What prevents oil-only products from absorbing water?

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Water has very high surface tension. Where air meets water, water

molecules cling together and form a strong bond, which creates a

membrane. Consider the insect that walks on water. Oil-only

(hydrophobic) sorbents absorb oil off of water because oil has low

surface tension.

 

In regard to universal sorbents being hydrophilic (having an affinity

for water): Surfactant (surface-active agent) is a detergent that is

added to polypropylene, which lowers the surface tension of water

and allows polypropylene to absorb it.

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What is the absorption rate of polypropylene?

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There are a few variables, but the rate is generally 12 - 15 times its dry weight. The variables are as follows:

- the weight/density of the fluid sorbed, which is different for all fluids

- loftier (fluffy) polypropylene provides more surface area for fluids to adhere to the fibers

- the actual fiber count (fiber diameter) / available surface area for absorption

 

The measurement/testing method is as follows:

Weigh a full-sized pad on a gram scale. Cut a 4 x 4" section and another of the same size from the opposite end of the pad. Derive the weight of a 4 x 4" section by dividing the square inches into the full-sized pad's square-inch measurement. Multiply that figure by the weight of the full-sized pad, and then record that weight. Saturate both pieces in the fluid of choice for 15 minutes, retrieve each sample with forceps, let drip for 30 seconds, immediately weigh them again, and record the weights. Take an average of the two saturated weights and divide that figure by the dry weight to determine absorption rate. Multiply that rate by the entire weight of a package of the pads or rolls that were tested, and then divide by the weight of the fluid absorbed (exa. water weighs 8.3 lbs per gallon). This will determine how many gallons the product will absorb.

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Why do hazmat products absorb aggressive chemicals, such as acids, yet universal sorbents do not?

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Actually, universal sorbents do absorb aggressive chemicals (refer to our chemical compatibility guide). The only difference between hazmat and universal sorbents is the color. We just market them differently. The exclusions are universal socks, pillows, and booms, as they may be filled with non-polypropylene post-industrial waste that may degrade and/or have adverse reactions upon contact with various aggressive chemicals.

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Why do socks, pillows, and booms have a lower absorption rate than pads and rolls?

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Socks, pillows, and booms have a dense spunbond polypropylene casing, which yields a slow rate of absorption/penetration. Additionally, these products are filled with chopped, compressed post-industrial waste (meltblown polypropylene or other post-industrial waste filler in universal products), so fluids do not spread as quickly or efficiently as they do throughout the uniform web of pads and rolls.

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Are polypropylene sorbents biodegradable?

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No, they are not, nor are many of the fluids that they absorb. Polypropylene is a man-made fiber that is derived from oil and natural gas. Regardless of man-made vs organic, it is important to understand that "biodegradable" is not always applicable.

 

In regard to organic waste, oxygen is required for microbes to efficiently decompose said waste, so to landfill and expect total decomposition in any sort of timely manner is pure fantasy. Additionally, absorbed fluids must be extracted prior to disposal. Otherwise, your sorbent will eventually decompose, yet the waste fluid may remain. Extraction methods include wringing, centrifuging, and washing.

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There are various methods for disposal, including landfill, incineration, and recycling/reuse. Consult with  your local, state, and federal authorities and licensed/reputable waste disposal companies for specific options.

 

Which is the best overall pad/roll composition for MRO applications?

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SM composite (spunbond pp / coarse fiber meltblown pp) is the best bang for your buck.

 

During meltblown polypropylene extrusion, fibers exit the die head, and high pressure air directs the fibers vertically on to a collector (conveyor belt). The side of the web that lands on the collector is less ropy, so the spunbond pp membrane is bonded to the ropy side. The final product looks and performs similarly to SMF composites (spunbond pp / coarse fiber meltblown pp / fine fiber meltblown pp), minus the expensive fine fiber mb pp membrane.

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Similar to SMF, SM is a dual-textured sorbent. Concerning usage, the low-linting, coarse fiber mb pp side faces the ground (or other surface), and the abrasion-resistant side faces up. The coarse fiber mb pp side exhibits a gripping characteristic when saturated.

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Why do thinner meltblown pp pads/rolls boast a higher rate of absorption than thicker pads/rolls?

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Every pad, regardless of density, has a top and a bottom side, and those sides have exposed fibers that immediately come into contact with spilled fluids. The inner fibers in a pad are blanketed with other fibers all around them. The section of a fiber that is touching another fiber will not absorb anything. In summary, as you lower the percentage of inner fibers in relation to the exposed surface fibers, absorption rate increases.

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Lofting (fluffing) meltblown polypropylene during the extrusion process increases the available surface area of fibers within the web, in turn increasing absorption at a much higher rate. Fiberweb meltblown equipment is top-of-the-line and allows for excellent control in both web density and thickness. Lofting products definitely yields a higher absorption rate, but it also increases the size of the package, which increases transportation cost per unit. It is a bit of a balancing act. When cost of transportation is low, adding more loft is a definite cost savings for the end-user when absorbing fluids to a pad's full capacity.

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