Soaking It Up

There’s more than one way to blot a spill

The aftermath of the Gulf oil spill is giving many readers an education in a booming industry that rarely comes to light: companies that make “sorbent” products.

No, that’s not a typo for “absorbent.” Turns out, there’s an ocean full of words to describe the process of using one substance to attract another.

The one most familiar, of course, is “absorbent.” But there’s also “adsorbent” and “desorbent.”

At the risk of oversaturation, here’s a primer from the Web site of Integrity Absorbents, which makes, um, “absorbents”:

Adsorption,” the site says, “is a process that occurs when a gas or liquid accumulates on the surface of a solid or, more rarely, a liquid forming a molecular or atomic film. It is different from absorption, in which a substance diffuses into a liquid or solid to form a solution. The term sorption encompasses both processes, while desorption is the reverse process.”

Carbon filters, for example, “adsorb” impurities in the air; the dirt clings to the outside of the carbon particles. Cotton batting “absorbs” liquid, expanding as it does so. You can squeeze the liquids out of the fibers, which is a kind of “desorption.”

The root of all those processes is the noun “sorbent,” which Webster’s New World College Dictionary defines as “any substance or process that adsorbs, absorbs, or desorbs.” The “ad-” prefix means “motion toward, addition to, nearness to”; the “ab-” prefix means “away, from, from off, down”; the “de-“ prefix also means “away from, off,” but implies undoing something that has been done.

And, as often happens with roots, only its offspring have verb forms. A substance can “adsorb,” “absorb,” or “desorb,” but it can’t simply “sorb.”

“Absorb,” of course, is the most common formation; in the Gulf, many of the booms being laid in the water are made of material that “absorbs” oil while letting water through. “Desorb” almost never appears in news reports. But in the month since the spill began, a movement to collect hair, feathers, and fur for use in booms that would collect oil has prompted several uses of “adsorb” in news reports. In hair booms, as they’re called, oil collects on the surface of the hair, fur, or feathers inside the boom, thus “adsorbing” the oil. (That’s why birds and furred water mammals like otters are so threatened by oil spills.) Unfortunately, the hair booms were deemed inappropriate for use in this spill: in a test, they became waterlogged and sank too soon.

Take a moment to “absorb” that thought.

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Merrill Perlman managed copy desks across the newsroom at The New York Times, where she worked for 25 years. Follow her on Twitter at @meperl.