that are:

Regulate viscosity

Anti-foaming substances

Substances that regulate friction

Additives that help handle hihg pressure

In Group 2 include additives that:

Are antioxidants

Inhibit corrosion

Decrease wear

The authors also note that it is possible that the additives are more toxic than the base oils - something that is worth remembering when hazard assessing the mineral oils.

Here is a curve with carbons numbers of the hydrocarbon chainss and their boiling temperature on the Y-axis with my notes in pencil. 

Naphta - what is it used for?

Whan looking at the curve above - the one with the different oil fractions as function of carbon number of the hydrocarbons - I knew all of the fractions - except naphta - 

this is likley becuase naphta is not used at home - yet it is actually the mother of some og the most important building blocks in the chemical industry:

Ethylen 

Propylen

C4-olefins

Benzene 

Toluene

Xylenes

Another important building block is methane made from the gasses

I found this highly interesting article on the subject on the internet - it is in Danish - so you can also practice your Danish :-)

What are vaxes? 

Waxes are long-chained paraffins (straight alkanes).

They are no desirable in lubricating oils - as the oils have their lubricating propertis becuase of the side chains in the hydrocarbon chains making the oil thick and greasy 

Waxes are instead used (not as hair wax - that is wax from non mineral origins) - but for candles (paraffin).

Metals in unused oils

Zinc substances as additives (antioxidants and anti-wear)

Magnesium

Barium (at least in the 90'ties)

Boron

Iron

Tin

Metals in used oils

Chrome

Aluminium

Iron

Copper

Tin

Molybdenum

Nickel

Cobalt

(when lead was allowed as an additive in petrol it would also be present)

https://www.tandfonline.com/doi/full/10.1080/10916466.2018.1511584#abstract

(Wolak et al. Determination of the content of metals in used lubricating oils using AAS)

Recommendations for handling of used engine oils (draft thus can only used for inspiration - final recommendations will be developed at the end of our current research project - Sikker Olie)

Workers are instructed to avoid inhalation of aerosols and vapours

Workers are instructed to avoid repeated skin contact. For example use gloves when doing oil change

The work should be planned so that the formation of oil vapours and aerosols is minimised

Where there is a risk of formation of aerosols or vapours, they should, as far as possible, be removed using ventilation or local exhaust suction. If this is not possible, appropriate personal protective equipment in the form of masks should be used.

Use work clothing and keep the skin clean. Change clothing every day, and in case of oil spillage change clothing.

Do not keep the work clothing in contact with the normal clothing

Do not put cloths that have been in contact with oils in the pockets

Have closed containers available for used cloths etc. 

Use protective goggles in case of risk of eye contact

Used oil on the skin is cleaned using soap and water - or with a special cleaning lotion

Wash before eating

The worker should have acces to showers at the end of the work day

If spillage occurs immediate cleaning is done with oil absorbing material

Do no clean by use of high-pressure cleaning

Waste is handled according to current regulations

And in the Danish version:

Anbefalinger til arbejde med brugte olier (dette er et arbejdsudkast – den endelige version vil blive lavet i slutningen af vores forskningsprojekt Sikker Olie)

Undgå at indånde aerosoler og dampe

Undgå gentagen hudkontakt – brug for eksempel engangshandsker når du skifter olie på en bil

Arbejdet skal planlægges så dannelse af dampe og olietåger minimeres

Hvis de alligevel dannes skal de så vidt muligt fjerenes ved ventilation og punktsug, hvis det ikke er muligt skal der bruges egnet maske

Brug arbejdsklæder og hold huden ren. Skift arbejdstøj hver dag, og hver gang der kommer olie på det.

Læg ikke arbejdstøjet sammen med dit normale tøj

Put ikke klude med olie i lommerne (brug evt. tøj uden lommer)

Der skal være spande til brugt tøj

Olieklude og fx twist skal i en aflukket container – hvorfra dampe ikke kan undslippe

Brug beskyttelsesbriller når der er risiko for stænk

Når brugt olie kommer på huden rensen der med vand og sæbe – eller en speciel rensecreme

Vask hænderne før du spiser og drikker (og før du ryger)

Der bør være adgang til brusebad efter endt arbejdsdag

Hvis der spildes olie skal det straks fjernes ved brug af absorberende materiale

Brug ikke højtryksrenser til at rengøre områder med olie

Affald skal bortskaffes efter gældende regler

Skin thickness When looking at oils we needed to look at the thickness of the skin. We learned that scrotal cancer was prevalent in chimney sweeper boys in the old days - and that was because the skin on the scrotum was thin - but I have not been able to locate data on the thickness of the skin on the scrotum. 

Instead I located a very useful article that gathered data on the epidermal thickness in humans in many anatomical sites. The article is by Lintzeri et al. published in 2022 in JEADV 36, 1191-1200

I made a curve of some of the anatomical sites - as you might know the epidermis is thick on the hands and fingers - and especially underneath the foot.   

What was interesting too was that skin was thinner in older people (some 60 years old) than in young people ~20 years old. There were no differences between the sexes.

By the way notice the eyelids - the epidermis is thin there and this is a site of cosmetics application (by the way the bars are minimum and maximum values). 

Polyaromatic hydrocarbons (PAHs) are really some bad boys what concerns toxicity - being carcinogenic - but also inducing developmental effects after dermal (skin) exposure

The PAHs can be removed from mineral oils by

1) Solvent extraction of PAHs with two or more rings

2) Hydrogen treatment, which primarily is used to reduce sulphur levels, but which can also reduce the PAH levels (by opening up the ring and saturation) 

Bitumen

Bitumen, asphalt or tar - what is it?

It can be found in natural deposits or it can be refined from crude oil

Here you can see that bitumen is the residual fraction of oil refining