Sorbents are materials used to recover liquids (leaks, drips, spills, etc.). Synthetic sorbents are made of polypropylene - a type of plastic - and are designed to adsorb liquids onto their surfaces, while more basic sorbents like rags, corn cobs, recycled cellulose, vermiculite or clay actually absorb the liquids into the material itself.
Polypropylene is a petroleum based product, and will naturally repel water while adsorbing any oil or oil-based liquids. Water-based spills can be absorbed by polypropylene products after they have been treated with a surfactant. Often sorbents are color coded to help the user select the correct one.
Consider how to dispose of the sorbents prior to purchasing them. If you plan to apply any spilled material that has been absorbed, it must be easily handled for dispersal at or below the labeled rate, to a labeled site, which has not already received the maximum rate allowed. If you select a material, like a pad, that cannot be applied, have a plan for how to dispose of the material (state sponsored clean-sweep hazardous waste collection, or private hazardous waste contractor). All materials for disposal require proper identification of the contents (product name, active ingredient, approximate amount).
There are three general types of sorbents.
Universal sorbents. Will absorb any liquid, including aggressive liquids, such as acids and bases, and are flexible enough to soak up cleaners, water-based fluids, alcohol and gasoline. Universal sorbents may be made from polypropylene treated with a surfactant or expanded silicates.
Petroleum sorbents. These are designed to absorb oil or other petroleum-based liquids. They will not absorb any water-based liquids. These sorbents are made of polypropylene or treated cellulose.
Maintenance sorbents. These are designed to absorb non-aggressive liquids found in industrial and business operations. Some are made of recycled cotton, wool, paper or corn cobs. There are also some made of polypropylene.
Forms of Sorbents
Booms, socks and mini booms can be placed around a spill or machine to keep the liquid from moving.
Pillows are good for absorbing large spills of liquids. They may also be used in maintenance mode for recurring leaks from valves or pipes.
Pads and rolls are used to catch drips and leaks as they occur. These can be used in high-traffic aisles or next to machines. Pads can be laid under machines, or valves.
Loose sorbents are granules formulated to absorb liquids when poured on the spill. Loose sorbents are typically used on small liquid spills.
When purchasing sorbent, consider the ratio of needed absorbent to the volume or weight of spilled material. Sorbent packaging lists the holding capacity, such as the weight it absorbs in relation to itself, for example, "Absorbs 10 times its weight." The capacity may be listed as the amount of liquid absorbed, for example "Absorbs 6 gallons." Assessing a sorbent's capacity by the number of gallons it will absorb is probably the most accurate way to judge its capacity. As an example; a polypropylene boom four feet long and three inches in diameter will absorb about 1 to 1 1/4 gallons of liquid. A polypropylene pad 16" x 20" that is 3/16" thick will absorb almost 32 fluid ounces of liquid.
photos: PSU PSEP