d-Limonene is the major component of the oil extracted from citrus
rind. When citrus fruits are juiced, the oil is pressed out of the
rind. This oil is separated from the juice, and distilled to recover
certain flavor and fragrance compounds. The bulk of the oil is left
behind and collected. This is food grade d-limonene. After the juicing
process, the peels are conveyed to a steam extractor. This extracts
more of the oil from the peel. When the steam is condensed, a layer
of oil floats on the surface of the condensed water. This is technical
grade d- limonene.
In the past decade, the use of d-limonene has expanded tremendously.
Much of the product goes into making paint solids, used to impart
an orange fragrance to products, and used as a secondary cooling
fluid. But the largest growth segment has been the use of d-limonene
in cleaning products. This has occurred in both industrial uses
and in household/institutional products. d-Limonene can be used
either as a straight solvent, or as a water dilutable product.
As a straight solvent, d-limonene can replace a wide variety of
products, including mineral spirits, methyl ethyl ketone, acetone,
toluene, glycol ethers, and of course fluorinated and chlorinated
organic solvents. As with most organic solvents, d-limonene is not
water soluble, so it can be used in the typical water separation
units. With a KB value of 67, d-limonene has solubility properties
close to that of CFC™s, indicating that it is a much better
solvent than a typical mineral spirit. Straight d-limonene can be
used as a wipe cleaner, in a dip bath, or in spray systems as a
direct substitute for most other organic solvents.
By combining d-limonene with a surfactant package, a water dilutable
and rinsible solution can be made. In most cases these products
are used in the institutional and household settings in place of
caustic and other water based cleaners. A concentrated solution
of a d-limonene/surfactant solution can be made to be diluted before
pre-diluted solutions can be formed. The use concentrations of d-
limonene in these situations are usually 5-15%. In general these
solutions are used as spray and wipe cleaners. The water dilutable
solutions can also be used in industrial settings where a water
rinse of the parts is desired to remove any residue which may remain.
d-Limonene is a very versatile chemical which can be used in a wide
variety of applications. It is extremely safe and more effective
than typical cleaning solutions.